90 eating ignition modules
08-05-2007, 05:48 PM
#1
Safety Car
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90 eating ignition modules
okay i have went thru 4 modules in as many weeks (at the track). car runs fine then starts to miss then dies and won't start. change module and i runs fine agian. then i make a couple laps and she starts to miss agian. then it dies. back up a couple sentences and read agian...and then one more time......and you are where i am at today.........i dont get it. new rotor and capand even bought a coil this time but still same thing....HELP!!!! i am sick of paying to race and wrenching/watching the whole time
08-05-2007, 07:35 PM
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what you mean by stock? i have not changed anything i have just replaced parts. new plugs, wires, cap, rotor, modual and coil at this point. do 90 have a electronic spark modual. the older cars and the 90 zr1 had one mounted to the blower fan housing but there no bracket of wireing on mine. i assume it becaus the 90 a sd not a maf car.....
08-05-2007, 07:56 PM
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I've read when ever you replace a defective Ignition Control Module, you should also replace the Pick Coil. (Bad Pickup Coil can take out the Ignition control Module).
Problem is to replace the Pick Coil you need to press off the distributor drive gear and shaft. If you don't have the proper tools it's easier to purchase a rebuilt distributor.
Problem is to replace the Pick Coil you need to press off the distributor drive gear and shaft. If you don't have the proper tools it's easier to purchase a rebuilt distributor.
Last edited by Hooked on Vettes; 08-05-2007 at 08:00 PM.
08-05-2007, 09:14 PM
#7
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A couple of items:
1) Make sure you are using heat conducting grease, not heat insulating grease, under the module. (Not saying you are doing the wrong thing. I'm just mentioning it for readers that might not know there is a difference.)
2) I have to respectfully disagree with needing to replace the pickup coil. In an EST distributor, the ECM controls the dwell. The pickup coil simply supplies RPM and engine position information to the ECM. I would expect that if there were problems with the pickup coil, the ECM would interpret this as a wildly varying RPM, and flag a code. However, there's always a one in a million chance that the pickup coil could be damaged without the ECM detecting it.
3) The ESC module for your vehicle, IIRC, was integrated into the ECM around your model year. The knock sensor wire goes directly to the ECM.
4) Are you replacing the parts with original Delco parts, or aftermarket parts?
5) Is there leakage path (corrosion) between the high voltage coil lead and the wire that goes to the C- on the distributor? A conductive path would try to put mucho voltage into the module switching transistor. Similarly, if there were a conductive path between the C- lead, and the white/green pickup lead, this could cause some excess voltage getting into the module input lines. The front end circuit is rather robust, but this is still not a good thing.
That's about all I can think of at the moment. Keep us updated on your testing results.
ps: Greetings from a recent Kokomo resident.
1) Make sure you are using heat conducting grease, not heat insulating grease, under the module. (Not saying you are doing the wrong thing. I'm just mentioning it for readers that might not know there is a difference.)
2) I have to respectfully disagree with needing to replace the pickup coil. In an EST distributor, the ECM controls the dwell. The pickup coil simply supplies RPM and engine position information to the ECM. I would expect that if there were problems with the pickup coil, the ECM would interpret this as a wildly varying RPM, and flag a code. However, there's always a one in a million chance that the pickup coil could be damaged without the ECM detecting it.
3) The ESC module for your vehicle, IIRC, was integrated into the ECM around your model year. The knock sensor wire goes directly to the ECM.
4) Are you replacing the parts with original Delco parts, or aftermarket parts?
5) Is there leakage path (corrosion) between the high voltage coil lead and the wire that goes to the C- on the distributor? A conductive path would try to put mucho voltage into the module switching transistor. Similarly, if there were a conductive path between the C- lead, and the white/green pickup lead, this could cause some excess voltage getting into the module input lines. The front end circuit is rather robust, but this is still not a good thing.
That's about all I can think of at the moment. Keep us updated on your testing results.
ps: Greetings from a recent Kokomo resident.
Last edited by 69427; 08-05-2007 at 09:16 PM.
08-05-2007, 09:25 PM
#8
Melting Slicks
Shane
Sorry to hear that you had throuble at the track again. If you need some parts to try out to narrow it down, let me know I have a bunch of L98 parts laying around.
