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almost have an 87 iroc for sale HELP ME

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Old 09-13-2010, 05:11 PM
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Car: '87 IROC-Z
Engine: 305 TPI vin F
Transmission: 700R4
almost have an 87 iroc for sale HELP ME

well i've checked all wiring, replaced the distributer, plug wires, coil and ecm and i still don't have any spark. was just at advance auto and they tested the new ignition module and it's good. how can i check the coil to make sure thats good? how can i check the pickup coil to make sure that's working (besides checking the resistance which was right in the middle of specs at 987 ohms)? what else should i check? please help
Old 09-13-2010, 06:14 PM
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Re: almost have an 87 iroc for sale HELP ME

Unplug the tach wire and try it.
Old 09-13-2010, 08:19 PM
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Re: almost have an 87 iroc for sale HELP ME

If it's really worn out badly, the top of the shaft will wobble in the housing. This prevents the pick-up coil from working as effectively. Check it.
Old 09-13-2010, 08:29 PM
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Re: almost have an 87 iroc for sale HELP ME

Not to sound dumb or retarded but have you checked the starter? The solenoid on the starter complets a circuit to allow starting/spark. I learned this back in HS and called it on my dad's Buick. I also had a no start issue on my 84 Firebird about a year ago. It would turn over and over and over but no start. Take the starter to Advance and have them check that. Good Luck!
Old 09-14-2010, 09:48 AM
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Car: '87 IROC-Z
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Re: almost have an 87 iroc for sale HELP ME

the distibutor is nice and tight. i'll check those wires and get back
Old 09-14-2010, 04:49 PM
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Re: almost have an 87 iroc for sale HELP ME

hmmm. yeah. starter?
Old 09-14-2010, 05:47 PM
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Re: almost have an 87 iroc for sale HELP ME

Sorry krazyfbird, The system yopu are referring to went away with beaker points. The starter circuit on HEI cars is not connected to the ign circuit in any way.

DnD, try unplugging the EST timing wire(tan/blk). This will eliminate a short to ground that could cause a no spark. Test ign coil for resistance. Primary should test at .5-1 ohm. Secondary should test at 22-27K. There should be no continuity between either circuit and the frame.
Old 09-14-2010, 05:53 PM
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Re: almost have an 87 iroc for sale HELP ME

One more thing, be sure to check for power and for primary ignition pulse at the coil as well once youve verified its good. A test light between batt+ and coil B- should flash when cranking. If not, you have a problem in the primary ignition system. Check for injector pulse. This will tell you if the PIP is being recieved by the ECM. If you have injector pulse, then the problem is either in the ign mod, ign coil, or wiring.
Old 09-14-2010, 07:01 PM
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Re: almost have an 87 iroc for sale HELP ME

How did it run when you unplugged the tach wire from the dist?

See my signature for helpful troubleshooting advice.
Old 09-14-2010, 08:10 PM
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Re: almost have an 87 iroc for sale HELP ME

HMMMM really? Then how come that solution worked on a 83 Buick LeSabre with a 5.0 in it with the HEI distributer? And also, how come the same thing worked on my 84 Firebird with an HEI distributer? I mean, I could be wrong of course but a simple check of the starter at advance or Autozone would prove if the starter was good or not. Anyway, til he gets it started and knows what he did to fix the problem, I will still say check the starter. lol
Old 09-14-2010, 08:15 PM
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Re: almost have an 87 iroc for sale HELP ME

How is it supposed to run when there's no spark? lol
Old 09-14-2010, 08:30 PM
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Engine: 305 TPI vin F
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Re: almost have an 87 iroc for sale HELP ME

well i have 8 volts to the coil while cranking at the red wire in and out. the white wire flashes the test light while cranking and i'm assuming the smell of fuel after cranking for a while that the injectors are firing. after i put in the new ecm and still had nothing i removed the new ignition module and had it tested at advance auto and it tested good. i'll try the est wire tomorrow. if it runs without the est plugged in what would the problem be? as for the tach wire, which wire would that be? and as for the wire from the starter to the dist, that may have been in use with the large cap hei, but it's not on my small cap hei. i've ohm'd the coil as i suspected that, and according to the way my chilton manual had me test it, it tested good. it is a msd streetfire coil that i put on approximately two months ago because it only acted up when the car was warm. acted just like when an ignition module begins to fail. wouldn't start warm, twenty minutes later it would start and run fine. that's when i replace the module but had slop in the distributor so i then installed a brand new jegs distributor and the msd coil along with jegs 8.0 wires. but it acted the same way, then two weeks ago it stopped starting and i haven't had spark yet. i checked resistance throughout all the wires and they were good. i found one wire that was about to fail. the small harness from the coil to the ign module had a wire that was almost broken. i repaired that but would like to find one of those new.
Old 09-15-2010, 04:38 PM
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Re: almost have an 87 iroc for sale HELP ME

well i tried unplugging the est wire and that didn't help. i think i'll have to amperage test the wiring harness maybe that'll show a problem. thanks for everyone's help. i hope we can figure this out soon. i'd really love to get a few more days of cruising with the tops out berfore it gets too cold for that. and as far as the tach wire, i don't know which one that is.

