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Esprit V8 Feels flat and no boost from turbos.

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Hi All,

With a recent slight warming of global temperature around Norfolk I managed to get outside to replace the osf wheel bearing. Outer bearing trashed and outer cage badly pitted so replaced. ( I have owned approx 50 or so cars over the years, and never seen a bearing in this state) Some improvement in noise reduction but seems as though my diagnosis was only partly right. Probably driveshaft, flat spotted tyre, or another bearing or something else ?)

Time for a test ride .........warmed up engine and because today is a thursday engine MIL light illuminated. Does this on random occasions. Engine intialy fired on about 4-5 cylinders and then went onto all eight. Engine rpm set at about 1500 rpm idle speed and takes some time to settle out or decay @ 900 or so rpm

Checked engine codes and appears to have been activated due to overboost. Strange since the engine hasnt been past 4000rpm and no boost noticable. Can hear, just (above the driveshaft, bearing, flat spoted tyre noise ) some evidence of turbo boost but performance is about on par with my Diesel Land Rover and that probably has more go and is more exciting to drive !

Thinking perhaps turbo or catalysts but would have thought even with one turbo, two turbos and perhaps one failed cat there would be at least some chance of breaking the national speed limit. Cabin area also has smell of fuel but this is not always, just on some days when its worse than others.

No evidence of burning engine oil or water vapour but less condensation appears from left exit tail pipe. Assume left cylinder bank feeds left tail pipe outlet or perhaps this gets switched internaly in the rear silencer ??

Plenty of possible faults here but having bought one of these cars didnt expect every forum topic to be relevant to my particular vehicle all at the same time. Just to complete the story - some hassles with selecting reverse which turned out to be a combination of worn translator linkage and incorrectly adjusted pedal.

Several exhaust manifold studs are missing nuts. Slight blow from left hand manifold which will probably seal up once I can make, fabricate a suitable wrench/spanner to actualy get access to the stud. Nice design Lotus !! and what material are these studs made from ............I have built and rebuilt more V8 engines than I care to mention and have not seen this many broken studs on all those engine put together than what I have here on one car !

Plently to go at here

Look forward to any postive ideas on fixing this and yes I have already thought about November the 5th !

Cheers and thanks for reading

Paul

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Upgrade today to remove Google ads and support TLF.

stock silencer does have an 'interchange'-section, sports-type is separate internally. So undo the silencer and watch out for blocked catalyst, undo the catalyst, inspect the turbo from exhaust and air-intake side, undo the spark-plugs, inspect them &test for correct sparks. Monitor the MAP-sensor data via OBD on 'live-stream' wile on the motorway... .

smell of fuel could mean 'no ignition' -or leaking fuel pipes (especially the Evaporatve pipes, for charcoal canister ventilation..) & the cross-over breather pipe for the two tanks in the sidebays.


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to name the things if I see them, that's what I call integrity..

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Thanks for the response Jim and Gunter.

I dont currently have a facility for working under cover but once the weather breaks a bit I will ramp up the car and have a look at the silencer, cats and turbo impellers. The lack of condesation on start up from the left tail pipe would indicate perhaps a blockage most probably due to a disintegrated cat monolinth. Will investigate this.

My concern is however that simply replacing the cats without finding the cause could lead to a similar problem in the very near future. Cats can be easily damged as you know by misfire, incorrect fuel - all related to rich mixture. I have a ELM 327 with Peters software and starting the engine from cold and running up until the cooling fans kick in shows no signs of a problem with any of the sensors other than a turbo overboost code.

Late last evening ( this car is on my mind - you get the picture) decided to try driving again and see if turbo boost was present etc etc etc. Starting from cold no MIL illumination this time. Drove car for a few miles and mashed the throttle in third gear. No turbo boost on the gauge or anything dramatic experienced, no sound of turbos spooling............nothing.

Like I said in the initial thread, if one cat was blocked, shagged or whatever surely the other turbo would still spool up or is the engine management on these cars designed to cut fuel, boost if a fault is detected with one part of the engine ?

