Idle surging. Slow adjusting to altitude?

[bluesuby89]

Drove my 89 GL to Kansas City from hight elevation 7500 feet yesterday. When I got here the engine was surging at idle. First off it would idle at 1500 rpm not 750. Then drop abruptly to 1250. Once there for a second it would surge between 1250 and 1000. Prior to leaving I had code 34 (EGR selonoid), which i did not fix.

 

So here was what I was thinking.

 

1.) O2 sensor is being slow to react to the lower altitude.

 

2.) The egr selonoid is the problem

 

3.) Vacume leak

 

4.) Distributor issues. But the tach was surging with the engine not just floating on it's own.

 

Also, the car seems to high but fine until it warms up a little. Then when at a stop light it surges. Was wondering what anyone else thought? Where should I start? Should I keep driving it and see if it adjusts itself to life with more O2?

 

Thanks,

bluesuby89

[presslab]

The o2 sensor responds in like 0.1 seconds so I don't think that is it.

 

Quite probably the EGR solenoid or a vacuum leak. Maybe the EGR solenoid is broken causing a vacuum leak.

 

You can plug the hose (on the manifold side) to the EGR solenoid and I believe it will disable the EGR system.

[bluesuby89]

Have another possiblity. The TPS. It runs at normal idle when i first start it up. Then when i come to a stop the idle remains high and then knocks down and surges. Any thoughts? Will check it out more tomorrow. Thanks

[Quidam]

Prior to leaving I had code 34 (EGR selonoid), which i did not fix.

2.) The egr selonoid is the problem

 

3.) Vacume leak

 

bluesuby89

 

I might have missed something. However, an egr valve sticking open will cause the symptoms you described.

 

hth

 

Doug

[matts87glsedan]

my car has been doing the same thing for almost a year now, so i watch this post with interest. All my previous threads regarding it got little to no response, i hope you have better luck . I am now going to go and check my egr (again).

[bluesuby89]

I checked all the vacuum lines and they all looked intact and fine. Then I plugged the egr solenoid lines and went for a drive. No change still surging. So i'm thinking it is not an egr problem.

 

So i decided to check the codes and this time there were none stored i got the 6 blinks. So I know don't know what to do. I'm going to clear the codes to get the light to shut off and see if anything new registers.

[bluesuby89]

So the GL was surging again today and I plugged in the green connectors and the surging went away immediatly.

 

So what do the green connectors disable? Because I think this is where my problem is.

 

I also checked and cleared the codes today. There were no codes. But when as a stop light when the car was surging the check engine light would come on. When I reved up to take off the light went off.

 

After all of this i checked to codes agian. Nothing. So whatever turned the light off didn't store a code.

 

Any ideas?

 

Thanks,

bluesuby89

[presslab]

I believe the ECU controls idle speed by changing the timing a bit. With the green connectors together it disables that, and the timing and the idle speed can be set.

 

Is the timing ok? Idle speed set correctly? o2 sensor voltage toggling? Did you check the TPS adjustment?

 

A smoke machine will find vacuum leaks quickly.

 

CEL but no codes? That's odd.

[bluesuby89]

I believe the ECU controls idle speed by changing the timing a bit. With the green connectors together it disables that, and the timing and the idle speed can be set.

 

Is the timing ok? Idle speed set correctly? o2 sensor voltage toggling? Did you check the TPS adjustment?

 

A smoke machine will find vacuum leaks quickly.

 

CEL but no codes? That's odd.

 

 

I checked the timing last week before i left for KC and it was fine. The Idle speed was fine last week as well and not is a little high when it does idle. I was going to look into getting a new exhaust while i was out here and get a new o2 sensor. But i'll disconnect it and see what it is doing. And was reading about how to adujust the TPS in the manual I have. Will look at that too.

 

The whole code thing is bothering me. I don't understand why it didn't store the code.

 

Thanks for the reply,

bluesuby89

[azsubaru]

a couple of ideas:

1) dirty idle air control valve

2) idle switch out of adjustment or bouncy.

3) see the 'Similar Thread's at the bottom of this page.

[hooziewhatsit]

I think azsubaru has the right idea; look up topics on the idle air control valve "IAC ".

 

When they get dirty they cause the exact problem you're having.

 

-Dave

[presslab]

I think azsubaru has the right idea; look up topics on the idle air control valve "IAC ".

 

When they get dirty they cause the exact problem you're having.

 

-Dave

 

I think only the XTs have a IAC. The GL/GL10 have a cold start bypass valve.

