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Short Term Fuel Trim


Pred247

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Anyone with stock cats get this pop too? Also anyone with high-flow/no cats NOT get this pop?

I have it too and I'm running straight exhaust.

'03.5 Final Edition Esprit ~ 5.7lbs/hp

mildly modded - 430rwhp, 353rwtq

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Anyone with stock cats get this pop too? Also anyone with high-flow/no cats NOT get this pop?

I have it too and I'm running straight exhaust.

I've had this "pop" both with a full stock exhaust system and with after market high flow cats and straight pipes.

This problem for me is only at idle and from what I can tell hasn't affected the performance or is noticable under load.

I haven't tried swapping injectors yet as it seems like a pretty big job to remove the intake manifold, although I have been considering trying it.

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  • 2 weeks later...

I have a couple more questions on fuel trim...

My short term fuel trims vary but not at the same percentage...

And my bank 1 long term stays at 3.13% and the bank 2 stays at 0...

Also my exhaust pops on idle and on overrun...

Any input on this issue?

Also My Throttle is only getting 40% when I floor it. I checked all the normal stuff... (Pedal travel, wires/tubes in the way, linkage movment, new TPS)

Edited by spoonito

Garage:

2001 Lotus Esprit V8

2003 Kawasaki ZX6RR

1994 Toyota 4Runner

Wish list:

MV Agusta F4-1000 Tamburini

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  • 2 months later...
  • Gold FFM

any general or final conclusions?

If not , there is an other car that "popps". Not long ago i had this O2 sensor problem (with code that says: "no sensor activity detected"[P0154]) . After reading some post here, i changed my defective LH front with the in european cars not used (..this is legal,right?) rear sensor. After some testing rounds on the road, no more codes in the ECM!

But the popping still exist. It sounds if it is in stereo on my car, both banks show intermittet exhaust smoke( no worrys, the smoke was only water steam, the car was cold as i have seen this..)!

Road going behavior:

If i want to accelerate from lover refs ( in 3. or 4. or 5. gear) the engine starts several times to "shake , rattle and roll" sounds like a "primitive" US smallblock and not a 180 degree crank. It does this "shaking" also in any engine speed ,if i drife with a constant speed for a while. Under higher speed conditions [with more than 3800 revs/min] the response at trottle is not the old "pulled on a rubber band" way, it does a short kick in the neck and after a few seconds it acellerate with no problems.

I inspected the spark plugs --- all LH plugs are slightly covered with black powder (-> rich condition) and the RH plugs show a clear brown/grey cover ( so all is normal on this side...)

means the LH spark plug symthom that a injector for the complete LH bank is working incorect? Is this typical for the 918 engine if it is more than 9 years old ( car is running over 101.000km ,and engine does run now more than 60.000km )

Edited by G

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Hi,

My 350 is doing the same thing,lumpy idle occasional pop.

I was getting a constant P0154 code.It wasent until I viewed live graphs through my ODB reader that I could see that both Bank 1 sensors were reading wave patterns and both Bank 2 flatlines.

I swapped the leads around to the correct order and now I have both pre cat sensors reading waves and both post cat ,flatlines. All as per proper readings.

Strange thing is that before whilst showing the fault code PO154(Bank 2 sensor 1 no reading) the engine was silky smooth.

Mine obviously got mixed up during the exhaust making but its strange it is rougher running now both banks are going into closed loop.

I currently have a race system with centre outlets and cat bypass pipes.I will be putting race cats back in next week for the mot.

I'm guessing that a slightly rough idle is normal on cars with race exhausts and filters but without a fault code how can you tell !!

Rich

Sport 350

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I've had the same popping noise out of the right exhaust since I purchased the car 3 yrs ago. Mine doesn't effect the idle much at all. I have changed to center exit exhaust but still have the original cats. The popping hasn't changed. Sounds like a VERY high percentage of V-8 owners have the same issue and its always out the right side.

As long as your not running too lean or have serious backfire issues I wouldn't worry about it. If you do solve the problem please let us know. Just curious, do you have Yohan's chip? or something similar.

Good luck

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Personally I'm still on the standard sport 350 ecu.I am thinking of changing to Marcus's Red Race ecu but havent got round to it yet.

I too think this is normal V8 behaviour.Nearly all the ones I have heard/driven are the same.

Rich

Sport 350

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  • Gold FFM

Would'nt think its normal, especially the shaking under acelleration and at constant revs. No tuned ECM fittet on my car, complete exhaust still in stock condition .... !

