Stuck/Broken/Torn FIAV?? Cannot figure out extemely high idle. 2500 RPM+!

[project_tsi]

Well today, I was going to go to TRE and have Jon check out my trans.

I leave and head down the road and pull up to a stop sign and the car all of a sudden idles at about 2500 RPM. I'm like OK??? I get out and try adjusting the Biss, maybe it came loose? But no, it was nearly closed. I couldn't see anyting physically wrong but I took it back home anyways.

Back home, I found that the "throttle closed switch" on the TB, the wire had broken off. I thought, great, easy fix, this has to be the problem. Fixed the wire, didn't help. Still super high, and steady (no surging) idle.

So I start to think, maybe the ISC somehow broke or stuck open? I know the ISC was bad b/c I've had idle surging problems for a while. But anyways, I get out the multimeter and check the resistance in the coils in the ISC. Coil check 5-6 failed. It didn't read anything at all. I thought, great I just have a bad ISC that finally took a big shit. I grapped an extra ISC laying around, checked it with the multimeter and it was good. Installed it, Still high steady idle at 2500 or so RPM.

Now I'm lost. DSMLink Idle is set at 1000. Not throwing any codes for TPS, ISC, etc. I've verified base timing at 5*. I've also checked and re-adjusted the throttle cable.

The trottle body has just been rebuilt by my buddy Jim. Its a 1g TB, with the FIAV still functioning.

Is there any way the FIAV is stuck or broken or torn or something? I'm lost right now on why it started this and hasn't stopped. Even after the car sitting for 5 hrs, it still did it.

Any ideas and advice are greatly appreciated.

Thanks, Dan.

 

[97gstnick]

I have this same problem but I'm not so sure that yours is as simple as mine. My throttle sticks just a tad sometimes. I'm going to guess that you have already tried to "blip" your throttle a few times and see if that helps?

 

[project_tsi]

Yeah I've driven the car around all day. It runs and drives perfectly fine except for that.

 

[97gstnick]

Well from my understanding, the FIAV works by a little wax pellet melting after the car warms up so it seals it off from having a high idle. I still can't picture how that works but whatever. Anyways, maybe that wax pellet won't melt of something? Hmmm, sounds retarted but who knows.....?

 

[project_tsi]

I dunno fully how it works either, I've never looked into it, that kinda why I'm asking about it.

Also, when Jim rebuilt the TB, he re-installed the FIAV using grey RTV, and not using the rubber oring type gasket. He's done this on several TB's now with no problems. But if the RTV were to have failed and let air in/out, could this cause the problem?

 

[97gstnick]

I dunno fully how it works either, I've never looked into it, that kinda why I'm asking about it.

Also, when Jim rebuilt the TB, he re-installed the FIAV using grey RTV, and not using the rubber oring type gasket. He's done this on several TB's now with no problems. But if the RTV were to have failed and let air in/out, could this cause the problem?

Thats how I have my FIAV, I RTVed it too. But yea, if there was a slight difference in angles of the connecting halves I believe air would get through. But I would think some coolant would get past it too possibly.

 

[97gstnick]

Here is a list of things to try out. Hahah, good luck...
http://www.dsm.org/how-tos/tttt/tttt3.html

 

[project_tsi]

Thanks for the help guys, I fixed it today.

I popped off the TB and first, found the idle set switch to be way out of adjustment, thus keeping the TB slightly open.

Second, and this is F'in scary as hell..... My Throttle plate screws were loose and the plate was rattling around...... Jim never used any loctite or peened the screws. I took care of it, but still scary as hell. If one of those screws were to back out bye bye engine.

 

[97gstnick]

Thanks for the help guys, I fixed it today.

I popped off the TB and first, found the idle set switch to be way out of adjustment, thus keeping the TB slightly open.

Second, and this is F'in scary as hell..... My Throttle plate screws were loose and the plate was rattling around...... Jim never used any loctite or peened the screws. I took care of it, but still scary as hell. If one of those screws were to back out bye bye engine.

Don't you mean "guy". haha, jk. Yea, your problem did sound like a slightly open tb thats why I asked if you tried tapping the pedal and see if it did anything. I have this same problem, guess I need to lube it up or something.

 

[2GeNTSi]

I'm having this problem as well. I just had a 6-bolt swap done w/ a 1g IM and TB and it idles extremely high on first start-up in the morning, though it goes away as soon as it is warmed up. When the idle is high, sometimes it's a constant +2k RPMs, and for a few seconds it might oscillate and then steady out.

Tested the ISC, 30 ohms across. I was thinking maybe it's the FIAV since once it's warmed up it goes away. I have a friend with a 1g TB that he'll sell to me for cheap so I'm gonna try it out.

 

[VisionPaintball]

Thanks for the help guys, I fixed it today.

I popped off the TB and first, found the idle set switch to be way out of adjustment, thus keeping the TB slightly open.

Second, and this is F'in scary as hell..... My Throttle plate screws were loose and the plate was rattling around...... Jim never used any loctite or peened the screws. I took care of it, but still scary as hell. If one of those screws were to back out bye bye engine.

what is the idle set switch?
thanks

 

[DearDoger]

My 95 gsx is also having the same problem. even on a cold start and it doesnt surge. Im gonna try the basic throttle cable, bliss, etc. if anyone knows a definent solution let me know

 

[absolute_DSM]

Second, and this is F'in scary as hell..... My Throttle plate screws were loose and the plate was rattling around...... Jim never used any loctite or peened the screws. I took care of it, but still scary as hell. If one of those screws were to back out bye bye engine.

Wow Dan, now that is a good catch. I bet youre glad your idle was acting up now! (or you might not have noticed at all )

 

[Avionixx]

what is the idle set switch?
thanks

It's a little toggle switch that tells the ECU that the throttle is completely shut. If incorrectly adjusted, it can hold the throttle slightly open or fail to tell the ECU that you've shut the throttle and you won't get injector shut off during cruise or properly return to idle speed. If I remember correctly, 2Gs do not have this switch. If you have DSMLink like me, you can toss the switch completely and just tell Link to simulate it.