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'84 G20 with weak idle/fluctuations


OGthevan
04-19-2010, 12:45 AM
i've got a 1984 g20 sportvan 305 engine with 144k current miles that I've made a project out of and in the process of getting it running healthy, and the one fix that has been on the list is my voltage fluctuations and getting a steady consistant idle because from time to time it will idle weak with kind of a low rpm weezing sound as if it were about to cut out. I recently put in a new (remanned) alternator and belts today and for the few miles that i drove it to test it out it seemed to be behaving great and my voltage was staying steady, and i was idling good. I just got back from the bar and as i was driving it was dropping again and would fluctuate a little as i accelerated and decelerated like it used to, theres a new distributor/cap on it and cables but that was from the last owner and was installed about 3,000mi ago since ive only had it for about 6 months. the battery is fairly new as well but is a no-brand as far as i have checked.

could it be the timing? the engine is rough i'd say but i take great care of anything i see wrong immediatly with the ole girl.

MT-2500
04-19-2010, 07:36 AM
i've got a 1984 g20 sportvan 305 engine with 144k current miles that I've made a project out of and in the process of getting it running healthy, and the one fix that has been on the list is my voltage fluctuations and getting a steady consistant idle because from time to time it will idle weak with kind of a low rpm weezing sound as if it were about to cut out. I recently put in a new (remanned) alternator and belts today and for the few miles that i drove it to test it out it seemed to be behaving great and my voltage was staying steady, and i was idling good. I just got back from the bar and as i was driving it was dropping again and would fluctuate a little as i accelerated and decelerated like it used to, theres a new distributor/cap on it and cables but that was from the last owner and was installed about 3,000mi ago since ive only had it for about 6 months. the battery is fairly new as well but is a no-brand as far as i have checked.

could it be the timing? the engine is rough i'd say but i take great care of anything i see wrong immediatly with the ole girl.

If idle is not right check for vacuum leaks and check IAC valve and TBI for carbon build up.
Check and set base timing.
Also a wheezing sound could be exhaust restriction.
Any check engine lights or codes?
Check engine vacuum at idle and at 2K rpm and post back readings.

OGthevan
04-19-2010, 09:05 AM
I'm not sure if i even have check engine lights on my year model, or at least i have yet to experianced them. when I was scanning around my engine conpartment I saw a rotted and split hose I dont know what went to but I did a temporary patch with duct tape of course.

to me the wheezing sounds more like the pullys and fan making a noise at low rpm when this symptom occurs but is least of my concern. plenty of carbon buildup does exist on my van, i discovered when pulling my tranny to replace a front seal I had to remove the pipes to the manifold, stuck my finger inside when it was cool and there was a layer about a few millimeters thick.

MT-2500
04-19-2010, 09:57 AM
I'm not sure if i even have check engine lights on my year model, or at least i have yet to experianced them. when I was scanning around my engine conpartment I saw a rotted and split hose I dont know what went to but I did a temporary patch with duct tape of course.

to me the wheezing sounds more like the pullys and fan making a noise at low rpm when this symptom occurs but is least of my concern. plenty of carbon buildup does exist on my van, i discovered when pulling my tranny to replace a front seal I had to remove the pipes to the manifold, stuck my finger inside when it was cool and there was a layer about a few millimeters thick.

Duck tape is not much repair on hoses.
Replace the bad hose and see if that helps.
Post back how it goes.
82 up have check engine lights.
And always check base timing.

OGthevan
04-22-2010, 05:28 PM
I replaced the line that was rotted and cracked, not sure what it helped, timing is still sounds a little bit off but will take care of that soon as the charging was my one concern. my voltmeter is now staying quite solid and takes only a small idle rev to keep the needle up there, but not in the red, the entire drive. The new alt is performing pretty well even though I am cautious about certain remanufactured parts.

One day I am going to brake a limb working in these cramped conditions that some of these vans have :banghead:

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