bad Idle....Low vacuum?????

[19TTA89]

I justed dropped the new motor in earlier this week....quick rundown of parts....212-212 cam....T&D 1.65 Rollers...msd 50's...Extender...CPT-65...GN-1's...Ported intake....JJ 62-65mm TB....Mease Plenum.

I am chasing down a rough Idle,But haven't really done alot of tuning on it yet.....TPS and Iac #'s seem good....The blm's hold steady at 128 on startup....But when it goes into closed loop....The idle goes to crap...and the blm's start climbing...It usually goes into the 150-155 range....Fuel pressure adjustments really dont seem to change it much...

I also noticed that the vacuum is about 15in at Idle....(About 750 rpm's)...IS that enough...Also this car is converted to vacuum brakes... I have sprayed some carb cleaner around the intake,Plenum,all the vac line,..there was no change in the idle....Also tapped on the maf(Which is a 3.5 In)And there was no change in the Idle...Right off the idle the car is smooth as glass..

Will be tuning tomorrow.....Any Ideas on what else to look for as far as the crappy Idle goes???

Thanks,Shawn

 

[19TTA89]

 

[Nick Micale]

With your combo, cam, heads, etc., my opinion is base idle needs to be reset as 750 RPM is too low in your case.

 

[19TTA89]

I was going to jump the idle up....But isnt that set by the chip???IS there any way for me raise the idle,without having the chip redone right away???

What I should ask is......If I adjust the idle at the TB myself...Will the chip try to compensate for it,And move it back???

Thanks,Shawn

If I hold about 850-900Rpm's I have about 18-19in. of vacuum....

 

[2 SLOW]

I have a 212-212 Comp cam in my car and had a simular problem. I found that I had to turn the set screw for the throttle blade to open it just a little more. The IAC couldn't handle it without the blade cracked open just a little more. I have about 14 inches at idle in neutral and 10 inches in drive at idle. It made the idle a lot better. My idle is set for 775 rpm in my chip. It might not be your problem, but it worked for me.

HTH

Oh, and I have ported GN-1 heads, 50 lb MSD's, ported intake and 62mm TB.

 

[TurboDave]

What chip are you running, and what are your Translator settings???

 

[Nick Micale]

Just open the throttle blade a little more like was said and see if that works.

 

[BlackWrath_86]

I had this problem too. In addition to the bad idle, the car would also shut off when lifting on the throttle after boosting. I also have a big cam and 1.65 rockers with ported big valve iron heads. Today, I reset the idle to almost 1000rpm via the idle adjustment recomendations on the turbo buick website. After a test drive all the bad symptons were gone. It sounds like a high idle but I think its has to be with flowing so much air.
HTH
PS If you adjust it by opening the throttle blade screw, make sure you re adjust the TPS settings.

 

[19TTA89]

Thanks for the suggestions....

I swapped out the 50 with some 55's and a modded ECM today....With a Lubrant street chip,The Idle was still the same 750 ish....I turned the throttle blade up so the Idle was about 900-950 and the car smoothed out nicely.......Only problem was each time I turned the car off and restarted,The Idle was back to 750 again....The TPS is set at .46 and 4.64 at wot...the IAC was around 20 at idle,But from opening the throttle Blade so much...I had the IAC reading 01 at one time...I am going to get a chip burned for this combo..From turboTweak....And start tuning agian..

The Car runs great just cruising it up the block a few times....Very smooth everywhere except for Idle....Havent really got into boost at all with it yet on the road.....

Thanks,Shawn

 

[19TTA89]

Originally posted by TurboDave
What chip are you running, and what are your Translator settings???

I was running an extender with the 50's...Now with the 55's It has a PTE street chip in it.

The Translator settings are 1-2 on...3-4 off.....Just set for the 3.5in maf...not rich or lean.....and wot is set to no change...

 

[TurboDave]

Originally posted by 19TTA89
I was running an extender with the 50's...Now with the 55's It has a PTE street chip in it.

The Translator settings are 1-2 on...3-4 off.....Just set for the 3.5in maf...not rich or lean.....and wot is set to no change...

I'll assume you have the base setting at 0 then. Try postion 1 on the base setting (don't forget to reset the ecm).

Also, turn dip switch 3 on, since you're not running an extender.