Pretty weird idle issues
10-27-2017, 02:21 AM
#1
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Join Date: Feb 2017
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Posts: 231
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Pretty weird idle issues
Yes I searched, I've yet to find the combination of idle issues I have. For low idles there are one set of fixes, and high idles there are another, and fluctuating idles there are another and I've got all of them.
1991 1.6 naturally aspirated, automatic if that matters, no A/C or P/S (belt removed). Deleted the charcoal canister over a year ago, no issues then. No changes before the problem started.
Fixes tried so far:
adjusted throttle cable (to 3mm slack specification)
cleaned out butterfly valve
new fuel filter
cleaned dash pot and re-lubed
checked all hoses and clamps, no issues or cracking, though it's possible I missed something
Issues:
on start up the idle sits around 1100 in park regardless of accesories on.
drops to between 700 and 800 in drive and drives fine for a while.
in this middle area between cold and fully warm, the idle in park will stay at the idle in drive of around 700-800
once warm (~30 min) will occasionally (every 3rd drive or so) fluctuate idle by around 400 rpm up and down and attempt to die after coming to a stop at lights (which got me thinking dashpot) I can get it to stay running by keeping on the gas a little or by shifting to park or neutral, both of which jump the idle to 1200-1500 depending on accessories. The fluctuation that makes it want to die is still there, it just bounces around higher in the band and can't get low enough to die. If I can get it through this roughly 1-2 minutes of BS without dying, it will drive regularly.
on a warm engine when idling, the idle is between 1200 and 1500 depending on accessories.
I'm thinking that maybe it's expecting for the A/C and P/S to be driven by the engine and that's causing the idle to stay a little high, which other than a little extra gas burnt isn't really that big of an issue for me. The problem is this seemingly random fluctuation that makes it try to die. If I were to adjust the idle down to compensate for the high idle, I feel like this issue would be more prevalent. The dying has a set of circumstances which it occurs under (engine warm, at stop light), but it doesn't occur every time, or even most of the time, so assigning a definite cause is eluding me.
Any help would be appreciated.
1991 1.6 naturally aspirated, automatic if that matters, no A/C or P/S (belt removed). Deleted the charcoal canister over a year ago, no issues then. No changes before the problem started.
Fixes tried so far:
adjusted throttle cable (to 3mm slack specification)
cleaned out butterfly valve
new fuel filter
cleaned dash pot and re-lubed
checked all hoses and clamps, no issues or cracking, though it's possible I missed something
Issues:
on start up the idle sits around 1100 in park regardless of accesories on.
drops to between 700 and 800 in drive and drives fine for a while.
in this middle area between cold and fully warm, the idle in park will stay at the idle in drive of around 700-800
once warm (~30 min) will occasionally (every 3rd drive or so) fluctuate idle by around 400 rpm up and down and attempt to die after coming to a stop at lights (which got me thinking dashpot) I can get it to stay running by keeping on the gas a little or by shifting to park or neutral, both of which jump the idle to 1200-1500 depending on accessories. The fluctuation that makes it want to die is still there, it just bounces around higher in the band and can't get low enough to die. If I can get it through this roughly 1-2 minutes of BS without dying, it will drive regularly.
on a warm engine when idling, the idle is between 1200 and 1500 depending on accessories.
I'm thinking that maybe it's expecting for the A/C and P/S to be driven by the engine and that's causing the idle to stay a little high, which other than a little extra gas burnt isn't really that big of an issue for me. The problem is this seemingly random fluctuation that makes it try to die. If I were to adjust the idle down to compensate for the high idle, I feel like this issue would be more prevalent. The dying has a set of circumstances which it occurs under (engine warm, at stop light), but it doesn't occur every time, or even most of the time, so assigning a definite cause is eluding me.
Any help would be appreciated.
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10-27-2017, 02:26 AM
#2
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Thread Starter
Join Date: Feb 2017
Location: a
Posts: 231
Total Cats: 9
My plan at this point is to go over all of the hoses again and double check with a can of carb cleaner to isolate pinholes, replace the PCV valve, probably with the FM one, check all the grounds, and replace the dashpot with a new one.
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