I've searched many many threads but I don't think I have found proper guidance for this.
I have a 2002 mustang 4.6l, AT, stock, no tune, no codes. I've had this issue for several years now and learned to live with it but am reaching out for any help.
Likely some type of idle problem but the characteristics of this issue are concerning. Basically, when I'm coming to a full stop at a light or stop sign, the rpms increase to about 2k or so. I either have to stay on the brake with all my force to prevent me from lunging the car forward or I put it in neutral and the rpms would increase even higher. It will stay this way for a few seconds then it'll suddenly drop and try to "correct" itself then over compensate by dropping the rpms low to the point of almost stalling or outright completely stall. The car usually has to be in a complete stop for it to attempt to correct itself, if not, I could let go of the brake and the car would drive at a higher than normal "no pedal input" speed due to the high rpms to a point where the car actually accelerates into the next gear on its own.
This issue happens with these two conditions:
1. Hard acceleration
2. With A/C on
If I drive normal, without the above two conditions, this issue doesn't exist. I've also noticed that I may be in the 45-50 mph range and it would hang around that speed for a minute without me pressing on the gas. It would then slowly decrease speed. Actually it may decelerate slower then normal at street/ highway speeds.
The unique thing about having this issue with the AC on is that I before I come to a stop, especially if I was accelerating too quickly, I would turn off the AC and the car world correct itself as I'm driving to a stop. Or I could just turn it off before I even start slowing down and it would be good by the time I'm coming to a stop.
What I've done after knowing of this issue:
-I've checked for vacuum leaks but could not find any. May need to double check this.
- Cleaned TB, IAC, MAF sensor
-Replaced IAC, TP sensor, and PCV valve. I've heard getting the IAC from the Ford Dealership may be necessary as parts from auto parts stores seem to not work as well.
- Replaced several hoses (vacuum and evap)
- AC system was replaced and runs great. (not due to this issue but could be relevant)
Could this be fuel related? I haven't done anything on that end.
I could post a video of this happening if asked.
Any help is appreciated!
I have a 2002 mustang 4.6l, AT, stock, no tune, no codes. I've had this issue for several years now and learned to live with it but am reaching out for any help.
Likely some type of idle problem but the characteristics of this issue are concerning. Basically, when I'm coming to a full stop at a light or stop sign, the rpms increase to about 2k or so. I either have to stay on the brake with all my force to prevent me from lunging the car forward or I put it in neutral and the rpms would increase even higher. It will stay this way for a few seconds then it'll suddenly drop and try to "correct" itself then over compensate by dropping the rpms low to the point of almost stalling or outright completely stall. The car usually has to be in a complete stop for it to attempt to correct itself, if not, I could let go of the brake and the car would drive at a higher than normal "no pedal input" speed due to the high rpms to a point where the car actually accelerates into the next gear on its own.
This issue happens with these two conditions:
1. Hard acceleration
2. With A/C on
If I drive normal, without the above two conditions, this issue doesn't exist. I've also noticed that I may be in the 45-50 mph range and it would hang around that speed for a minute without me pressing on the gas. It would then slowly decrease speed. Actually it may decelerate slower then normal at street/ highway speeds.
The unique thing about having this issue with the AC on is that I before I come to a stop, especially if I was accelerating too quickly, I would turn off the AC and the car world correct itself as I'm driving to a stop. Or I could just turn it off before I even start slowing down and it would be good by the time I'm coming to a stop.
What I've done after knowing of this issue:
-I've checked for vacuum leaks but could not find any. May need to double check this.
- Cleaned TB, IAC, MAF sensor
-Replaced IAC, TP sensor, and PCV valve. I've heard getting the IAC from the Ford Dealership may be necessary as parts from auto parts stores seem to not work as well.
- Replaced several hoses (vacuum and evap)
- AC system was replaced and runs great. (not due to this issue but could be relevant)
Could this be fuel related? I haven't done anything on that end.
I could post a video of this happening if asked.
Any help is appreciated!