On the subject of Cats. I wont pay the asking price for these (£400 + pair) so if damaged I reckon a trip to the local exhaust wholesale outfit may yeild a cat from another vehicle that can be utilised with a bit of cutting and welding.

Anyone know of a suitable sized cat that would do the job ?

Re the cabin fuel vapour - this seems to be coming from the passenger seat belt slot in the cill area. I have read various threads about leaking tanks and if this is the case I cant beleive that a manufacturer could produce what was a £50,000 + car and wrap the tanks in open cell foam. The tanks appear to be protected from the weather and if it is condensation that has caused the foam (sponge) to soak up moisture/water and rot through the tanks this is outrageous. The difference in cost between the foam types is pence/cents and if this affects all these cars then I reckon its a manufacturing fault.

Will investigate the fuel vapour issue and let you know my findings

Thanks again for you advise/help

Paul

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first: your really not the only one who worries about the open-cell foam. Even on my engine rebuild i covered that problem by a rebuild in this area.. . And for your information -the tank bay is not sealed, as soon as you have the carpeted covers off you will see it -there is an easy way for rain to pass along the air intake part (the black plastic that holds the mesh..) on every body-side.

second: The original ceramic catalyst can also fail by age and steady vibrations (as you say 'no boost' on the dial -it means you have an pre '98 car than ?!)

third: for about 90-110 Euros each you can get 98mm / or 120mm metal catalyst from various e-bay dealers. Mainly out of the track-day/quarter-mile part-suppliers... . It is an cheap and easy fix to open your existing catalyst housing, replace the broken internals by cutting off the ends of the round aftermarket parts, and fit them into your original casing, fix them by some small weldings on the edge -put the original casing parts back on

-ready !!

Edited by Günter

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to name the things if I see them, that's what I call integrity..

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Hi Paul

What car is it you have BTW as your bit on the side says S3?

Re the fuel smell, I think this is more often caused by the fuel tank breather tubes which tend to crack making the fumes come into the cabin. They are a small plastic pipe that run above the seat belt slot.

I spoke to Steve @ SJ Sports cars about the tanks and foam. He swears there is no problem as long as there is no water leaks. Some people do have a problem but mine on a 1985 TE where fine. I did notice a small leak on the rear window and fixed it.

Buddsy


 

"Belief is the enemy of knowing" - Crrow777

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first: your really not the only one who worries about the open-cell foam. Even on my engine rebuild i covered that problem by a rebuild in this area.. . And for your information -the tank bay is not sealed, as soon as you have the carpeted covers off you will see it -there is an easy way for rain to pass along the air intake part (the black plastic that holds the mesh..) on every body-side.

second: The original ceramic catalyst can also fail by age and steady vibrations (as you say 'no boost' on the dial -it means you have an pre '98 car than ?!)

third: for about 90-110 Euros each you can get 98mm / or 120mm metal catalyst from various e-bay dealers. Mainly out of the track-day/quarter-mile part-suppliers... . It is an cheap and easy fix to open your existing catalyst housing, replace the broken internals by cutting off the ends of the round aftermarket parts, and fit them into your original casing, fix them by some small weldings on the edge -put the original casing parts back on

-ready !!

Thanks for your info Gunter

Good info on the Cats - spoke today to Pete @ PNM and he reckons the lack of boost could be due to wastegate capusules inoperative/damaged but also that the ceramic cats have a tendency to disintegrate over time and this can lead to a blocked pipe or silencer.

Had the car up on ramps this afternoon (in the pooring rain) and can confirm the actuator rods are free. Looks as though the cats on this car have been on there for some time as each of the 3 studs have no visable thread left. Badly corroded, so will need to try some heat and some penetrating oil to help free up things before I can remove the cat pipes and inspect.

