94 Grand Prix SE 3.1 V6 127k backfires barely runs - Page 2

fritcr · #16 08-25-2009, 04:29 PM

Thanks Rich...that certianly makes sense. I can't get him to call me back. I will have to run up there and see if he has found anything. what a PITA.

Kelsey92504 · #17 08-30-2009, 10:04 PM

I had a 94 Grand Prix for a long time, and I once changed the ecm. When I pulled the ecm out of the car, there is a cover on that ecm, with a chip inside of it. If the ecm was changed and they swapped the chips from one to the other, than that would cause it. Late 80's to early 90's you were supposed to change the chip when you swapped ecm's. In 1994 and later you don't swap the chips. If this has been done, then you need to get a different ecm, and get it flashed to your car, or find the original chip for the ecm in your car. Good luck

fritcr · #18 08-31-2009, 06:32 PM

I got a hold of my mechanic and the timing chain is also fine. He said there is a little slack in it but not bad enough to cause a problem. He also said that he has messed with it so much that now it will not start and run at all. I'm really wondering if it is a problem with the ECM. Problem is...what do I do about it? If I get a new one it will not have a he chip will it? Or if I can find a 94 gp 3.1 can I swipe the ecm (chip included) that might fix it? I'm not sure what to do with it and my guy is moving his shop this week to a new location. He will tow it to a new location but I don't know what else to do.
Rob

fritcr · #19 08-31-2009, 07:15 PM

I found a used ecm for it on ebay but is that all I would need? If the chip was in it from the other car would that work in mine?
Sorry for all of the questions...
Rob

tblake · #20 09-02-2009, 01:37 AM

Find out if the chip is in it. If so, it could be worth a shot.

fritcr · #21 09-03-2009, 03:30 PM

Ok, I found the ECM on ebay it is out of a 94 4door just like mine and it does have the chip in it. Said it was running fine but smashed in the back. They just cut the wires and pulled it out...bracket and all. I can get it with shipping for $52.00 buy it now. Would you try this? I also called the dealer and got the part number for my car and it is the same number that's on this one. Dealer said they have to be programmed to my car but if it came from the same exact type car would it still have to be programmed? These ECU, ECM's or whatever will fit in several other cars that year with the 3.1.
As ALWAYS!!! Thanks soo much for everyone's help!
Rob

tblake · #22 09-03-2009, 08:18 PM

I do not know Rob, if it were mine, I might try it, but 52 is steep for a part just to throw at it.

I know 93 and older OBD1 Cars did not have to have the ECU programed, just swapped and and prom from the old one put into the new one. 94 was that great year where OBD2 was just starting to be produced. Might call 94's and 95's OBD 1.5. Its frustrating sometimes. Most all of them require a Tech2 to scan because they are actually OBD2 software based, but have an OBD1 plug or vice versa.

fritcr · #23 09-23-2009, 04:43 PM

Well update...mechanic got moved. I bought the ecm from ebay and he put it in today. No go...still won't run. I'm out of ideas and don't have more $$'s to put in it. Anything else I can try or have him try? I hate to junk it...at 127k it is still a pretty nice car if it would run.
Rob

tblake · #24 09-23-2009, 08:10 PM

Aw Shucks!

Just curious, did you ohm check the injectors? I think they may be batch fired in your car which means that if one is shorted internally the current that is supposed to go to the remaining injectors will all flow through the single one because current will always take the path of least resistance.

Ohm check all 6, but that may require removing the UIL. Or at the very least unbolting it, and angeling it upwards. You may want to replace its gaskets. Look for approx 12.2 ohms. Anything a little higher would be ok, but any of them less and they are shot.

troy1 · #25 09-24-2009, 04:25 PM

Where are the crank and cam sensors on this car? I'm wondering if the reluctor wheel loosened up or the teeth got damaged on either of them. I agree with the timing being off but it almost sound like its electrical not mechanical if everything the mechanic says is correct.

tblake · #26 09-24-2009, 08:13 PM

I know the newer 3100's had 2 crank sensors, one on the back of the block, and the other behind the balancer. I am not sure about the 94 ones though.

Should almost just tow this to someone who has a scan tool capable of watching OBD1 data streams and see what is up.

richtazz · #27 09-25-2009, 08:29 AM

The PCM's in the 94-95's are obd-1, but still need to be programmed. You cannot switch the PROM from your old one into a new one, or just install a used PCM as-is. If the PCM is changed out, it must be re-flashed to work properly.

On the crank sensor issue, your car does have 2 CKPS's, one in the back of the block and one behind the harmonic balancer. The one in the back of the block picks up it's signal from notches in the crankshaft. The one behind the balancer gets it's signal from reluctors in the balancer.

In review, in your first post you said you changed 2 crank sensors and 2 cam sensors. On the crank sensors, did you change the same one twice (and if so, which one), or one of each?

junk_jivin38 · #28 11-08-2009, 10:32 AM

i had a geo tracker with a similar prob...after tearing it apart 3 times,found the woodruff key holding the timing belt pulley to crankshaft had come out somehow and was ground into a little ball,leaving the pulley to randomly spin on the shaft...with a little dremel work and grinding on a new key,was able to fix it w/out replacing the shaft,which had damage to the keyway

i realize its a completely different vehicle,but worth looking at

fritcr · #29 11-25-2009, 11:55 AM

I still don't have my car back. I'm not sure I can answer all of these quesitons but will try. I know he said he had changed the crank shaft sensor 2 times. I figured he meant one of them. I didn't know there were 2.
Anyway, as of yesterday....he has put a different engine in the car out of a wrecked one. Said it runs pretty good but not just perfect yet. He was putting plugs and wires on it and will let me know. This has been a nightmare....now I will some HUGE bill here at Christmas to contend with. And to top it all off...my 16 y/o daughter backed into MY personal GP GT that drive everyday. It is in the shop and I don't know what it is going to cost me either. I'm having the rust issue below the gas door fixed at the same time. Merry Christmas to me.
Rob
Thanks for all of the adivce with this...I should have just went up and towed it somewhere else right off when he couldn't find what was wrong.

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