6th Gen ('00-'05): Monte running rough under load?????
#21
05-23-2017, 10:56 AM
P0300 is random/multiple misfire. This indicates the failure is within a primary ignition component like the ICM or PCM. Heat is the worst enemy of any electrical component, especially the ICM. There's supposed to be heat sink lube between the coil packs and the ICM to shield the ICM from heat generated by the coil packs. ICM's degrade quickly without that insulation. I'm not suggesting the fire alone melted out the lube and/or damaged the ICM, but age plays a factor too and it might have been just enough to push it over the edge. I wouldn't kick yourself too hard if you have to take it to a shop. You've given the a car a second life for minimal $. Sometimes two heads are better than one.
Good luck and please keep us posted Steve
Good luck and please keep us posted Steve
#22
05-23-2017, 11:41 AM
Don't confuse heatsink lube (compound) (AKA- "Thermal Compound) with Di-electric grease.
The purpose of heatsink lube is to act as an insulator to displace heat generated by the coil that could damage the ICM. There is no direct electrical connection where the lube gets applied. Just smear it around on the bottom surface of the ICM. You may notice some dried residue on that surface that is lube that was applied at the factory.
Video:
The purpose of heatsink lube is to act as an insulator to displace heat generated by the coil that could damage the ICM. There is no direct electrical connection where the lube gets applied. Just smear it around on the bottom surface of the ICM. You may notice some dried residue on that surface that is lube that was applied at the factory.
Video:
Last edited by plumbob; 06-18-2017 at 12:40 PM.
#24
06-18-2017, 03:39 AM
I might be gaining a little on this problem.
Today I drove the car and it was running bad as usual. So, tonight I messed with it again. Still the codes I am getting are P0300 and P0131. I decided to start back at the beginning and go old school with it. I cleared the codes and with it idling checked every connection and vacuum line again. No problems found there, each connection looked good and when I moved the connections the idle did not change. It will run smooth then every few seconds miss a beat or two. I remembered that on a couple of occasions I did get a P0304 code, so I checked out cylinder 4. The wiring to the injector look good, and when wiggled and tugged on there was no change in the running. So I did what we did back in my days in a shop and pulled the plug wire to see what it did to the running of the engine. As expected it had a steady miss at idle. I had ran the engine for an hour or so by then so it was too hot to pull the plug, I will do that tomorrow. Anyway, I ran the engine with the number 4 plug wire unplugged and the lug on the coil covered with a rubber cap for safety. I ran it that way until the engine light came back on. I then pulled the codes again. I suspected that I would get a P0304 code, but no, I got P0300. I wanted to watch the plug wires in the dark to see if I could detect any arcing, but with the stupid headlights always on I could not get it dark enough to see any lightening show. So, I re routed the plug wire from under the engine mount to across the top of the engine keeping as much of it as possible away from anything metal or grounded. Started it and it ran better. It still has a slight miss every few seconds. I can just see the engine shudder slightly and can hear the exhaust change for one hit. I took it for a drive and it ran 99 percent better. I did not experience the hard miss and lack of power we have been getting. When I floored it to accelerate it was surging and cut out slightly but under normal driving condition it ran great. Of course once in a while it did run good, so it might just be another trick. I will see tomorrow when it is hot outside again.
If this did solve the problem then it is time for plug wires. It is possible that the fire damaged the number 4 wire. It looks good, but it doesn't take much of a crack in the insulation to cause problems.
Of course this car is possessed so tomorrow it might start to miss again. When the engine is cool tomorrow I will pull that plug and see what it looks like.
Today I drove the car and it was running bad as usual. So, tonight I messed with it again. Still the codes I am getting are P0300 and P0131. I decided to start back at the beginning and go old school with it. I cleared the codes and with it idling checked every connection and vacuum line again. No problems found there, each connection looked good and when I moved the connections the idle did not change. It will run smooth then every few seconds miss a beat or two. I remembered that on a couple of occasions I did get a P0304 code, so I checked out cylinder 4. The wiring to the injector look good, and when wiggled and tugged on there was no change in the running. So I did what we did back in my days in a shop and pulled the plug wire to see what it did to the running of the engine. As expected it had a steady miss at idle. I had ran the engine for an hour or so by then so it was too hot to pull the plug, I will do that tomorrow. Anyway, I ran the engine with the number 4 plug wire unplugged and the lug on the coil covered with a rubber cap for safety. I ran it that way until the engine light came back on. I then pulled the codes again. I suspected that I would get a P0304 code, but no, I got P0300. I wanted to watch the plug wires in the dark to see if I could detect any arcing, but with the stupid headlights always on I could not get it dark enough to see any lightening show. So, I re routed the plug wire from under the engine mount to across the top of the engine keeping as much of it as possible away from anything metal or grounded. Started it and it ran better. It still has a slight miss every few seconds. I can just see the engine shudder slightly and can hear the exhaust change for one hit. I took it for a drive and it ran 99 percent better. I did not experience the hard miss and lack of power we have been getting. When I floored it to accelerate it was surging and cut out slightly but under normal driving condition it ran great. Of course once in a while it did run good, so it might just be another trick. I will see tomorrow when it is hot outside again.
If this did solve the problem then it is time for plug wires. It is possible that the fire damaged the number 4 wire. It looks good, but it doesn't take much of a crack in the insulation to cause problems.
Of course this car is possessed so tomorrow it might start to miss again. When the engine is cool tomorrow I will pull that plug and see what it looks like.
#25
06-18-2017, 12:36 PM
I might be gaining a little on this problem.
