Hi, Sorry to be a P.I T.A about this problem again but...
I checked for play in my dist. today and found that it moves up/ down about 1/8", so I installed a thicker washer to eliminate the play.
Re-installed the dist. and noted that the 'jumping' around timing problem has mostly disappeared except:
when gradually increasing rpm, the timing retards a maximum of 2 deg, but when the engine reaches 2500 rpm, it immediately advances itself to 12 deg. It does this every time at the same rpm. This is of course with the tan/ black wire disconnected. It doesn't seem that the problem is mechanical, but electrical, due to the very sharp immediate timing advance. Could it be the ignition module? How can I test it?
Thanks,
Jeff

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88 Trans Am 305 Auto Red/Silver, MSD coil,wires, ported plenum, gutted airbox, TB bypass, comp cams 08-408-8, everything else stock

 

Anyone?

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88 Trans Am 305 Auto Red/Silver, MSD coil,wires, ported plenum, gutted airbox, TB bypass, comp cams 08-408-8, 206/212 @ 50 .480/.487 110 LSA everything else stock

 

if your ignition module was bad, you would be stalling and hesitating like crazy. is what you are descibing verified with a timing light or with a scanner?

 

btw, if your distirbutor moves up and down at all, something must be wrong with your hold down bolt or strap.

 

The timing variation was verified with a timing light. To make sure the timing light is good, I checked it on another car- rock solid.
Sorry I wasn't more clear on the dist. It was actually the shaft that was moving up and down, not the whole dist.




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88 Trans Am 305 Auto Red/Silver, MSD coil,wires, ported plenum, gutted airbox, TB bypass, comp cams 08-408-8, 206/212 @ 50 .480/.487 110 LSA everything else stock

 

I've had similar, actually worse, ignition problems with my '84 Z-28. They were first caused by my own error. I somehow hooked up the wires wrong coming from the HEI to the cap. The tabs were broken off and I wasn't paying attention. I caught it when the car wouldn't start. I changed them around to where they should be and then it would start, but I did some damage. The car would die and not start when hot, had poor throttle response and the tachometer would read almost double of the actual RPM.

I changed the module and coil ( they were old anyhow), and then the capacitor. Fixed the problem.

Now similar symptoms are back again after my alternator fried.

I am going to swap out the ignition system again and see if I have any luck. I'll let you know.

 

This is completely normal. Its part of the limp home strategy.

[This message has been edited by Brent (edited October 01, 2001).]

 

Brent, do you think my car is in Limp home mode? it doesn't throw any codes at all, but sometimes when I start it, it runs horrible, and throws 34, 42, 44 at me. But if I re-start it a couple times, it runs good again, and no codes. Wouldn't the SES light be on in limp mode?
Thanks,
Jeff

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88 Trans Am 305 Auto Red/Silver, MSD coil,wires, ported plenum, gutted airbox, TB bypass, comp cams 08-408-8, 206/212 @ 50 .480/.487 110 LSA everything else stock

 

I don't know. During limp home the SES flashes.

Multiple codes at once? I'd check all the ECM grounds. Then try tapping on the ECM while the engine is running.