Idle Problems

Recently, I've been noticing some idle problems. When I start my car cold, the idle hunts in a 500 rpm range between ~1500rpm and 2000rpm.

When the car warms up, the problem goes away.

Even more recently, I've noticed that when I come to a stop, the idle does not go down to the 750-900 rpm that it should. Instead, I've seen it idle somewhere around 1300-1400 rpm.

Can someone help me diagnose this problem.

Would bypassing the thermo valve on my throttle body solve this problem?

Weird, my car did this today too. Figured I had my first vacuum leak ever. I can see my vacuum fluctuate on my PMS unit. Hopefully it goes away when I drive home [img]tongue.gif[/img]

Maybe something strange in the air today...

Definately weird. I did consider a vacuum leak. But I wanted to see what other possiblities were also.

A vaccuum leak is the first thing to look at... however, chances are good that the culprit in this case is either the IACV or Thermo valve. I say this because both of these devices are most active when the car is cold... and become far less invasive once the car reaches operating temperatures.

Joe, did you ever call me so I could walk you through the test procedure on this ??? If not, ring my phone babee.

Aaargh [img]mad.gif[/img] ! My idle problem didn't vanish on the way home. Mine won't seem to go below fast idle wither cold or warm. when cold, it idles fine at fast idle around 1,300 or so. Once it's warm, it will idle there, and then try to drop, but once it tries to drop it jumps back to about 1,700, then down to 1,300 and starts the process over.

Would this be consistent with a fast idle thermo valve problem?

Wow! 2 Thumbs up on that one Jim! [img]graemlins/thumbs_up.gif[/img] [img]graemlins/thumbs_up.gif[/img]

I'll have a couple minutes tomorrow afternoon to do this. I'll definately let ya'll know then.

IF the thermo valve is the problem, the coolant bypass trick should fix the problem, right?

If it's the IACV, then I'm guessing I'll have to clean out (?) the screen, right?

I blame this ALL on Cali's 91 octane gas!!! jk.

Yes.
Here is a quick test (pay attention Joe, this will save you a phone call):

First, warm the car up to operating temp. Remove the intake tube at the throttle-body end. Now, look inside the lip of the throttle-body: you will see TWO holes about 1 1/2" back from the lip... the lower one is at the 8 O'clock position... the upper one at about the 10 O'clock position. With the car running, place your finger over the lower hole. If the idle drops to normal and stabilizes, then the THERMO valve is the culprit. If there is no change, you must test the IACV. This is a bit more tricky because if you simply cover the upper hole, the car will probably stall. Instead, slowly slide your finger across the hole so as to reduce the open area gradually. Once the hole is about 90-95% covered, the idle quality should be normal. If you can cover this hole completely, and the idle is still "hunting" (going up and down in a rythmic pattern), then the IACV is most likely the spoiler.

Good luck.

Hey, between this board and the Helms manual, every now and then I learn something or get something right [img]biggrin.gif[/img] . Thanks for the testing tip on the IACV as well.

Well Jim, after doing your test, these are my results:

I drove the car for approximately 20 minutes, so I know that the car was fully warmed up.

I stopped the engine for about 5 minutes. I noted the engine rpm to be approximately 1200 rpm at idle. It wasn't as high as 1400 rpm like the other day, but 1200 still seems pretty high.

After plugging the thermo hole, I noticed that the engine rpm dropped back down to approximately 800 rpm. Unplugging it brought the engine rpm back up to about 1100 rpm.

What are my options now? Does this absolutely mean that it is the thermo valve or is a vacuum leak still a possibility?
1) bypass the thermo valve? This is only a temporary solution though, I think. I live in California, and will probably need to have my car re-smogged in about 1.5 yrs, so I can live with this solution for a while.

2) Is it possible to buy a new thermo valve?

Thanks again for the replies.

Here's a picture of the valve

http://members.aol.com/cooldred/FIT.jpg

I kindof have the same problem but to a lesser extent. My car will do it's normal cold idle/high rpm at startup, and once it's warm, drop the RPMs down to between 600 and 900. My problem is when I come to a stop at a light or something after either a short block or a long highway stint, the car will stay at roughly 1200 RPM for approximately 15-30 seconds after I stop before dropping back down to between 600 and 900 RPM.... It doesn't matter if I push in the clutch way before the stop while braking, it starts the 15-30 second count down after the car is completely stopped. It only does this when it's cold out... I think it has something to do with the fact that there is no water/coolant going to anywhere near the TB. It doesn't really bother me, just thought I would post up my experience, perhaps get some input into it.

