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| 88 2.8 no spark (Page 1/2) |
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OriginalDoug
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DEC 01, 11:52 AM
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So I've got an 88, that's actually a 2.8 to 3.4 L swap from a camaro, and it's a bit of a Frankenstein, as the body is the base model
Anyways, it's got a blown head gasket but runs and limps around for the moment. However when we were trying to diagnose the head gasket we had the distributor cap off at one point and now that the whole car is back together it won't start and isn't getting any spark.
So I followed the tests outlined in this document
https://docs.google.com/doc...1&rtpof=true&sd=true
and got all the way through test 6/7 meaning I didn't get spark anywhere, but I am getting 12 V to the gray plug on the coil, and I did see the switching signal when poking the white wire on one of the plugs. (However I didn't have a test light so I assumed the voltage jumping around up and down on the multi meter I was using was the same thing... I guess let me know if that's not the case)
So all of that testing is supposed to tell me that it's the ignition coil that's bad... Only problem is that I just put a new coil in before doing these tests, I also put a new ICM in before the tests also.
All that said, the distributor cap and rotor don't look very good so I am ordering those also, but since I'm not getting any spark at the coil, they might not be the actual issue.
Now to throw an additional bit of complication into the whole thing, I attempted to build myself a little LED test light to run test 7 again in case what I was seeing on the multimeter didn't amount to a blinking light for the switching signal. I'm not sure if my DIY tool didn't work correctly or not, (though I tested it on a 9V battery and it worked as expected) but when I did the test using it, I got a pretty good shock.
I pulled away when I got zapped obviously, and in the moment between when I pulled away and before my wife stopped turning the engine over, all of a sudden I was getting a spark arcing across from the point where you put the plug wire on the coil, to the metal band that runs around the coil.
Upon seeing that, I quick set up to test a spark plug directly on the coil, and upon turning the engine over I got spark!
So then I put everything back together quickly and had the wife try to start the car... No dice.
Took it back apart and tested for spark at the coil, and got nothing again...
And so now I'm kind of at a loss for what's going on... a bad connection somewhere, or a short somewhere. Anyone have some insight on this?
Thanks, Doug
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Gall757
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DEC 01, 01:18 PM
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If the tachometer moves up a bit when you crank the starter, the ICM is probably good, but they can fail so many ways, most people get a new one.
You get extra points for trying to test the ICM, but you cannot duplicate the temperature stress. You should take it to an auto parts store where they have a testing machine.
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OriginalDoug
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DEC 01, 02:22 PM
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Thanks for the reply, I keep forgetting to check the tach when cranking it over, I'll check that this time.
That said, I did already put a new ICM in, so unless it was bad out of the box (which I hear is possible) I don't think that's the problem.
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OldGuyinaGT
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DEC 01, 03:55 PM
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I have an 88 GT with stock 2.8. I had a no spark condition occur suddenly just last week, whilst exiting an interstate. I had taken the advice of many on this forum, so I had a spare ICM with me, ready to swap out. I changed it, but in the course of so doing found that it was not the problem. What WAS the problem, was that the coil terminal in my coil-to-cap wire, had somehow completely corroded away. I would not have thought to check that except that it fell off when I reinstalled the cap after swapping the ICM. Fortunately I was also carrying a spare coil wire so i was back running in a few minutes. I still have no idea how this happened; I had dielectric grease on it and it was new when installed. I admit, however, that I hadn't looked at it or even thought about it in about 4 years/20000 miles. But I'd never seen anything like this before in almost 50 years working on cars.
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Skybax
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DEC 01, 07:39 PM
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Since you had the cap off I would make sure you didn't pinch or break one of the two wires going to the pickup coil from the module. I would also check the two connectors at the ignition coil.
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Patrick
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DEC 01, 08:04 PM
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| quote | Originally posted by Skybax:
Since you had the cap off...
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...make sure the center contact (which is supposed to touch the rotor) is not missing.
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OriginalDoug
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DEC 02, 02:59 PM
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I'll check both of those things when I get a chance and update the thread when I do.
Thanks for the responses!
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zkhennings
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DEC 02, 03:50 PM
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| quote | Originally posted by Patrick:
...make sure the center contact (which is supposed to touch the rotor) is not missing. |
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I have even had a distributor cap where the spring in the center contact was bad, car started fine but broke up badly when trying to rev it out as the center contact started to bounce around with not enough spring pressure to keep it in contact. It was a new distributor cap.
The 2 wire harness between ICM and coil seems to go bad often. I have had it cause no spark intermittency in my 2.8.
Also the pins that go into the coil from both gray and black plug can make poor contact, especially if they are aftermarket. The metal used is thinner and I had to S mine a bit to get good contact.
Also a decent amount of aftermarket but new ICMs are trash right out of the box  Maybe fine a NOS one as current AC Delco quality is going downhill.
The fact that you got the coil to spark but then it stopped leads me to believe you have an intermittency in the 2 wire cable, the ICM itself is no good, or the coil itself is getting intermittent power from the black connector. I built a new 2 wire cable by buying the plugs with pigtails (Rockauto has AC Delco ones I believe) and soldering and shrink wrapping them. I never had another issue while I still had the 2.8. It is cheap to make and not a bad idea to replace regardless.
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Skybax
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DEC 02, 07:16 PM
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OriginalDoug
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DEC 03, 09:47 AM
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Some really good ideas here, I appreciate everyone's help.
I haven't had a chance to dig back in yet (having a 6 month old will do that), but tonight and this weekend I'll see if anything posted here helps.
The center contact in the cap does seem pretty loose and moveable, so it's very possible I'm having what you had.
I was also thinking about replacing both of the wire harnesses going into the ICM. Neither looks in great shape, so that might be next on the list.
I already forget what brand ICM I bought, but it was either ACDelco or maybe Standard? If nothing else works I'll go get it tested or get a new NOS one.
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