Phil
Sorry to hear that you had throuble at the track again. If you need some parts to try out to narrow it down, let me know I have a bunch of L98 parts laying around.
Phil
08-05-2007, 09:37 PM
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Ok, the old memory is getting a bit dim here, but here are a couple things to check. Please excuse me if they seem a bit "obvious".
1. When you replaced the coil. Did you also replace the ground strap that sits under the coil and is basically a metal tab that is bent to slide into the cap housing and connect to the wiring harness that plugs into the cap?
2. Did you replace the coil with one with the right color/polarity of wires? If I remember correctly, the ones for Camaro/Firebird and older types of in-cap coils use a red and yellow wiring scheme on the coil contacts and (again if I remember correctly) my L98 uses the red and white colored wire connections. I believe that the polarity is different between the two color schemes. I've been told that it will run for a short time with these swapped, but not for long.
Good luck and keep us posted!
Brad
1. When you replaced the coil. Did you also replace the ground strap that sits under the coil and is basically a metal tab that is bent to slide into the cap housing and connect to the wiring harness that plugs into the cap?
2. Did you replace the coil with one with the right color/polarity of wires? If I remember correctly, the ones for Camaro/Firebird and older types of in-cap coils use a red and yellow wiring scheme on the coil contacts and (again if I remember correctly) my L98 uses the red and white colored wire connections. I believe that the polarity is different between the two color schemes. I've been told that it will run for a short time with these swapped, but not for long.
Good luck and keep us posted!
Brad
08-07-2007, 08:15 AM
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what do you mean by the c- wire?
i replaced the ground strap yes
my car came with a hypertech coil...had red yellow. the replacement i bought at the track has red and white wires...... both have done same thing...lol
i used the grease that came with the modules....all 4
i replaced the ground strap yes
my car came with a hypertech coil...had red yellow. the replacement i bought at the track has red and white wires...... both have done same thing...lol
i used the grease that came with the modules....all 4
08-07-2007, 10:11 AM
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what do you mean by the c- wire?
C- is the wire that goes from the coil primary winding to the module switching transistor. It is the same wire that used to go from the coil to the points in older systems. i replaced the ground strap yes
my car came with a hypertech coil...had red yellow. the replacement i bought at the track has red and white wires...... both have done same thing...lol The following comments are my personal philosophy: I refuse to buy aftermarket ignition parts because you have no way of knowing what you are buying. Nobody hands out electrical specs with their ignition parts. You certainly wouldn't buy a cam without specs, would you? A possible failure reason, and I just say possible because I can't electrically measure your system by long distance, is a mismatch of your coil and ignition module. If you are running a low inductance coil with your stock module, two things happen. Lower spark energy, but more importantly, it will cook your module. I don't know if this is your situation, or not. I'm just trying to point out possible electrical issues. BTW, what ignition modules are you installing?
i used the grease that came with the modules....all 4
C- is the wire that goes from the coil primary winding to the module switching transistor. It is the same wire that used to go from the coil to the points in older systems. i replaced the ground strap yes
my car came with a hypertech coil...had red yellow. the replacement i bought at the track has red and white wires...... both have done same thing...lol The following comments are my personal philosophy: I refuse to buy aftermarket ignition parts because you have no way of knowing what you are buying. Nobody hands out electrical specs with their ignition parts. You certainly wouldn't buy a cam without specs, would you? A possible failure reason, and I just say possible because I can't electrically measure your system by long distance, is a mismatch of your coil and ignition module. If you are running a low inductance coil with your stock module, two things happen. Lower spark energy, but more importantly, it will cook your module. I don't know if this is your situation, or not. I'm just trying to point out possible electrical issues. BTW, what ignition modules are you installing?
i used the grease that came with the modules....all 4
08-07-2007, 11:14 AM
#12
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the last one i bought was from auto zone and got same brand coil and mod. i hink i got a line on a whole distributor.....if so will be putting that in asap to see if that fixes it.
08-07-2007, 07:06 PM
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I had the same problem on my '89 Chev PU. Chased the problem for 2 years and finally changed the distributor. No problems for 2 years then I sold the truck. I think the problem got fixed.
