Roaming idle while rolling (fine when <10mph!)
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Roaming idle while rolling (fine when <10mph!)
I have a B18B1 installed in my Del Sol. I removed the FITV. When warmed up and sitting still my idle sits at a stable 850rpm, but when I'm rolling and I push the clutch in, my idle bounces between 850 and ~1500rpm. The moment the car drops below about 10mph the idle settles down to 850rpm and stays there, which leads me to believe this is something intentional or perhaps funky with electronics. If I remember right it also typically settles down if I have the A/C running. I'm running a stock computer and have no CEL.
I google'd it and had a few results but no answers - is this ok? Is it supposed to do that?
I suppose the first step toward diagnosing it is running with the IACV unplugged, huh?
I google'd it and had a few results but no answers - is this ok? Is it supposed to do that?
I suppose the first step toward diagnosing it is running with the IACV unplugged, huh?
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Re: Roaming idle while rolling (fine when <10mph!)
one of the inputs for the iacv is the clutch switch. the ecu uses it to adjust idle, in advance, under varying load conditions. ac switch is another input.
you can try unplugging the iacv, but that only tells you that it's an issue between the iacv, the ecu and all of their inputs.
if the problem only occurs when depressing the clutch, it's going to be an issue between the clutch switch input and the ecu
you can try testing the iacv as well. but i'm pretty sure it's gonna be fine, since you say idle is stable with ac on
you can try unplugging the iacv, but that only tells you that it's an issue between the iacv, the ecu and all of their inputs.
if the problem only occurs when depressing the clutch, it's going to be an issue between the clutch switch input and the ecu
you can try testing the iacv as well. but i'm pretty sure it's gonna be fine, since you say idle is stable with ac on
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Re: Roaming idle while rolling (fine when <10mph!)
Is this switch the button on the pedal, or is it under the hood?
If I let go of the clutch pedal while rolling the idle continues to roam until the car goes below about 10mph. Would it tell me anything if I pulled it out of gear without using the clutch?
If I let go of the clutch pedal while rolling the idle continues to roam until the car goes below about 10mph. Would it tell me anything if I pulled it out of gear without using the clutch?
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Re: Roaming idle while rolling (fine when <10mph!)
No, the idle is fine. I suspect if we had hills here and I were to sit in neutral at the top of one, and start rolling down, the idle would start bouncing once I passed 10mph.
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Re: Roaming idle while rolling (fine when <10mph!)
hmmm. k scrap the clutch input idea.
any other driveability issues with this?
have you checked your codes?
so the idle only lopes in neutral, when rolling?
any other driveability issues with this?
have you checked your codes?
so the idle only lopes in neutral, when rolling?
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Re: Roaming idle while rolling (fine when <10mph!)
No other driveability issues. I had an ameteur mechanic swap the engine for me and he didn't bother connecting 3/4 of the sensors. I got everything as it should be, to the extent of my knowledge, and the CEL went off and stayed off. It behaves otherwise like it should.
The only issue is the loping idle, in neutral, when rolling.
Some googling reveals similar issue in a Ford:
http://www.therangerstation.com/foru...ad.php?t=98087
I can't find it now but another had the same (or a very similar) issue in his Prelude after a swap.
The only issue is the loping idle, in neutral, when rolling.
Some googling reveals similar issue in a Ford:
http://www.therangerstation.com/foru...ad.php?t=98087
I can't find it now but another had the same (or a very similar) issue in his Prelude after a swap.
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Re: Roaming idle while rolling (fine when <10mph!)
Found another:
http://www.gassavers.org/showthread.php?t=8444
http://www.allcorsa.co.uk/forums/sho...ng-41414.html?
Someone ventured an explanation:
My idle bounces when rolling like described, perhaps it stops bouncing when I engage the A/C because it loads the engine slightly?
Is this replicable in your car? Thanks for your help so far!
http://www.gassavers.org/showthread.php?t=8444
http://www.allcorsa.co.uk/forums/sho...ng-41414.html?
Someone ventured an explanation:
The reason the idle is doing this is because you are coasting along in neutral - the ECU is designed not to go to idle until the wheels are stationery. It's to keep the drive smoother when in start-stop conditions like heavy traffic.
To demonstrate this to yourself find a hill - park the car facing down the hill. Put it in neutral and let the engine idle. Then take the handbrake off and roll down the hill. The engine revs will increase to about 1000rpm as soon as the ECU senses that the wheels are rolling.
To demonstrate this to yourself find a hill - park the car facing down the hill. Put it in neutral and let the engine idle. Then take the handbrake off and roll down the hill. The engine revs will increase to about 1000rpm as soon as the ECU senses that the wheels are rolling.
This week I was going to swap components from my 92 VX to 94 VX till I figure out what was causing my idle to bounce when rolling in neutral on 94 VX. Just before doing the swap I took 92 VX for a test drive and found that it's actually doing the same thing when I turn AC off!
I then checked 94 Civic VX and it also idles fine with AC on when rolling in neutral. Basically they both have the same condition:
Idle at stop - with A/C ON and OFF - Fine
Idle while rolling in neutral - with A/C ON - Fine
Idle while rolling in neutral - with AC OFF - slowly (5-10 seconds) bounces between 900 and 1200 RPM
So am I on a wild goose chase here?? Should I spend any more time trying to troubleshoot this, or did they just came like this from the factory?
Also both cars idle at around 900 rpm at stop, is this normal?
I then checked 94 Civic VX and it also idles fine with AC on when rolling in neutral. Basically they both have the same condition:
Idle at stop - with A/C ON and OFF - Fine
Idle while rolling in neutral - with A/C ON - Fine
Idle while rolling in neutral - with AC OFF - slowly (5-10 seconds) bounces between 900 and 1200 RPM
So am I on a wild goose chase here?? Should I spend any more time trying to troubleshoot this, or did they just came like this from the factory?
Also both cars idle at around 900 rpm at stop, is this normal?
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Re: Roaming idle while rolling (fine when <10mph!)
interesting. try disconnecting the vss and see if it still does it. but AFAIK, the vss is not an input the iacv uses. could be wrong though
and when this is occurring, the brake pedal is not depressed at all, correct? because the brake switch is an input for the iacv. hmmmm. so is the eld.
check your codes too
and when this is occurring, the brake pedal is not depressed at all, correct? because the brake switch is an input for the iacv. hmmmm. so is the eld.
check your codes too
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Re: Roaming idle while rolling (fine when <10mph!)
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Re: Roaming idle while rolling (fine when <10mph!)
yea, that makes sense. the high idle should have been the giveaway. bet it's sitting a bit closer to 750 +/- 50 now. if not, try adjusting idle as per procedure
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