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Esprit V8 Feels flat and no boost from turbos.

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The post cat sensor would therefore have been located in a pre cat position which is not good. ...

why ?! On 'older' systems the rear o2-sensor is 'ignored' by the ECM on fuel calculations -so you will not get any code, even if you blank up the rear holes and run without any rear sensors fitted.


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

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Upgrade today to remove Google ads and support TLF.

why ?! On 'older' systems the rear o2-sensor is 'ignored' by the ECM on fuel calculations -so you will not get any code, even if you blank up the rear holes and run without any rear sensors fitted.

Hello Gunter

The post cat oxygen sensors appear to read the oxygen content in the exhaust as shown by the OBD software (using Peters Esprit V8 software). Whether these contribute to the ECU fuel map is unknown but the fact that there is a electrical signal I would have thought would mean somethings going on.

To clarify : I have cut out the larger portion of the cat pipe so that the 120mm diameter section is no longer used. I have also dispensed with the smaller 100mm diameter cat insert since these were completely knackered as shown by the images in my earlier posting. So what I have is a uniform diameter "expansion box" or cat locating section with the pre cat sensor located in its original position and the new cat section welded in place followed by the addition of a post cat sensor mounted after the cat converter.

The layout of the sensors is similar to yours Gunter but its just that I have one cat ( smaller diameter) but probably longer in lenght 130mm monolinth

This means that the orginal position of the post cat sensor would be in a position where it would also be positioned pre cat like the first oxygen sensor on the curved pipe that exits the turbo.

If the post cat does nothing, then this would mean that the precat sensor is used to read oxygen content and the engine management calculates the amount of fuel to supply based on what is exiting from the turbo.

The way I see it is that the post cat sensor must do something otherwise it would be pointless locating it in this position.

I would have thought that the first (pre-cat) sensor measures (through electrical signals) the oygen content of the exhaust gas and then as the gas passes through the cat monolinth the second (post) cat sensor, takes another measurement to determine the effectivness of the catalytic converter. Adjustments to the fuel map are then altered. This condition is based on the system running in "closed loop" and not open loop feedback which would be completely different.

Correct me if I am wrong but I would think precat is used for open loop and then when up to temp and the engine running in closed loop both oxygen sensors are being used ?

Need to get this straightened out as I cant fix something if I dont understand how it works

Cheers

Paul

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.

Is it possible to switch the connectors for pre/post cat sensors?

Hi Jim, yes they can be switched but I am not sure where you are heading with this one ?

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Your thoughts with 1th sensor ->ECM mapping/calculation, 2th sensor catalyst existence verification is right.

But mention: later california *emission-board* certifications/European emission laws required to guaranty the functionality and existence of an catalyst element. Therefore all the later GB/Euro cars/US cars have the remappet ECM programming with the fault-code setting if the rear sensor is not fitted. Same is for some countries/markets as for requiremts like catalyst-overheat[Japan/US !?], EVAP [uS,..] , fuel-tank pressure warning and all that stuff with relations to emission laws... .

On my German certified car (production '98-Euro2 emission-registered) it stated an note on the OBD data-logging tab: *California Air-research emission phase1* -with an realtime sensor reading/voltage for the rear sensors, but an side note behind it where the fuel-mapping would be on the other front sensors saying something like: 'long/short term not available, sensor reading is not required on calculation..'

My car does have 3 working, and 1 cracked sensor [rear] fitted now for a long time -and it does not have o2-sensor codes and runs the same as with 4 sensors..

with other words: on ECM driven engine systems *open-loop/closed-loop* means only engine/water temperature is ready, sensor/catalyst are heated up to working temperatures ..what means the engine regulation can start via realtime reading on those sensors. open-loop means it is still running from 'pre-set' mappings/idle conditions/cold start conditions.

the two sensort fitted behind each other are just to pass the emission laws/national requirements. it does have nothing to do with open/closed-loop


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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 explanation Gunter.

