Interesting lean condition. Your thoughts please?

[GIG4FUN]

Drive the car everyday runs perfect. Let it sit Friday night to Monday morning and It chugs and coughs and pegs +17.2 to "---" readout on the wideband. It's been like this as long as I can remember. (I just drop the clutch and rev it a bit and struggle through it all.) The duration is for about a half mile to a minute. It does it while still in open loop. It is not closed loop that makes it go away... it is "time". I just put up with it until now. I am interested and a solution. I have a few ideas but I don't to taint your thinking.

Only after it sits the weekend, day to day is perfect.
Full tank or low tank.
Never thrown a code.

Thank you,
Russ

 

[Error404]

what kind of tune do you have?

 

[cekim]

Drive the car everyday runs perfect. Let it sit Friday night to Monday morning and It chugs and coughs and pegs +17.2 to "---" readout on the wideband. It's been like this as long as I can remember. (I just drop the clutch and rev it a bit and struggle through it all.) The duration is for about a half mile to a minute. It does it while still in open loop. It is not closed loop that makes it go away... it is "time". I just put up with it until now. I am interested and a solution. I have a few ideas but I don't to taint your thinking.

Thank you,
Russ

Assuming that you are right and it is still lean in closed loop after the PCM programmed start-up open loop time has passed...

Fuel pressure during this?
Front O2 sensor voltage readings?

Wild stab I'd say the O2 heaters are not functioning correctly and your front O2 readings are FUBAR until the exhaust heats them up...

Also possible your tune is FUABR in the low RPM open loop portion used by cold start?

Getting desperate after that - maybe a marginal fuel pump warming up?

One more wild stab - intake or TB loose until they warm up and expand (unmetered air getting in until the parts heat up and get pulled together...)

 

[GIG4FUN]

what kind of tune do you have?

Doug's Perf 92 tune
I have SCT Advantage III Pro Racer package as well

 

[GIG4FUN]

Assuming that you are right and it is still lean in closed loop after the PCM programmed start-up open loop time has passed...

Fuel pressure during this?
Front O2 sensor voltage readings?

Wild stab I'd say the O2 heaters are not functioning correctly and your front O2 readings are FUBAR until the exhaust heats them up...

Also possible your tune is FUABR in the low RPM open loop portion used by cold start?

Getting desperate after that - maybe a marginal fuel pump warming up?

One more whil stab - intake or TB loose until they warm up and expand (unmetered air getting in until the parts heat up and get pulled together...)

good ideas... thank you.

It fattens back up to stoich before closed loop and I do not see it lean out again until it sits over the weekend.

 

[cekim]

good ideas... thank you.

It fattens back up to stoich before closed loop and I do not see it lean out again until it sits over the weekend.

hope you find it...

Also check out the MAF readings during this period...

 

[Hawgman]

Sounds all too familiar. That is how my hell started.

 

[GIG4FUN]

hope you find it...

Also check out the MAF readings during this period...

me too.. After tomorrow morning I won't have to piss with it again until next Monday LOL. It drives fine day to day. It is when it sits over the weekend ..that first few hundred yards they're shitty.

With a full tank or low tank it is the same. I should have said that in the first post. (I did edit it just now)

 

[GIG4FUN]

Sounds all too familiar. That is how my hell started.

I'm not thinking that all hahaha. I had this problem since last fall! honestly, for over a year.... I've been (and still am) too busy to get to the bottom of it.. until now ! I kinda made up my mind to get it stopped. Maybe I better just trade it in on an '08.

by the way I got NO CODES! I have NEVER had a one.

 

[ZmanM3]