TPI swap - idling problems

ct91rs · #1 02-27-2005, 11:17 PM

I pulled a TPI setup out of a non-running '86 Iroc 305. I put it into my 91 RS (also with a 305). After installing it and changing the fuel pump, I had to run direct power to the pump (not knowing which wires to connect), and a jumper wire from the ignition to the starter solenoid. The car would start, but it ran very rich, and it would barely idle. If I gave it throttle, it ran real smooth, but as soon as I backed off, it wanted to die. I replaced the IAC and TPS, with no effect. I ordered a wiring harness from Painless Wiring, and now I know which wires to run for the fuel pump power, but with everything connected it will not crank over, and the fuel pump does not come on. I am leaning towards the computer being bad, and I am going to replace it tomorrow. If anyone has any experience with such a problem, or any suggestions, I would really appreciate it!

Chuck

drvngstorm05 · #2 02-27-2005, 11:26 PM

i don't believe that the pcm from a 305 tbi will work with a tpi setup, the pcm is located above the passenger side footwell, i'm pretty sure ur gonna need to get one from a tpi car to make it work... i'm not sure why ur fuel pump isn't comin on, and i don't know why it won't crank... are u sure u don't have a battery problem?

ct91rs · #3 02-27-2005, 11:36 PM

i appreciate the suggestion, but I pulled the ECM out of the '86 and put it in the '91. Power isn't the problem, there are 12 volts at the starter, but the ECM isn't sending power to the soleniod...

drvngstorm05 · #4 02-27-2005, 11:38 PM

damn, hmm that's a brain teaser... is ur ignition switch good?

Morley · #5 02-27-2005, 11:51 PM

When you replaced the IAC did you reset minimum air and then set the TPS?
I assume you are using the ECM from the TPI along with the calpack, otherwise you'd get a check engine light right away.
Your cranking problems may be coming from VATS, the 86 didn't have it but the 91 does. So, the prom can't recognize VATS and VATS won't engage the starter enable relay.
Also double check your fuel pump relay wiring, make sure there is 12 volts on the 10 ga wire, if there isn't the pump won't run even if the relay engages.
I have a wiring diagram for 91 firebirds, The engine wiring will be the same for Camaros. I can E mail it to you if you'd like.

drvngstorm05 · #6 02-28-2005, 12:55 AM

morley... u know ur shit dude, wow i'm in awe

89IROC&RS · #7 02-28-2005, 01:50 AM

morley covered the major bases, but something else to concider is that the 91 system is a speed dencity system, where the 86 would be a MAF system if it were fuel injection based. So that could account for your fuel control problem. but its really late so i might be out in left feild here. morley wanna check me on this.

Morley · #8 02-28-2005, 02:44 AM

Quote:

Originally Posted by 89IROC&RS

morley covered the major bases, but something else to concider is that the 91 system is a speed dencity system, where the 86 would be a MAF system if it were fuel injection based. So that could account for your fuel control problem. but its really late so i might be out in left feild here. morley wanna check me on this.

Well, he converted from 91 tBi to 86 tPi, so MAF vs MAP doesn't come into play, he (I'm sure) changed all of the sensors from the TBI over to the required TPI's.
There is another possibility. A friend at work has been doing some experimenting with an 86 calpack...and there in may lie your problem.
He has an 86 prom (calpack) that he was getting weird readings from when he tried to read it, so being a true experimentor...he installed it in his perfectly running 88 TPI IROC..it ran like total crap, tried to stall, shook like a junkie going through the DT's..
We've been brainstorming as to what might be going on and think we've hit upon an answer. I'll get with him tomorrow and see what he came up with over the weekend.

ct91rs · #9 02-28-2005, 09:52 PM

I put in a new ECM today, and I had to run a jumper wire from the ignition down to the soleniod, so now it cranks and the computer powers the fuel pump, it fires, but the timing seems to be off. (I had the distributer out and all the wires off) I don't think it is possible, but does anyone know if you can set the TPS without the car running?

will69camaro · #10 03-01-2005, 01:15 AM

I wish my friend that is an Expert on early GM fuel injection was a member here. I'm sure he could help with ANY TPI/TBI related questions. I'll ask him to join so he can share his wealth of knowledge on the subject for anyones questions. He's helped me with my problems and hasn't been wrong yet and he said he's 100% sure about all his info on the TPI setups (he swapped a TPI into his 86 elky).

