Coil and Injector ?
10-27-2006, 06:54 AM
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Coil and Injector ? First let me explain that I'm having backfiring issues and the motor runs really rough as though it's not firing on all cylinders. I think this may be caused by a bad opti cause it's making a grinding noise, but I could have other issues contributing to this problem.
I have an MSD Blaster coil. Last night I noticed that the red center portion moves about a 1/4 inch inside the magnet part. This seemed odd to me, so I pulled an old stock unit out that I had and it had no play at all. Is this play normal for MSD or might I have a bad coil.
I also unplugged each injector one at a time while car was running. This test raised a couple ?'s. When one injector was pulled, it made no difference in how the motor ran. The other 7 did. I did this twice to be sure in a different order each time and got the same result on the same injector.
Does the injector plug harness have a particular order in how it's plugged into the injectors. The two front injector plugs on each side will only reach a specific injector, but the rear two on each side could plug to either one. If there is a specific order, I'm wondering if these could have gotten crossed the last time the intake gasket was replaced.
I have an MSD Blaster coil. Last night I noticed that the red center portion moves about a 1/4 inch inside the magnet part. This seemed odd to me, so I pulled an old stock unit out that I had and it had no play at all. Is this play normal for MSD or might I have a bad coil.
I also unplugged each injector one at a time while car was running. This test raised a couple ?'s. When one injector was pulled, it made no difference in how the motor ran. The other 7 did. I did this twice to be sure in a different order each time and got the same result on the same injector.
Does the injector plug harness have a particular order in how it's plugged into the injectors. The two front injector plugs on each side will only reach a specific injector, but the rear two on each side could plug to either one. If there is a specific order, I'm wondering if these could have gotten crossed the last time the intake gasket was replaced.
10-27-2006, 08:22 AM
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Okay, coil ? answered. Spoke directly to MSD and they said there should NO play and if thwere is then the coil is bad. Fellow LT1 owners make note and always check the coil for play first. First time I've delt with it.
10-27-2006, 09:33 AM
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Interesting, I called MSD again to see if a different tech would give me the same answer and wouldn't you know it, a completely different answer. This one said that having some play is normal.
Called local parts store and had him pull one and it doesn't budge. Go figure.
Called local parts store and had him pull one and it doesn't budge. Go figure.
10-27-2006, 09:59 AM
#4
The MSD tech line is horible. I called them a few times to conferm if my coils resistance values ok, and I got a different answer everytime. They also have tech forums. I posted the same question and got still a different answer on there, so I just gave up.
I doubt there is anything wrong with the coil. All of the injectors are wired indpendent of the other injectors, so if you have found one that when unpluged doesnt change the the way the motor runs I would say that the cil with the problem.
If it is the same cil everytime I would assume you have a plug wire that is burnt. Take off your wires and check them for burns and holes. You could also check the resistance of the injector, the wires running to the injector, and compair them to other injectors from a cil that is firing. Also look for vacume leaks around the intake manifold, they can also cause odd misfires.
If that checks out ok, I would pull the valve cover on the side of the bad cil and check to make sure your valvetrain is still working proberly. Sounds odd but its happend to plenty of people, but you my have broken a rocker arm stud.
If that doesnt solve anything I would then move on to coil/ opti problem. Check the opti harness, and all other associated wiring for problems.
I doubt there is anything wrong with the coil. All of the injectors are wired indpendent of the other injectors, so if you have found one that when unpluged doesnt change the the way the motor runs I would say that the cil with the problem.
If it is the same cil everytime I would assume you have a plug wire that is burnt. Take off your wires and check them for burns and holes. You could also check the resistance of the injector, the wires running to the injector, and compair them to other injectors from a cil that is firing. Also look for vacume leaks around the intake manifold, they can also cause odd misfires.
If that checks out ok, I would pull the valve cover on the side of the bad cil and check to make sure your valvetrain is still working proberly. Sounds odd but its happend to plenty of people, but you my have broken a rocker arm stud.
If that doesnt solve anything I would then move on to coil/ opti problem. Check the opti harness, and all other associated wiring for problems.
10-27-2006, 10:11 AM
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Originally Posted by foggedz
The MSD tech line is horible. I called them a few times to conferm if my coils resistance values ok, and I got a different answer everytime. They also have tech forums. I posted the same question and got still a different answer on there, so I just gave up.
I doubt there is anything wrong with the coil. All of the injectors are wired indpendent of the other injectors, so if you have found one that when unpluged doesnt change the the way the motor runs I would say that the cil with the problem.
If it is the same cil everytime I would assume you have a plug wire that is burnt. Take off your wires and check them for burns and holes. You could also check the resistance of the injector, the wires running to the injector, and compair them to other injectors from a cil that is firing. Also look for vacume leaks around the intake manifold, they can also cause odd misfires.
If that checks out ok, I would pull the valve cover on the side of the bad cil and check to make sure your valvetrain is still working proberly. Sounds odd but its happend to plenty of people, but you my have broken a rocker arm stud.
If that doesnt solve anything I would then move on to coil/ opti problem. Check the opti harness, and all other associated wiring for problems.
I doubt there is anything wrong with the coil. All of the injectors are wired indpendent of the other injectors, so if you have found one that when unpluged doesnt change the the way the motor runs I would say that the cil with the problem.
If it is the same cil everytime I would assume you have a plug wire that is burnt. Take off your wires and check them for burns and holes. You could also check the resistance of the injector, the wires running to the injector, and compair them to other injectors from a cil that is firing. Also look for vacume leaks around the intake manifold, they can also cause odd misfires.
If that checks out ok, I would pull the valve cover on the side of the bad cil and check to make sure your valvetrain is still working proberly. Sounds odd but its happend to plenty of people, but you my have broken a rocker arm stud.
If that doesnt solve anything I would then move on to coil/ opti problem. Check the opti harness, and all other associated wiring for problems.
I called the local auto parts store and asked them to pull a coil and it didn't move at all. After work I think I'll pick up the new coil and switch it. I'll also change the plug wire with a good old one I have to check that.
Last edited by mack; 10-27-2006 at 10:44 AM.
10-27-2006, 10:47 AM
#6
The plug wires being new makes me think thats the problem even more. Usually after plug wires being changed is when you see the most problems. Wires are going to hang slightly different when changed.
Most of the things I recomended to check, except for maybe vac leaks, can happen with out any previous signs of problems to new or old motors.
Most of the things I recomended to check, except for maybe vac leaks, can happen with out any previous signs of problems to new or old motors.
10-27-2006, 01:18 PM
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Alright, I'll go over them again. I think I may change the ignition control module while I'm doing the coil. I'm still going to pull the opti and check the length of the cam dowl to be sure the engine builder didn't overlook the fact that most new cams have a longer dowl pin that will destroy opti's if not cut. This would explain 3 opti's in 27,000 miles.
