High Idle, different from surge...

[EricGRIT09]

Okay, so I've been searching for anyone else who has had the same problems that I am having, and I can't find another situation just like this.

I am having a really bad high idle problem, but with absolutely no surge, and it only happens when the car is warm and in warm weather. On a warm day, my car will steadily idle at 1100 RPMs, but then after driving around and the engine bay getting warmer (still on a warm day) it might idle at 1800 RPMs. Drive for another 5 minutes and hit a stop light, it might idle at 2400 RPMs. 2400 RPMs is usually the highest it gets, and if it stays warm it will idle here until the car cools down again. This seems completely random, except for the fact that warmer usually means higher idle.

The car usually idles pretty well (750-900 RPMs) in colder weather probably under 40 degrees. Now that summer is getting here, it is getting much worse

Any ideas? No boost leaks, recirculated bov. I will probably just replace my ISC, all vacuum lines and maybe replace my throttle body gasket.

 

[mindset]

Test the ISC first.
I was thinking maybe it might be the coolant temp sensor.

 

[gonzalaga1]

I have this issue too. I've been conveniently ignoring it because the weather has been cool. the longer I drive the car, the worse it gets. I can usually get it to reduce the idle speed about 800 rpms from wherever it is by blipping the throttle.

I have a new TPS, a used (but working) ISC, cleaned out throttle body, connected coolant lines (so shouldn't be FIAV). I suspect the cruise control box, because it definitely seems mechanical in nature (not a stuck TB, or worn lines).

I would like to get this fixed as well. There are a ton of half-baked posts about this but no concrete solution.

 

[EricGRIT09]

You know what, you may be on to something with the cruise control. My cruise is broken and I just have it tucked back behind the battery. Looks like its time for either a fix or a cruise delete.

 

[gonzalaga1]

You know mine is non-functional too, but everything is still hooked up. I just figured it was something the previous owner did...

From other threads I've read here it's a real headache to fix. So now the question is, which one of us is going to install the 1g NA throttle cable?

 

[stevo911]

Cant you just disconnect the vacum line from the cruise control?

 

[misphit]

Sounds to me like your throttle cable is too tight. As you drive and the engine warms, the heat is pulling the cable/housing backwards, forcing your throttle plate open which is causing your super high idle. My suggestion is to loosen the cable mounting point on the intake manifold (?) and adjust to add some slack to the throttle cable. This is a pretty common problem.

 

[EricGRIT09]

That does make sense. And in this case, if the heat was causing the throttle cable to be too tight wouldn't the TPS % tell me if it was pulling on the cable? Or would the percentage be so small it wouldn't be seen on a logger?

 

[Jimmyskrew face]

That does make sense. And in this case, if the heat was causing the throttle cable to be too tight wouldn't the TPS % tell me if it was pulling on the cable? Or would the percentage be so small it wouldn't be seen on a logger?

Do this, easiest way to check, I had the same exact issue with my 2g 6b swap. On hot humid summer days the car would just idle high and stay there when I got stuck in traffic or at a light. When your home one day and it starts doing that, get out the car and close the throttle body with your hand and see if the idle drops. From there you'll know if its ## cable. But make sure you eliminate all the other options first, (testing the ics, checking your fiav, and cleaning your tb) I did all those first then I went after the throttle cable as a last resort. Also worst case senario... tb shaft seal.

 

[spitefire1]

ive had this same problem and it was my coolant temp sensor. and if that doesnt fix your problem try loosening your throttle body cable it might be to tight.

 

[misphit]

But make sure you eliminate all the other options first, (testing the ics, checking your fiav, and cleaning your tb) I did all those first then I went after the throttle cable as a last resort.

WTF kind of advice is that? It takes all of two minutes to loosen the cable mounting bolts, add some slack, and retighten. OP, as I said before, check the cable. Who cares what the datalogger reads for now.

 

[2GeNTSi]

I don't think my cable is too tight (I've checked it before and it doesn't seem tight in my eyes) but I still have this issue too. I've done all the common sense checks: ISC, TPS, TB rebuild, boostleak test, and everything was addressed.

The one thing I can't seem to fix because I can't find the same sensor is the CTS, everywhere I go they have a different sensor than what I need. Kragen, Pepboys, and even the dealership had all the same sensor but not the one that I removed from my car.

I'll check again on the cables, but I doubt that it's gonna solve it. The car does this even when it's not warm out, but it does seem to aggravate it more. It's more of a problem if I go around town, shut it off, then start it back up a few times.