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Obviously it is relative.If your car is shaking under acceleration and it is generally running very unevenly then I would check it out immediately at a dealers or specialists.

What I am saying is that all the V8's I have driven which is 7, all have popped and banged a little and had varying idle speeds.

It sounds like maybe you need to check it out further especially if the engine feels rough in acceleration.The only time I have felt the engine to be rough or strained it was a damaged CAT.

I too would check the injectors.

Rich

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  • Gold FFM
......I too would check the injectors.

Rich

all my LH bank spark plugs are covered with the same black powder (carbon) from rich fuel combustion. Therefore it seems to be the best way to lift up the plenum and refit the fuellines (ore attach a "flying" spare) and pressure up the system. Can be that the RH single injector in the back of the plenum is leaking some extra fuel in the inlet ports, right?

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

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  • Gold FFM
....BTW, what fuel are you using ?

A leaking injector in combination with low quality and/or low octane fuel for a longer time will also show very similar signs ...

Cheers

Marcus

Yes of course ; maybe you have heared the rumours (in germany); im the guy that uses low oktane fuel ! But with my normaly low power requirements no problem since i bought the car in 2003.

At my trip back home from the Presberg Hillclimb viewing with "LCD" last weekend i filled up the tanks with higher ratet fuel, but no change in behaviour... .

Even with the highest ratet ethanol/petrol mixture [E10-E50] that i testet in the past years, the engine ignites properly and fails only in polution testing because the burnable mixture is to lean... .

the shaking an rough run occurs only in last time, --- maybee an O-ring in one injector goes weak in contact with the ethanol fuel! Sounds stupid do do such things, but i'm interesstet in those fuels and we learn the best from self experiences!

And of course, as long as Lotus shows the Exige 256 not an any event, and i can not get any further informations about that car from Andreas M. the only way ist to test it for your self.... <_<

Edited by G

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

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Ethanol !!! :evil:

IMHO, its not a good idea to add Ethanol to the fuel. It can affect the rubber sealings (O-rings).

Please check your O-rings and maybe have all your injectors tested.

Testing your O2-sensors should also be a good idea. They might be inaccurate.

And just a tip, please use at least good 98-petrol which is available everywhere here in Germany. Using something lower is wrong economy, IMHO.

Cheers

Marcus

[quote name='G

Marcus

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  • Gold FFM
Ethanol !!! :question:

*

*

*

Cheers

Marcus

OK you say so, but even the "Users Hanbook" says E10 is possible. And so far no problems with periodically testing this over the last years... !

An simple faulty o-ring seems to be no big problem to fix, even as an DIY guy i think . If it is this problem, than i have to use my former working contacts a further time to find the right parts. Other guys be more interestet in "bling bling" ore horse power mods, my interest is in renewable fuels. We all take a huge amount of money for our hobbys, every man in his own way..... :thumbsup:

Maybe after weekend i can say more....

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

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  • Gold FFM
Gunter,

I'm interested in your expirince with 'greener' fuels. Please keep us updated.

Regards,

Peter.

It's really simple, with E10 (that Lotus offers as an optional fuel) no problems with start and idling, runs smoth even in fall and spring time. With E50 (that's the highest grade i'have testet) the car can ignite in start and idle conditions, no really visible loss of power under acelleration (dont forget, ethanol has lower engergy content!) . In colder conditions the engine needs a good battery to start. It fails during german emission (mot-T

Edited by G

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

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Don't you need larger injectors for Ethenol? I think Lotus claimed that was the main change needed for the Exige that runs on E85. Saab said the same on their conversions in Sweden.

Maybe Marcus could do a E85 ECU chip for the V8. However, the seals-Ethanol issue will still need to be addressed.

How widely is E85 available in Germany? I worked for Aral/BP in Germany last year and can't remember any of the petrol sites I was involved with having E85.

Regards,

Peter.

[quote name='G

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  • Gold FFM
Don't you need larger injectors for Ethenol? I think Lotus claimed that was the main change needed for the Exige that runs on E85. Saab said the same on their conversions in Sweden.

Maybe Marcus could do a E85 ECU chip for the V8. However, the seals-Ethanol issue will still need to be addressed.

How widely is E85 available in Germany? I worked for Aral/BP in Germany last year and can't remember any of the petrol sites I was involved with having E85.

Regards,

Peter.

