Mechanics

FORD MUSTANG RPM PROBLEM

2002 Ford Mustang • 80 miles

2002 Mustang GT
with 75mm Dragon plenum and tb. Vortech v2 blower.
My idle hangs up around 2000-3000 rpms from time to time for no apparent reason.
I have replaced the TPS, IAC, and EGR.
I have cleaned TB, intake tubes, IAT, and MAF sensors.
I have re-tightened all connections on intake from air filter to blower, down to the air to air intercooler, to the TB.
Checked for vacuum leaks.
Checked for vacuum leaks and re-tuned the ECU.
Avatar
Cav68
March 29, 2013.




Re tuned pcm? Is this aftermarket?

Roy

ASEMaster6371
Mar 29, 2013.
Yes, re-tuned oem pcm with custom tune.

Tiny
Cav68
Mar 29, 2013.
I have a boss who had one of these with an 2002 camaro and he had software issues with the idle system.

Is there any diags you can do for your software?

Roy
AD

ASEMaster6371
Mar 29, 2013.
Roy,

To answer your question, I have three different Mike Murillo tunes for my car, 91 octane, 93 daily driver, and 93 high output. I reflashed the pcm last night with 93 DD and the car is idling fine, around 850- 900 which is normal for my blower setup. I would not think that all three tunes are bad, but I can be wrong. I will have to get some miles on the car and I can connect my OBD II scanner and retrieve some data.
Here's what I also did, I used one of those IAC spacers that makes the IAC hole smaller in diameter than oem. That mod seems to help, it drops the idle down much quicker when I push in the clutch to shift. I know, from doing much research that Ford purposely made the IAC hole large to create rev match when shifting at high rpms. Unlike Nissan who programs it into their pcms which can change and learn from driver habit. Ford's method of rev matching just hangs to long for most people's taste, but I understand the reasoning behind it, prevent damage to syncos in the tranny when shifting at very high rpms.
I also checked the voltage on the TPS and it read very low around.02 and it should be between.96-1.0 volts on these casr from what I found out on many different Mustang forums. I replaced the TPS again, and it now reads.99, which.97-.99 is ideal. I test drove the car last night up to operating temp which on my car is around 205-210 and did not get the throttle sticking/hanging at high rpm highway sppeds.
One thing that I did discover last night too, is that I have a small coolant leak under my thermostat housing on the aluminum crossover that is in front of the intake manifold, driver side. Could that possibly create the throttle sticking/hanging at highway speeds over 3000 rpms? Could coolant be getting into my intake? I checked my oil this morning and it is not milky looking at all. Maybe I will get one of those block testers and check to see if exhaust vapors are getting into my cooling system, would that be something worth while doing?

Cav

Tiny
Cav68
Mar 30, 2013.

AD