 

[2GturboTALON]

If you have an electronic boost controller such as a greddy profec make sure the dip switches on the back are set for internal wastegate setup. I had the same problem but it was due to me setting the dip switches on my EBC wrong

 

[Jimmyskrew face]

WTF kind of advice is that? It takes all of two minutes to loosen the cable mounting bolts, add some slack, and retighten. OP, as I said before, check the cable. Who cares what the datalogger reads for now.

Its called troubleshooting.

 

[Jimmyskrew face]

I don't think my cable is too tight (I've checked it before and it doesn't seem tight in my eyes) but I still have this issue too. I've done all the common sense checks: ISC, TPS, TB rebuild, boostleak test, and everything was addressed.

The one thing I can't seem to fix because I can't find the same sensor is the CTS, everywhere I go they have a different sensor than what I need. Kragen, Pepboys, and even the dealership had all the same sensor but not the one that I removed from my car.

I'll check again on the cables, but I doubt that it's gonna solve it. The car does this even when it's not warm out, but it does seem to aggravate it more. It's more of a problem if I go around town, shut it off, then start it back up a few times.

You have a part number on the sensor?

 

[2GeNTSi]

I don't think there is a part # on it. Not that I recall at least. I'll check when I go home this weekend.

I loosened the TB cables up, I'm not sure if it changed anything but I'll know soon. I'll keep you guys updated, but if this fixes it then I'll be really really surprised. It makes some sense because I did have it adjusted to the point where it wasn't showing any readings on the TPS.

 

[RD_Blade]

Please post your results. I've been trying to nail down this exact problem since I bought the car a couple months ago.

I cleaned out the throttle body and MAF. Also disconnected the MAF harness and idle dropped back to normal (750).

I tightened the vacuum line connections. And this seemingly fixed the prob the first time I tried it. Every other time it had no affect.

I don't have much opportunity to fiddle around under the hood and my knowledge is quite limited. So I'm really hoping this thread will lead to a definite fix.

 

[2GeNTSi]

Please post your results. I've been trying to nail down this exact problem since I bought the car a couple months ago.

I cleaned out the throttle body and MAF. Also disconnected the MAF harness and idle dropped back to normal (750).

I tightened the vacuum line connections. And this seemingly fixed the prob the first time I tried it. Every other time it had no affect.

I don't have much opportunity to fiddle around under the hood and my knowledge is quite limited. So I'm really hoping this thread will lead to a definite fix.

So far so good, but it hasn't been warm enough outside to give a definite answer. Like I said in my last post though, it makes sense if the cable is causing the tb to stay open though.

 

[misphit]

Its called troubleshooting.

Generally when troubleshooting, one starts with the easy stuff and moves on to more complex procedures; not the other way around.

 

[RD_Blade]

So far so good, but it hasn't been warm enough outside to give a definite answer. Like I said in my last post though, it makes sense if the cable is causing the tb to stay open though.

Hah! It worked! I just adjusted the throttle cable, too. The car was idling high at the time so I saw the results instantly. I had to slide it to damn near the end of the track.

It just seems strange to me that heat will cause the cable to tighten. Heat makes metal expand, not shrink. Eh...who cares? My idle is fixed!

Edit:

Thanks, BTW, misphit!

 

[2GeNTSi]

Nice!

I'm so glad I fixed mine as well. It's pretty embarrassing sitting at a light when your car is idling at 2k. I finally put my 3" downpipe back on as well, so now I can enjoy the throatier exhaust note.

I can't believe I overlooked such a small detail, I actually made it worse when I was trying to find the culprit. I remember one day I was doing tests on the ISC and TPS, and then I decided to tight up the throttle cable to make it a bit more responsive.

 

[forumboarder154]

I have same problem and I have a 95. When I restart car by disconnecting battery it idles fine and then messes up again.

 

[stevo911]

Boarder you're issue sounds like a sensor issue o2 or coolant disconnect the cable is loosing the values in the ecu.

 

[RD_Blade]

I'm so glad I fixed mine as well. It's pretty embarrassing sitting at a light when your car is idling at 2k.

Not to mention the way it slams into reverse on an auto. The high idle / tight throttle cable mimics some of the symptoms of a bad motor mount. And I can't imagine that being good for the trans.

 

[PC5505]

I had the same problem and it turned out to be a coolant sensor. The wire had cracked and was only working intermittently.