idle issues only with A/C off

[kozy]

So I'm new to the Grand Prix and my 2000 GTP has an idle issue that I'm trying to resolve. The idle moves around between roughly 600-900 RPM when in neutral or sitting in gear at a stoplight with the A/C off. My first thought is maybe that I have a vacuum leak somewhere but there could be other culprits also. Strangely though, if I turn the A/C on the idle problem goes away and it idles smooth as can be.

Can someone provide some pointers of places to start looking for the reason behind this?

 

[FordMan77]

Might want to check for vac leaks (the large "T" under the S/C snout is a known culprit) and also maybe check the IAC. When the A/C is on it bumps the idle a bit IIRC. What happens if you have the A/C off and hold the idle up just a tiny bit? Does it smooth out like with the A/C on? Could also try cleaning the MAF with approved cleaner. Couldn't hurt.

 

[kozy]

Well, I started checking vac lines beginning with the T under the s/c about like you said. The lines on that T weren't pushed on all the way and were brittle. Replaced them all with new vac hose. Then, I look at the T fitting between the engine and the firewall and I see this....where is the capped off line supposed to go to? Anywhere?



Then, this hose connecting to the throttle body is too small for the nipple so the previous owner just connected it with electrical tape


This thing I'm holding (don't know what it is) isn't bolted down anywhere, just left loose!


aaaaaaand to top it all off, I have a random loose wire coming out of the backside of the engine and I don't know what's it's for or where it's even supposed to be connected.



This poor car needs some SERIOUS attention!!!

 

[BrandonHall10]

Then, this hose connecting to the throttle body is too small for the nipple so the previous owner just connected it with electrical tape


This poor car needs some SERIOUS attention!!!

I had to replace that hose almost immediately after buying my car also. Can't remember what I was doing, but I just bumped it, and it seemed to turn into dust. The plastic and rubber out here gets so brittle.

Anyhow that hose is GM Part: 24506665.

 

[kozy]

I took care of this one today. Was able to cobble together hoses from the scrap pile at autozone to hook everything up. Now I just need to figure out what's going on with the other pics I posted on the rear of the engine (stray wire, Evap purge solenoid that's not secured, and T fitting that has one end blocked off.

 

[BrandonHall10]

LMK if you need any reference pics from a (nearly) stock 2000 GTP. I'll take any excuse to show off my engine bay.

 

[kozy]

Hell yeah! That would be awesome. I just figured out that the T in vacuum line on the back of the engine isn't supposed to be there, so I replaced that with a straight hose to the MAP sensor.

The last two things I still haven't been able to figure out are how to mount the evap purge solenoid and also what the exposed black wire (seems to be coming out of the injector for cylinder 4) is supposed to be for. If you posted reference pics that help me figure both of those issues out that would be AWESOME!

I was just telling my wife that I wish I knew someone around here with a bone stock 2000 that I could use as a reference to figure out what's missing off this car I just bought!

EDIT: The rough idle is still happening even after replacing all the vacuum hoses. I just found out that one or both of the hoses connecting to the EGR are leaking. On top of that, the EGR vakve isn't even bolted to the engine like it should be.....it's just laying loose and the only thing holdi it up are the hoses!!!!!

 

[BrandonHall10]

Okay... From what I can tell, you're missing the small bracket that the purge solenoid mounts to:

As for the wire coming from the #4 injector... All I can tell you is, mine doesn't have that. All 6 injectors are identical.

And my vac lines follow the under hood sticker, verbatim.

Just looks like someone replaced the hard line with hose.

I know it's a drive, but if you're ever down this way, swing by. Take as many pictures as you need. Of the car, that is.

 

[kozy]

Okay... From what I can tell, you're missing the small bracket that the purge solenoid mounts to:

/QUOTE]

It looks like I'm missing that black metal rod that the solenoid bolts down onto. The rod connects on the other end to the alternator I think. I'll have to hit a junkyard to see if I can find that. Thanks!!!

I've been to Tucson once in the 5 years I've lived here lol but if I make it down there again I'll hit you up.

 

[BrandonHall10]

No problem. Haha! I didn't even notice the rod was missing. Ya, it runs from the back of the sc to the alternator.

I suppose there's not much reason to come to Tucson if you don't have family, or work here. But the Sonoran hot dogs might just be worth the drive!

 

[kozy]

Update after this past weekend.....I tracked down and fixed 5 separate leaks in vacuum hose attributed to either broken rubber or hoses not connected properly. Also found that the EGR isn't bolted to the engine and the hose connecting the EGR to the intake manifold was busted. Put some JB Weld on that to seal it all back up and now the idle is much smoother.

 

[kozy]

Ok Brandon, I have one more pic that I hope you can reference from your car. The long bolt in this picture sticking out of the block, what is supposed to be here because this bolt certainly looks out of place. For reference, the large pulley in the pic is the belt tensioner for the supercharger.

 

[BrandonHall10]

Same here;

Only mine is tight! :th_biggrin1:

I would like to know why GM used such a long dong stud there. I assume there's a reason. (?)

 

[kozy]

Hmm weird. Hopefully someone will pipe up and tell us the purpose of the damn thing. In the meantime, thank you for letting me know I'm safe to screw that nut down tight!

 

[BrandonHall10]

No problem. Glad to help.