Like your idea about finding some cats from ebay - I hear the standard Lotus cats are close to a £1000 !! but reckon that I can sort this with a couple of aftermarket units and some cutting and welding. PNM do some CEL200 Cats for about £400 each but this is not in my budget just now and anyway it would give me sleepless nights knowing I had paid £800 for a couple of stainless steel pipes.

I will get these pipes removed shortly and post my findings

Cheers

Paul

Hi Paul

What car is it you have BTW as your bit on the side says S3?

Re the fuel smell, I think this is more often caused by the fuel tank breather tubes which tend to crack making the fumes come into the cabin. They are a small plastic pipe that run above the seat belt slot.

I spoke to Steve @ SJ Sports cars about the tanks and foam. He swears there is no problem as long as there is no water leaks. Some people do have a problem but mine on a 1985 TE where fine. I did notice a small leak on the rear window and fixed it.

Buddsy

Hi Scott, yes it says S3 but this is my late fathers car - I have a Esprit V8 and a couple of other headache cars.

Hope you are right about the fuel breathers but have read much on the forums about tank replacement on the V8 vehicles. If it stops raining for the weekend will investigate the petrol tank issue and post my findings.

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...-or leaking fuel pipes (especially the Evaporatve pipes, for charcoal canister ventilation..) & the cross-over breather pipe for the two tanks in the sidebays.

As said, it is now on you to investigate it further

and for reference (no guaranty that it works on your emission-testing..)

a2ab_1.JPG-that's what I fittet into mine


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to name the things if I see them, that's what I call integrity..

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As said, it is now on you to investigate it further

and for reference (no guaranty that it works on your emission-testing..)

a2ab_1.JPG-that's what I fittet into mine

Thanks for the picture Gunter

Have seen similar 200 CEL items on ebay here in the UK for approx £95 each. The way I see it is you get to upgrade the system to something that flows better and with a mornings work you save yourself over £600 .........

Think it will be afew days before I get to remove the cat pipes as the nuts are rusted solid so currently soaking in penetrating oil. Better this way than breaking the studs and then all the hassle that goes with replacing these.

Cheers

Paul

(PS Todays job is to check out that leaking pipe(s), breathers, petrol tank)

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You can cut /split the nuts -or simply use some kind of *dremel* hand-grinder, and grind them off.. .

for the other thing: same question, other post..


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to name the things if I see them, that's what I call integrity..

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Just a few thoughts: If the cat is blocked on one side,, it will feel like a rev limiter with the performance falling off very fast at about 5K. You will also notice a significant difference in the force of the exhaust pulses from the tailpipes. Next, if the boost controller pipe falls off (the red one in the front right engine bay) you will get unlimited boost briefly (but with no real reading on the guage as this is in circuit with the pipe in question. Then a hose will blow off (such as the blue idle air valve pipe) and you will lose all boost due to the air equalizing with the atmosphere through the open hose connection. In all these cases, the wastegate rods will "feel" normal. Hope this is of interest

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Just a few thoughts: If the cat is blocked on one side,, it will feel like a rev limiter with the performance falling off very fast at about 5K. You will also notice a significant difference in the force of the exhaust pulses from the tailpipes. Next, if the boost controller pipe falls off (the red one in the front right engine bay) you will get unlimited boost briefly (but with no real reading on the guage as this is in circuit with the pipe in question. Then a hose will blow off (such as the blue idle air valve pipe) and you will lose all boost due to the air equalizing with the atmosphere through the open hose connection. In all these cases, the wastegate rods will "feel" normal. Hope this is of interest

Thanks for your response John

Had an afternoon atempting to undo 6 badly and I mean badly corroded cat to turbo pipes - 3 broken studs later and inpection of the cats proved one is completly shot with several peices of ceramic monolinth and ash..........not good.

It would seem the previous owner or perhaps a prospective buyer of the car took the car for a test drive, booted it and since performance was poor (due to the blocked cat) held the pedal to floor (perhaps) with the result of an overboost code.

Could have been that or a sticking wastegate capsule as these were a bit seized when I checked them the other week.

