OK my fiero (86SE V6 auto) idles at 3k rpm's. New TPS and IAC.. Possible new EGR valce coming.. But how do I locate vacum leaks when it idles at 3000 RPMS!!!! The whole WD40 thing doesnt work atleats at 3000rpms anyway

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ICQ# 16477998

This will sound wiered, but I saw a mechanic do it once, and I tried it when I had a leak, and it works. Take a piece of tubing, like a small part of garden hose, and put one end up to your ear. Move the other end all around the different vacume hoses, and if there is a leak, you will hear a loud hissing sound threw your end. The mechanic that I saw doing it, was actually using a stethoscope believe it or not, but a piece of hosing works fine to. It might be somewhat of a crude method to find leaks, but it works!
Peace
Kyle

That hose to the ear thing sounds like a good idea not only vacuam leaks even valve train noise

The BEST method! Stethescope works, but is awkward. Engince stethescope is better shaped. Rubber hose works just fine, as long as the motor isn't TOO loud (I.E. open headers ). Consider using an ear-plug on the other ear

Remember guys, this thing is IDELING at 3000 rpm's...Not sure if I could hear it or not.

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ICQ# 16477998

Have you driven the car yet? If not, take it for a drive!
A new IAC needs to be set by the computer. In order to accomplish this, the car must be driven over 35 mph so the computer can gather the correct information to set it.

3000 RPM sounds like you've either got a defective IAC, the harness from the IAC to the ECM is either damaged or not properly plugged into the IAC, or your ECM has gone south. 3000RPM is about what you see if you unplugged the harness from the ECM module and started the engine.

Indiana_resto_guy is correct though in that you can't really properly diagnose anything until the ECM has reset and you're running in closed loop mode. It can take a few miles of driving at > 35MPH for the ECM to reset.

Been drivin over 35..Put new IAC and TPS yesterday..Went to work today here like 25+ miles, how far should I travel? I also tried the limp mode thing by crossing the 2 connectors in the diag connector. it idled ok for about 2 secods then jumped back to 3000 rpm's.
Question about the EGR valve... OK if I depress the diaphram and hold my finger over the vacum opening, the diaphram stays up, BUT the little pinlt thingy on the bottom will come back down and is REAL loose, like 1/8" loose.. Shouldnt this STAY up no matter what if the diaphram is up?

hook up a small handheld tach in the eng compt. if it idles fast but stays stable rpms, spray a little shot of starting fluid around lines and watch for rpm to jump up. that will give you an area to search more carefully.

Ok...I say lets try to rule out the IAC do this:

Ground the Computer terminals
Put the key in the ON position
Go listen to the IAC for a minute...is it making noise?
Unplug it.
Turn key off.
Try to start the car.

If it doesn't idle at 3000 then set the idle to 500-600. If it does you've got a nice big hole in somehthing.

Turn off the car and plug IAC in.

OK ive tried WD40, starter fluid AND carb cleaner, Idle does not fluctuate. So possibly NOT a vacum leak????? As for grounding terminals and listening to the IAC, what do I ground? Im so at a loss here.

Unplugging the IAC while running won't do anything.

What I suggested screws the IAC all the way in, and at that point you unplug it. Then you set your base idle with the engine running and IAC unplugged. It will be obvious, if the IAC is closed and not functioning, 3000rpm is caused by an leak.

You won't get 3000rpm out of the idle screw, but at least you can set it properly.

Joe

Idle screw?

quote Originally posted by CanadianGT: This will sound weird, but I saw a mechanic do it once...Take a piece of tubing, ...put one end up to your ear. Move the other end all around... and if there is a leak, you will hear a loud hissing sound.

So weird, that it's exactly what I did! And it worked for me, to find a crack in the EGR tube, up under the plenum.

Here's one way to isolate the IAC as a cause for high idle (on V6's): Remove flexible air intake between air cleaner and throttle body. Start engine. Now stick your finger into the throttle body and cover the hole in the base of the throat - that's the passage the IAC breathes through. Covering the hole is just like seating the IAC (blocks the passage), so if the engine still doesn't slow down enough, you need to look elsewhere for vacuum leaks.

Of course, don't let your hand get pinched / sucked in, etc., etc. A real concern at 3000rpm! Be careful and good luck !

