Ignition Module Connection Question

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Mar 13, 2007 | 10:26 PM

barrypaul2005

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Ignition Module Connection Question

I've had an intermittent starting problem on my '89 vette for some time even after replacing the coil/ditributor/rotor/magnetic pick up/module. I've focused under the distributor since playing around and re-connecting it always fixes the problem.

I've focused on the ignition module and its connections. I've replaced the ECM to Ignition module harness (EST/refernce/bypass/ground 4 wire harness).

For these GM parts:

1986-91 Distributor /Ignition (L98)
=========================
1892261 .. TERMINAL BLOCK, (INCL CAPACITOR)
1986260 .. TERMINAL BLOCK, (TO ELEK PKG)
1977207 .. POLE PIECE AND PLATE (2 wires)

I'm guessing I replaced the 1986260 (ECM harness?) and the 1977207 (pick-up?) so all that's left is the 1892261. Can anyone confirm this?

Also - any suggestions on what can cause an intermittent start problem that once started, never stalls. (If I turn the key to start, is this the same circuit to the ignition module (+12V) as when the key is in run position?)

thanks

Mar 14, 2007 | 12:22 AM

jfb

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Joined: Mar 2001

Posts: 54,124

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From: Cincinnati, Oh USA

The ignition module gets 12v in both start and run. When it won't start, that is the time to do some testing to find out why. Check for spark and timing with your timing light while someone cranks. Unplug an injector and connect a noid light or a low power 12v light like a side marker light across the injector socket and see if it pulses while cranking. Measure the fuel presssure and see if it falls rapidly after the ignition is off, you may have leaky injector/s. Check for stored codes.

Mar 14, 2007 | 02:46 AM

TPI84GMC

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Joined: Jan 2007

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From: Mesa Arizona

I'm having similar problems only no spark what so ever!

Mar 14, 2007 | 03:38 AM

ChickMagnet

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Joined: Feb 2007

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From: I am the chick magnet. not the corvette.

Quote:

Originally Posted by barrypaul2005

Is it cranking but just not starting? Had the same issue, and got to the point where it wouldn't start any more. I replaced the ignition module, and I also replaced the fuel filter as well. It's been running fine now for a few days. Not sure if I can attribute that to the fuel filter being clogged or the ignition module...but hey, it runs now. I don't think it was the fuel filter, most likely the ignition module, but if you haven't changed that in a while perhaps you should, it's only $12 and real easy.

Mar 14, 2007 | 10:37 PM

barrypaul2005

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Joined: Sep 2005

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I've had intyermittent starting problems for over 4 years ... always fixes itself by waiting (5 minutes up to 3 hours) but I was always able to get it started by re-installing the ignition module which touches all the wires - one of which is appearently intermittent.

Always cranks - but when it doesn't start there's no spark. But one thing for sure is that it's never once stalled out on me once it starts ... so that makes the problem very hard for me to identify. Dealer and pep boys couldn't figure it out though repl;aced everything except for the inetrconnecting cables of the Ignition module which I highly suspect. I've soldered the crimped connections and that sure seem to fix the problem for over a year - but it had a 2 minute wait problem the other day so I want to do a better reconnect job (soldering is tough since sio many heat sinks when connected - so I'll get what ever harness are available and then ree-solder the rest and let you know how it turns out.

Mar 14, 2007 | 10:42 PM

jfb

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From: Cincinnati, Oh USA

Soldering your connector wires is a good idea!

Mar 14, 2007 | 10:54 PM

SunCr

Le Mans Master

Joined: Dec 2000

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From: San Diego, Ca

Mine was a hard start (cold) from the Factory. Replacing the injectors 12 or so years later cured it. You might just scan it first and see what the signal is from the Coolant Temp Sensor. That acts as a choke. Should read ambient on a cold engine that's sat overnight. Warm up in sync with your gage readout, though that's a different signal. I doubt the module has anything to do with a hard start. ECM fires the injectors has long it has a reference signal and you've replaced everything that's involved with that. How often it fires them - in miliseconds - depends on the Coolant Temp Sensor. Of course if they're partially plugged or one or two has a weak coil, that won't help the situation either.

Jun 7, 2007 | 03:47 PM

Stealthvette

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Joined: Dec 2000

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From: Blue Ridge GA

Quote:

Originally Posted by barrypaul2005

I've had this exact same issue on my 86 L98 since I bought the car in 1999. I've been carrying a spare Ignition Module and screwdriver with me to make the swaps when this happens, thinking the IM's were going bad. I've been swapping IMs about every 6 months for 8 years.

This happened again a few days ago, I jumped in another car and went to my appointment. A couple days later I go out and the car starts right up. Now, I'm not so sure it is the IM. My VATS has been bypassed so that shouldn't be shutting things down. However, I've noticed that there is no fuel pump whine when the car won't start. I can predict with 100% certainty when I don't hear the fuel pump, that the car won't start.

Now, a friend of mine told me to pump the throttle when it won't start. He said it is a "typical L-98 starting issue." I haven't had opportunity to try this fix as the car seems to start if you let it sit awhile so I haven't tried it yet.

Just as stumped as you!!! And my wife is scared to go anyplace in my Vette for fear we get stranded.