appreciate it, would greatly help so that I can gut some of this junk wiring...just looking for an ecu right now...hopefully I can find one close to home.

 

ok... so here's where I'm at now. I found an original GM replacement ECM, picked it up last night...it's from an 86 IROC w/305 TPI...same PN 1226870. Put it in the car and it wanted to start but wouldn't stay running, changed the prom chip and she fired right up and sounded GREAT. About 45 seconds later the ECM let the magic smoke out. Opened it up and the same chip is fried, I don't know where to start looking for the cause. Essentially all the parts replaced are OEM replacements with the exception of the coil and optima red-top battery. I checked the wiring and can't find any breaks or opens to cause a short.

Any help is appreciated, Thanks in advance

 

I got the car running finally, however it will only idle in the driveway. I can get it to rev up if I hit the throttle in park or neutral, but if I stick it in drive it starts acting like a miss or like it's got a cam. I don't know what cam is in the car, I would guess it's the stock cam, but the PO did a lot of crazy stuff to the car as I've said prior in the post. I don't know what would cause the issue...it will idle just fine, but not drive worth a crap. I was curious about the transmission wiring, I read in another post that there are differences in the trans between years, the one in the car is out of an 87 TA with the 350 tpi. I didn't know if that might be part of the drive issue.

As always any help is appreciated.

Oh, before I forget...I got an ecm from a 6 cyl 2.8 mpfi car, the ecm number was the same (1226870) and I put my prom into it, just didn't know if that would be an issue as well. I have a few different proms that I was looking through from my crap ecms, was unsure if I had to use the one out of my car originally or if another one would work, with the exception of the v6

 

I am gong to take a stab at this. I will bet you have a shorted Injector or shorted injector harness. The Injectors are High impedance 14-16 ohms resistance. If the injectors are low impedance or one is shorted, this might be causing the injector driver chip/transistor on the board to go up in smoke. You could also have a stuck injector due to varnish build up in the fuel system. That High octane gas could have broken the varnish loose in the fuel lines and raised all manner of hell with the fuel injectors.

When you say the PO did a lot of crazy stuff, what will it take to "undo" all that? If you have wires running everywhere, that is the first thing you need to fix. I would get a wiring diagram and start checking every component and the related wiring to see if there is some kind of "southern engineering" going on! Then I would unhook all the extraneous BS PO installed "repairs"! You cannot just keep throwing ECMs at the car. SOMETHING is burning them up. 85 model cars have an ESC Module, just like the carbureted cars the ECM does not control the spark timing as in later cars.

Have you jumpered the ALDL connector and tried to pull the codes from the ECM using the SES Light?

 

I understand that I can't just start throwing ecm's in the car...I found the issue that was burning them up. I had a bad egr vacuum solenoid that was literally burnt up, replaced it and stopped burning up the ecm. I agree with the fact that the Torco probably loosened some crap up. My question at this point is why it's running like dump, as in backfiring through the intake and generally crappy performance off the line. I can't get it a block from my house.

The only code that I'm getting is from the knock sensor when the wire gets disconnected ( I have it rigged since the PO cut the wire for some reason), but as soon as I get it reconnected it goes away. I have the wiring all back to the way it should be, or as close as I can get it with the a/c and the a.i.r. deleted out of the car, with the exception of the evap canister solenoid...can't find the wiring. All of the injectors ohm out at between 16.2 and 16.4

Could the trans be an issue since it's from an 87, or maybe the ecm from the 2.8 mpfi...I thought that as long as the ecm #'s are the same that the only thing that needed to change is the prom...

 

I doubt the Trans. Did you use the original VSS from the transmission? Check the VSS Signal.

You are correct, if the ECM is the same number then the EPROM change should be all that is necessary. My 7730 ECM was originally out of a 2.5 4 cyl car.

It is possible that all that "crap" from the fuel system has made its way to the injectors and plugged the screens and reduced the flow. If you had a mechanically obstructed injector, it might not set a code.

Is the TPS Voltage properly adjusted? Should read .54 v w/ throttle closed and rise smoothly up to about 5.0 v at WOT.

Have you had a timing light on the car and actually checked the timing? Set the base timing at 6 BTDC with the timing bypass disconnected. Reconnect the connector and make sure that the timing mark moves to the advance direction several degrees, maybe as much as 20 degrees.

What about the MAF sensor. There are checks for that as well. If is is not working correctly, that could cause the issue as well. I do not have a MAF car, so I have not spent a lot of time studying the MAF Circuit. This is a pretty complex circuit and the diagnostics are complex as well. Others might advise on this who have more experience with MAF cars. I do know, if you have a MAF sensor, it must operate correctly.

 

as far as the vss, it's mechanical. The transmission from the 87 TA was an electrical, I changed the tail shaft to the one from my 85 trans.

I will go and check all of the injectors again just to make sure that I don't have a bad one or two.

the last time that I checked the tps and the maf I was getting the right readings, but as anything else when working with a 25 year old car, you change one thing and four more things show up...

