I have developed this problem that has me puzzled..if i'm cruising on the hwy for say 30-40 minutes at about 60mph the car will start chugging and the wideband will read lean..if i give it more gas it will stop..but return to lean again after about 10secs...after going through this process a bunch of times it will eventually stop doing it... but will start doing it again at some point...so it an intermittent problem.

Car seems to be fine during wot pulls and the wideband reads normal.

Thoughts?


fully built turbo h22
s300
3inch exhaust with a cat installed.

 

Do you have this or any other problems at any other times or is the only issue happening just when driving 60mph for half an hour? Specificly, If you push it hard for awhile and the motor gets hot does it create any noticeable effect?

 

it seems to be mostly after driving the car after about 30 minutes on the hwy...city driving and spirted driving doesn't seem to be affected.

 

VSS sensor maybe, info from it tells ECU/ECM fuel injector duration, shorter duration at highway speeds would = a lean mix, right?
Maybe just a poor connection.

Low fuel pressure, [fuel pump, fuel filter or PGM-FI Main Relay] would most likely also show up during "spirted driving" and "wot pulls" although I did have a friend who could autocross all day without an issue but on the way to/from the track, [highway speeds] it would just stop running and be fine 15-20 minutes later, turned out to be the PGM-FI Main Relay, [cold solder connection]. 94

 

The fact that it only happens after driving for half an hour points to a problem caused or aggrivated by heat. Nothing else that I know of changes from when you first hit 60mph to when you've been driving 60mph for awhile. Make sure the bottom of the radiator is cool when the problem happens. Also, when you are able to make the problem go away while driving, see if immediately pushing it to redline brings the problem right back.

 

Thanks for the suggestions..it gives me somewhere to start...cause im really at a lose.