Hooked up my OBD reader to assess the lambda sensor situation and with the Esprit V8 software a fault highlighted a problem with cylinder bank number one running @ 0.9v. From what I have read 1.0v is rich and 0.01 lean.

Swopped over the lambda sensors rear ones first - no difference. Still get misfire when ECU switches over to closed loop.

Swopped first in line lambdas left to right and still get the misfire when the engine starts to warm which appears to coincide with closed loop running. So with this I can only assume that the lambda are okay but there is another fault.

Removed spark plug plate for cylinder 4,3,2,1 .......right bank when viewed from behind the car and although the previous owner had a service stamp only a few weeks ago, the plug extensions where soaked in water/condesation.

Plugs 4,3,2, looks as though they are the original plugs as badly corroded. Plug number 1 is turning but wont pull out.

The bastard socket has jamed (due to the rubber washer that locates in the plug socket) and will not pull out. Light is now poor so out with the araldite to stick the socket extension to the socket and see what happen tomorrow.

Feels as though the plug has broken off in the head and this may explain the misfire.

With 4 cylinders hooked up to the ignition and 3 plugs removed, turned the engine on the key to blow out all the dust and crud and engien suprisngly ran ! cleared out most of the rubbish that was sitting in the plug wells !!

Strange thing is that with the cats blocked the engine ran on all cylinders but on thinking about it the load on the ignition would not be great without any horsepower greater than about 50 which is probably what I was getting with no boost and blocked cat.

I am looking forward to getting this engine running correctly as I have spent more time crawling under and over it than I have driving

So to recap ........ODB reader says lamdas sensors, process of illimination says spark plugs !!

Once I get this last plug out ( I am already thinking the worst case scenario = helicoil which I think is impossible in situ) will find out.

Paul

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Hi Paul

Oh dear - that is starting to sound bad and far more work to get sorted. :D

I hope that you don´t find any more serious problems when you start digging deeper.

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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Cheers Mike .........trying to remain optimistic but almost everything else on this car is turning out to be a bit of a pain so see whats what when I manage to get the socket clear and hopefuly the spark plug .

Anyone out there got an endoscope for hire ?

No not for the spark plug but for the previous owner ........I am wanting to see how far up his arse the hammer goes when I throw him back his split arse mechanic tools !

Paul

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your code-reader says *Lambda-sensor* as for the fact that there isnt a real 'spark-plug' code in the ECM monitoring programmed. What you can monitor is *misfire on on cylinder/bank* but you have to find the reson for it in DIY anyways.. .

Would say the car is simply bad maintained ?!

..the sparkplug -normaly changed between 70.000-100.000km was broken, or caused a 'bad earth current running' on the wrong way.. . So there was unburnd fuel steady on this bank, causing rich condition sensing on the probe [to much HC compared with O2], and/or an 'afterburning' next to the real hot catalyst [as this is one of the hottest parts within the exhaus system of every modern car..]

sidenote: as also this car story sounds like -an other one for the grave digger-

..anyone knowing what happend with the *Moscow Esprit* that wasnt running/firing some month ago.. ???

PS.

Paul, you do not need the offered 'drain-pipe' mod for the spark plug openings in general. But in any way -use additional silicone/sealant under the screw-heads for the cover ,and under [between] the cable passing rubber block & on the cover sealing end, next to the cable-block !!

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 all, finaly solved the engine misfire mystery !

Yesterday morning allowed conditions where I could actualy see down into the spark plug well on number 1 cylinder. Its awkward since you need to use a small inspection lamp and peer down into the engine bay from outside through the side window. Its either that or light + mirror etc etc

What had happened was the end of the spark plug lead had attached itself (corroded) to the end of the spark plug so removing the lead had resulted in this part of the lead being stuck to the end of the spark plug. The spark plug was still screwed in place and the plug well was half full of water and other debris.

