Idle surge (1K-2K)

[theKnifeArtist]

The other day, couple minutes after start up, my idle starts surging from around 1000 to 2000. This condition also made it run weird, for example coasting in second gear and applying a small dosage of throttle would make it buck.
I looked it up and found this thread.

http://www.supramania.com/forums/showthread.php?t=68367&highlight=idle+surge+2000

so i pulled the EFI fuse and it worked. cool. i thought i'd research it later.
and so it happens again obviously.

i ran codes and have 14, 24, 34(fuel cut)
i just looked these up now, so i got an ignition fault and an air intake temp sense fault (heh thats a new one). i haven't looked into this yet, but i thought i'd post my concern to get some info flowin.

Any help appreciated.

 

[shaeff]

My first guess would be that you have a boost/vacuum leak, as indicated by the code 34. Start there. Code 14 has to do w/ the igniter. I'll shoot in the dark and tell you to check the connection, AND the ground. The ground is done through the case, and if it gets corrosion on between the front and back half of the case, it's likely to not function properly.

As for the code 24, check the connection on your AFM. Also try bench testing it:
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=FI&P=96

 

[theKnifeArtist]

so,
Code 24: i'll check out the AFM and connection
Code 14: I have my ignitor grounded to the battery from it's ground screw. So ground is taken care of. I guess i'll check the rest of it.
Code 34: I'm pretty sure that's the code that's set when you hit fuel cut...or have an air leak. I'm pretty sure i hit somewhere around 14psi and fuelcut the other week, so i'm ruling out an air leak..unless you have any more ideas.

 

[shaeff]

But you said you cleared the codes. If you have a code 34 again, then something is amiss if you haven't hit FC since you cleared them.

 

[theKnifeArtist]

does pulling the efi fuse clear codes? i read these codes before i pulled it for the first time.
if the codes are not clear now, i'm gonna clear em and see what comes back assuming the surging problem comes back.

 

[shaeff]

Pulling the EFI fuse clears the codes, as can be seen by clicking the link in my sig.

 

[theKnifeArtist]

sorry for the long delay.
so i checked the previously cleared codes right after the surge event and no codes. I tried it twice actually. That sucks. Any ideas?

 

[sneakypete]

i had the same problem a few years ago when i had an afm. couldnt figure it out for the life of me. turned out it was the afm itself. try swapping another afm in there if you can get your hands on one, or test the wiring to the ecu
hope that helps
-pete

 

[theKnifeArtist]

interesting. was yours intermittent? Mine has been running flawlessly(knocks on wood)for the past couple days.
I just bought this afm from someone on here to replaced mine that was...electrical cleaner-ised. Damn another afm, hah
i'll check out the wiring.

 

[sneakypete]

at first it was intermittent, but after about a day or two after the first incident, the problem became permanent.

 

[theKnifeArtist]

so i'm reviving this thread.
Once it starting getting pretty cold outside, i didn't have this problem anymore.
It was fine for the longest time and then starting doing it again.
I figured out that a simple key cycle would make it perfectly fine again, so i did that a couple times. Yeah i know thats bad, but maybe it'll aid in diagnosis.
With a clean slate no codes, then having this problem arise, it does not throw any codes. Just today this happened again, but i can no longer get it to stop.
The car will actually propel itself while in gear if the rpm is low enough and it starts to surge.

What would cause this?

Any more ideas?


i'm gonna take it to work tommorrow and check out the isc valve