Torque South

Ever since it rained hard the other day my beater 88 gxl has been stuck revving high at idle. Since it occasionally switches to surging I swapped the air flow meter but it didn't help. The throttle cable is not stuck. Could it be the throttle position sensor?

misterstyx69

iTrader: (142)

Spray the throttle linkage to make sure they aren't Corroded.
You should be able to see if the Springs,etc are Corroded and clean them accordingly.Also see if the throttle body is fully closing or the Screw on it is hindering it from Closing.The TPS would make it buck though,and it doesn't hurt to check it to see if it is out of whack.

RotaryRocket88

iTrader: (7)

The TPS can cause surging idle at certain RPMs, but that would be the symptom, not the cause. I'd agree that the throttle linkage should be the first place to look. Take the intake duct off, so you can get a look at the primary throttle plate. It should be allowed to close nearly all the way.

Torque South

The linkage doesn't seem to be stuck, it opens and closes all the way with the intake off. I checked for vacuum leaks it doesn't seem to have any. Does not buck, drives perfect just stuck at 2300 rpm instead of idle and occasionally switches to surging after driving a while. Diconnecting the tps drops a few rpm, but still runs fine and high. TPS had power and ground.

It really "feels" like it's stuck on accelerated warm-up. Thanks, I would like to figure this out because I feel like a dumbass. The fact that it started after the rain is not making too much sense at the moment either. Could the throttle plates be fine but it's getting too much fuel somehow which is raising the rpm? Or is the warm-up stuck somehow? Damn I feel stupid

RotaryRocket88

iTrader: (7)

More fuel without more air would reduce engine speed and cause it idle roughly.

What happens if you unplug the BAC and AWS valve? If it's accelerated warmup related, disconnecting those two should drop the idle speed.

Torque South

When I unplug the cylindrical thing on the driver side of the uim that has coolant running through it nothing happens. I searched and read in another thread that if this is the idle air control motor, it is malfunctioning. (I think it is the iac motor right?) I removed it to make sure it's not clogged with carbon or stuck, It moves easy but only a little bit (.5 inch) I'm confused. Let me see what else I can unplug aroung the tb...

Now ever since I dicked around with that thing it's gotten worse !!!! Now it's at 3000 rpm, either me dicking with it has created an additional problem, or that's what it is (my fake turbo hood does drip water right on top of it?)

Like I was saying when I unplug the green connector nothing happens

RotaryRocket88

iTrader: (7)

IAC? Isn't that a 1st gen device? An S4 will have a BAC (Bypass Air Control) valve on the UIM. It's a solenoid. It sounds like that's what you unplugged anyway. The second thing I mentioned, the AWS, is a gold colored valve with 2 black rubber hoses and a white 2-wire plug. It's right next to the oil filter, and under the BAC.

Torque South

Blocking off the BAC has no effect. It's hard for me to see how I raised the idle even further messing with it when blocking it off has no effect. I will disconnect the AWS now.

WOW once again I finally arrive at the simple and obvious fix after driving myself nuts and going around in circles. Thanks RR88!

Solution: AWS stuck, disconnect AWS. Idle settled to 1100 rpm.

RotaryRocket88

iTrader: (7)

Well that was easy . You can also just remove the AWS, or leave it unplugged. You'll still get the ~3k cold start since the BAC still directs air into the manifold. It'll be maybe a few hunderd RPM lower than w/ the AWS, but it makes no difference in terms of how easily the car cold starts.

Torque South

BULLSHIT! I reassembled the car and the same thing is happening! But the AWS is disconnected! WTF??? I ******* give up for real

Torque South

Ok I will try disableing the BAC again because when I thought it was fixed I had it blocked off. There is still hope I just want my 1200 rpm back.... damn my life sucks

RotaryRocket88

iTrader: (7)

Or not so easy...

Are you letting the engine warm up at all? It's supposed to idle at about 3k when cold. The manual claims it's only 17 seconds, but it's about a full minute in my experience.

Leave both the BAC and AWS unplugged and start the engine. It should rest at around 1500 rpm cold, then slowly drop to 750 rpm at full operating temp.

Torque South

Thanks for all the good advice RR88. It seems unplugging the BAC has absolutely no effect under any conditions, but now that I've blocked it off and left it unplugged along with the AWS it started up at 1500 and settled at 1100 and got lower until now it won't idle at all. So maybe I need to adjust the idle up. Or a leak? Probably the idle. I think I am making progress.

Torque South

I had a leak at the tb, tightened it up and the idle settled at slightly above 1000. Noisy and thirsty but liveable with for a $300 junk. Thank you thank you thank you. Normally I'm not this big of a moron mechanic but this whole episode was before I finally got some **** again and a few beers (basically I am a psycho without my regular dose of those). Also running around at work between fixing bigger problems on other cars and lose track of where I left off trying to squeeze in 2 minutes of working on my own crap when the boss not beez lookin. So this is resolved for now. I really appreciate it

RotaryRocket88

iTrader: (7)

No problem. I've had to screw around with idle enough times to know what a pain in the *** it can be.

rebarrage

mine is doing the same as ts so hopefylly your suggestions will work rr88 thanks!