85 running rough
Thread Starter
Racer
Joined: Sep 2003
Posts: 322
Likes: 0
From: Gap PA
The only code I got was 33, and that was for the MAF sensor, which I unplugged at one point just to check that.
The code just hasn't cleared itself yet.
So no codes....I am going to go the fuel route next.
Also, using a tip I learned at a young age, I used a paper clip and some dilectric (I know I didn't spell that right) grease and shorted out each spark plug boot at the spark plug, using a test light. I had spark at all 8 cylinders. I don't think I have an electrical problem.
The code just hasn't cleared itself yet.
So no codes....I am going to go the fuel route next.
Also, using a tip I learned at a young age, I used a paper clip and some dilectric (I know I didn't spell that right) grease and shorted out each spark plug boot at the spark plug, using a test light. I had spark at all 8 cylinders. I don't think I have an electrical problem.
Last edited by 85RIT; Jan 15, 2007 at 05:03 PM.
Thread Starter
Racer
Joined: Sep 2003
Posts: 322
Likes: 0
From: Gap PA
Borrowed a compressions tester, and all cylinders were between 135 and 145 PSI. The rule is the lowest has to be no more then 30% less then the highest, so I passed that test.
What I did find was that when I took the plugs out, the left side (2,4,6,8) plugs were a bit wet, and smelled a fuel. The right side (1,3,5,7) were dry as a bone and had no evidence of fuel on them. 1 had a bit of oil on it, I know I have some leaky valve seals, so that did not concern me.
What I'm not sure of is how wet is too wet and how dry is too dry
I guess this all leads back to a possible fule problem.
What I did find was that when I took the plugs out, the left side (2,4,6,8) plugs were a bit wet, and smelled a fuel. The right side (1,3,5,7) were dry as a bone and had no evidence of fuel on them. 1 had a bit of oil on it, I know I have some leaky valve seals, so that did not concern me.
What I'm not sure of is how wet is too wet and how dry is too dry
I guess this all leads back to a possible fule problem.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
I think you have lead us to believe what the problem is. The cylinder compression test is fine...tired engine, but fine. Previously you stated the right exhaust manifold was hotter than the left. From what you just stated about the plugs all being wet on the left and dry on the right, I believe you have a electical problem with the fuel injector wiring. Sounds like the ECM is keeping a constant ground on the left bank injectors keeping them open the whole time the engine is running (when the ECM is getting refrence pulses from the distrubitor).
I will suggest to purchase a noid light to test the injector wiring connectors. And also a fuel pressure guage to see what the fuel pressure is and how it reacts when the key is "on" and then two seconds after. Also what the fuel pressure is when cranking and at idle and under load.
I think you will find with the noid light that the left side injector wiring stays lit, where as the right side injector wiring blinks.
I will suggest to purchase a noid light to test the injector wiring connectors. And also a fuel pressure guage to see what the fuel pressure is and how it reacts when the key is "on" and then two seconds after. Also what the fuel pressure is when cranking and at idle and under load.
I think you will find with the noid light that the left side injector wiring stays lit, where as the right side injector wiring blinks.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Wanted to add that when all the spark plugs on that injector bank are wet is usually indicates a injector wiring problem. If one or two were wet, I would not suggest that and think a possible couple leaky injectors.
Thread Starter
Racer
Joined: Sep 2003
Posts: 322
Likes: 0
From: Gap PA
I actually had it backwards.
The RIGHT side plugs were wet, and the LEFT side dry.
The RIGHT side manifold was hot, and the LEFT side cold.
I think your theory is correct anyway, and I will proceed and let you know.
Thanks for all your help, and being patient with me. I wish I had more time to spend with the car but I don't.
The RIGHT side plugs were wet, and the LEFT side dry.
The RIGHT side manifold was hot, and the LEFT side cold.
I think your theory is correct anyway, and I will proceed and let you know.
Thanks for all your help, and being patient with me. I wish I had more time to spend with the car but I don't.
Thread Starter
Racer
Joined: Sep 2003
Posts: 322
Likes: 0
From: Gap PA
OK.
I tested the injector wire harness. I do have power to all the injectors (per test light and checking fuses) but the LEFT SIDE (which had dry plugs and a cold manifold) is not working.
When the noid light was hooked up it was not blinking, thus meaning the ECM was not telling the injectors to open.
It is my understanding that the ECM does not supply power to the injectors, just the signal to get them to open.
So either I have a short in the light blue wire (straight out of the FSM diagram), or the ECM is not supplying signal to the injectors.
Anyone down this road before?
I tested the injector wire harness. I do have power to all the injectors (per test light and checking fuses) but the LEFT SIDE (which had dry plugs and a cold manifold) is not working.
When the noid light was hooked up it was not blinking, thus meaning the ECM was not telling the injectors to open.
