Hi Guys,
Hopefully together we can figure out an issue I'm having with my mustang. I've identified the culprit but don't know how to fix it. My mustang will idle up around 2k rpm when the engine is cold. It bounces back and forth for a couple minutes slowly coming down to around 1200 rpm. My SCT tuner has it set at 1200 rpm (due to large cams) along with my set screw so those are fine. I've checked and tested my maf sensor, tps sensor, throttle body linkage, clutch cables and have replaced all of my rubber hosing in case I had a vacuum leak. BTW I have a brand new maf, throttle body, tps and IAC that I replaced looking for the issue I'm having. My mustang never used to do this before the addition of my power adders. It would start up and hit the proper idle instantly at start with no warming up needed. I'm sick of the people saying that's normal when its cold because its NOT. Even cold the engine should not rev up like that. So last night I was playing with my IAB with the car running and noticed when I unplugged it during idle my rpms were more consistent and it idle'd exactly how it should. It also sounded better. Mind you I already replaced this item and did a ground check and voltage check to make sure the harness and wiring are good which they are. So I believe my problem lies within this IAC. When my mechanic added everything to my car he said the problem was the same and the only way to keep it from idling high at start was to block off the IAB with a plate and drill a small hole to allow some air to bypass and it would calm down the start idle. I have since removed the plate he installed before I had it tuned. I felt like removing the complete IAB would just eliminate the issue all together but I also feel like my PCM and Tuner should be able to modify and adjust the amount of air coming in to reduce it from revving to 2k rpm on cold starts. After its warm it has no issues. So I'm stuck still trying to figure out my next step. I'm currently learning my sct tuner and I'm thinking of adjusting my custom tune by going into the settings to find out which part of the tune modifies the IAB. But I'm not sure what to do or how to find it.
Mods
Trickflow Twisted Heads 44cc
Edelbrock Intake Manifold and Heads
75mm Throttle body and Plenum
Stage 3 Comp Cams .050 lift
BBK Fuel Rails
Accel Coils
39 lb injectors
255 LPH Walbro Fuel pump
Long tube headers
Steeda Pulleys
Cold Air Intake
90 Ford Peformance Maf Sensor Changed to SCT BA3000 Maf Sensor
High Performance Spark Plugs
Optimum Battery
Bigger Alternator
SCT Tuner X3
More mods but not sure those matter
Short Video Of My Mustang GT Click Here
Hopefully together we can figure out an issue I'm having with my mustang. I've identified the culprit but don't know how to fix it. My mustang will idle up around 2k rpm when the engine is cold. It bounces back and forth for a couple minutes slowly coming down to around 1200 rpm. My SCT tuner has it set at 1200 rpm (due to large cams) along with my set screw so those are fine. I've checked and tested my maf sensor, tps sensor, throttle body linkage, clutch cables and have replaced all of my rubber hosing in case I had a vacuum leak. BTW I have a brand new maf, throttle body, tps and IAC that I replaced looking for the issue I'm having. My mustang never used to do this before the addition of my power adders. It would start up and hit the proper idle instantly at start with no warming up needed. I'm sick of the people saying that's normal when its cold because its NOT. Even cold the engine should not rev up like that. So last night I was playing with my IAB with the car running and noticed when I unplugged it during idle my rpms were more consistent and it idle'd exactly how it should. It also sounded better. Mind you I already replaced this item and did a ground check and voltage check to make sure the harness and wiring are good which they are. So I believe my problem lies within this IAC. When my mechanic added everything to my car he said the problem was the same and the only way to keep it from idling high at start was to block off the IAB with a plate and drill a small hole to allow some air to bypass and it would calm down the start idle. I have since removed the plate he installed before I had it tuned. I felt like removing the complete IAB would just eliminate the issue all together but I also feel like my PCM and Tuner should be able to modify and adjust the amount of air coming in to reduce it from revving to 2k rpm on cold starts. After its warm it has no issues. So I'm stuck still trying to figure out my next step. I'm currently learning my sct tuner and I'm thinking of adjusting my custom tune by going into the settings to find out which part of the tune modifies the IAB. But I'm not sure what to do or how to find it.
Mods
Trickflow Twisted Heads 44cc
Edelbrock Intake Manifold and Heads
75mm Throttle body and Plenum
Stage 3 Comp Cams .050 lift
BBK Fuel Rails
Accel Coils
39 lb injectors
255 LPH Walbro Fuel pump
Long tube headers
Steeda Pulleys
Cold Air Intake
90 Ford Peformance Maf Sensor Changed to SCT BA3000 Maf Sensor
High Performance Spark Plugs
Optimum Battery
Bigger Alternator
SCT Tuner X3
More mods but not sure those matter
Short Video Of My Mustang GT Click Here
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