 

If the cold start valve is sticky it will just increase idle speed as if the engine were cold... I don't think it would cause surging.

[bluesuby89]

Yesterday I was able to pull over when it was surging and look at the code and it was 24 (IAC Valve).

 

So I started by cleaning it off and dumping some seafoam down it let it sit then started it up. That didn't fix it. I'm going to take it off this weekend and clean it out real good. If that doesn't work then buy another one.

 

I'll probably have to make a new gasket for it if i screw up the old one. I'll tell you guys what ends up working. So azsubaru was right.

 

Thanks

[presslab]

I had a look at the service manual. Looks like the MPFI had the "auxiliary air valve" which is just a cold start idle valve. The SPFI has the "air control valve" which sounds like what you have.

[matts87glsedan]

a clean of my IAC didnt solve my problem, i removed it and disassembled and cleaned with carb cleaner. perhaps it needs replacement though... i also get no code stored. but hey it cant hurt for you to give it a try. i also set and tested my tps as per the FSM directions... it didnt solve the problem either, but again , you might as well rule it out yourself... good luck

[matts87glsedan]

did you figure this out? (bump)

[bluesuby89]

Not yet. I cleaned out the Air Control Valve and it was running better for a couple of days. But now it has returned. When I first start up the car after sitting over night it idles fine. But then when i get to a stop light it surges or has a high idle 1250 rpm. Pretty random on which one occures.

 

I'm going to look at it some more tomorrow. I'm not sure where to go next. I was thinking maybe the spring on the inside of the valve was worn out and wasn't setting in the right spot at idle. I do feel the problem is with the Air Control Valve. I looked up a new one and they are kinda pricey. Any luck with yours?

[matts87glsedan]

no

 

i do have a parts car that idled fine , maybe tomorrow i'll take the IAC off it and swap it onto my sedan. I noticed last night that i was getting a code 51 while i was driving , but i cant find my manual to look it up...

[bluesuby89]

I looked it up in my manual and code 51 is the neutral switch. It says that the cel is tripped when the switch remains in the ON position during operation. Do you have an automatic?

[matts87glsedan]

ohh thats from me doing the SPFI swap .. doh! no my car is a 5sp dr . doesnt look like i'll get that IAC in tonight, i just got off work and i'm out of daylight... prolly this weekend i'll do it.

[bluesuby89]

I have been thinking about my problem today. Is this what yours has been doing?

 

 

I am going to look into cleaning the maf sensor tomorrow. Just another thought I would try. Good luck

[hooziewhatsit]

The other thing I've done is take the solenoid off the valve, and spray some lubricating stuff into the solenoid.

 

-Dave

[matts87glsedan]

yes my car sounds like the video when he unplugs his MAF. quick short repetition. I went out and pulled the plug on my MAF for kicks, and it gave no change in the cars idle at all... i expected something to happen. then i pulled the plug on the IAC and it immediately stalled. could someone more knowlegeable than i tell me if those are normal results?

 

The other thing I've done is take the solenoid off the valve, and spray some lubricating stuff into the solenoid

. i'll try this too.

[bluesuby89]

Well I cleaned the MAF sensor today. Was really dirty and had stray hairs on it. There is no doubt the car runs better and has more power. I would recomend cleaning it on any car if it hasn't been done in a while. However, it does still surge.

 

Was your engine cold when you unplugged the IAC ? Because there will be more of a drop in idle when cold (according the manual) thus it would make it drop too far and stall the engine. There is a method in my manual on how to check the IAC and mine passed their test. If you don't have it I could type it up.

 

I too unpluged my MAF sensor with engine running and the idle picked up. I also unplugged the IAC but the idle dropped. I need to try to unplug the both when the idle is surging.

 

One last question. What type of lube to use? I cleaned out my valve and removed the solenoid. I used throttle body cleaner which says it lubes too. Is there something better and safe to use?

 

Thanks and good luck

[matts87glsedan]

Was your engine cold when you unplugged the IAC ? Because there will be more of a drop in idle when cold (according the manual) thus it would make it drop too far and stall the engine. There is a method in my manual on how to check the IAC and mine passed their test. If you don't have it I could type it up

 

well the engine was warm, but i had shut it off then went out and started it, so it could have been in its high idle startup mode at the time... its interesting that your idle picked up when you unplugged the MAF, it makes me think something may be up with mine, i'll have to clean it also... must find the can of sensor cleaner now... thanks for the offer about the IAC test, but i found my manual now so i'll just look it up again..