Today I drove the car and it was running bad as usual. So, tonight I messed with it again. Still the codes I am getting are P0300 and P0131. I decided to start back at the beginning and go old school with it. I cleared the codes and with it idling checked every connection and vacuum line again. No problems found there, each connection looked good and when I moved the connections the idle did not change. It will run smooth then every few seconds miss a beat or two. I remembered that on a couple of occasions I did get a P0304 code, so I checked out cylinder 4. The wiring to the injector look good, and when wiggled and tugged on there was no change in the running. So I did what we did back in my days in a shop and pulled the plug wire to see what it did to the running of the engine. As expected it had a steady miss at idle. I had ran the engine for an hour or so by then so it was too hot to pull the plug, I will do that tomorrow. Anyway, I ran the engine with the number 4 plug wire unplugged and the lug on the coil covered with a rubber cap for safety. I ran it that way until the engine light came back on. I then pulled the codes again. I suspected that I would get a P0304 code, but no, I got P0300. I wanted to watch the plug wires in the dark to see if I could detect any arcing, but with the stupid headlights always on I could not get it dark enough to see any lightening show. So, I re routed the plug wire from under the engine mount to across the top of the engine keeping as much of it as possible away from anything metal or grounded. Started it and it ran better. It still has a slight miss every few seconds. I can just see the engine shudder slightly and can hear the exhaust change for one hit. I took it for a drive and it ran 99 percent better. I did not experience the hard miss and lack of power we have been getting. When I floored it to accelerate it was surging and cut out slightly but under normal driving condition it ran great. Of course once in a while it did run good, so it might just be another trick. I will see tomorrow when it is hot outside again.
If this did solve the problem then it is time for plug wires. It is possible that the fire damaged the number 4 wire. It looks good, but it doesn't take much of a crack in the insulation to cause problems.
Of course this car is possessed so tomorrow it might start to miss again. When the engine is cool tomorrow I will pull that plug and see what it looks like.
Today I drove the car and it was running bad as usual. So, tonight I messed with it again. Still the codes I am getting are P0300 and P0131. I decided to start back at the beginning and go old school with it. I cleared the codes and with it idling checked every connection and vacuum line again. No problems found there, each connection looked good and when I moved the connections the idle did not change. It will run smooth then every few seconds miss a beat or two. I remembered that on a couple of occasions I did get a P0304 code, so I checked out cylinder 4. The wiring to the injector look good, and when wiggled and tugged on there was no change in the running. So I did what we did back in my days in a shop and pulled the plug wire to see what it did to the running of the engine. As expected it had a steady miss at idle. I had ran the engine for an hour or so by then so it was too hot to pull the plug, I will do that tomorrow. Anyway, I ran the engine with the number 4 plug wire unplugged and the lug on the coil covered with a rubber cap for safety. I ran it that way until the engine light came back on. I then pulled the codes again. I suspected that I would get a P0304 code, but no, I got P0300. I wanted to watch the plug wires in the dark to see if I could detect any arcing, but with the stupid headlights always on I could not get it dark enough to see any lightening show. So, I re routed the plug wire from under the engine mount to across the top of the engine keeping as much of it as possible away from anything metal or grounded. Started it and it ran better. It still has a slight miss every few seconds. I can just see the engine shudder slightly and can hear the exhaust change for one hit. I took it for a drive and it ran 99 percent better. I did not experience the hard miss and lack of power we have been getting. When I floored it to accelerate it was surging and cut out slightly but under normal driving condition it ran great. Of course once in a while it did run good, so it might just be another trick. I will see tomorrow when it is hot outside again.
If this did solve the problem then it is time for plug wires. It is possible that the fire damaged the number 4 wire. It looks good, but it doesn't take much of a crack in the insulation to cause problems.
Of course this car is possessed so tomorrow it might start to miss again. When the engine is cool tomorrow I will pull that plug and see what it looks like.
Also consider the brand of the current plugs. These 3800 engines only like ACDelco Irridiums or NGK Platinium. Also, use ACDelco plug wires.
#26
06-19-2017, 03:45 AM
The plugs are Autolite. At least they are not Champion plugs!
Tomorrow I am going to try to get to town and pick up a set of plugs and plug wires.
Drove the car today a little. It still has a miss, but it is running different than it has been. I don't know if it is better, but it is different. Instead of a hard misfire every few seconds under load, it is a steady miss under load. It doesn't buck like it did, but it is still missing. The code is still p0300, so still no idea what cylinder is missing the most.
I was able to pull the number 4 plug. It is not fouled out. It almost looks like it is running lean.
Tomorrow I am going to try to get to town and pick up a set of plugs and plug wires.
Drove the car today a little. It still has a miss, but it is running different than it has been. I don't know if it is better, but it is different. Instead of a hard misfire every few seconds under load, it is a steady miss under load. It doesn't buck like it did, but it is still missing. The code is still p0300, so still no idea what cylinder is missing the most.
I was able to pull the number 4 plug. It is not fouled out. It almost looks like it is running lean.
#27
06-19-2017, 03:54 AM
I also used carb cleaner this morning when the engine was cold. Ran it while I sprayed the carb cleaner around the intake gasket and on all vacuum connections. The idle did not change, so I am ruling out vacuum leak or intake gasket leak.
#28
06-20-2017, 09:38 PM
Well, it looks like I finally got this thing running smooth. I replaced the spark plug wires and got a little improvement, but it was still running a little rough. I replaced the coils and the ICM and so far it is running good.
Next I need to replace the rear struts and find out why it keeps telling us we have a low tire.
Next I need to replace the rear struts and find out why it keeps telling us we have a low tire.