Have run the car without the cat pipes and turbo impellers seem to be rotating as they should, so its now just a question of finding some universal cats (probably 200 Cell units) and carrying out some cutting and welding.

Checked the 2 red pipes that run to the boost solenoid and they look okay.

Let you know my findings when I get the refurbished cats on and have checked out the wastegate capsule diaphragms.

Cheers

Paul

You can cut /split the nuts -or simply use some kind of *dremel* hand-grinder, and grind them off.. .

for the other thing: same question, other post..

Many thanks for the info Gunter.

Seems as though the diagnosis is/was a blocked cat. Near side cat was okay bit off side ( behind driver in Germany) was completly shot. Several peices of ceramic material and plenty of ash.

Started engine with cats removed and turbos spin okay but due to hot exhaust gases probably not a good idea to road test to determine if boost system works as it should. From your link it appears the cats are in two sections one being approx 100mm x 130mm long and the other 120 x 170mm long.

The shorter section requires the location of the oxygen sensor so expect this would make contact with the cat substrate/monolinth when fitted ? As you can tell I have not cut my cat pipes at this stage but need to find out how the standard cats are assembled before ordering parts etc etc.

Pleased that I have, I think, found out the root cause of the problem but 3 of the six studs have sheared off in the turbo housing. The car is a 1996 registerd 1997 so those pipes have been on there for some time and were very badly corroded. See if I can get a right angle drill running of my compressor to dril and tap or just drill & nut/bolt.

Time for some extensive interweb searching for suitable donor or universal cats for repair of my Esprit cat pipes.

Thanks again for your help

Paul

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Hi Paul

Was this the car that was for sale in Lowestoft ?

If it was, I was half tempted myself, but I did notice the comments about difficulty with reverse and possible leaking fuel tank ?

Mine smells sometimes and there's no logic or pattern as to when it does and when it doesnt !

Anyway good luck getting it sorted


Colin

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...Many thanks for the info Gunter.

Seems as though the diagnosis is/was a blocked cat. Near side cat was okay bit off side ( behind driver in Germany) was completly shot. Several peices of ceramic material and plenty of ash.

Started engine with cats removed and turbos spin okay but due to hot exhaust gases probably not a good idea to road test to determine if boost system works as it should. From your link it appears the cats are in two sections one being approx 100mm x 130mm long and the other 120 x 170mm long.

The shorter section requires the location of the oxygen sensor so expect this would make contact with the cat substrate/monolith when fitted ? .....Thanks again for your help

Paul

You cant weld ceramic monolits -this is the reason for fitting every ceramic internal between small metal rings. As you can see the front (starter)catalyst internals are really short, measured by the point of weldspots for the small rings. This means the monolith heats up really fast (this was at least the aim , to pass the emission homologations for US-California emission board phase one/Euro2 certifications.) The second o2-sensor is only there for reference (for example to test that the starter cat is fitted (US legislations..) ..and the bigger main-catalyst does the most work of emission conversion.

The second o2-sensor does not 'hit' the front monolith, the sensor fits just behind it... . If you not have to worry on emission legislations as in the US (functional rear o2-sensor, with notable differences on sensor reading -due to the starter cat in place..) compared with the front sensor -it is more effective to place only the bigger rear catalyst insert. This is big enough to convert the emissions, but does not exactly heat up to working temperatures in cycle-time for the US emission tests , but as it is bigger in diameter improves the gas flow... .

Edited by Günter

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to name the things if I see them, that's what I call integrity..

*********************************************************************

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You cant weld ceramic monolits -this is the reason for fitting every ceramic internal between small metal rings. As you can see the front (starter)catalyst internals are really short, measured by the point of weldspots for the small rings. This means the monolith heats up really fast (this was at least the aim , to pass the emission homologations for US-California emission board phase one/Euro2 certifications.) The second o2-sensor is only there for reference (for example to test that the starter cat is fitted (US legislations..) ..and the bigger main-catalyst does the most work of emission conversion.

