Jimmyz

iTrader: (3)

Is it possible to have an exhaust leak that I could not hear and said leak to cause a lean condition on one B2S1 but not B1S1? This lean condition only occurs "off pedal"...exhaust leak or intake? I've done all the basics to pin point this with no luck. New 02 in B2S1, checked for intake and injector leaks with choke cleaner, visually looked for exhaust leaks and header cracks.

Leak down is next, but will LT Grot header make this condition always be there? Cars Hunts for idle and stalls everytime in a parking lot scenerio or turning braking and stopping at the same time.

Any ideas?

Another_User

It sounds like an intake leak. Check everything, PCV, TB, etc. Do you have a log you can post of where you are going lean?

Jimmyz

iTrader: (3)

yes but have no idea how to post it. This only happens when I'm off the gas pedal. So i thought exhaust since the engine is sucking air in vs. pushing it out.

Corpsvette

How funny, I was just getting ready to make a post asking if this is normal and I don't mean to hijack your thread but I have a new 2004 with only an aftermarket airfilter. I have been making a few logs with my HPtuner and wideband and I noticed that when I let off the gas after a WOT or high RPM run, my AFR shoots up to like 19. I too wonder if this is normal or do I have a problem. The car is virgin, untouched and less than 3000 miles. Thanks and Jimmyz, I hope you find an answer too.

Jim K.

Slowhawk

iTrader: (12)

Could also be a tuning problem since it is stalling all the time too.

Another_User

It would show lean when you take your foot off the pedal because that is when vacuum is the highest. That is why you would run lean. If you are convinced it is your exhaust, check to make sure your O2 sensors are tight. If they are not in all the way it could throw your readings lean, but I bet it is an intake leak somewhere. Check your intake, PCV, MAF housing, TB, and vacuum hoses.

Sonny

iTrader: (1)

DFCO in effect.

Jimmyz

iTrader: (3)

WTH does that mean?

Another_User

Not necessarily. But possible I guess. DFCO=Decelleration Fuel Cut Off. The PCM pulls fuel and spark when you let off of the gas.

Jimmyz

iTrader: (3)

I don't think thats it either as it's only happening on one bank. I think its an exhaust or more probably an intake leak I can't find DAMN IT!

Jimmyz

iTrader: (3)

WELL! Still having the issue. Have replaced most everything (IAC motor, sensors) and fixed the exhaust leak which I thought was the problem but the car still hunts. Mostly happens in open loop @ operating temp. when I'm turning the steering wheel at a stop or just barely moving. The steering load seems to trigger it everytime. No issue when braking but power steering EVERY TIME. Intake leak is all I can think of...at this point.

SSkeet

I seem to be having this problem too, but on my new 408, that was just put in the car. I start it up, it idles fine @ 13:1 for about 30 seconds to a minute, then slowly starts to work its way up to very lean 17:1 or so and then the wideband cant read anymore because its so lean. The tuning is right, I am pretty sure...

itchygomey98

iTrader: (2)

JimmyZ - Have you tried swapping the drivers and passengers side O2 sensors around? If the problem switches banks, then that would be your problem. I wouldn't think that your problem is tuning due to it only being one bank. What intake are you using?

SSkeet - It does NOT sound like the tune is right. It sounds like when you are in open loop it is ok, but when it goes to closed loop you are lean. That would lead me to believe that your OLFA table for idle is correct, but the VE table is not. Are you running SD?

Nickn20

are you taking a tailpipe reading or is this at the header? tailpipe on a single exhaust and the sample tube in a tailpipe I see this all the time. your car will not idle at 17:1 I wouldn't think.....

Jimmyz

iTrader: (3)

LS6 intake and yes I've tried the swap still the same. i think it a combo of cam center line, a leak someware and tuning. We'll see..Lamar Walden Automotive is looking for the problem now.

BTW, I thought closed loop was associated with the cold starts not the other way around, no?

itchygomey98

iTrader: (2)

If it is only one bank, and you have already switched the sensors around without any change - it really sounds like an exhaust leak. How do your plugs look? Maybe you have an injector that's gone to hell on ya.

Jimmyz

iTrader: (3)

Could be both exhaust and a bad injector...I'm leaning towards an intake leak or bad injector thats dripping at idle.

narcszm

dip the motor in soap water and watch for bubbles.

samz28

do the cyliner balance test, that may show the injector thats not firing at least it will help you. i have hptuners 00 if you want to dick around the the vcm scanner, bout a mile from gatech.

Jimmyz

iTrader: (3)

Leak down showed bad cylinders leaking on 1, 5 & 7. I've got a problem with the seats or valves. This is NOT a tuning issue...thanks anyway guys, it's mechanical.