Doesn't wanna idle after warmed up

[SVTFreak]

AFR 165's, TFS Stg 1 cam, GT40 with exploder lower, 75mm throttle body, spacer, 73mm vortech MAF, egr disconnected.

Car runs great (like a scalded ass ape), and idles great until good and warmed up. About 5 or so miles, it starts to die when you let off (push in clutch and return to idle). It tries to catch, but if it can catch, itll surge, sometimes dying, sometimes not.

Originally, i had codes 15 (prolly from the hypertech chip), 31 and 67. Wouldnt idle at all, MIL stayed on, and was VERY rich. Pulled IAC, cleaned, and checked the EGR plug (have sensor plugged in it to fool the puter). Reset codes, and immediatly ran fine. No more rich smoke, more power but still this nagging return to idle issue. No more codes (other than 15) atm.

A couple people (one mustang guy) has suggested maybe the computer needs some learn time. Ive done 20 or so miles. It seems like just maybe its gotten a little better, but might just be my wishing. Coiuld it be this?

ideas?

 

[Kdubslugga]

Doubtful on the computer relearn crap. What are codes 31 and 67? i know 66 is mass air not sure if 67 is as well

 

[SVTFreak]

33 is EVP out of range.
67 is some kinda shift position sensor problem. Not sure why since its a 5 spd car. But cleared when i cleared them all out.

 

[SVTFreak]

New code today. 96, AIRB Air bypass valve not working. Although ive cleaned it and it moves freely. Could it be stuck again or could i need the little plate to go between it and the TB?

 

[92 LX]

Your 67 is probably the clutch switch. You need to have the clutch to the floor when you do a KOEO test. I use my str wheel club to push & hold the clutch in when I'm doing this test.
Good Luck.

 

[Kdubslugga]

Could just be going bad, ive got a good IAC here at the house, PM if your interested!! Give it to ya cheap.

 

[SVTFreak]

Your 67 is probably the clutch switch. You need to have the clutch to the floor when you do a KOEO test. I use my str wheel club to push & hold the clutch in when I'm doing this test.
Good Luck.

Didnt know this, always did it just sitting there. Ill try that just to see. Local shop suggested it might be computer for an auto but i doubt the guy that had it woulda done that.

 

[SVTFreak]

Could just be going bad, ive got a good IAC here at the house, PM if your interested!! Give it to ya cheap.

Thanks man! Might get with ya after i try it. Ill pull a good one off neighbors GT to try out first. Gonna recheck idle screw, TPS voltage, and clean it again to make sure a chunk didnt lodge it and see what happens. Working till monday so itll have to wait lol.

 

[liljoe07]

Clutch doesn't have to be down to run a KOEO test. BUT, you can try and hold the clutch down and try to run the Key,on engine running test. Which is what you need to do.

Code 67 is probably from the trans switch(NGS). And if the KOER codes flash with the clutch down, then that's where I'd look.

Don't worry about the EGR code right now. Is the EGR code, code 31 or 33?

 

[SVTFreak]

Joe, it's 31 (out of range). I'll try a koer test Monday when I'm off. Assuming a small laundry list of items I have is done. I now have reason to believe the tps voltage at idle may be too high. Going to fix that and clean iac once more then try it and do koer. More then!
Thanks everyone!

 

[liljoe07]

31 is a EGR PFE sensor low voltage code. Could one of a few things. Bad(worn) EGR valve assembly, wiring, or the white sensor on the back of the EGR valve.

Clean the 10 PIN connectors first and re-run the KOEO codes. See if it shows back up.

As far as the TPS, it didn't show in the KOEO codes, so its not likely a problem. TPS just needs to be in between the failure code range of .6v-1.19v. .8v-1v is just fine though.

 

[SVTFreak]

Update. The EGR sensor that i had plugged into the harness to fake the computer was bad. Replaced it and had same issue. Apparently you cannot just plug the sensor in cause itll show out of range even though its ohms measure in acceptable range. Bolted it into an EGR valve (just left it loose, didnt even connect vacuum) and the car runs fine now!

Moral of this story, when you have an issue and have MIL codes on and stored, fix those first and many times the issue will be taken care of along with it.

 

[liljoe07]

I missed the part about having an EGR simulator in. That's what happens when you skim read a post.