The second o2-sensor does not 'hit' the front monolith, the sensor fits just behind it... . If you not have to worry on emission legislations as in the US (functional rear o2-sensor, with notable differences on sensor reading -due to the starter cat in place..) compared with the front sensor -it is more effective to place only the bigger rear catalyst insert. This is big enough to convert the emissions, but does not exactly heat up to working temperatures in cycle-time for the US emission tests , but as it is bigger in diameter improves the gas flow... .

Thanks for the response Gunter

I have just sourced a couple of 120mm x 275mm Long Stainless steel bodied metalic 200 Cell Cats from a company here in the UK. The monolith which is made of a metailic material is approx 130mm long which is probably longer than the orginal fit ceramic type.

It looks like I will be deleting the small cat from the system and cutting and welding to enable the use of this unit.

The only minor snag is the post cat oxygen sensor (which fits between the per and post cats) would be in the wrong place so I am going to source some weld in bungs + some sensor wiring extensions and fit the sensor toward the end near the tapered connector which joins to the silencer/muffler.

Dont know if this is feasable : I cant forsee any problems but there may be something I have overlooked.

On a partly related note : managed to drill out the 3 broken studs with 90 degree electric drill from the turbocharger housing. Tapped some 8 x 1.25mm threads in 2 of the holes but on the last one the tap snaped !! Bastard.

As anyone who has used taps before knows, these are brittle and cannot be drilled out. One way would be to burn them out, other would be to remove the turbo and have a machine shop remove with a spark erroder..... however.......came across a tool which utlises the three clearance flutes of the broken tap.

The tool is called a Walton Tap Extractor and they are inexpensive @ approx £2.00 for a 5/16" which is just under 8mm. Company name is www.cromwell.co.uk ...............hope this works.

This may be useful for someone else doing a similar job or am I the only person daft enough to work on my car outside in near freezing temperatures !

Paul

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as you say, those taps to create 'new' treats are brittle -what means if it snaps, just hammer it into more (smaller) pieces with a small punch. It's a little bit risky on cast iron parts to hammer (you know the *don't use the hammer -why? Because its the tool of...* thing :D ), but works some times to get those broken ones out... .

Are you sure that the middle section of your 120mm[diameter] aftermarket-cat is 130mm long, and that there was no 98mm[diameter] section available? As the internal monolith is mostly shorter than the whole middle section, between those 'universal'-fitting cones on the aftermarket catalysts. So you can have one insert that really fits within the original place... .

And most aftermarket catalyst parts have the second o2-sensor relocated, thats common. The wiring should be long enough, but you cant 'clip in' the connectors onto the rear frame-crossmember this way (not much of a problem , I think..).

A 918 engine, with good compression, stiff wastegate springs, K&N-aircleaners [or similar] and 200cell metal catalysts -that's making a lot of fun !

Hope you get your 'feels flat'-problems sorted ! thumbup.gifthumbup.gif


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to name the things if I see them, that's what I call integrity..

*********************************************************************

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post-9597-126859876651_thumb.jpg

Hi All,

With a recent slight warming of global temperature around Norfolk I managed to get outside to replace the osf wheel bearing. Outer bearing trashed and outer cage badly pitted so replaced. ( I have owned approx 50 or so cars over the years, and never seen a bearing in this state) Some improvement in noise reduction but seems as though my diagnosis was only partly right. Probably driveshaft, flat spotted tyre, or another bearing or something else ?)

Time for a test ride .........warmed up engine and because today is a thursday engine MIL light illuminated. Does this on random occasions. Engine intialy fired on about 4-5 cylinders and then went onto all eight. Engine rpm set at about 1500 rpm idle speed and takes some time to settle out or decay @ 900 or so rpm

Checked engine codes and appears to have been activated due to overboost. Strange since the engine hasnt been past 4000rpm and no boost noticable. Can hear, just (above the driveshaft, bearing, flat spoted tyre noise ) some evidence of turbo boost but performance is about on par with my Diesel Land Rover and that probably has more go and is more exciting to drive !