The socket I was using had become lodged into the end of the plug. The rubber washer insert inside the socket which holds the plug in position for removing and installation of the plugs, had wedged itself onto this small metalic part and that prevented the socket being removed. So every time attempts were made to locate the extension bar in the socket and remove, it would simply pull out and leave the socket in place.

The cylinder head design is such that long nose pliers were too large to get hold of the socket.

Solution was to araldite the extension to the socket and leave overnight. This worked and allowed the socket + extension bar to be removed. Next was work with screwdriver, pliers and a clamp to allow removal of the plug lead end. Could have done with some of those forceps they use in the medical profession.

Soaked up the water from the plug well and removed the rust etc which was from the metal part of the spark plug. Spark plug accessable so was removed. Fired engine up with plugs removed ( 1-2 seconds) from this bank of cylinder to clear any minor debris. The engine actualy runs with 4 plugs out but there is a fair bit of fuel spraying about so wouldnt advise doing this for any longer.

New plugs installed and carried out a temporary repair of number 1 spark plug lead. The rubber part of the lead end is glued into the outer shroud so difficult to effect a good repair but all the same simply crimped the carbon wire and insulator to the cleaned up spark plug fixing and started engine. Runs perfectly so far and runnig up until the fans cut in was running okay. (Road test later ).

Coolant warning light now illuminated and after further investigation, appears some leakage is apparent from the turbo housing area on this bank of cylinders.

So put on my Sherlock Holmes Hat - I reckon the original fault with this engine was a bad plug or faulty lead ( they look like the orginal leads and there is no record in the service history of these being changed).

The misfire from that cylinder resulted in excessive fuel being dumped into the exhaust and after some time resulted in damage to the first cat in the system. Since this is a very hot part of the exhaust system and with temperture reaching several hundred degrees C, this caused the welding of the first cat to the second as shown in my earlier pictures.

Blocked Cat = No Boost = Other problems = Poor Performance.

Poor maintenance and a previous owner who didnt want to spend any more money on the car other than a dubuios £450 for a service ( bit much for an oli and filter change coz thats all they did) meant this has been a time consuming expericence to rectify for me.

So big thanks for the time spent responding to my posts, Gunter, Mike and you all.

Next job is plug leads ( £135 for magnecores, some other aftermarket £103 or OE Lotus ?? or two sets of Elise for e.g leads as this works out @half the price) coolant loss, nsf wheel bearings ( Just sourced a set for £17.90 inc vat Made in Romania not France) from a local bearing supplier and some other minor issues such as replacement lambda sensor.

Checked out the bearing specs and the axial loading etc etc is the same as the SNF OE items but better than £40 ish from dealership

Off side rear sensor works but when a "Lotus Dealership" ( yes they know who they are ) replaced the sensors 18 months ago, they didnt use any lubricant, so removing the sensors resulted in a damgaged sensor plug thread .......muppets. These were Delphi ES10057 VE42J ( Not OE !)

Sun is shinning so time to top up with fuel, coolant and try a short test drive ( no MOT so got be a a bit careful)

Cheers

Paul

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Hi Paul,

Sounds as though you´re heading fowards the end of your struggle.

You might want to consider having a look at the injectors. Either get them cleaned/checked or replaced... this could also contribute to poor running.

Moscow Chris (with a little help on parts) completed the full rebuild of his engine some time ago. My guess it will still be a little while before Moscow is thawed enough for him to drive it though.

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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so two more cars saved from scraping-yard by TLF advice ?! :thumbup:

Paul, if you have problems on finding o2-sensors -see *parts crossref* section. You can find some ranged from around 55Euros [for someone with soldering/criming skills] and up to 100-170Euros... .


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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 advice and comments Mike, Gunter

Just taken the car up the road for a breif test ( loosing coolant from turbo housing so didnt want to cane it) and other than the noise from the front n/s wheel bearing it seems to accelerate pretty quick .........seeing just over 0.5 Bar in 3rd gear and engine appears to be running fairly sweet.

So thanks again guys and as you put it Gunter........another one saved from the scrap yard !!

