2zzge rough idle and stalling

[captain crescent]

Ok ladies and gents.

I currently have a issue with my racecar. The engine is idling rough , with a slight hunt when it hunts the engine makes a soft sucking chuff sound.
At idle the scan tool is showing -20.3% on the short fuel trim (no1) and the o2 sensor ft b1 s1 is also reading -20.3%. the daily driver(same model of car) is reading around -1.6% short fuel trim.

Also under low rpm and under deceleration whilst driving the engine stalls occasionally

I have had a camcon controller hooked up to it ( and i think the issue has developed since it was installed 6 months or so ago) I have disconnected this controller and the wore on the ECU that run to the AFM and to the VVT solenoid have been joined back together.

The Ecu is not throwing any fault codes.
I have swapped the ecu from the racecar to my daily driver it runs fine in daily.
I swapped the o2 sensor from daily to racecar and also the AFM with no change.
Static and ignition timing has both been checked and have all tested fine
All cylinders have good compression and no more than a few psi difference.

Any positive feed back would be greatly apreciated:)

The o2 sensor from racecar is white so would tell me that the engine is leaning out. As seen in pic below

[jaypines]

try cleaning the throttle body.. especially the idle control valve. sometimes the valves get seized or get gunked up with carbon and not moving freely.

[captain crescent]

Its all clean and ICV spins freely.
I have tried so amnt things its hard to remember them all and list them

[matt dunn]

Still run the AFM?

If so try another one as have had those issues with that type of AFM before.

[captain crescent]

Afm has been swapped between my two cars no change

[crispy'86]

Have you got access to air flow meter cleaner? try cleaning the afm, all the connector plugs for the ecu, afm etc with contact cleaner. Check your pcv valve, vacuum hoses for leaks. A good idea is to check for air leaks with ether or something similar, spray around the manifold etc. has this problem just developed or has it done it slowly over time, has the hunting get worse over time? Sounds to me like it's got some form of vacuum leak. Maybe check the air flow meter sealing o-ring make sure it seals in the air box. what octane fuel is it and how old is it? fuel injectors all good?

[jaypines]

whats your long term trim?

[matt dunn]

Afm has been swapped between my two cars no change

Did you reset the fuel trims when you swapped them,
or just chucked it in to try?

[captain crescent]

Have you got access to air flow meter cleaner? try cleaning the afm, all the connector plugs for the ecu, afm etc with contact cleaner. Check your pcv valve, vacuum hoses for leaks. A good idea is to check for air leaks with ether or something similar, spray around the manifold etc. has this problem just developed or has it done it slowly over time, has the hunting get worse over time? Sounds to me like it's got some form of vacuum leak. Maybe check the air flow meter sealing o-ring make sure it seals in the air box. what octane fuel is it and how old is it? fuel injectors all good?

AFm has been cleaned and I swapped between the two cars.(the other car runs fine)
i have checked many thimes for vacuum leaks but will do again.
It has developed a bit over time.
Brand new fuel in yesterday 98 octane
Injectors have not been checked as yet.

[captain crescent]

whats your long term trim?

Long term trim is low between -2.3 and 2.0 so within specs

[captain crescent]

Afm has been swapped between my two cars no change

Did you reset the fuel trims when you swapped them,
or just chucked it in to try?

Battery lead or Ecu fuse pulled for each attempt at swapping things over

[captain crescent]

I have sprayed brake clean all around all manifolds hoses etc no change in idle.
I pulled the spark plugs one seems to be running sligtly lean but it could be due to the engine leaning out.

[Lith]

Have those trims ever been comparable with your daily? Makes it seem very much like the ECU *thinks* it is running rich and trying to compensate, which is unusual as with most issues it'd think it were running lean - the only thing straight off hand that would make me think it thought it was running rich were if there is a bad earth relating to the O2 sensor signal to the ECU making it think it is running richer than it really is.

Does whatever diagnostic you are running to get those numbers tell you what voltage/lambda/AFR the ECU thinks it is dealing with from the O2 sensor? And what about TPS?

I would bet from that trim that it is idling/cruising around 17-18:1 AFR which is really far from ideal and would definitely cause your driveability issues (and make it amazingly cheap to run) - and again it is pretty clear it has decided that it is something it needs to do as opposed to it happening due to a mechanical issue. 20% also sounds like a "maximum trim" type number so wouldn't be surprised if it would go leaner if it could, so some sensor input must be confusing the crap out of the stock ECU for it to think it needs to do that.

[Shrike]

check the ecu temp water temp sensor

[Lith]

Water temp related trims are usually only for warm up enrichment, if it was faulty I'd expect it to be rich (like what most sensor problems would probably result in happening)

[Rick]

Blocked or dirty fuel filter??

[captain crescent]

Have those trims ever been comparable with your daily? Makes it seem very much like the ECU *thinks* it is running rich and trying to compensate, which is unusual as with most issues it'd think it were running lean - the only thing straight off hand that would make me think it thought it was running rich were if there is a bad earth relating to the O2 sensor signal to the ECU making it think it is running richer than it really is.

Does whatever diagnostic you are running to get those numbers tell you what voltage/lambda/AFR the ECU thinks it is dealing with from the O2 sensor? And what about TPS?

I would bet from that trim that it is idling/cruising around 17-18:1 AFR which is really far from ideal and would definitely cause your driveability issues (and make it amazingly cheap to run) - and again it is pretty clear it has decided that it is something it needs to do as opposed to it happening due to a mechanical issue. 20% also sounds like a "maximum trim" type number so wouldn't be surprised if it would go leaner if it could, so some sensor input must be confusing the crap out of the stock ECU for it to think it needs to do that.

I had not checked the fuel trims until more fault finding yesterday so I'm unsure if they ever were comparable . This bad earth you mentioned where would I be looking for this? On the earth wire from o2 sensor to Ecu? The voltage reading from the o2 sensor which is around 0.605 v to 0.0670v i have seen around 0.800at times i think. throttle position sensor says 9% . it does see to perform pretty well under revs hiting lift and accelerates pretty comparabally to my daily driver. the only thing is whilst driving is whilst backing off or low rpm i mean just on the throttle the engine will cut out/ turn off.

The short fuel trims read at the -20.3% on idle and through the rev range until i release the throttle where it wil cut back to around -2 and will climb up to the-20.3 in increments around 1 to 3 % at a time untill it reaces the high level. the fuel trim numbers and the 02 sensor readings are pretty similar all the way through and both read -20.3 at idle.

any more feedback is welcome im ment to be competeig this weekend......

[Lith]

I should have asked, is it a narrow band or wide band on the Corolla? 1v from a narrow band should be pretty much 1lambda, any lower indicates it is rich... which it clearly isn't

[captain crescent]

Blocked or dirty fuel filter??

Havnt been there as its all in the tank . but its running fine under load and revs wouldnt that rule blocked filter out?

[captain crescent]

I should have asked, is it a narrow band or wide band on the Corolla? 1v from a narrow band should be pretty much 1lambda, any lower indicates it is rich... which it clearly isn't

I am unsure but am led to beleive it is a narrow band . someone maybe able to tell me more or tell me how to find out