Idle is all over the place!!! Anyone have secret??

reeber · Jul 6, 2005

OK... Here's my issue. Check out "My Garage" before you answer this question. My issues:

1. Under heavy breaking, car stalls.
2. Under light braking, car's idle dives, sputters, jumps to 1500 RPMS, drops, then as I slow down to a stop, it levels out to about 800 RPMS.
3. When I start the car in the morning to warm it up, the idle floats from 750 RPMs to about 1100 RPMS. Once I drive it for a bit, that goes away.
4. After revving the car, it takes a while for the car to drop RPMs

Other than the copper cap restricter plate trick, is there any other suggestions to fix this. It's starting to drive me nuts.

mac1009 · Jul 6, 2005

I had a similar problem w/ my car. It ended up being that because of the tight clearances w/ the powerpipe/MAF/filter combo, that for some reason, there was a gap between the MAF and powerpipe. Basically, I was pulling more air that the MAF was metering, and it threw everything off.

B's 96 GT · Jul 6, 2005

same problem but no fix yet. changed the Idle air control valve and didn't help. I'll let ya know if I find it.

ProCharger GT · Jul 6, 2005

i had the same problem. had jerry w from sct raise my idle a little bit (idles at 1K now, a bit too high, but that will be fixt in a few days) and that solved the problem. you probably dont have enough vaccum pressure; i would get the car re-tuned.

96WhiteNight · Jul 6, 2005

You might have an air leak, check all your intake gaskets and connections. My throttle body gasket was cracked and was doing the exact same thing.

hognutz · Jul 6, 2005

I would check the IAC to start with. I bought a plenum TB off ebay. it had been used for dyno runs so it had IAC and egr on it.

I swaped it on and the car would die if I cam to a hard stop. If I just braked normally it would dip down to 500rpms them come back up.

swapped my IAC back on and the car runs good.

Mirrahasmycar · Jul 6, 2005

Check all hose connections, sometimes if there is a loose connection it will cause a problem like this, also try turning off the AC, the AC and vent will cause the idle to run a little bit higher than normal, and the idle doesn't drop completely untill you stop in just about every mustang on the road, I would check all the hoses to the intake, the valve cover vent hoses, and also make sure your mass air meter it plugged in, there is also another small piece on the intake that takes a reading that could also cause this, good luck

reeber · Jul 6, 2005

mac1009 said:
I had a similar problem w/ my car. It ended up being that because of the tight clearances w/ the powerpipe/MAF/filter combo, that for some reason, there was a gap between the MAF and powerpipe. Basically, I was pulling more air that the MAF was metering, and it threw everything off.

That is a good point. My clearances are very tight there too. How did you fix it? It's very tight in there and you really have to move the intak pipe, power pipe, and the supercharger all over the place just to get it to fit.

mac1009 · Jul 6, 2005

reeber said:
That is a good point. My clearances are very tight there too. How did you fix it? It's very tight in there and you really have to move the intak pipe, power pipe, and the supercharger all over the place just to get it to fit.

Bust the hell out of your knuckles until you get it tight. Also, I noticed pretty much every hose clamp on my car has loosened over time, so I'm assuming that's why it happened. I had a small gap in the bumper that I could reach up into the fenderwell and check the tubing. I don't know if it's the same on the pre-99 bodies, but you can check it in 20 seconds that way.

Dave

reeber · Jul 7, 2005

I checked all the hoses and the clamps. Although some of the pipes do not line up correctly, it seems that all the hoses are in place and sealed. I don't think is it that

Jinx · Jul 7, 2005

Did you try pulling any codes? I had a similar problem with the whole stalling/power-drain during braking with my truck. I know they are 2 different animals, but mine turned out to be the EGR system. New EGR valve, DHCP sensor and EGR solenoid (the culprit) solved the problem. The solinoid never threw a code though because the electronics were good but the mechanicals were bad.

Good luck

reeber · Jul 8, 2005

My check engine light is on. I pulled the codes and Bank 1 and Bank 2 are both showing too lean. That's just because of the lack of cats. Could that be throwing it off?

Jinx · Jul 8, 2005

reeber said:
My check engine light is on. I pulled the codes and Bank 1 and Bank 2 are both showing too lean. That's just because of the lack of cats. Could that be throwing it off?

I just noticed that in your "garage" you don't have any MIL eliminators listed. This could be why your CEL is on? Do you have MILs??

reeber · Jul 8, 2005

I do, but they don't seem to be working properly.

jstreet0204 · Jul 8, 2005

reeber said:
My check engine light is on. I pulled the codes and Bank 1 and Bank 2 are both showing too lean. That's just because of the lack of cats. Could that be throwing it off?

No cats won't cause lean codes, you've got a vacuum leak somewhere.

reeber · Jul 8, 2005

jstreet0204 said:
No cats won't cause lean codes, you've got a vacuum leak somewhere.

I checked everything for a leak and cant find a thing that could possibly be leaking. I guess I have to check again for the third time. I seem to think it's a vacuum leak as well, but am having a really hard time pin-pointing it.

Jinx · Jul 8, 2005

You might try this around some of the clamps, connections and gaskets....

With the engine at idle, lightly spray a sensor safe TB cleaner around these areas, one at a time, and listen for changes in the engine idle. If there is a place where the engine is drawing in alot of air, you should hear a difference in idle when the cleaner enters the combustion chamber.

jstreet0204 · Jul 8, 2005

reeber said:
I checked everything for a leak and cant find a thing that could possibly be leaking. I guess I have to check again for the third time. I seem to think it's a vacuum leak as well, but am having a really hard time pin-pointing it.

Try using a propane torch to check for leaks
http://www.teamfocus.us/checkingforvacumleaks.htm

reeber · Aug 2, 2005

After confirming that there is NO vacuum leaks at all, I am wondering if it could be my MAF? I do have a Pro-M that is calibrated for 38lb. injectors, but running 60 lb. injectors. However, I had the same problem with when I had the 38's in it. Could it be a bad sensor? Would this cause the idling issue?

forpit2000gt · Aug 2, 2005

you need the MAF cal. for the injectors. Did the car ever act propely or did something change?

Idle is all over the place!!! Anyone have secret??

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