Thinking perhaps turbo or catalysts but would have thought even with one turbo, two turbos and perhaps one failed cat there would be at least some chance of breaking the national speed limit. Cabin area also has smell of fuel but this is not always, just on some days when its worse than others.

No evidence of burning engine oil or water vapour but less condensation appears from left exit tail pipe. Assume left cylinder bank feeds left tail pipe outlet or perhaps this gets switched internaly in the rear silencer ??

Plenty of possible faults here but having bought one of these cars didnt expect every forum topic to be relevant to my particular vehicle all at the same time. Just to complete the story - some hassles with selecting reverse which turned out to be a combination of worn translator linkage and incorrectly adjusted pedal.

Several exhaust manifold studs are missing nuts. Slight blow from left hand manifold which will probably seal up once I can make, fabricate a suitable wrench/spanner to actualy get access to the stud. Nice design Lotus !! and what material are these studs made from ............I have built and rebuilt more V8 engines than I care to mention and have not seen this many broken studs on all those engine put together than what I have here on one car !

Plently to go at here

Look forward to any postive ideas on fixing this and yes I have already thought about November the 5th !

Cheers and thanks for reading

Paul

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Just to give an update on the blocked cat saga.

Managed to get around to removing the old standard ceremic cats from my Esprit V8. As you can see one cat is perfectly okay but he other shows how the first (small cat in the system) has come loose/broken up and more or less welded itself to the larger cat pipe.

Holding these up to the sun or bright light - with the good one you can see light but the other not a thing !!

The abnormaly high back pressure on the right hand bank of cylinders meant that no boost was available from the engine at all.......nothing. Not sure why no boost was apparent on the other "good" side and this remains a bit of a mystery sinc ethe car has a sports silencer/muffler without internal crossover or interchange.

After getting around to welding in the new 200 Cell cats, new oxygen sensor bosses and fitting the pipes, ran the engine. Disconected battery earth to reset the ECU and car fired up fine. Intial warm up rpm (1200 rpm ) decayed to a steady 850 ish rpm.

Then engine appears to run on 4 + 2/3 cylinders for some reason...........exhust note differs from left to right and is clearly audible.

Not sure whether the ECU has to re-learn by being driven or can the ECU learn from engine warm up to fans cutting in ?

Thought maybe the ECU was set up to run with the blocked cat but would require reset. Armed with this logic

Inserted ignition key

Depressed throttles pedal 10 x in 20 seconds

Switched off ignition.

Ignition on, wait for fuel pumps to build pressure then restart engine..........running on all eight cylinders for a few minutes and then blipped throttle a few times and back to the 4 + 2/3 = 6 or 7 cylinders. The right hand tail pipe seems to be popping and sounds a bit like a misfire.

I havent got around to checking plugs, ignition leads, compression etc etc but wondered if the ECU re-learning.

My main concern is if there is a misfire ( which is a new development and was not there even with the blocked cat) and there is excessive unburnt fuel could this damage the new cat ? No smell of unburnt fuel..............MOT just expired and no opportunity to try it on a run.

When ECU is reset does the engine run without any apparent or noticable difference ? should a difference be noticed if the ECU has been reset ? or in other words, how the **** do you tell if indeed the ECU has reset ?

Any ideas ?

Help greatly appriciated ....

Paul

as you say, those taps to create 'new' treats are brittle -what means if it snaps, just hammer it into more (smaller) pieces with a small punch. It's a little bit risky on cast iron parts to hammer (you know the *don't use the hammer -why? Because its the tool of...* thing laugh.gif ), but works some times to get those broken ones out... .

Are you sure that the middle section of your 120mm[diameter] aftermarket-cat is 130mm long, and that there was no 98mm[diameter] section available? As the internal monolith is mostly shorter than the whole middle section, between those 'universal'-fitting cones on the aftermarket catalysts. So you can have one insert that really fits within the original place... .