It is my understanding that the ECM does not supply power to the injectors, just the signal to get them to open.
So either I have a short in the light blue wire (straight out of the FSM diagram), or the ECM is not supplying signal to the injectors.
Anyone down this road before?
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
I would recheck the injector fuses or switch them out, just to cover that. Then if the same, I would trace down a possible short in the wiring in the engine bay and at the ECM. Make sure the 4 wire connection at the distrubitor is sending the refrence pulses. I have read of the injector driver in the ECM going bad. The ECM grounds the injector wiring when the refrence pulses are recieved from the distrubitor.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Check your pickup coil...the ECM gets the signal from the pickup coil. Even in the cheapo POS Haynes manual it tells how to ohm the Pickup coil and check the wiring associated with it.These are batch fired injectors, follow any injector wire back to where they all connect and check the connection associated with the bank in question.
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Thread Starter
Racer
Joined: Sep 2003
Posts: 322
Likes: 0
From: Gap PA
I had information about the injector wiring going to the ECM out of an '86 FSM. It said that connection D1 has a light green wire out of it to the left side injectors, while D15 has a light blue wire out of it to the right side injectors. I was supposed to have power at D1 and D15 with the key on, but I do not. I have power at certain C prongs, but not one D prong
Is this correct? I dropped my ECM and I had a black wire with a white tracer going to D1. I could not tell which one went into D15.
Is this correct? I dropped my ECM and I had a black wire with a white tracer going to D1. I could not tell which one went into D15.
Thread Starter
Racer
Joined: Sep 2003
Posts: 322
Likes: 0
From: Gap PA
www.chevythunder.com was where I found the correct wire harness information.
I found that all of the prongs on the D group had no power with the key on, saying basically that the ECM was bad. Then I accidently shorted two prongs out and I think I fried it.
I had to get a new one anyway, so oh well.
The D group of prongs had the wires for the left side injectors, which were not firing, so I think I have found my problem.
Thanks to all who helped.
I hate electrical problems. You can't fix them with a hammer.
I found that all of the prongs on the D group had no power with the key on, saying basically that the ECM was bad. Then I accidently shorted two prongs out and I think I fried it.
I had to get a new one anyway, so oh well.
The D group of prongs had the wires for the left side injectors, which were not firing, so I think I have found my problem.
Thanks to all who helped.
I hate electrical problems. You can't fix them with a hammer.
Thread Starter
Racer
Joined: Sep 2003
Posts: 322
Likes: 0
From: Gap PA
I just looked quick on Ecklers, and its 99 bucks with a 70 dollar core charge. You don't get the 70 bucks back if they can't rebuild your ECM.
Is there anything that I need to swap over between my old and new ECM?
Is there anything that I need to swap over between my old and new ECM?
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
I belive you can get one reome NAPA. Also I saw one in the parts/wanted section for $40. Also call some salvage yards or ebay.
You will need to remove your chip. Two 1/4" screws hold the plate on, then you just push the tabs down beside the chip. The tabs read "PUSH".
You will need to remove your chip. Two 1/4" screws hold the plate on, then you just push the tabs down beside the chip. The tabs read "PUSH".
Thread Starter
Racer
Joined: Sep 2003
Posts: 322
Likes: 0
From: Gap PA
All right folks, I was being a huge dummy.
The ECM does not supply power. To complete the curcuit, power runs from the fuse, to the injector, then to the ECM. I was checking the prongs in the ECM, not the wires in the plug for power.
So I now have to make sure power is getting to the ECM from the injectors. I just have to check the plug with the key on.
The reason why I had power at the ECM prong C16 with the key on is because it was getting 12V from the battery because the other plug was still plugged into the ECM. And now, I accidently shorted C16 out with something, so I have to check all of my fuses that protect the ECM.
Even with this, if I do have power from the injectors to the ECM plug, that means the ECM is not supplying signal and its bad anyway. If I don't have 12V from the injectors, its a simple short some where, and a jumper will be run.
I just hope I didn't fry my ECM when that maybe wasn't the problem.
I will keep you guys posted.
I guess we all live and learn.
The ECM does not supply power. To complete the curcuit, power runs from the fuse, to the injector, then to the ECM. I was checking the prongs in the ECM, not the wires in the plug for power.
So I now have to make sure power is getting to the ECM from the injectors. I just have to check the plug with the key on.
The reason why I had power at the ECM prong C16 with the key on is because it was getting 12V from the battery because the other plug was still plugged into the ECM. And now, I accidently shorted C16 out with something, so I have to check all of my fuses that protect the ECM.
Even with this, if I do have power from the injectors to the ECM plug, that means the ECM is not supplying signal and its bad anyway. If I don't have 12V from the injectors, its a simple short some where, and a jumper will be run.
I just hope I didn't fry my ECM when that maybe wasn't the problem.
I will keep you guys posted.
I guess we all live and learn.
