First things first.

I just realized something, I think its related to a problem I have been trying to find. The car is an 86 Grand Prix, it has a 88 350 with TPI, 89 chip, 2004r trans, and for some reason it seems that it doesnt wanna lockup the torque converter anymore. If you know the 200's, theres no place for a VSS on there. The GP's (all of them AFAIK) have what appears to be some sort of optical sensor or similar that mounts to the back of the speedo, and it runs to a little box with 3 wires, which I subsequently hooked up to the F-body ecm. I checked when I first had everything setup, and it was reading the speed correctly at the ecm, the speed I read off different scanners matched the speedo. About a year ago, we had the speedo redone so it would read higher than the stock 85 reading, its now double that. I am pretty sure that screwed up the speed the ecm is seeing now that I realized how thats all hooked up, so the question is, how do I fix it? I dont have a scanner and havent borrowed one yet to verify thats the problem, but I am pretty confident thats what it is.

Other thing is the idle. Ive played around with it, burned chips, adjusted, tried all sorts of settings, and it still wants to bounce around in the neighborhood of 150rpm's up and down around what it *thinks* its target rpm is. Speaking of target rpms, I set it higher than the stock 600 in the chip (750 to be exact), and it still wants to idle near 600. Something in there is copping an attitude for sure. I'll have to go check the vacuum later, but its not very much I know that. I'd guess about 12-14 is what it has.

Any ideas I would appreciate.

 

I'm not sure, but is your speedo registering anything at idle? That may cause a problem with the idle circuit. Only other thing is the IAC and maybe a vacuum problem.

Max, is it a stock TPI engine? If so, it should pull from 17-21 in.Hg at idle. So maybe it's a vacuum leak related problem. I don't know, but since no one's replied yet I thought I would get the ball rolling.


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1990 IROC 350
Mods: Too busy trying to make it run right to mod it.
Airfoil, Dynomax cat-back, MSD coil, 180 t-stat, Bald Eagle tires,
Hypertech fan switch, Accel 23# injectors, Holley AFPR, ported plenum,
Ported Daytona Yellow stock base, Moroso valve covers, other stuff,
Ruger P95DC, hot wife, new oil filter, thick rubber floormats, no cats.
18.0 @ 85MPH since I'm one big-a$$ MF
"It's better to have and not need than to need and not have."

 

JUST a thought: doesn't the IAC help control idle? Wouldn't a slow or failing/dirty IAC cause something like this? Something with it not being able to catch up to the needed level/position in time?

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http://www.tcnj.edu/~esposit3
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Member of FBS, The F-Bod Squad, 3 guys so far and I don't think we're growing

• '89 Trans AM, 305 TPI, 5-spd
• '86 Firebird, 2.8, Auto

AOL IM Name: JimmyTime5

 

Well I just had the TB off today, and it was pretty clean... and now its spotless, so thats not it.

Jethro, its far from stock. I dunno if its registering anything at idle, that would be funny if it was I have a SLP cam in it, 224/232 with .497/517 lift, and 10.3:1 compression. Its pretty fast but needs some bugs worked out, but I really think the idle should be better... I cant imagine a car that will break the tires loose on the 2-3 shift going uphill at 85mph should idle so poorly

I do have to get a scanner hooked up and see what the deal is with the MPH at the ecm, but I am pretty sure its screwed right now. I am more interested if thats how this particular VSS works and how the heck to fix it if that is indeed the problem.

Thanks for the input

 

bttttttt

 

the first time i swapped tpi into my cutlass442, i used the 200r4 optical eyething behind the speedo, and i had a high idle and it would stall on the highway exits. the second time i used the eye from a 86 tpi camaro and it idled at 500 rpm and never stalled. i also notice that the little green or yellow box with the electronics is different. so i guess you just need one from a camaro.

 

Thanks for the reply, looks like my theory is correct. Now all I gotta do is figure out how to feed the ecm the correct signal from somewhere... With the speedo redone to read 170, no way the Camaro VSS will work for me