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Timing problem with 88 GM truck


KField's Avatar
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12-05-04, 04:00 PM   #1  
Timing problem with 88 GM truck

My son has an 88 Chevy pickup with a 5.7 TBI and manual trans. We did some top end work and had the intake manifold off. We had problems with this truck prior to the service but I don't think it was ignition timing. When we reassembled it and installed the distributor, we disconnected the timing connector as instructed and set the timing to the 0 degree mark as stated on the underhood label. However, when we reconnect the timing connector, the timing does not change. And it does not change when the rpms are increased to 2500. It should end up with 33 to 35 degrees total advance at 2500 as far as I can tell. It never changes from 0 degrees. Needless to say the truck runs like crap and we can't use it. Can someone tell me where the timing signal is presented to the computer? Is it from one of the modules in the distributor? What I'm driving at is what to replace to remedy this situation?

Thanks in advance.

Ken

 
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12-05-04, 04:46 PM   #2  
It's done through an EST connection at the distributor connected to the module where the signal travels to the ECM for adjustment and back to the distributor. If there's a problem with the EST circuit, it should be setting a code.

 
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12-05-04, 04:52 PM   #3  
The check engine light is on. Is there a way for me to retrieve the code or do I need special equipment?

Ken

 
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12-05-04, 06:10 PM   #4  
You can jumper the ALDL (Assembly Line Diagnostic Link) between pins A & B. Turn the key to "On" and count the flashes of the "Check Engine" light.

HTH

Matt

 
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12-05-04, 06:30 PM   #5  
Thanks for your replies. I will work on pulling that code and post back if I am still in the dark.

Ken

 
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12-06-04, 05:44 PM   #6  
Well, no codes flashed so I assumed none were set. I replaced the distributor, ECU, and water temperature sending unit (for ECU) one at a time and nothing has changed. Initially after I set the timing, it advances when I reconnect the timing connector. Then after a minute, it ends up back at 0 (the factory setting) again. Sometimes the engine stalls it is running so rough. If I advance it with the distributor, it runs fine but the ECU is supposed to do that for me. Does anyone have a 'next thing to try'?

Ken

 
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12-07-04, 05:22 PM   #7  
Why don't we back up the turnip truck here?What was the original problem?Are you 100% sure the intake gaskets are installed properly and are the correct ones?Please describe the actual symptom(in detail) that leads you to think it's timing.Are the valves adjusted properly?My point is removing an intake and distibutor did not cause the timing to not advance assuming all wiring has been reconnected.So the problem may or may not be self induced if it was not there before.If the valves are not adjusted properly the rattle could cause spark retard from the knock sensor.If the timing is correct at idle the timing is not causing the stalling or running rough.

 
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