I would hate to take it to a dealership...I could only imagine what they would charge, if there was actually anyone around in any of the dealerships around here that knew anything about the tpi. The last comment I got from a tech at the local dealership was that the tpi is just a crappy lt1...maybe...but what came first?

 

I think that the VSS for 1985 cars was a 2000 pulse unit on the back of the speedometer. I forgot about that.

I have one word for that so called "tech" at the local dealership "DUMBASS" (that is one word, right?)! TPI is so simple, have you read any of the tech books that outline the operation? Get rid of the MAF and you eliminate most of the issues. The PO is the most dangerous part of the equation! And the local DA mechanic. Other than neglect, ignorant mechanics and deterioration there is not much that goes wrong. You have looked for vacuum leaks, cracked hoses, etc? I keep going back to the Plugged up injector screens or tips. If the injectors are plugged, nothing that you do is going to help. I have seen a lot of headaches caused by varnish in the fuel system! Good Luck!

 

Ok, here's the update skinny... I found my EGR solenoid fried so badly that it was grounding out on the intake, which was the issue with frying my ECM. I found a "good" ecm from a v-6 car and swapped my prom into it (same part #)...the car fired right up and was running great at an idle and had very good throttle response, went to pull it out of the driveway and BLAHHH (literally the sound), went through the trans and made sure that everything was good, wiring, valve bodies and solenoids (trans from an 87 T/A 350 tpi) everything appears to be right.

Back to the engine...got it fired back up and idled rough, evened out, then just slowly died...ran for approx 35 min on idle and then slowly started dropping until it quit... will not fire now, no spark, lots of fuel...other than the ecm being bad again, no idea on where to begin to start...everything is new, dist., coil, cap and rotor, iac, esc mod, spark plugs and wires...I know there's more, just been a while since I had some time to dig into the car...had to change the heater core since it decided to develop a leak.

As always, any help is appreciated.

 

at this point if I can't get this tpi running properly, I was wondering about an ltx conversion and what that would take...I have an lt1 from a 95 caprice cop car (not aluminum heads), all the wiring, ecu, engine is complete from maf to oil pan. I was unsure what wiring I would have to tap into, or how difficult it would be. I have heard that if you drill a hole and run the stock dist. you can use the stock ecu... I was wondering how difficult it would be to run the motor with the optispark.

Just looking for options...thanks for the help.

 

Wow this sounds like my issue only thing is I'm running a carburetor...I thought that route would eliminate issues like this...I've done everything, from checking plugs replacing coils checking rotor caps tdc fuel, timing and still no start...the only thing I didn't do was advance it, which don't make sense cause if I advance wouldn't I be still in the intake stroke and cause engine harm??? I don't wanna take over this post because the originator still didn't find his issue and I read this whole post tryna see did I miss anything

 

Nope...didn't miss anything. Been busy on the other project... 79 Porsche 928 euro...don't shoot me...lol. Just got back at it a few days ago...still gutting po wiring...will post more since the weather is getting nice again.

Tia
Josh

 

Got back at it today. Got the car fired up, it's running like dump, but it's running now. I may have to see if the IAC is set properly, it will not stay idling, but if I keep my foot on the throttle or finger at the TB it will stay running at about 1200 rpm. I noticed that there is some discoloration starting inside the ECM near the same chip that kept frying, so I'm trying to track some final stuff down before I fry this ECM too. I have another ECM waiting just incase...here we go...starting to get elbow deep again. Any input is appreciated.

Thanks,
Josh

 

Hey how did you make out with this?

 

No dice...she's still dead. Busy schedule and crappy weather have not allowed me a whole lot of time.

 

Dont keep chucking ecms at it. You have some power feed grounding out somewhere. Or a bad sensor thats shorted. Take a few steps back and double check all your wiring. Make sure your power and ground off the battery are good. Make sure you have a solid chassis to motor ground. <--- ive seen cars go batshit when the ground strap near the cowl <inside engine bay by/below the Pass side wiper> gets disconnected or rotted. Double check the 3 relays by the brake booster and make sure there not arcing or rotting at the connectors. a quick visual inspection of the connectors can sometime help see arcs. CHECK YOUR COOLANT SENSOR WITH A DVM. Double check the IAC to make sure its not shorted etc. Any motor or hi imped devices usually blow up computers like what your having. <an injector takes alot to drive, the IAC takes alot to drive> You got to have a wire thats shorted to ground that frying your pcm. Check the power feeds to each sensor. Most of them should be around 5 volts. They should all be around the same voltage. You have any pics of your engine bay? Wiring Harness? PCM parts that are burning?

A little tip to help with the ground you can take some jumper cables and connect them to ground. Attach the black and red on one side to the negative cable on the battery <with the cable connected> and then atttach the red on the opposite side to the motor and then the black to the body. remember only the NEGATIVE/GROUND side. If you have a bad ground cable/etc its a quick way of testing that.

 

Take pics. Post them. the AC/air delete. Any evap things missing. Etc. Most of the systems your complaining about have the same power feed. So guaranteed one of those <disconnected wires> were prolly cut in a bad manner. or maybe a pcm input is getting voltage applied to it. PICS PICS PICS