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Old 06-16-2010, 04:58 AM   #1
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Car: 1988 IROC
Engine: 350 TPI
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erratic ignition timing

I was setting the timing on my car the other nite and while doing so the timing started bouncing all over the place. So much so that you couldn't even read the numbers on the balancer. I have never seen anything like this at all. Would a bad pickup coil cause this? If not, any suggestions would be greatly appreciated.
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Old 06-16-2010, 05:35 AM   #2
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Re: erratic ignition timing

Did you have the EST connector disconnected during the process?
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Old 06-16-2010, 01:38 PM   #3
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Re: erratic ignition timing

Yes.
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Old 06-17-2010, 04:57 PM   #4
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Re: erratic ignition timing

Was the idle steady and your sure the timing lights good (simple stuff first)? I would first check over your ignition system things like a bad ignition module plug wires running too close together inducing voltages in adjacent wires could cause your issue. If your ignition system is in good shape then mechanical reason for this happening are things like a worn distributor gear or a timing chain that needs to be replaced. But again before you tear apart your motor simple stuff first.
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Old 06-17-2010, 05:25 PM   #5
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Re: erratic ignition timing

Quote:
Originally Posted by tpi88camaro View Post
I was setting the timing on my car the other nite and while doing so the timing started bouncing all over the place. So much so that you couldn't even read the numbers on the balancer. I have never seen anything like this at all. Would a bad pickup coil cause this? If not, any suggestions would be greatly appreciated.
The cheap-*** timing gun I bought jumps all over the place like that unless someone touches that black clip that you hook onto the spark plug wire. Something about human skin touching it and it works perfectly. wtf?
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Old 06-17-2010, 05:33 PM   #6
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Re: erratic ignition timing

Have to love electronics lol. Coincidentally thats what i do (electronics engineer) and this is a phenomenon i see a lot actually in electronic circuits. It may be that you are acting as a shield or a filter shorting out electrical noise thats causing the timing light to falsely trigger. I'm guessing you have an inductive timing light. May want to making sure your plug wires have ample spacing so there not inducing voltages in each other or cross firing and make sure your connections are good.
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Old 06-18-2010, 01:23 AM   #7
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Re: erratic ignition timing

Quote:
Originally Posted by Rolling Thunder View Post
Was the idle steady and your sure the timing lights good (simple stuff first)? I would first check over your ignition system things like a bad ignition module plug wires running too close together inducing voltages in adjacent wires could cause your issue. If your ignition system is in good shape then mechanical reason for this happening are things like a worn distributor gear or a timing chain that needs to be replaced. But again before you tear apart your motor simple stuff first.
Mechanically, the engine is as sound as can be. It's got less than a 1000 miles on it. Timing light is good too, or at least it was the last time I used it. I was doing some reading in my service manual and it says that if the plug wires are run too close or are touching the wire to the knock sensor that that can have an affect on timing. Coincidentally I had just installed new power and ground cables from Innovative Wiring. They are awsome by the way. So I need to crawl back under the car and check the plug wires running to cylinders 2 and 4 since they are run underneath the headers. I'll let you know what I find after I check things out more.
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Old 06-18-2010, 01:36 AM   #8
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Re: erratic ignition timing

Well even though it may be a new motor you can still run into issues like the distributor drive gear can have issues with accelerated wear if it is made from an incorrect material for your application little detail things like that always get ya lol. Also I wouldnt worry about the knock sensor as even though it does have a hand in setting the timing its done through the ECM so disconnecting the EST wire prevents it from having an effect on the timing. Anyways best of luck.
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Old 06-18-2010, 01:36 AM
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