This car seems to have been looked after reasonably well but a big gap in the service record is no doubt the reason for some of the faults. The drive up the road with at last some boost from the turbos thumbsup.gif means I now have the enthusiasm for getting on with the other jobs

Plenty of smallish jobs to do .........driveshaft oil seals leaking as well !! the list goes on but should be a good car when Im finished.

Thanks again

Paul

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driveshaft-seals is even more an 'easy part' to do...

undo the driveshaft from the gearbox-splines, inspect the fre-play on the bearings, and prior to 'undo' test for play internally on the splines & inspect the outer seals for damage on the dust lip & sealing lip, in most cases the oil is simply passing along the splines internally and not on the outer sealing. Use good 1000grid wet sanding (same as in a body shop for painting..) and repolish the sealing ring area on the driveshaft ends. If you want it -replace the inner O-type sealing ring, but more importand, on the driveshaft refit use sufficient amount of sealing compound on the drive shaft splines (clean them, fit silicone [or similar] up to the point were the hole for the pin is)... .

My box was out for engine rebiulds, clutch work and other 'problems' far often, it is an factory-replacement box -dated from the mileage point ~40.000km . Car is now on 117.000km + ...and still on this original sealing rings.

If the sealing rings are in god shape , but technically a bit 'hardened'/aged -undo the spiral inside, open it on the end [think you know that those spirals have an 'end' ?! ] ....shorten it by 1-1.5mm and fit together again, insert it with 3 Fingers and some small srewdriver ends/hooks... does offer more miles to get out of them :thumbup:

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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Thanks for the tips Gunter

Replaceing the oil seals looks like quite a straightforward job but its good to get some advise from someone who has been there and done it before.

I can live with the leaks from the transaxle for a bit longer but need to prioritize on the more important MOT test jobs such as the n/s/f wheel bearing and the coolant leak.

Wheel bearing is okay as already replaced the off side one a couple of weeks ago but the coolant leak may be a bit more involved. Here we go again........ jack up the car, roll about with gravel and stones sticking in your back, wind, rain and plenty of grit, coolant, oil etc dripping onto your head or into your eyes !! I think you know what I mean !

Another point worth a mention : since sorting the engine misfire issue, the previous strong fuel vapour smell in the cabin seems to be much better.

Could be that here is not much fuel in the tanks or simply that the engine is burning the fuel rather than throwing it out through the exhausts. Think I will change the engine oil soon as oil + fuel is not the best lubricant for bearings etc etc

So I reckon another few hundred quid spent on front tyres, (inside edges badly feathered = wheel bearings + top ball joints) plug leads, oil change, oil filters, K&N Air Filters, Lambda Sensor oil seals should, I hope, get this car back on the road ready for the spring/summer.

Air con wants recharging but probably wont bother with this as I prefer windows open and roof panel out if it gets too hot this summer

Cheers

Paul

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Paul,

On the output shaft seals, if you don't have the Lotus tool for inserting them, make note of the seal depth before you remove them. There is no shoulder in the case behind the seals to control the insertion depth.

And assume you know you'll need to drain the gearbox oil as well which is probably due to be changed anyway from the sound of the DPO's maintenance record...


1995 S4s

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Paul, my advice on the gearbox-driveshaft was meant to use them for more miles -not generally to change them as soon as there is a dripping... . That's what I say -they were never 'out in full' on my box. It is just the way to get the car running, money is better spend on fuel bills in the summer time.. .

Mentioning fuel -undo both sides on the rear-quarter trim panels. As soon as the car is running nd on working temperatures stop the car, get on the back an make an 'sniff test' on every point. By the age of the car there is EVAP, breather, crss-over and other pipes in the fuel/ tank-breather system to mention... .

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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Thanks for the info Mike,

Like I said in my earlier post to Gunter, its good to have sound advise from people out there who have actualy done these maintenance tasks and little bits of info here and there means the job should only need doing once and not the do it once, cock it up and then have to do it again !!

Thanks again

Paul

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