Fast idle on DECEL ONLY

[imdrax]

Searched and no real answers emerged. On decel only the car will idle at 2krpms until I come to a stop and then hold a rock solid 800rpm idle. It does it everytime and I can even feel it while im decelerating in gear; for instance if im driving at 30mph in 2nd and then graze off the throttle it SHOULD engine brake but it doesn't, it coasts as if im still inputting throttle.

My afc shows 0%throttle so I know my throttle plate or cable isnt sticking. I ohm tested the IACV and it checks out. Is there some sort of decel idle control from the factory? None of my old DSM's did this and my roomates 93 GSX does not do this.

 

[92GSXtacy]

I just got my 91 GVR4 to stop doing that, turned out to be a faulty Idle Switch i think. I say I think because I also fixed the ABS the same day but I highly doubt that had anything to do with the decel high idle....

 

[imdrax]

The ABS is disabled on my car. You had the same issue and it was resolved by replacing the idle switch? Did you have a normal Idle while the car was at a standstill?

 

[92GSXtacy]

Yea, it idled right at 900 which is where it was set in ECMLink. I went through 2 ISC's, a spare TB, and a new BISS; nothing worked. Swapped the Idle Switch and she runs perfect now. Although now I am wondering if the ABS DOES play some role in this...does yours drop to a normal idle around 10mph?

I'm going to go disable the ABS and check this out in the morning....I'll post up my findings tomorrow.

 

[imdrax]

Mine wont drop to a normal idle until I am at like 1-2 mph if that. Pretty much a complete stop is needed. Where did you get a replacement idle switch (closed throttle switch)?

 

[92GSXtacy]

From Mitsu. The Galant is a father/son project so being partially his car it gets all the good stuff usually...

 

[imdrax]

Where did you order and how much? I was only able to find one place online and it was 90!!! Really steep.

 

[92GSXtacy]

I couldn't find it online anywhere so my father went to the local dealership and got one, I have no idea what he paid but I'm sure it was ridiculous. Where did you find it online?

 

[imdrax]

Just one of the Mitsu part sites.

So for a little UPDATE: Went through the engine bay and was checking everything over, come to find the coolant lines for the FIAV had been removed by the previous owner. I believe this to be my issue. I have already ordered a bypass plate and when it arrives I will update again. Thanks.

 

[imdrax]

The FIAV has been bypassed and IACV left in tact. The car still has a 2k-2.5k idle while moving. After looking at some logs I noticed a few things.

First off lets say Im coasting to a stop in nuetral or with the clutch depressed. While the rpms are fast the logger shows a steady 69hz until I come to a stop and as soon as the idle drops to normal the HZ drops to around 35hz.

Secondly while the engine is fast idling on decel the logger shows an iDC of around 3% and as soon as I come to a stop and the idle returns to normal the DC drops to .7%.

Does anyone have anything else I should check out, Im running out of ideas? I am going to try and adjust the TPS tomorrow because at 0% im showing 12.8% on the logger and supposedly I should be seeing 8-9% at 0% throttle.

 

[steve]

I think I've seen posts on the GVR4 board where the disabled ABS causes this.

 

[Rubidon]

Imdrax I have the exact same thing happening on my '97 Eclipse GS. I am a noobe so most of the abbreviations I don't know yet but I will learn. So please keep us posted. FIAV? IACV? BISS? I thought my idle switch is integrated into the throttle position switch?

 

[steve]

Your GS is a 420A engine and little of what's being discussed applies directly to you.

 

[imdrax]

Steve I will try and search through the GVR4 boards. That forum is very hard to find information however so I stick to the DSM sites. I am not even sure what the PO did to disable the ABS so I will need to look the car over because I know for a fact the ABS block is still intact with all lines running to it.

EDIT: went ahead and searched through the GVR4 boards on EVERY abs thread with not a mention of said problem.

 

[steve]

GalantVR-4.org: idle while driving

GalantVR-4.org: Idle Issue

GalantVR-4.org: Car wants to hold revs when above 15mph

GalantVR-4.org: high idle rpm >13mph!

 

[imdrax]

Thank you, I have a hard time understanding how to search correctly on that forum, you have to use + and - and I usually just come up with pages or RE: posts.

Edit: fixed!! Steve u's a badass!

 

[steve]

What did you have to do? Pull a fuse or put it in?

 

[imdrax]

Well the 60amp was already missing, I could not find the 20amp that was mentioned. I unplugged the front connector near the ABS block and my ABS light went off and the decel idle returned to normal. I searched a long time for that answer but I was searching things like "ABS" and "DECEL" I never thought to just search "IDLE".

 

[steve]

Cool, now when somebody else has the problem they might be able to find the solution here.

 

[Rubidon]

I am glad you got your car fixed but I think my car is non-ABS. I don't think this will help me!!

 

[tsi4g63dohc]

i removed my abs fuse and now i have no idle at decel but when i hit my brakes it gos up !!! weird