OK, I think I found the idle screw..I unplugged the IAC and turned the idle down, it went down ALOT , but I think its still a bit high. Gonna replace EGR valve later and try that, it may need replacing anyway but damnit to hell if I can find a vacum leak.

Loki,

Make sure you let the computer screw the IAC all the way in(let it sit there for a minute). Then set the idle screw. Don't just adjust the idle screw, you'll mess the computer up.

Check that EGR tube carfully for leaks.

Good luck!

I had a similar problem when I replaced my fuel pump on my 1986 V6. I accidently knocked the hose that runs along the firewall, that's about 1/2 inside diameter. It was too large to hear a hiss but I had mistakenly gone down the IAC path. Also, something i've done when tracking a vacuum leak, crude but effective, is to take a rag and plug up the air intake hose with the car running. What happens is the car suck air harder through the vacuum leak and you can usually hear it.

Joe,
Let the computer screw in the IAC???? What? Imlost now

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ICQ# 16477998

quote Originally posted by Loki: Joe, Let the computer screw in the IAC???? What? Imlost now

Yes, when you ground the diagnostic terminals on the ADL connector, and turn the key in the ON position, the computer screws the IAC in. It will do it as long as you have it ON for(it should make a buzzing noise). So wait 45-60seconds to make sure it is fully seated and then unplug it. Your IAC is now closed. Turn the ignition off and **unplug the jumper from the terminals. Start the car and get it to idle at 500-600rpm by adjusting the idle screw. You can start with it screwed all the way in, and idle it down. This will open the throttle plate just enough so the car will "never" stall. Now turn the car off and plug the IAC in. Restart the car and it should now idle properly.

Joe

**Note: Ok, I am 99% sure you have to remove the jumper. 1% says if it doesn't run at all, try leaving it jumped.

Ahhhhhhh OK gottcha..Will try that when it cools down some

Unplug the map sensor and see if it idles better. Might want to swap it anyway.

Also, now you need to check the voltage on the TPS since you adjusted the idle. Should be .54 at idle.

Where do I check the voltage? What wire? Will check map in a bit....

I don't remember(someone help!) exactly which wires are what...I usually just probe around till I figure it out. Using a scan tool is the easiest way!

On the TPS connector you've got 3 wires. So cut some paperclips an inch long(make sure they don't touch eachother when IGN is on!). slide them along side the wire, between the weather protection seal and wire, in pretty far. Hopefully this will give you a decent connection to test. Either this or just probe the wires(pierce the insulation). You are looking for under a volt...I think you use the middle and bottom wires(don't remember). Test it by opening the throttle plate, the voltage should rise to almost 5V.
When you have the corrct wires, bend the tab on the TPS to read .54.

Mine has 4 wires Ill go do some checking, what about the MAP sensor? Is it bad? Idled down when unplugged and idled back up when plugged back in????

quote Originally posted by Loki: OK, unplugged Map and it idled ALOT less, plugged it back in and rpm's went up..So that would mean bad? Now that im getting the idle set what would cause the sluggishnish off idle for 1-2 seconds? Maybe try another TPS?

Good possibility the values on the MAP have shifted. Get GM replacements of what you find bad. Generic parts are crap.

4 wires on the TPS??? Um, should 3 on a flat connector IAC has 4 wires, square connector.

[This message has been edited by Joe Torma (edited 08-22-2001).]

Maybe crap but I get them close to free

No wonder you car doesn't idle
Just kidding!!!

I've gone through so many TOMCO and STANDARD IACs and TPSs to develop a slight hatred twords 'em.

Keep us(me?) posted!

OK replaced Map sensor....Idle is still be low the 3k it WAS at but still having the problem af stalling when gas is depressed from a take off. It acts this. If the car is running (V6) at idle, and you move the arm on the TPS it bogs down till it can cathc up. Thats what my car is doing when yuou press the gas. Possible bad TPS out of the box? There a way to test those?

quote Originally posted by Loki: If the car is running (V6) at idle, and you move the arm on the TPS it bogs down till it can cathc up. Thats what my car is doing when yuou press the gas.

They all will do that.

If at idle and in park yes..But im the car trying to go forward and it does that... I know its not supposed to do that then..hehe