Last edited by dnd_perf; 09-15-2010 at 04:42 PM.
Old 09-15-2010, 07:11 PM
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Re: almost have an 87 iroc for sale HELP ME

Is there some sort of crank sensor at all? What is the est wire? Let us know when you get it fixed.
Old 09-15-2010, 07:29 PM
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Re: almost have an 87 iroc for sale HELP ME

Electronic Spark Timing its like an electronic vaccum advance. you unplug it to set base timing. i guess it shuts down the Electronic Spark Module. the magnetic pickup is the "crank sensor"
Old 09-15-2010, 09:05 PM
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Re: almost have an 87 iroc for sale HELP ME

hey, pull your ECM out of the dash and un plug all the connectors out of it and wait about 5 minutes. I had the exact same problem in my 87 iroc, i put in a brand new MSD distributor and coil in my car and it still wouldnt start. (no spark) i unplugged my computer for a bit, gave it a few taps and plugged it back in and it started. i dunno if it was just a fluke but its worth a shot.
Old 09-15-2010, 09:33 PM
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Re: almost have an 87 iroc for sale HELP ME

i had the same problem going to an aftermarket coil the problem is the coil harness plug doesnt make good contact with some aftermarket coils try going back to the factory style coil to see if it works
Old 09-16-2010, 01:10 PM
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Re: almost have an 87 iroc for sale HELP ME

Originally Posted by dnd_perf
as for the tach wire, which wire would that be?
IIRC tach wire will be the white wire on the grey connector on the top of your coil. Unplug the grey connector and use a jumper wire to hook up the black wire as that one supplies power to the coil.

I had the same problem, same symptoms, and I think it was sofakingdom's advice I followed to fix it. Takes about five minutes to check and doesn't cost you anything if you can find a scrap of wire in your garage.
Old 09-16-2010, 03:20 PM
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Re: almost have an 87 iroc for sale HELP ME

If you have pip at the ign coil and no spark, there is a problem either with the coil or secondary circuit. I assume youve checked spark at the coil wire? You know the ign coil is a simple device. If its getting sufficient voltage and an on/off signal, its got to produce spark, unless its defective.

8 volts is a little on the low side even while cranking. Try starting the engine with a battery charger connected in "jump start" mode. The higher voltage may do the trick. If it does, check wiring to the starter from batt+, engine block from batt-, also check fuse links from starter batt term. Try to isolate the cause of voltage drop between the battery and the ignition coil. Igntion switch perhaps? Good idea to perform the tach test also.
Old 09-21-2010, 03:25 PM
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Re: almost have an 87 iroc for sale HELP ME

well i found a bad wire. the red wire between the ign module and the coil. had to buy a new plug from napa. $23, holy crap!!! anyways still won't start
Old 09-23-2010, 11:21 AM
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Re: almost have an 87 iroc for sale HELP ME

whoops!!! well after correctly checking pulse to the coil, i've found that i don't have it. what controls that?
Old 09-23-2010, 03:35 PM
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Re: almost have an 87 iroc for sale HELP ME

Originally Posted by dnd_perf
whoops!!! well after correctly checking pulse to the coil, i've found that i don't have it. what controls that?
Im also having a no start issue with my 88 tpi 5.7 did u check for voltage at a purple and white wire? U need to check voltage while cranking the engine. I think it should be 1.5 volts if there is no voltage im pretty sure but not a 100% sure that the ECM is FU**ed!!
Old 09-23-2010, 10:52 PM
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Re: almost have an 87 iroc for sale HELP ME

Originally Posted by bmwm3
Im also having a no start issue with my 88 tpi 5.7 did u check for voltage at a purple and white wire? U need to check voltage while cranking the engine. I think it should be 1.5 volts if there is no voltage im pretty sure but not a 100% sure that the ECM is FU**ed!!
purple and white wire where? at the ignition module?
Old 09-25-2010, 01:35 AM
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Re: almost have an 87 iroc for sale HELP ME

Originally Posted by dnd_perf
purple and white wire where? at the ignition module?
It is at the modulle and also at the ECM!!
Old 10-03-2010, 06:14 AM
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Re: almost have an 87 iroc for sale HELP ME

well after way more money than i wanted to spend, she's running again. after checking and rechecking wiring and different electronic pieces, my father and i decided to "throw" another ignition module at it just for chuckles (even though it was tested and passed at a local advance auto) and guess what. she lit right off and purrs like a kitten!!! haven't had any issues yet. but if i have any problems i will definitely post on here again.
THANK YOU GUYS SO MUCH FOR YOUR HELP!!!!
Finally after a few long weeks there is one more third gen out there helping to seal our highways and keeping the tire companies in business!!
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