And most aftermarket catalyst parts have the second o2-sensor relocated, thats common. The wiring should be long enough, but you cant 'clip in' the connectors onto the rear frame-crossmember this way (not much of a problem , I think..).

A 918 engine, with good compression, stiff wastegate springs, K&N-aircleaners [or similar] and 200cell metal catalysts -that's making a lot of fun !

Hope you get your 'feels flat'-problems sorted ! thumbup.gifthumbup.gif

Thanks for your advise Gunter.

Purchased a tap extractor which I had to order for a 3 fluted tap. Wasnt until I checked the remains of the tap I had been using that I realized the tap wa sin fact a 4 hole tap. £20.00 down the drain !

Seriously pissed off with this so ground down a centre punch to enable a half reasonable swing with a small hammer - two hits and the broken off tap shattered. Poked the broken bits out and used another tap to tidy up the threads. Job done.

Dont know if your cat were this bad but have a look at my recent posting - the first small cat had worked loose/broken up and welded itself to the larger diameter main cat - a mess.

Saga continues with other problems .............

Paul

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Running fine for a few minutes on tickover and then going "off", would suggest, faulty Lambda sensor.

When the engine starts, the lambda's are in "open loop" and the ECU runs a preset map, after a minute or so, the Lambda sensors

have heated up and the system should siwtch to "closed loop" and the lambda readings have a direct bearing on how much fuel the ECU

runs, independantly to each bank, which can make it run erratic on one bank.

This would also have a big effect on the general running fo the engine upto 45% TPS.

If you have an ODB reader, plug it in and watch closely what is happening with all four lambda sensors and do a search on all the

great threads on here for understanding how the Lambda's work.

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Running fine for a few minutes on tickover and then going "off", would suggest, faulty Lambda sensor.

When the engine starts, the lambda's are in "open loop" and the ECU runs a preset map, after a minute or so, the Lambda sensors

have heated up and the system should siwtch to "closed loop" and the lambda readings have a direct bearing on how much fuel the ECU

runs, independantly to each bank, which can make it run erratic on one bank.

This would also have a big effect on the general running fo the engine upto 45% TPS.

If you have an ODB reader, plug it in and watch closely what is happening with all four lambda sensors and do a search on all the

great threads on here for understanding how the Lambda's work.

Thanks for your reply Jim,

I have Peters, Esprit V8 software running on a ELM 327 device so can check out the oxygen and other sensors.

My inital thoughts were that the ECU has been learning the fueling and other engine running parameters in a condition where the cat converter was blocked and therefore would adjust fuel and spark on the faulty cylinder bank in an attempt to allow reasonable or smooth running.

Since changing the cats, the ECU would need to re-learn the fueling requirements and adjust accordingly. I can only assume the most efficient way to do this would be to reset the ECU and let the ECU learn again.

Oxygen sensors were working okay before the installation of the new 200 cell cats so it seems strange that these would suddenly fail or play up.

I am thinking on the lines that the old maps (pre changing cats) are still valid and the fuel and spark settings are now incorrect.

Best way of course is to hook up the diagnostic tool and carry out some data capature but before I do this I wanted to be sure that the ECU has been reset. This make sense ?

Cheers

Paul

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Hi Paul,

I would definately reset your ECU and start from a ´clean sheet´ on adaptive values.

If you´re o2 sensors are serviceable and you don´t have any other faults, you should be in good shape in little to no time.

Hope you get to enjoy your car soon !

Cheers,

Mike S


1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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Hi Paul,

I would definately reset your ECU and start from a ´clean sheet´ on adaptive values.

If you´re o2 sensors are serviceable and you don´t have any other faults, you should be in good shape in little to no time.

Hope you get to enjoy your car soon !

Cheers,

Mike S

Cheers for the response Mike and for confirming my thoughts on this.

As you may have read, disconnected battery earth and also used the other method of igntion on and depressing the throttle pedal 10 x. but ..............using both methods the same engine symtoms are applicable so I am thinking ( perhaps ....paranoia ) that the ECU is not reseting for some reason.

