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fed up with my ignition!!! someone with some knowledge help me out!

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myblack98gst

15+ Year Contributor
578
1
Jun 22, 2003
Elizabethtown, Kentucky
okay I have been hunting this problem for a good while now my car has issues that I cannot seem to hunt out. at this point it pretty much points to the ECU which sucks.

basically I have sparatic issues one run it will be perfect the next after I let out of the gas it will have a missfire that will last for an unknown amount of time. coil 1/4 just stops firing all together.

I have swapped out to a 93 cam angle sensor because my 90 the wires were hard and cracked and could not find one any better junkyard diving. the car ran the same before and after.

swapped the PTM out for a 93 also so I could get rid of the tach adapter to make the 93 eprom work correctly. while I was doing this I bypassed the factory wiring harness concerned that could be causing the problem so I just ran wires directly from pins 54-55 out to the module then straight from the module to the coils. still runs the same.

I have tried a couple of different coils with no real difference. another thing I have noticed is if you pull the plug wires off one by one while it is running. the towers for 1&3 are significantly stronger than on 4&2?? 4&2 will stop arcing within a 1/2 inch of pulling the wire off. 1&3 will stop arcing the wire and jump over to the bracket they are very obviously stronger??


so here is my questions?

1. is there a component in the ECU that can be replaced to possibly correct the missfire issues I am having?
2. whats with the spark energy difference between the towers of the same coil?
 
I would say that your ecu is taking a crap. PM steve. he is one of the few I trust to repair a messed up ecu.
 
Well their isn't enough info to say the ECU is taking a dump. Best thing to do is to check the dwell on both coils. Also the coils are for 1&4 and 2&3. You can check dwell with any dwell meter. You have to use the negitive/trigger of each coil to check it. It will probably only show you degree's of dwell but you should be able to see if one coil is off from the other by a significate amount.

I can't totally remember if the ECU controls dwell or of the ignitor controls dwell but I'm pretty sure it's the ECU. I always have to set dwell on MegaSquirts using the stock ignition. But your dwell is the charging time of the coil and thus also directly effects the amount of energy that the coil will output.

P.S. Before you do anything use a good DVOM and ohm out your grounds. A bad ignition ground will create all sorts of problems like you describe. I'm almost willing to bet good money it's a ground issue. The ignition has it's own ground seperate from the ECU and various sensors. It should be located on the firewall somewhere, but I don't remember. You should not see more than 5 ohms on any ground. Anything higher than that you need to fix. I personally won't accept anything higher that .5 ohms on any ground. Clean every ground on the firewall and chassis up with some sand paper and replace any bad connectors.
 
yeah sorry I know the 1/4 2/3 thing I was apparently still fed up while I was typing and not thinking.

another piece of important information I failed to present is. The misfire ONLY happens if I take it to high rpm close to or at rev limiter (8,500) it will not do this if I shift earlier or if I am just driving around like normal.
 
The ignitor on our cars ( all DSM's) Are "dumb ignitors" as they are called and rely soley on the ECU to control dwell time.

Sorry i'm not of much more help but hopefully that gives Maglin a little more to work with , or at least eliminate part of his suspisions
 
I kind of thought they where dumb. I've always had to set the dwell time in the MSII installs I've done. Anyways again I say check your grounds. Clean them all up. Only thing that will cause is a possibly better running car. You also might have one coil that is bad. You need to check them with a Ohm meter. Check the primary and seconday sides of both coils. They should be pretty low on the primarys like 10-21 ohms if I recall. And the secondarys will be like 18K+. You can get the specs they should be online with a handy google search. If one is way off from the other then one of them is bad. Get a new coil pack or a COP setup. Don't bother wasting time with salvage yard parts for the coils.
 
I know it is not much help at all but why don't you try a different ecu if you swapped out everything else? They are quite cheap and awailable nowadays or you can always borrow one from a buddy.
 
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