'95 Chevy Astro van driveability issues

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Old 11-14-05, 04:27 PM
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'95 Chevy Astro van driveability issues

Help, please! As a favor to a friend, I'm working on her Astro conversion van (1995, 4.3 V-6, distributor ignition, auto trans). Rough idle and part-throttle and hunting for a steady speed were the principal complaints. Before starting to work on it, I read trouble code 32 by the ALDL-jumper-MIL-flash method. This was the only code displayed. But before doing any work on the code, the water pump needed to be replaced. After re-connecting the battery, the code was gone, but the rough idle and part-throttle condition remain. I have not taken the van for a real-world test/re-learn drive yet, but I'm not yet comfortable turning my friend loose with the van, either.
My research into the code 32 points to the EGR system. My Haynes emission manual said it could be EGR or MAP, but the Alldata we have access to at school says EGR only. Having printed the available pages, I read something about "backprobing". I've never had the opportunity to learn this skill; how is it done? I suppose it's done with a voltmeter, but with the suspect device connected or disconnected?
As a last bit of information, my friend's son-in-law says the van was run for a while with no air filter, and he admits to having changed the ignition timing. He seems to be pretty sure he advanced it a little. I want to re-set the timing to factory specs before proceeding too much further. A sticker under the hood says to disconnect a "timing connector" before setting the timing; is this the two-wire connector on the back side of the distributor body, or is it somewhere else? (It's probably obvious we're doing this without any kind of manual, huh?)
I had an '89 Olds 88 Royale that set a code 32 once, and it was maddening trying to figure it out. But, when I cleaned the carbon out of the EGR passages, it cleared right up. Wasn't too hard, just time-consuming and labor intensive. I could start with this procedure on this vehicle, I would just rather not pull the valve and intake if there's no need.
Any input on these MANY questions or experience with chasing this code would be greatly appreciated! Thanks in advance - Chris
 
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Old 11-20-05, 08:54 AM
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Just an update on the van - I have discovered from the owner that the Dexcool antifreeze/coolant was mixed with ethylene glycol AFC prior to the water pump failure/replacement last year. As the coolant was still pink when I drained it, I returned it to the cooling system. I think that is what contributed to the water pump gasket failure that recently downed the vehicle. I will now flush the system and replace the AFC with fresh Dexcool.
I also recently tested fuel pump pressure and engine vacuum - 61 psi with key on, 59 psi with engine running and 15-16 inches of vacuum at idle. I'm pretty sure this is due to the altered ignition timing (I think it's retarded; the son-in-law thinks he advanced it). I want to reset the timing, but I still don't know where the timing connector I'm supposed to undo for the procedure is located. I'm told by a co-worker that it's under the dash, an orange wire with black tracer. If I can find one, a manual is going to come in REAL handy!
Again, any input/advice will be greatly appreciated. Thanks in advance - Chris
 
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