Any ideas on how to determine this i.e., that the ECU is actualy reseting and allowing the engine to run from a clean sheet ?

Cheers

Paul

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Paul, as you can see by my advice with 'hit the treath-tappet with a punch' it means you're not the first -and you will be clearly not the last with this experience.. :) same is for the look of your catalyst -As i even managed to 'free-up' the exhaust with a tent pole on an campground of the Hokenheim-racetrack some years ago.. .

What surprises me is that you really need to relocate the o2-sensor mountings, as for the 'non-availablity' of shorter 98mm dia inserts. Thought those small & short catalysts are still available on the market. And in the other way -in GB on a emission test, there will be no one who worries about equal signals from first & second o2-sensor in the line -if you decide to go the 'only main catlyst' optional way.

Check that all your sparkplugs 'fire' equally, and have an clear sign of clean combustion.

An ECM doing 'relearning' means mostly high idle RPM, an stalling engine after the first starts of the engine -and it does not want to rev-up fast on the highway... . But there was never something like an 'unequal' firing..

Edited by Günter

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to name the things if I see them, that's what I call integrity..

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Paul, as you can see by my advice with 'hit the treath-tappet with a punch' it means you're not the first -and you will be clearly not the last with this experience.. rolleyes.gif same is for the look of your catalyst -As i even managed to 'free-up' the exhaust on an campground of the Hokenheim-racetrack some years ago.. .

What surprises me is that you really need to relocate the o2-sensor mountings, as for the 'non-availablity' of shorter 98mm dia inserts. Thought those small & short catalysts are still available on the market. And in the other way -in GB on a emission test, there will be no one who worries about equal signals from first & second o2-sensor in the line -if you decide to go the 'only main catlyst' optional way.

Check that all your sparkplugs 'fire' equally, and have an clear sign of clean combustion.

An ECM doing 'relearning' means mostly high idle RPM, an stalling engine after the first starts of the engine -and it does not want to rev-up fast on the highway... . But there was never something like an 'unequal' firing..

Many thanks for your advise again Gunter

Spoke with Brian @ Lotus technical today about the resetting ECU procedure and he confirms that removal of the earth lead should allow the ECU to go into learn mode once reconnected.

Anyway - drove the car today and at last I have some boost from those turbos rolleyes.gif Boosting to about 0.5 Bar but back to stationary still get intermitant loss of 1 or 2 cylinders on the right hand side ( this was the blocked cat side) . Increase rpm to 1200 - 1500 and it clears.

Brian suggests perhaps an air leak on the induction side so looks as though I will be removing the plenum etc but will do the easy things first and check out the spark plug condition and colour.

Cats are showing some sign of discoloration - I purchased some 120 mm diameter 200 Cell units but when these arrived they are a design which is crimped/welded at either side so the actual diameter of the cat unit is probably nearer 100mm. The unit which is now welded in place is the same diameter as the first expansion box. I have done away with the smaller cat so just have 130mm long units and 100mm diameter (internal cat measurements).

The post cat sensor would therefore have been located in a pre cat position which is not good. Therefore I welded in some new sensor bosses post cat close to the mounting of the rear silencer union/connector. The eletrical harness is a bit tight but its okay and has some spare to move with engine movement.

I have only probably covered about 5 - 6 miles so not much of a road test but I do not experience any of the so called stalling situations at all and the temperature is up to normal running temp so on closed loop.

With engine cold there was no boost available (didnt want to wreck it anyhow) but as the engine warmed up started to get the boost from the turbos. This would idicate that this part at least of the ECU programme is working so all appear to be going as it should.

Maybe its an air leak or possibly a bad spark plug ........I will find out. Posted the message on the forum just to see if anyone could offer a solution before I get involved with crawling under/over that car again ..........will also hook up my OBD software and check out whats happening with the oxygen sensors etc etc hopefully tomorrow.

Thanks again for your help

Paul

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