car wont idle below 1400.

[jdmawd]

quick question, i just finished putting the car back together and for some reason it will not idle below 1400 RPM's here is a quick list of my settings


fuel pressure 37 psi base line (vac line off)

vpc all knobs at 12 oclock

S-afc every thing zero across the board air flow type karmen.

when it does dip below 1400 it sounds like its running on 2 cylinders, right before it dies.

 

[nowayout]

here a few questions.

What size injectors and chip.


Most of the VPC chips are 550 cc.


Is it running really rich.
When you pull a plug and look at it is it black.


Answer these question and I might be able to help you.

 

[o0talontsiawd0o]

you probably have the dreaded idle surge that i am going through right now. It is probably becasue of a faulty isc. There are dozens of articles across the web that explain what idle surge is, and how to correct it on dsm's.

 

[2-0turbo]

Check your BISS too. Also, check to make sure you have a little slack in your throttle cable. If you have taken that off and preloaded the throttle body just a bit, the ISC will be fighting you the whole time. Could also be your idle switch is bad. TMO logger or equivalent will check that switch for proper operation. I don't know anything about VPC, so if it is not these three things, I'm lost.

 

[nowayout]

A vpc will never idle like a stock car.
Especially if you have big injectors 720 cc and bigger.

But you can tune it so it's livable on the streets.



Lue

 

[NJGSX96]

I sent you an email too, but to keep the thread going for ideas..

Timing marks line up?
What is your base timing set at? If it is off, your car won't idle. if it is
off enough, it won't even start.
Make sure you are getting spark. New plugs and wires? Not platinum plugs, right? Pull the wires and plugs out, reattaching the plugs to the wires so they rest on the valve cover. have someone crank the motor over and you should see them all fire.
Also, for my cams which I just installed (264/264), I had to lean it way out on the AFC (-25) and full lean on the VPC idle. Wouldn't idle otherwise for me. Same for the 3 other cars I installed cams on. Some not as extreme, but they all had to be leaned out a good amount. Had to go real lean down low to get them to idle. Might not be as extreme for you, but something to check.

I am going to bet it has to do with your cams. your car is dumping in so much fuel that it can't idle. That is the easiest thing to check so try that
first. Then deal with the spark.

I have to rip apart my exhaust right now. I'll check my mail and this thread in a bit.
Let me know how you make out.
Good luck.
Rich

 

[nowayout]

Try to lean it out first.

 

[jdmawd]

nowayout:
sorry i forgot i deleted a lot of stuff from my mod list, i have 650's and a 660 vpc chip. i have not pulled the plugs and looked at them yet.

NJGSX96:

You're the man i have not looked at my timing at all. Honesty it could be anywhere ill have to check that first. Plugs and wires are new and not platinum.

2-0turbo: I know I don't have much slack in the throttle cable ill check that also I have a pocket logger I think I can check the idle switch with it. If so I will do that also.

o0talontsiawd0o:

Idle serge would be great right now, I have what's called take you're foot of the gas and the car dies.

 

[NJGSX96]

Originally posted by jdmawd
...I have what's called take you're foot of the gas and the car dies.

That has happened on all 3 cam installs I have done. I bet it is your timing or too much fuel. Keep us posted.

 

[jdmawd]

OK here is the deal, when I first start the car timing goes from 5 to 8*'s once I give it gas to keep it running timing shoots to 35-38*'s I don't have a timing light so I will have to get one to set the timing. I used the logger to check for error codes, none came back.

 

[jdmawd]

OK i moved the pressure sensor from the bov vac line, to the fuel pressure vac line and switched two vac lines i had backwards at the throttle body, and its better. still wont idle with my foot off the gas. i can hold the gas at 8-900 rpms and it will idle, not very well but it will idle. once i take my foot off the gas(closing the throttle body door) the car dies. i think its the BISS and the timing. this stuff is great fun, i forgot the car had a act 2600 in it, and tried to inch the car forward and almost put the car up in the yard:laugh: even with problem this stuff is great fun.

 

[nowayout]

Idle the car at 1k rpm. Play with the idle knob on my old car I had to turn all the 6 o' clock to get the idle to be steady enough.
But I have 720 injectors with a 550cc chip in the VPC.


My experience with VPC is they idle like #@%#@%#@%#@% under 1k RPM. Just the way it is. Jack in milwaukee who has the fatest 3KGT idles his at 1500RPM or it will just die.

Idle my old Supra at 1000 RPM and it still goes up and down.

Maybe some on this board has got there to idle smooth @ 750 RPM.


This is the main reason I'm not getting a VPC agian. It works great up to a certian piont.

This is just my personal experience with a VPC/GCC setup so correct me if I'm wrong on DSM's


I'm hoping AEM EMS will do a better job.

 

[jdmawd]

bad idle i can handle, no idle is my problem. if i take my foot off the gas the car dies. if i hold my foot at 900 it will idle but as soon as i take my foot off it will die. im almost positive its the BISS and or the timing. as soon as the sun goes down (its like 100* here in DC) i will go back out

 

[jdmawd]

YES..... IT RUNS

got it figured out, my base line fuel pressure is way off but fixable. the problem was it was super rich at idle it idles smooth now at around 950 rpms. tomorrow i will re adjust the base line fuel pressure make some small s-afc adjustments now idle on the vpc is full lean and -37 at 1K on the S-afc. i attribute this to a very high base line fuel pressure setting. 37 was actually 47. (i have bad eyes when looking at autometer gauges. but all and all im happy ill keep you guys posted. and thanks again for all you're help on the thread you guys are awesome

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[nowayout]

Isn't this #@%#@%#@%#@% fun.


Good that it's running.

 

[NJGSX96]

Awesome dude. now come up to Jersey and help me pull my center diff out so I can ship it to Speed Design tomorrow!

Seriously, congrats on finding the solution. Now get her all prepped and ready to go and get that beast on the road.

 

[jdmawd]

nowayout:

actually it is fun even the problem are a learning experinece


NJGSX96:

i would love to give you a hand, if it can wait till the weekend. you guys were right it was a rich condition and a timing issue/BISS the turbo sounds nasty even at idle speeds. i don't know if removing the mass air made it more audible but the turbo sounds like a jet engine when i rev the motor i love this stuff.

 

[nowayout]

I have had my fun over the years too.

Wat until I tear into my car this winter it be a lot off fun.



It's like a drugs, you keep coming back for more.

 

[NJGSX96]

Just busting dude. I got the tranny covered. Diff is out and looking good. All cleaned up and ready to ship to Speed Design.

Glad you figured it all out. And you guys are right. It is fun, even when it is a problem. Nothing like fixing things on your own.