William

Morley · #11 03-01-2005, 02:12 AM

Quote:

Originally Posted by ct91rs

I don't think it is possible, but does anyone know if you can set the TPS without the car running?

No, the only GM procedure for TPS setting is key on engine off.
Triple check your plug wire locations and distributor placement, this will cause a lot of what you are seeing.
IF..all of that is good there is a possibility that you got a hold of an early 86 TPI ecm & prom, the early proms (calpack) had a problem shared with the 85 prom chips. GM had them burned and then stored them (whereever) and didn't put the silver sticker over the UV erase window until they were ready to install them in the ECM. This exposed the PROM to light, one band of which is UV, and this started the eraseing process (VERY slowly) and once started it will not stop and slowly corrupts the information on the chip.

ct91rs · #12 03-01-2005, 08:55 PM

I appreciate the help guys. I pulled the cap back off and rotated the engine to TDC on cyl. 1. The distributer seems to be in the right place (rotor is facing cyl. 1 when I place the cap back on). I rechecked the plug wires and the firing order is ingrained in my head 1-8-4-3-6-5-7-2. If I rotate the dist. counter-clockways the engine has trouble turning over? and if I turn it too far clockways it won't fire at all. So I find a happy medium when it wants to start, but it doesn't want to keep going. I'm pretty sure that the fuel pressure is fine. (When I keep cranking it over I get a real strong gas smell. I have now replaced the computer, the pick-up coil, cap and rotor, wires, plugs, ignition coil, tested and the ignition module (it checks out fine). I don't think I would get it to fire if I was out 180, but I don't know. Thursday I'm going to put in another Electronic Spark Control module I have and see if that makes any difference. Any other ideas?

Chuck

Morley · #13 03-02-2005, 02:17 AM

Quote:

Originally Posted by ct91rs

Any other ideas?

Chuck

Do you know anyone that has an 87 or 88 TPI car? If so, see if you can borrow their Calpack and try it in your car. I am still leaning towards a bad prom/calpack.

BTW, it will "fire" if the dist is 180 out...fire right out the throttle body. You'll know if it is 180 out, but if it were off just 1 position on the rotor it would be hard to spot without doing what you did.

Don't get discouraged, you've done the hard part in getting it all swapped over and actually got to run, many have tried and failed and given up. Now you are just down to getting it to run "right".

ct91rs · #14 03-02-2005, 02:16 PM

Morley-
Your knowledge is greatly appreciated. Its nice to be able to get ideas from people who know something about TPI's. I'm wondering if you have any suggestions on who I should order a new prom/calpack from. I would prefer to have one programmed without the EGR, but I don't know if it's worth the cost. Should I just buy an aftermarket one from hypertech?

89IROC&RS · #15 03-03-2005, 11:14 AM

hmm, musta misunderstood the swap you were doing with the TPI.

but i also agree with morley that the Vats may be a problem that you circumnavigated by running direct power lines. I dont know if this would have a negitive effect on how the car ran though. Id have to look at my schematics that i dont have with me right now.

with the new system installed, have you run the car for codes???? just happen to think of this. could point you in the right direction.

Also, something to think about, are the wires going to your ICM (igntion control moduel) backwards? when working on my RS the plastic connector had broken off of the two wires that run from the distributor to the ICM so i had to guess which terminal they went on, well i got it backwards. the car ran, but it was not happy, the whole car was shaking it was spitting, i had the air cleaner off, and the car stalled and sprayed a two food tall mist of fuel back up and out of the throttle body. i switched the wires back around and it purred like a kitten. the symptoms you are describing sound a lot like what i was going through with my IROC when the ICM went bad. Its a cheap part, and i would suggest looking into that before buying a whole new ECM. www.gmpartsdirect.com has them for 47 bucks or something. takes about 4min to put it in.

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