Stalling Problem

[jfb31]

I have an '87 GN. The only engine mod's are a GNX oxygen sensor, an RJC plenum spacer, and a Dynomax dual exhaust. The car has 35000 miles and runs great except for an annoying stalling problem. It has stalled under hard acceleration, backing out of the driveway, and under normal acceleration. It starts right up after stalling and idles nicely after a brief warm-up preiod. I live in sunny Hawaii so the ambient temperatures are 65-85 degrees. The stalling problem precedes the engine mod's so I don't think they are the cause. There are no error codes showing using the Tomco pass-key. This is '87 GN number 4 for me and I've never experienced this problem before. Any help is appreciated.

Thanks in advance :cheers:

[kenmosher]

I suspect that resetting the minimum idle air setting and TPS will most likely fix the problem.

http://www.gnttype.org/techarea/maintenance/maintpage.html

(IAC reset articles)

If not, start looking at a bad IAC or an air leak around the plenum.

[jfb31]

I have a TPS-TEC module installed and by all indications the TPS is set correctly. I pulled the IAC valve off and the pintle seems to be seized. I'm assuming the pintle should have a degree of travel if it is not stuck. I cannot move it at all by hand. Also it has quite a few wrench scars on it which would indicate it has been removed at least once in it's lifetime ( I purchased the car with 34000 miles on it). I'm going to go ahead and replece the IAC valve and see what she does from there.

[Keller]

While you're at it, consider removing the TPS-TEC. In *MY* opinion, its not necessary. A properly adjusted TPS is fine, and a gizmo in line is not needed. John at Casper's and I differ on opinions on this. You may have you make modifications to the TPS to get it adjusted right. (I don't think any of them were right from the factory...) And the TPS-TEC compensates for this. But so can a patient and compotent guy with a wrench. See the articles on the website, and see if its something you want to consider.

[vipers t type]

You may want to look at your short and long term fuel trims.They will tell you if you have a vacume leak and or rich condition.It sounds like to me that you have a vacume leak of some sort.Your ECM will commands your injector pulse with thus for more fuel if their is a vacume leak.With this your GN will stall and or spitt ans sputter under a load. :D

[cpushrink1]

I have an '87 GN. The only engine mod's are a GNX oxygen sensor, an RJC plenum spacer, and a Dynomax dual exhaust. The car has 35000 miles and runs great except for an annoying stalling problem. It has stalled under hard acceleration, backing out of the driveway, and under normal acceleration. It starts right up after stalling and idles nicely after a brief warm-up preiod. I live in sunny Hawaii so the ambient temperatures are 65-85 degrees. The stalling problem precedes the engine mod's so I don't think they are the cause. There are no error codes showing using the Tomco pass-key. This is '87 GN number 4 for me and I've never experienced this problem before. Any help is appreciated.

Thanks in advance :cheers:

What you explained is that it happens while giving your car a little gas. Check you Fuel filter, and vacuum lines. One small problem with a Vac, will cause this problem.

[Keller]

I'm going to go ahead and replece the IAC valve and see what she does from there.
After replacement, the minimum air setting procedure Ken noted is still required. Have a look at it. You'll need to reset your TPS as part of this procedure as well. (Which would be a prefect time to eliminate your TPS-TEC ;) ) Just be sure to check WOT TPS with key on and engine OFF.

[jfb31]

Thanks for all the tips. I should have a new IAC in hand by tomorrow. Now I suppose I'll have to break down and buy a scan tool in order to set the IAC and TPS with any degree of accuracy. On another note, can anyone recommend a good aftermarket chip for a non-racing application? I just want a few extra horses, I don't need to get into the 12's.

[ronbuick]

Let us know what you find out.

Ron

[jfb31]

Okay new IAC installed and set along with TPS. Stalling not yet evident but I don't want to say I'm out of the woods yet. It still stumbles when it is cold but I've had that happen with other 87 GN's I have owned. I checked for vacuum leaks and found none. The fuel filter was replaced 500 miles ago and all intercooler hoses are tight. I am going to break down an buy a Scan Tool and then perform the idle RPM, IAC, and TPS setting again to make sure it's right. I just wish I hadn't bought the TPS-TEC first. I would have saved 90 bucks. Oh well, live and learn. Thanks for the help.