Rough idle at startup
10-24-2005, 10:25 AM
#1
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Rough idle at startup
I've done searching and have been keeping track of this problem for a long time...
Symptoms:
rough idle showing a bouncing needle and surging throtle on first cold-start only, sometimes leading to the car stalling without being given additional throttle (car starts fine after first stall or continues to run rough if not allowed to stall)
Solutions:
1 Battery? A dead (or dying) battery shouldn't even let the car turn over, right? Mine measured 12.1VDC, which I know isn't good, but my car has shown no other low-voltage symptoms (reset clock, calendar), but the battery is probably due to be replaced - Optima 34R, I think?
2 MAF? I haven't done any MAF work on my car, so it could be the result of a dirty MAF from the looks of some prior posts
3 Coilpacks? Coilpacks were replaced when my engine was rebuilt I think. Spark plugs were for sure
4 Coolant sensor? I've heard that the rough idle was caused by a bad coolant sensor too
I pointed out the rough idle to the dealership when I was under warranty (this has been an ongoing issue basically since I got the car) and they told me it was the "nature of the engine". That sounds like a load of bull**** to me. If every VW engine wasn't reliable like this, they'd never sell any cars. On any note, they checked and the car wasn't throwing any codes - engine or maf related. Are there any fixes I'm missing? I might just start replacing parts and hoping.
Symptoms:
rough idle showing a bouncing needle and surging throtle on first cold-start only, sometimes leading to the car stalling without being given additional throttle (car starts fine after first stall or continues to run rough if not allowed to stall)
Solutions:
1 Battery? A dead (or dying) battery shouldn't even let the car turn over, right? Mine measured 12.1VDC, which I know isn't good, but my car has shown no other low-voltage symptoms (reset clock, calendar), but the battery is probably due to be replaced - Optima 34R, I think?
2 MAF? I haven't done any MAF work on my car, so it could be the result of a dirty MAF from the looks of some prior posts
3 Coilpacks? Coilpacks were replaced when my engine was rebuilt I think. Spark plugs were for sure
4 Coolant sensor? I've heard that the rough idle was caused by a bad coolant sensor too
I pointed out the rough idle to the dealership when I was under warranty (this has been an ongoing issue basically since I got the car) and they told me it was the "nature of the engine". That sounds like a load of bull**** to me. If every VW engine wasn't reliable like this, they'd never sell any cars. On any note, they checked and the car wasn't throwing any codes - engine or maf related. Are there any fixes I'm missing? I might just start replacing parts and hoping.
10-24-2005, 10:52 AM
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1) Highly unlikely, 2) Bad MAF would throw a CEL if it were the culprit, 3) Possible, but again...
a bad coil pack(s) would throw a CEL, 4) A $6 part, and worth changing out regardless. I change mine every 5k miles and have never had a start-up issue since then. If you DO have a CEL on right now, run the codes, it's the only real way to know whats causing your issue.
10-24-2005, 10:59 AM
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doesn't sound like coilpacks or battery; my vote=coolant sensor
like Kinetic said, it's a $6 part and takes 5 mins to replace.
Sounds to me like something is resetting itself on the 2nd startup.
\_Q_/
PS: <b>Replace the battery anyway!</b> 12.1v is too low. If you don't want to drop the coin for Optima, Wal-Mart has one for $39 and Costco for $49. Worth it. Less than the cost of dinner.
Sounds to me like something is resetting itself on the 2nd startup.
\_Q_/
PS: <b>Replace the battery anyway!</b> 12.1v is too low. If you don't want to drop the coin for Optima, Wal-Mart has one for $39 and Costco for $49. Worth it. Less than the cost of dinner.
