Idle problem when cold

[NSXPOWR]

I have an 87' GN that used to idle up and down when cold and when you put it in gear it would die. I adjusted the throttle stop screw and the tps sensor. Now it idles pretty well until it is put in gear. It still dies until it warms up. I noticed that when I scan the sensors the park-neutral switch, it never shows it's in park, but it does show when in neutral. Car will start in any gear. Will this switch cause this kind of idle problem? Like I said the idle is now fine until I put it in gear, and then it will die until it warms up.
Thanks John T.

 

[BoostKillsStres]

Hopefully you don't have the stock chip in there as it had those type problems.

Also, depending on where you have the throttle blade screw currently set, you may be out of range for the IAC to control the idle. There should only be 1 to 1.5 threads on average on the throttle lever side of the air screw in order for the IAC to be able to correct for idle otherwise your letting so much air through the IAC's setting will stay at zero. If you changed the air screw much you'll also want to recheck the tps setting.

Can you view the IAC counts with your current scan tool?

I'm pretty sure the switch can't effect the idle at all as long as it allows you to start the car, thats the only real control it has.

HTH

 

[smooth87]

i've got an 87 gn, and i have the same problem. and i am fairly sure that i have a stock chip. my car still has the safety switch in place. it wont start unless its in park or neutral. stock sucks.. hope this helps.

 

[crs]

Idle problems

I've been having this problem for about 6 months. Does your car die when you put in gear all the time, or just when it's cold? Mines doesn't die all the time in gear, but it dies in gear cold or warm. I have a ATR chip in it. I've cleaned my IAC, adjusted my TPS, raised my idle up a tad bit, and little things like that! Good luck, and post if you fix the problem!

 

[scottyb]

My stock chip had the same symptoms and it got worse when I added the K&N. I put in a Red Armstrong 93 and it got a little better. I put in a the Thrasher 92 a few weeks ago and it is smooth as glass. No hunt, no cold stumble, no tip-in stumble. All I can say is WOW! I have never touched my idle or IAC settings in the year I have owned the car.

 

[d0n_3d]

all i can say is that i used to have this same exact problem with my car when it was stock...make sure your tps is set at .40-.44 and iac counts are between 15-40 at idle...also an aftermarket chip helps and free flowing intake and exhaust too...my car after the basic mods and tuning idles excellent even at cold start idle...the rpms will go no higher than 1800 when i first crank it up and then it slowly goes back down to the 750-850 rpm range and never goes up or down like it used to...make sure the pcv valve and plugs and such are all new and good too...02 sensor plays a major factor as well...

 

[SPOOLFOOL2]

Bad idle

Make sure you have the correct PVC valve. It drove me nuts for a year and a half untill I figured it out thanks to someone on this board. I'd bet that this is a very common problem on these cars beacase most auto parts places don't realize that our cars take a special PVC. And chances are that the one hanging on there wall that says " FOR GM CARS " is'nt that one. A new one is about five bucks through Poston's. So if your not sure then just change it.

 

[SPOOLFOOL2]

Oh yea, Thanks Neal.