Won't Idle

[ACLR8R]

I replaced the head gasket, and now I cant get the car to idle right. Once it gets moving its fine, drives fine. It's not really throwing any codes, it threw a low MAT voltage once. I checked it and started the car again and the code was gone. It seems to missing at idle and is idleing to low (from 450-750rpm, often idles all the way down and dies) TPS is set at .42. Its strange because it ran fine before the headgasket and now this. Occasionally on the T-link most of the sensors will drop to zero for a second then come back.

Anyone have some suggestions?

 

[pawpz]

same

im having the same damm problem that iv been chasing for a while!!!when i let go of the gas peddle the rpm drops to 450 then bumps back up to 750 does the same thing at idle. im waiting on my new coil pack wires and plugs to see if thats it..good luck ill let you know how it goes.

 

[ACLR8R]

im having the same damm problem that iv been chasing for a while!!!when i let go of the gas peddle the rpm drops to 450 then bumps back up to 750 does the same thing at idle. im waiting on my new coil pack wires and plugs to see if thats it..good luck ill let you know how it goes.

My coil pack, ecm, O2, TPS, wires, and plugs are all new. I have also redone my grounds, and still cant figure it out. Been trying to track it down for a little while now too. Let me know if you come up with anything!

 

[pawpz]

ok. ill will do that! should get all parts by friday so I should install everthing some time next year!!lol..jk ill let u kno how it goes by monday!!

 

[SlickTR]

Have you checked your EGR valve?

 

[ACLR8R]

Have you checked your EGR valve?

Yup, stumbles when I move the diaphram.

 

[mikestertwo]

I have also redone my grounds

Define redone grounds. Do you mean tightened them on the back of the head?

 

[ACLR8R]

Define redone grounds. Do you mean tightened them on the back of the head?

Actually they were looking a little rough, so I put new rings on all of them at the back of the intake (grounds from the head).

 

[pawpz]

what up?

i just changed my egr and iac...problem GONE!!did you check your iac valve?

 

[ACLR8R]

i just changed my egr and iac...problem GONE!!did you check your iac valve?

Actually I spent a couple of hours working on setting the IAC, and TPS. I got the IAC numbers down from 150+ to 50-65. It idles now which is good, but still has a miss at idle.

 

[GRAY86T-TYPE]

Had this same problem with the Iac in my car. I put in a standard iac, and for three months the car wouldn't idle right, and would have a miss. Then I put the IAC I took out back in (after cleaning it), and I played with the idle adjustment screw alittle and it fixed the problem. AC Delco is the only sensors I would normally put in but they weren't available when I needed it. I set mine at around 20, and the car idles between 775 and 825. Car never ran better

 

[ACLR8R]

Had this same problem with the Iac in my car. I put in a standard iac, and for three months the car wouldn't idle right, and would have a miss. Then I put the IAC I took out back in (after cleaning it), and I played with the idle adjustment screw alittle and it fixed the problem. AC Delco is the only sensors I would normally put in but they weren't available when I needed it. I set mine at around 20, and the car idles between 775 and 825. Car never ran better

It's a delco (might be the original, I havent touched it in the 7 years i've owned the car). How did you clean it? Carb cleaner? When I looked at it, it was fairly black. I wonder if i should just try a new one.

 

[turbojd]

Yeah spray the IAC with some carb cleaner or brake cleaner,also spray out the throttle body also.

 

[bmackinnon]

Actually I spent a couple of hours working on setting the IAC, and TPS. I got the IAC numbers down from 150+ to 50-65. It idles now which is good, but still has a miss at idle.

Still too high.... remove the iac and clean it and the passages real good w/carb cleaner. Then reinstall and further open the throttle blade so that the iac closes down to around 20-25 counts when warm in park.... then readjust tps, etc, etc.... you know the drill.... :smile:

Edit - also make double-triple sure you don't have any vac. leaks as a result of the prior work.... they wreak havoc on the idle quality....

 

[ACLR8R]

Yeah spray the IAC with some carb cleaner or brake cleaner,also spray out the throttle body also.

Cleaned it with carb cleaner, didnt make a huge differnce but I'll play around with it and the settings again tomorrow.

 

[ACLR8R]

Well finally got the settings in the right range, but still has a slight miss. Checked plugs and they look fine, cant find any vacuum leaks. At least I can drive it now, I'll keep plugging away

 

[GRAY86T-TYPE]

My Car also had a miss also (along with the IAC problem). Replaced the coil pack and the injectors. It was most likely an injector, but the coil packs can cause this too. I would try the coil pack first, then I would try to get the injectors cleaned.

 

[ACLR8R]

My Car also had a miss also (along with the IAC problem). Replaced the coil pack and the injectors. It was most likely an injector, but the coil packs can cause this too. I would try the coil pack first, then I would try to get the injectors cleaned.

I replaced the coil pack about 6 months ago, and the injectors are probably 1-2 years old. I think I'm going to take it to a shop and have it scoped. That should be able to tell me what cylinder and hopefully, why.