My car idles at 2000 rpm and I can't bring it down. The idle adjust is all the way in. The throttle flap is square. The timing is not advanced. Grrr. There are no vacuum leaks. I've pulled and plugged and...... the only thing that will drop the idle is pulling the vacuum hose OFF the MPS. Which isn't what I was expecting since max vacuum on the MPS should tell it to tune for idle - I would have thought pulling the hose would speed it up if anything (unless shorter pulses=leaner mixture=faster idle?).

I'm not sure what to do next. Any recommendations?

Take the feed end of the AAR hose off the airbox, and plug that line.

Drop?

AAR failed open.


M

With every vacuum input closed, including AAR, (except MPS) it still won't drop. Pulling the MPS hose is the only thing that will drop it.

QUOTE (Rand @ Jul 8 2005, 09:41 AM)

With every vacuum input closed, including AAR, (except MPS) it still won't drop. Pulling the MPS hose is the only thing that will drop it.

Do you mean pulling the MPS hose without plugging it?


Andrew

Pulling the hose off the mps causes an instant drop - to a normal idle speed. Putting a thumb over the end drops it further, almost to a stall. Plug it back in and idles climbs back to 2k.

Well, pulling the MPS hose will make it run the richest it can. With the hose plugged it should drop the idle a lot. Have you pulled a vacuum on the MPS?

Vacuum leaks are the only way it can idle high. You can't get a high idle from a mixture problem.


Andrew

How long has it been doing this? Read the plugs, what color are they burning?

Use a flamable spray, CONSERVATIVELY (please clay... ) spray at key areas of the intake system, very small, local shots..

You may have an unmetered air leak! Oh my God! Unmetered air fines are HUGE!




M

QUOTE (redshift @ Jul 8 2005, 10:26 AM)

..............Use a flamable spray, CONSERVATIVELY (please clay... ) ............. ........ M

Great, you're gonna get this thread locked too.
Politics......

Andrew

And if you use Aqua-Net in the silver/pink can, it will seal the leak!


M

QUOTE

Vacuum leaks are the only way it can idle high. You can't get a high idle from a mixture problem.

Why would pulling the hose OFF the MPS increase idle then? Plugging the hose into the MPS can't create a bigger vacuum leak than leaving it off/open.

I'm pretty certain I don't have a vacuum leak. For testing purposes, I have every intake vacuum hole plugged tightly except the MPS hose. If I plug that one too it chokes it to a near stall.

The plugs are great. The car runs perfectly. Just won't idle right.

QUOTE (Rand @ Jul 8 2005, 10:47 AM)

QUOTE Vacuum leaks are the only way it can idle high. You can't get a high idle from a mixture problem. Why would pulling the hose OFF the MPS increase idle then? Plugging the hose into the MPS can't create a bigger vacuum leak than leaving it off/open. I'm pretty certain I don't have a vacuum leak. For testing purposes, I have every intake vacuum hole plugged tightly except the MPS hose. If I plug that one too it chokes it to a near stall. The plugs are great. The car runs perfectly. Just won't idle right.

You are right. That does not make sense. However, the point is, if your timing is set correctly, a vacuum leak (including a throttle that is stuck partly open) is the only way to get a high idle.



It's plausible(?) that the idle drops when you pull the hose off the MPS because it is now running super rich.


Is this a car that you just got running, or was it fine before?



Andrew

Bite me Miles!!! You guys act like I am the fucking political police........

That word can be used here in the right context.

As for the thread, if you are going to spray flammable stuff into a running engine compartment, have a fire extinguisher handy!

QUOTE (ClayPerrine @ Jul 8 2005, 12:18 PM)

Bite me Miles!!! You guys act like I am the fucking political police........ That word can be used here in the right context. As for the thread, if you are going to spray flammable stuff into a running engine compartment, have a fire extinguisher handy!

Did I miss something? Didn't want to hit a nerve. I was just joking. I know you will lock down political threads and I don't care. That's the rule around here so I don't bother even starting. If I want to discuss it, I do it privately or somewhere else.

Andrew

QUOTE (phantom914 @ Jul 8 2005, 02:26 PM)

QUOTE (ClayPerrine @ Jul 8 2005, 12:18 PM) Bite me Miles!!! You guys act like I am the fucking political police........ That word can be used here in the right context. As for the thread, if you are going to spray flammable stuff into a running engine compartment, have a fire extinguisher handy! Did I miss something? Didn't want to hit a nerve. I was just joking. I know you will lock down political threads and I don't care. That's the rule around here so I don't bother even starting. If I want to discuss it, I do it privately or somewhere else. Andrew

Naaa.. you didn't hit a nerve. I was just taking a dig at Goatboy.....

There are other places for vacuum leaks other than all those little hoses. There's a gasket under the throttle body that often cracks. The hoses between the plenum and the intake runners can leak, and the gasket between the intake runners and head can leak. You could also have an internal leak in your MPS.