i have an 87 iroc with a 5.0 tpi. it is idling fast (about 1500 in park and around a grand in gear) i was wondering what i could do to fix the problem. i was reading on other posts that a vac leak could cause it. i also read on another post that if the heater only blows out of the defrost vents (which mine does) then there is a valve vac seal (gm #16032395) that could fix the problem.. i guess my question is this: is it likely that this could be the reason for my fast idle? how could i check it before spending the time and money replacing that seal? it would be awesome if i could kill two birds with one stone though! thanks!

 

There are a couple of things that would cause your Idle to be out of the norm. Like the IACV, Intake Manifold leak, Sticky Throttle blades or a vacuum leak. In your case, since you have already stated that your Blower selector switch doesn't allow for you to switch from Defroster to Vent to floor, It sounds like you have a vacuum line problem. I woudn't be changing any gaskets until you determine if that is the area of the problem though. If you take WD-40 or starter fluid with your engine running and start spraying your vacuum lines you will notice a major increase or decrease in engine rpms. It will help determine where the leak actually is. Try plugging all your Vacuum lines off your TPI system 1st. If I remember right. The Power Brake booster, Then you have 2 off the plenum side and I think 2 off the bottom of the Throttle body. You can easily put a rubber cap over all the nipples that come off of these. If you idle comes back down it will help your trace your vacuum leak also. Also check to ensure your throttle blades are fully returning to a closed position. You can spray all the spings down with a silicone lubricant.

 

ok, so the hard vac line coming through the firewall had a huge hole in it and the other end was not even hooked up to the heater controls. i plugged off the line and it did not help my idle... BUT i am wondering where in the heck the vac line goes on the back of the heater controls.. there is a little round deal with about 6 places to hook a line to... any specific one?? what do i do about the 5 other places?? plug them off or leave them alone? i know it is a little off topic but i would really appreciate a little wisdom here.

 

If I get the chance tonight, I will take a picture of the valve you are referring to under the dash. I have never played around with it either. But, I know there are several rubber lines that go to it and I am not sure exactly what that valve does or how it even works. Did you find any additional lines off or holes in them.

 

there are more lines that go to the heater controls!?! crap! i had the controls pulled out of the dash and could only see one, and it was disconnected. a pic would be so awesome. i did some searching in the engine compartment and didn't come up with anything.hopefully i will get a chance to look it over more thoroughly today. thanks for the help!

 

ok ibm tech... i found the cluster of colored wired and hooked them up. now i guess my question is: where does the single black vacuum line that comes from the vac canister and through the firewall go?? i traced mine and i was laying behind the hvac unhooked but i can't see where it would go. thanks a million!

 

The Vacuum canister should have a rubber line that runs up the drivers side of the car and plug into a T connector right next to the cruise control. If you are talking about the plastic molded connector that goes to the heat divertor valve located near the right side front of the engine. I do not know where that line ultimately runs to.. Mine goes directly to the firewall and I have never traced it after that. Maybe someone else has some insite. Have you put a rubber caps on all the vacuum nipples on the engine to see if it has slowed down yet? I would also unplug the Vacuum Booster line and cap that one. Check for a broken or cracked hose.

 

no, i have not capped the vac ports coming off of the engine. i need to run to o'reillys and get some caps... i am all out. it sounds like we are on the same page with the line going through the firewall. it goes from the vac canister into a tee and then through the firewall it then runs under the steering column and into the console area right behind the heater controls... it was not hooked to anything though... that is what has me stumped at the moment. i still REALLY want to get it idling right. i just kind of got side tracked.

 

I know the fustration of getting a proper running engine. Ever since I put the S/C and Intercooler on my new engine, I haven't had the chance to get it out on the street and get it tuned. It runs very very strong and shouldn't take more than 1 week to get it running right. But, I think if you cap everything off, that should help you eliminate all leaks. The engine should run better. Just make sure you don't cap off the fuel pressure regulator. You are on right track getting your heater working also. Kinda sucks if the windshield fogs up and you can't get it dry.. But, I will try tonight to get all the pics and track the hoses down.