Surging Idle, Only when car is Hot

[Danman765432]

Well Since it started to get warmer out my car has been having this surging idle and then it dies....If i shut off the car and start it up again it is fine....but say I let it sit for 10-20 mins and try to start it up, it seems like it cant find idle. It actually goes from 500 to 1500 rpms and then it finally dips and dies. It did this to me somewhat last year too. This also only happens when the car is hot.

I also do have my hot idle set pretty high because it used to die last year when started cold.

I am also thinking about getting a new radiator because my temps seem to get higher now too....not to being to hot but right in the middle of the NORMAL.

I also recently put on a new belt, and autolite 24 spark plugs gapped at .035 for my nitrous.

Just let me know your opinions on what you think it is.

I think i might just need a tune.

Thanks,

Dan

 

[Danman765432]

bump

 

[final5-0]

Try giving your isc and maf a good cleaning

Grady

 

[1TallMF]

+1 on cleaning the IAC, mine was sticking causing it to idle funky, cleaned it with TB cleaner and all is well. If that doesn't help, try resetting the idle. If you do a search you'll find hundreds of threads regarding this issue.

 

[1TallMF]

Also, make sure there are no vacuum leaks.

 

[Danman765432]

I have done all that stuff...Cleaned MAF and IAC...also reset the idle so it actually runs somewhat right.

 

[final5-0]

I saw you say you had to up your idle some.

I guess you are talking about using the tb blade stop screw to raise the idle.

Having to do that indicates a problem and doing that can throw off the other
systems that are in place for a stable idle such as the isc and such.

Grady

 

[final5-0]

Are you throwing any codes that could help you with the prob

Grady

 

[Danman765432]

none that i know of...i will probably scan it tomorrow...

The first idel problem happened with my cobra intake swap but there are no vaccuum leaks...I have tested every single line....I do leak a tiny bit of coolant because I did the swap before I knew about the blue gaskets leaking.

I also have never had my car tuned...even though it shouldnt really need to be, with just a cobra intake swap...

I also believe my tensioner pulley might be loose a tiny bit...when i changed my belt the other day i noticed that my car sounded like it had a cam in it and i started to look under my hood and noticed that the tensioner pulley would move up and down slightly.

I don't think that has to do with this but just putting that out there.

Do you think that my IAC could be shot...this is my stock one that is still on there and im going on 85k miles on the car?

Thanks Grady and everyone else for the ideas so far...

-Dan

 

[final5-0]

Do you possibly have any lower intake bolts loose allowing a v leak around that
area

IIRC, I think I've seen some say they cleaned their isc and things did not get better
with issues such as you speak of here.

Then ... they went to a new part and things were good to go.

It is possible it could be bad I guess

Grady

 

[HISSIN50]

Dan, very good thoughts from Grady et al.

Now, I was going to contribute earlier, but...................

Last summer or so, did we not go back and forth with some PM's in which I outlined how I like to set my idle? I think so, and thus didn't reply here earlier because if so, my method isn't working for you.

If none of that is the case, I'd set the hot, no load idle with zero IAC load. If you set it at the commanded idle or just a hair above, the puter should be happy and the IAC should not be doing anything at hot, no load idle............

This is my preferred method because the only time I need the IAC is when I load the idle or when the engine is cold. One less POS part to be reliant upon.

If you do replace the IAC or even clean it and it looks like the bottom of a porta-potty at a concert, consider an oil separator if you dont have one. It just might help a bit with keeping things clean in there.......

Good luck bud.

 

[Danman765432]

JT - Yeah we actually went through several pms about setting the hot idle and it was working perfect but it seems like is slightly thrown off now...Also this heating thing is pissing me off...even on really cool nights it gets up to about midway on NORMAL where it would normally only be at the middle of the O. So I am thinking of just getting the new stock replacement radiator, new thermostat and possibly a new IAC and a new throttle body soon...I think when I am done with those I should be good to go...This is just going to put my plans farther back for getting a handling package but oh well.

EDIT: Another rant is that my oil pressure seems to be to high now, even though we have a dummy gauge it is still higher then it normally sits...Also the other day when I popped my hood my dipstick was out like an extra 3 inches, so I guess that is a sign of pressure. (Cant remember if I forgot to put it in all the way or it got blown out)