so my wife and i took the Z06 to DC for memorial day weekend. we were there for 5 days. the car was fine the 600 miles we drove to get there and the entire time we were there. on the way back home i noticed it was leaning out in 5th and 6th under medium throttle and was actually going rich under decel.

it usually runs around 13.7:1 cruising and around 12.5:1 under hard acceleration. i had the cruise set at 75 or 80 and saw that the a/f was jumping around. it was bouncing between 14.5 and 15.5, sometimes even hitting 16. i took it out of cruise and tried to apply some throttle to see what it would do, and it would cut out and go completely off the gauge to the lean side. when i'd let off, it would go to about 13.6-13.8. usually it goes full lean under decel since it doesn't give it much or any fuel at all. it was basically acting the exact opposite of how it should have.

we pulled off at a rest stop to use the bathroom and take a quick break. once we got back in the car, it was acting just fine. after our next stop, it started acting up again. i thought maybe the altitude had thrown it off, but it kept it up until we got home. i made sure to take it easy because i didn't really want burnt pistons.

anybody have a clue what may be going on? i haven't driven it since tuesday and my wife said she hasn't really noticed it doing anything unusual driving it to work and back. i'm getting ready to complete my nitrous install this weekend and i don't want to blow the car up if this happens again.

 

Any codes? When was the last time the fuel filter was changed?

 

last time we pulled codes with hp tuners, there was a ton of stuff. it's a heads/cam car and the check engine light stays on, lol. i'll have to see if i can pull them again to see if there's anything unusual.

as for the filter, i'm really not sure. i wouldn't think a filter would be giving it fuel on decel though. i'm thinking it's either a weird issue with the tune or maybe the ecu switched to a low octane map that may not be tuned for some reason.

 

If not the tune, it could very well be the filter. The filter can work like a restriction, allowing some fuel through, enough for lower rpm and as you pointed out, decel, but will not maintain enough flow for higher loads high rpm. In fact, that's pretty classic. Hope you find the issue. Post back with what you end up finding.

 

It actually sounds like an O2 sensor flaking out.How many miles on the car?

 

it has a halltech on it. i had just cleaned and re-oiled the filter before we left on the trip. any chance some oil on the maf could do it?

it only has 2 O2 sensors aside from the wideband and they appear to be somewhat new. the engine was built less than 20k miles ago and was tuned with efilive. the chassis has 95k miles

 

Oil on the maf could cause some issues, but I was speaking of the fuel filter in my post. I guess it would have helped if I had said what filter. Hope you find the cause.

 

You might want to look for air leaks or un-metered air getting in there after the MAF and check the PCV connection tube going to the intake. You don't need HP Tuners to pull your codes so hopefully you are aware that you can get them from the DIC.

 

gotcha. i'll have to check on it. i had the battery out for a couple of days and now the check engine light has been off for an entire day, which never happens. it's still hunting around during cruise but my buddy's gto does that too. it seems to be okay for the moment, but i still may put a filter in and clean the maf

it's possible when i had the filter off that the coupler at the t-body wasn't fully seated and just driving around caused it to loosen up some. i made sure it was all good this time when i put things back together, so we'll see. i know about the codes, but with the list we got last time, i'm afraid the DIC would be overwhelmed, lol