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Author Topic: Random Idle Drop  (Read 2384 times)

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Offline FuzzyDropbear

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Random Idle Drop
« on: May 16, 2008, 11:33PM »
Hi guys,

I recently swapped my ECU over from a stock one to one with a Stage III chip. The issue I have is that the modified ECU makes my pinny idle strange. It will idle fine for a while and then randomly drop or increase 100 - 200 RPM (when warm) and then settle back down. It doesn't do it constantly, just at random intervals. The rev drop is more pronounced when starting from cold, the engine will idle in the usual range for cold start but then will drop down 4-500 RPM and then increase back to usual, again, at random. It also idles (when not being random) at around 1000 RPM (idles about 850-900 RPM with the stock ECU).

I have run the ECU in diagnostic mode and it returns code 55 (nothing wrong). When the stock ECU is put back in, it idles normally. I thought the issue might have occurred because the ECU came out of another car, so I reset it, but it didn't make any difference.

Just wondering if there is any fix to this, or whether the ECU is gone as the problem totally disappears when the stock ECU is in place?

Cheers,


Rob
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Offline SleepaTi

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Re: Random Idle Drop
« Reply #1 on: May 17, 2008, 11:10PM »
from the similar issue i had it was coz i had a man ecu in an auto, manuals don't have the idle-up thingie when u put it in drive causing it to die off

an auto ecu in a manual will have similar effects

could also be your iac playing up, mine was clogged full of carbon when i cleaned it out for the new engine
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Offline Kranzy

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Re: Random Idle Drop
« Reply #2 on: May 18, 2008, 07:48AM »
Quote from: SleepaTi on May 17, 2008, 11:10PM
an auto ecu in a manual will have similar effects

could also be your iac playing up, mine was clogged full of carbon when i cleaned it out for the new engine

Auto ECU in manual is no problem at all, I was running one for years with no issues at all.

My bet is your IACV is not working properly.
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Offline FuzzyDropbear

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Re: Random Idle Drop
« Reply #3 on: May 18, 2008, 11:29PM »
Quote from: Kranzy on May 18, 2008, 07:48AM
My bet is your IACV is not working properly.

Thanks for the replies! Will check that out hopefully within the next couple of days.

I just found it strange that the problem only occurs when the chipped ECU is in place.
« Last Edit: May 18, 2008, 11:31PM by FuzzyDropbear »
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Offline Kranzy

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Re: Random Idle Drop
« Reply #4 on: May 18, 2008, 11:33PM »
It could be an issue with the chipped ecu, but its not going to be due to it being a manual ecu in auto car or vice versa.
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Offline Unbalanced_

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Re: Random Idle Drop
« Reply #5 on: May 19, 2008, 12:48AM »
I put an auto ECU in my manual and it did whack things to my idle.
Idle would vary in between 500 and 1500 - And it was sort of rev when idling, raising and dropping within that range. Put the manual ECU back in and its all good.
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Offline Kranzy

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Re: Random Idle Drop
« Reply #6 on: May 19, 2008, 01:10AM »
Im speaking on a U12, U13 may be totally different.
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