Yes, larger injectors is one way to do such things, or a higher fuelpressure or more opening time. But that all depends on the options that your fuel system can offer. The time to inject/open and (therefore the amount of injectet fuel) is highly limited if your system is stock. I have now to deside between a plug on system that "modifies" the "open" signal for each primary injector. Or take larger injectors with stock ecm. Both versions would offer the use of any amount of ethanol, but a modified programming would be also an interesting option! But Marcus sayd he think it is not a good fuel... , (a totally contrast to what any Campcar Team Manager would think..)

Hey Marcus think about it again!

Last year the E50 fuel was one of two optionals, available in some smaller ("independent") fuelstations. This year the ordinary fuel has to have a regular content of 5 percent Ethanol in it, and you can get pure ethnol from the free market also. Some fuelstations who also offer plantoil(Raps) and LPG have now only E85 available.

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

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Ethanol !!! :thumbsup:

IMHO, its not a good idea to add Ethanol to the fuel. It can affect the rubber sealings (O-rings).

You can't even buy petrol with less than 10% ethanol where I live, or in many other parts of the USA. Lotus has surely compensated for this...

Visit Sanj's Lotus Esprit Turbo SE pages

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Yes Sanji,

Thats right, also here there is up to 10% Ethanol already added to the fuel. Thats why I said, that he should not add any more ...

Cheers

Marcus

You can't even buy petrol with less than 10% ethanol where I live, or in many other parts of the USA. Lotus has surely compensated for this...

Marcus

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  • Gold FFM
G

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

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  • Gold FFM

next update:

to find out witch pin is the positive feed on injectorconector, i had to disconect the plenum (this was additional action, taken for my ethanol plans..). And to find any leak from the injectors it was also nessesary to do some work there ...

The broken rubber conector for red pressure pipe on the plenum is renewed. The memory chip said P0106 three times (think this is a effect from the ignition in *on* position while i testet the injectors with disconected plenum)

cleared all codes and gone on a test run: no codes, no shaking, runs normal as years before. :)

But i had also fittet some new sparkplugs. As i want to pull out the ignition cables after test run and inspect the plugs if any not typical signs visible next problem occurs. :crybaby:

The Spark-Plug socket wount fit corectly, the reason is simple: lost the brass metal part/conecting clip. only the cable was in my hand. the rest was on the plug.

after some inspection i guess it is easy to refit all.

Only one question: :lol:

Is there a siliconcoatet ignitioncable with carbonfibre core used in the esprit system, or lost i something? (for example a core made from copper)

If not, than im sure i can refit the metalclip (complete cable is dismantelt now...) and "crimp" the clip on the cable again.

Edit: managed the problem with my own skills, just "recrimped" the conector and fit all cable parts together...!

Edited by G

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

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  • 8 years later...

I’ve had the same popping noise problem on my Y2K V8 and am hoping that by re-kindling this thread we might be able to get some answers between us. I had a bit of a rough idle when I first bought the car, plus wanted to do a few mild upgrades and so far I’ve changed/upgraded/fixed:

Injectors (RC SL2-240 calibrated/cleaned prior to installation)

Air Filters (K&N 33-2547. Also fixed an air box mold defect.)

Sports cats/center exit kit from PnM

New O2 sensors (JAE/ Denso 234000-5560). Checked OK with Freescan (thanks Peter!)

Exhaust leak – noticed when I upgraded the cats. Replaced a couple studs. All good.

Vacuum Leak – 1/8” diameter pipe to climate controls was split

Spark Plugs

 

Changing the injectors fixed the rough idle, but I’ve still got the popping on the Right Side. I also notice a bit more condensation from the right side on cold days. The condensation was the same prior to changing the injectors.

When changing the plugs (which I did some time after the injectors) all were in good shape, light brown carbonization, some corona stain on the insulators but nothing out of the ordinary.

Changing the air filters didn’t change much – just sounded better. Same with the sports cats. Center exit kit was all cosmetic/acoustic and made no difference to the popping.

The only thing I can say for a fact is that the popping noise starts when the ECU goes into Closed loop operation. Possibly a clue there? The popping is also less noticeable if I use non-oxygenated gas (OR 91).

I'm in Minnesota, so the driving season is pretty short. I’ll look at a few things and if I don’t get anywhere I think I’ll just upgrade the ECU- not sure whether to go with the HTU or the Read Race ECU. Also like the look of Johan’s ECU upgrade. If anyone has any experience of these upgrades I’d love to hear from you.

 

 

 

 

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