<font color="#a62a2a" size="1">[ December 06, 2002 11:05 AM: Message edited by: exciv2000 ]</font>

Joe,

The only way to "Bypass" the thermo valve is to REMOVE it and create a plate to cover the open holes in the base of the throttle body. The common misconception is that by running coolant directly from the head to the IACV, and skipping the inlet/outlet passages of the thermo valve... that it is "bypassed". NOT TRUE... bottom line.

Your thermo valve may be serviceable. This is easiest once you remove the throttle body from the intake manifold. Looking at the firewall end of the thermo valve, remove the two small screws holding the cover plate. Inside, you will see a bronze colored button with a white ring surrounding it. There are two recessed grooves in this ring... directly across from each other and passing through the center of the assembly. Using an open pair of needle-nosed pliers, screw the white ring in a clockwise rotation until it stops... when it suddenly becomes difficult to turn further (the ring is somewhat fragile... breaking it will require the purchase of a new thermo valve). Now, re-install the plate and throttle body. Don't forget to have an extra T/B gasket just in case the one you have gets damaged during this process... there is no sense in fixing one vaccuum leak and creating another !!!

heheh

I had the same problem a while back...thanks for the help about a year ago Jim [img]tongue.gif[/img]

Eventually, instead of getting a new valve (mine was still fluctuating even with the screw all the way in), I just ended up wrapping the SOB in some quality duct tape and popping it back on, covering the holes.

Worked like a charm!

Excellent. That may be another option if screwing in the inside piece is not enough to fix the problem.

A big question on my mind. . .and I may be alone in this with some other Cali people, is whether doing something like that is smog legal?

Joe,

You cannot see the ring from cooldred1's pic. It is located under the plate on the end of the Thermo valve pointing toward the LEFT side of the picture.

Thanks for the pic Cooldred1! Is the white ring that Jim talked about in his post visible in this picture? Or is it in one of the 2 holes that I can't really see into?

OK, I got around to checking my problem. first things, first, no fast idle thermo valve on a manual transmission car [img]redface.gif[/img] .

But, I did try covering the IACV port and when I do this, the car idles steady at low RPM levels again. This means the problem would be the IACV leaking then, right? I assume so since this proces should have isolated the IACV and any related vacuum leak.

So, I assume I simply have to replace the IACV?

I also finally threw a CEl, codes 71-74 I beleive, meaning a random misfire and one of the suspects for the code is the IACV.

CPA, you don't have a fast idle thermo valve? Did I misunderstand something?

Well, the Helms manual only lists the fast idle thermo valve for automatic transmission - seemed odd to me. Also, I only had one port in my throttle body that goes to the IACV. Now I question myself....Maybe its an OBD II vs OBD I difference?? I'll go pull it apart..again!

<font color="#a62a2a" size="1">[ December 08, 2002 08:01 PM: Message edited by: cpa ]</font>

My thermo valve is located on the underside of the throttle body. It has a coolant hose going directly form it to the head. The coolant hose exits the thermo valve area at approximately 2'oclock when looking at it from the passenger side.

But you said that when you took off your intake, you only have 1 hole on the inside, right?

Maybe it IS an OBDI vs. OBDII difference. [img]confused.gif[/img]

Yes, the Thermo valve is only present on a '94-95 Integra GSR... the '96+ cars do not have them. The Civic is a different story.

Hey Jim, what exactly does screwing in the white ring do? I don't think I'll have time to do it until this Thursday nite or so and was just curious.

Another thing, I haven't removed my TB since I installed it with the supercharger. What's the easiest way to clamp off the coolant lines so that I have minimal amount of coolant leak? I know that clamping the coolant line to the thermo valve is one.

Woohoo [img]biggrin.gif[/img] ! My IACV valve is being replaced for free at Acura. I forgot that it was covered under the extended emissions warranty that Acura had to provide for certain early OBDII CA cars in a settlement with the CARB. It's nie to get something back here in CA given how restrictive the rules are.

It closes off the amount of air that bypasses the T/B plate... thus allowing idle control back to the IACV, MAP and throttle body.

Cool! Thanks Jim! I sent you a PM just now, but go ahead and ignore that.

Does anyone from Cali (or Jim) know if this affects the smog legality of the car? I don't even know if the question is relevant, but I thought I'd ask. [img]wink.gif[/img]

Jim,

I did like you instructed. Removed the TB and screwed the white ring in fully clockwise. It's true that the car doesn't idle nearly as high when cold started (only about 1500 rpm), but it does settle down to a very manageable 1000 rpm otherwise. I guess I need to adjust the idle adjustment screw now. Just wanted to say thanks to everyone for their help.

God I love archives.

My car is idling at 3000 rpm until the temp gauge gets higher, then it drops to 1200, and finally to normal.

The idle is really rough, and jumps for awhile between 1500 and 3k. (really rough idle)

Unless you guys know another culprit for it being this high, I'll have the mechanic look into this when I drop my car off this weekend.