Engine Odd idle creep issue

sav22rem22

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So on my 89 Gt I recently tried to turn the timing up to 10 degrees. Now my balancer could be off but the engine seemed to accept it fine and still idled okay except after a test drive then the cars rpms creeped the longer the car idled. They also seem to surge a little.

The only codes the car has in the memory and current is smog related stuff. There isn’t any sensor codes. The car is very basic and before I tried to turn the timing up it idled and ran very good. It would alway return to a perfect idle and stay there. Now even after I’ve turned the timing down to around 6-7 degrees where it was before it won’t idle correctly. Nothing else has been changed.

It idles correctly at stop lights or stop signs now but when I pull back into my drive way and let it sit for a minute the rpms just slowly creep up. If I free rev it the rpms will never come down to where they were. The throttle body is new the iac is new the tps is new there are zero vacuum leaks. I’ve verified the timing is still at what I set it at. Like I said there were zero problems before I tried to up the timing to 10 degrees

This is driving me crazy. Also before I upped the timing, when I unplugged the iac at idle the car would die like it should. Now I unplug the iac the idle drops but doesn’t even become unstable. I haven’t changed the tps or the throttle set screw so that can’t be the issue. On my last test drive before leaving the driveway the exhaust smelled very sweet and when returning my car was climbing in temperature and along with the temperature the rpms also climbed. Do you all think this could be a head gasket issue? There doesn’t seem to be any coolant in the oil and the radiator isn’t bubbling when I open the cap although even after sitting for a day or two when I open the cap it still blows coolant out.

What do you all think? I’ve been through the surging idle checklist a million times and at this point I’m out of ideas and ready to give up. I’ve fought and fought with this car and finally it idled good and was very driveable and then all of the sudden after bumping the timing up to 10 degrees and then dropping it back down the idle creeps and rises along with the temp.
 
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sav22rem22

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Also I’d like to mention that I’m burning through an incredible amount of fuel. I’ve driven the car maybe 20 miles and most of that is on backroads and that’s just for testing. The rest is idling. I’ve used half a tank doing this. This wasn’t like this before hand. So I’ll list out a mod list if it helps. I have a 65 mm throttle body with a fender cold air intake, stock maf with 19 ib explorer injectors, explorer upper and lower with egr, smog stuff like the pump, thermactor crossover, and cats have been deleted before I even got the car. It has a 255 lph pump in it with a stock fpr. The fpr holds vacuum and no fuel is in the vacuum line, the O2 sensors are of questionable age but they aren’t throwing any codes. Like I said even with this setup the car ran great before I turned the timing up.
 

General karthief

wonder how much it would cost to ship you a pair
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Ok, you have 3 threads going, I can't keep up
Did you verify that the balancer was good?
Oh, wait, did you say you didn't check it yet in this thread? :doh:
Did you go any farther with this?
See where I'm going?
Car diagnostic/repair is a little like a road map, it can show you where to go or you can just wing it and hope you stumble on the right destination.
 

nickyb

WAIT,you now have a pair?
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You can follow the surging idle checklist, also did you pull the spout connector when you timed it? 6 to 7 degrees is awfully low.
 

sav22rem22

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Feb 6, 2020
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Ok, you have 3 threads going, I can't keep up
Did you verify that the balancer was good?
Oh, wait, did you say you didn't check it yet in this thread? :doh:
Did you go any farther with this?
See where I'm going?
Car diagnostic/repair is a little like a road map, it can show you where to go or you can just wing it and hope you stumble on the right destination.
Yeah I apologize for that I’m in a bit of a panic. I checked out everything with the cylinder 7 issue however I haven’t redone the rest because I can’t get the car running long enough without it acting up and I haven’t verified the harmonic balancer yet as I actually did a lower intake retorque today so I haven’t had time. Tomorrow I will re run the cbt and see what that says then I’ll see if the balancer has slipped. If it’s slipped and slipped bad I’m afraid I’ve got my answer so you’re right my apologies
 

sav22rem22

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Feb 6, 2020
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You can follow the surging idle checklist, also did you pull the spout connector when you timed it? 6 to 7 degrees is awfully low.
Yes I pulled the spout. I know that’s low but that’s the only way I can get the car to not spike up in idle. Yeah I’ve followed the checklist to a T but I will be going over it again when I check the validity of my timing marks.
 

sav22rem22

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Okay so I verified my timing and the balancer was a few degrees off and pretty wobbly. So now that I had my last worrying issue out of the way I decided to go further with this .So I set it accordingly and I’m at about 10 degrees now. Since I also mentioned in this thread that the car was getting warmer than I liked and the idle was acting funny I got a spill free funnel kit recommended by someone on here.

I installed the funnel and put a bit of coolant in it. As the car was warming up it was idling great. No surging. Staying exactly where I had it set. As soon as the thermostat opened this happened


So after the bubbles stopped a bunch of coolant got sucked down and the idle speed went up a few hundred RPMs and this repeated a few times until no more bubbles surfaced and the coolant level appears to be staying the same. However for some reason my idle speed went from the about 700 I had it at (stock cam) to around 900. Turning the car off and on made no difference. I would also like to add that the only codes present are smog things like the crossover tube is clogged and things of that nature. No worrying codes. I’ve cleaned the maf, I’ve checked my TPS, I’ve cleaned the 10 pins, brand new ACT, ECT isn’t new but there is no codes for it, there are no vacuum leaks. I’ve smoked tested and completely sealed everything up. Does anyone have any ideas on this? This is pretty bizarre. Like I said it idles perfect and at the RPM I set until the thermostat opens. Then from there it doesn’t necessarily surge it just ups itself

Edit for further clarification: I’ve let the car run for about 45 minutes now and no bubbles have come up since. Just idle acting funny
 
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General karthief

wonder how much it would cost to ship you a pair
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I have found when the engine gets up in temp range very small things concerning vacume, how are things like pcv valve seal, dirty screen, the egr plate can get oxidized and leak coolant or vacuum at the gaskets, egr can act funny after warm up. Intake ever been off?
 

