Truck wont idle

[mhays26]

OK, I think about everyone knows my story. JDM built block, ported heads, secret squirrel grind turbo cams, turbo kit, wtf ever. OK, Started the truck for the first time last night and it idled quite a bit rough, just kinda wrote it off to the tune. Started adjusting the tune tonight and still couldnt get away from the super sucky idle. The only way I can get the truck to start is to give it quite a bit of gas and hold it above 1500 rpm. After I do that for a few minutes, I can slowly ease off the accelerator and let the truck run. When I get completely off the pedal, the truck either immediately dies (most of the time) or once it ran for a minute or so. Surging intently from 600 rpm to 1200 rpm. When it would drop down to 600 it would pull about 19 on the vac gauge, then when it surged up to keep running, it would jump to about 10. Any ideas on something to look for? Already checked the IAC to make sure it was engaging, checked all the main vac lines, made sure the MAF was functioning correctly. Im baffled on this one, and I know its a difficult question to field via computer, but Im open to ideas.

Matt

 

[Fade 2 Black]

You're using PRP right? If you have live link log these:

AIR_CHARGE_TEMP

DOWNSTREAM_ACT

COOLANT_TEMP

STFT_BANK1

STFT_BANK2

LTFT_BANK1

LTFT_BANK2

MAF_AD_COUNTS

ISC INTEGRATOR

RPM

LOAD

SPARK_ADVANCE

MAX_ SPARK

Wideband a/f ratio

Most likely you'll need to tweak the IAC and or the a/f to stabalize the idle. Set the static idle rpm to 8-900 to help keep it running at first so you can do some logging. Try to get the IAC intergrator to .5 or less if you can, the drawback is it will have to run for 20+ seconds idling to get a good reading.

 

[lightninmike]

How about tps voltage and the throttle blade being to far open via the set screw. Just a thought as i have no idea about the tuning aspect of things........ yet anyway.
Oh yeah how about the maf being to close to the bov/ wastegate??? maybe blowing back thu a bit?

 

[Fade 2 Black]

He had it running pretty well before the new motor so I think the main issue is the cams, mine still wants to die when it's hot on startup sometimes.

I guess he's done until the am. Good luck Matt!

 

[latemodelracer2]

i had to set my static idle higher when my motor was new. once broken it i lowered it and the idle has smoother out with miles

 

[mhays26]

Sorry bout the no responses, I Shut it down kinda early last night. Was frustrated as hell and had no real ideas. Bob, shoot me your phone number cause I lost it, I got something Id like to try. Im going to look at what you guys have told me this afternoon and keep trying.

 

[Fade 2 Black]

PM returned Matt. :thumbsup:

 

[nicktoney]

i doubt this will work for you, but my buddy has a turbo can and put a bigger BOV on it.. its an 89 shelby daytona.. he hooked the vaccum line up to the bov from the wrong source and it wouldnt idle for shit, and if it did, it was shitty... check that maybe? hell idk? he switched it and now its fine

 

[mhays26]

i doubt this will work for you, but my buddy has a turbo can and put a bigger BOV on it.. its an 89 shelby daytona.. he hooked the vaccum line up to the bov from the wrong source and it wouldnt idle for shit, and if it did, it was shitty... check that maybe? hell idk? he switched it and now its fine

The vac line to the BOV is ran through the electronic boost controller and thats hooked up right. One of my buddies from Polk that does that for all their cars came over to the house and made sure we had that done right. So Im still confused. Bob is going to work with me and we are going see if I overlooked something in the tune

 

[mhays26]

Tried lots of different stuff, none of them seem to work. Completely drained the battery trying to get it to run. Anybody got any ideas at all? Truck will not run below 1200 rpm.

 

[lightninmike]

Will the truck run with out the turbo feeding it?

 

[mhays26]

Will the truck run with out the turbo feeding it?

I dont guess I understand the question. Take the turbo off the truck? Why? Id have a big hole and no way to get air into the intake. excess oil shooting all over the place, and a giant exhaust leak. What did you have in mind by trying that?

 

[lightninmike]

No no, leave it on the truck but take off the intake tubing from the cold side of the turbo to the TB. I guess what i mean it to see if it will run N/A but dont go thru the hassel of taking the whole damn thing off. More or less to see if the turbo is creating to much turbulance thru the maf.
Does that make sence now?????

 

[Derek@Amazon]

matt have you checked for boost leaks? try spraying eather around all the cupplers...

 

[mhays26]

No no, leave it on the truck but take off the intake tubing from the cold side of the turbo to the TB. I guess what i mean it to see if it will run N/A but dont go thru the hassel of taking the whole damn thing off. More or less to see if the turbo is creating to much turbulance thru the maf.
Does that make sence now?????

I can just cap where the BOV recirculates and see if that changes anything. I dont think it will because it ran fine before the new motor went in and nothing has changed with the turbo setup when I put in the new motor.

matt have you checked for boost leaks? try spraying eather around all the cupplers...

Ive checked some, but this seems like much more severe than a small leak. Im going to devote some more time to that tonight

 

[lightninmike]

Perplexing:??:

 

[mhays26]

Perplexing:??:

Youve got that right man, In the last year, its been on the road for 1.5 months, now its sitting in my garage under its own power, reassembled and still wont move, that frustrating. BTW, Thanks for all the help guys, I just hope one of these ideas leads to a solution

 

[Chi3f]

i imagine you already checked this but do you have good vacuum?

 

[QUIK BRIK]

Try PMing Driven to Build on Nloc. I believe he had the same problem, it was a compressor surge, and he took it to JDM, and they contacted PTS and it was some sort of plate that needed changing. Same prob. idle surge and then shut off. Hope this helps.
Tom

 

[mhays26]

i imagine you already checked this but do you have good vacuum?

At 1200 rpm, where it runs, vac is 19. For a fully built block, I thought that was really good. Now, the more I lift off the throttle from there, the lower it goes, before it finally dies about 10

Try PMing Driven to Build on Nloc. I believe he had the same problem, it was a compressor surge, and he took it to JDM, and they contacted PTS and it was some sort of plate that needed changing. Same prob. idle surge and then shut off. Hope this helps.
Tom

Sent Dan a message to call me. I dont remember him saying anything about that happening. And you have no idea what the problem was?