7991LXnSHO

wanna catch the space herp
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Does your timing “wobble” with the pip off? It should not.
With the pip engaged, the computer will play with the timing.
If it is wobbling with the pip out, I suspect something mechanical. The harmonic balancer could be actually wobbly. The timing chain could be loose, or the cam or distributor gears worn. The distributor itself could be worn enough for the shaft to “wobble”.
Now, about the thread title - it sounds like you are having a problem with a lazy weirdo. :fight:
 

sav22rem22

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Feb 6, 2020
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I have found when the engine gets up in temp range very small things concerning vacume, how are things like pcv valve seal, dirty screen, the egr plate can get oxidized and leak coolant or vacuum at the gaskets, egr can act funny after warm up. Intake ever been off?
Well now that you mention it my pcv valve grommet to intake seal isn’t the best. It always comes out with the valve itself. I could most likely improve that. I cleaned the screen before the intake swap and that was about a few weeks ago. Hmm that makes me think because my egr hasn’t functioned in a while due to a guy I took the car to. I actually put a block off plate on the car today for temporary until I can get the egr stuff working again. The intake was off recently for the explorer swap. I’ve retorqued the lower twice since
 

sav22rem22

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Feb 6, 2020
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Does your timing “wobble” with the pip off? It should not.
With the pip engaged, the computer will play with the timing.
If it is wobbling with the pip out, I suspect something mechanical. The harmonic balancer could be actually wobbly. The timing chain could be loose, or the cam or distributor gears worn. The distributor itself could be worn enough for the shaft to “wobble”.
Now, about the thread title - it sounds like you are having a problem with a lazy weirdo. :fight:
Does your timing “wobble” with the pip off? It should not.
With the pip engaged, the computer will play with the timing.
If it is wobbling with the pip out, I suspect something mechanical. The harmonic balancer could be actually wobbly. The timing chain could be loose, or the cam or distributor gears worn. The distributor itself could be worn enough for the shaft to “wobble”.
Now, about the thread title - it sounds like you are having a problem with a lazy weirdo. :fight:
By pip I’m assuming you mean the spout for the timing advance? It’s pretty stable with the spout disconnected while I set the timing. As far as I’m aware everything is still original and the timing components could all be very worn. Distributor is original as well. I’ll actually look into this here soon. Thanks for the ideas. Lol the thread title would explain my “helping hand” perfectly
 
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7991LXnSHO

wanna catch the space herp
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Yes, it was Brain Cramp time! Pip is the sensor and a character in a Dickens book. The Spout is the thing that makes us shout obscenities when we loose one.
The pip is in the back of my mind as a possible electrical problem, but I do not think it is likely to cause this issue.
 

sav22rem22

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Yes. Brain Cramp. Pip is the sensor and a character in a Dickens book. The Spout is the thing that makes us shout when we loose one.
Yep sound about right lol. I’ve been very careful not to lose mine. Seems far too easy to lose. I’ve heard all about the PIPs going bad and causing all sorts of issues. Is there an in between on them where they’re failing but still working?
 

7991LXnSHO

wanna catch the space herp
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I’ve had a suspected one fail at temp only, but usually they and the GM equivalent are go, no go parts.
 

sav22rem22

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I’ve had a suspected one fail at temp only, but usually they and the GM equivalent are go, no go parts.
Ah okay. Yeah all my problems are at temp only and what’s really bizarre is I actually just got done with a test drive a few minutes ago and the car settles back down to it’s perfect idle after a drive. Super weird
 

a91what

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Have you done a base idle reset?

If the vss (vehicle speed sensor) is acting funny or disconnected. The ecu may be adding air via the idle valve.
 

sav22rem22

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Have you done a base idle reset?

If the vss (vehicle speed sensor) is acting funny or disconnected. The ecu may be adding air via the idle valve.
Solid point. One thing I forgot to mention is that I do have a memory code for the VSS. The wiring at the vss is sketchy and the whole trans harness isn’t in great shape. Would this affect idle even if the car hasn’t moved? I also know the wiring is bad for the VSS because when I come to a stop the car barely catches itself. Definitely on my next thing to fix

Also yes I’ve done the base idle reset and I’ve got it perfectly where I want it and it maintains this perfect idle RPM until it warms up a bit then it raises itself a couple hundred RPMs and chills there
 

sav22rem22

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So everyone in this thread has given me some wonderful insight and advice on things to check on next and one thing I wanted to add to sort of wrap this thread up is that I talked to Matt from Leech Motorsports and asked him if there was something in the base A9L tables that force the target idle RPMs to go up. Not only does the computer up the idle RPMs based on temp, it also ups the target idle after a few minutes of just idling no matter the temperature. He theorizes that it was to boost the RPMs to keep the garbage factory alternator charging things. So thanks everyone for the help
 
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