Terrorist 5.0
Member
- Joined
- Oct 16, 2023
- Messages
- 173
- Reaction score
- 39
Hi everyone. After driving the Mustang for a couple months, I decided it was time for an IAC restrictor plate to let the RPM's drop a little faster between shifts, as it was making me slow down traffic sometimes when I actually waited for it. Just a little faster RPM drop would be nice, nothing drastic, especially after I tried driving with the IAC disconnected. I bought the plate, along with a new IAC, as my other one was on its way out for a while. I also wanted to turn the idle up as the previous owner had it set at 500-550 RPM. I put everything together with the small hole facing away from the motor as many people have done and had good results, and went to set the idle. AFAIK there is no agreed on procedure, but I went about it like this:
1. I let the car sit all day so it was nice and cold.
2. I set my throttle stop. The instructions said a 0.010" feeler gauge until it dragged but I didn't have that so two pieces of standard paper sufficed, anyway that plus 1 and 1/2 turns.
3. I started the car cold with the IAC disconnected, and had someone just barely keep it running for 2 minutes.
4. I adjusted the IAC bleed out around 1 and 1/2 turns.
After this the idle was still quite low so I turned the throttle stop another 1/2 turn in like the instructions said, and the idle was good. I shut the car off, plugged the IAC in, started it, and it idled at 650 RPM. Perfect. Shut it off, unhooked the battery, and let it sit overnight.
The next day, I went to cold start it, and the RPM's shot up to 2000, and came down to around 800 in around 7 or 8 seconds. Fair enough, I haven't driven the car yet to judge it. I went for a drive and the RPM hang was awful. Way worse than before. The RPM's even jump up a little now if I don't wait long enough to push the clutch in after letting off the gas. Went home, flipped the plate around, same thing. Tried adjusting the idle down to where it was before, same thing. I set the idle as per the instructions perfectly, and unhooked the battery, and am now waiting for a couple hours for the car to be cold again to see what happens. Any ideas? The car has no vacuum leaks confirmed (smoke tested).
The main things I am looking for is:
1. What is the target TPS voltage when the car is idling? I know the TPS in the SN95 isn't adjustable, but I want to know so I can set my throttle stop accordingly, and I am also going to buy a multimeter to check out what the situation in the sensor is.
2. What is the computer's target idle RPM? AFAIK it is around 650.
3. Which way is the plate supposed to go? It is conflicting everywhere I look.
Thanks everyone.
1. I let the car sit all day so it was nice and cold.
2. I set my throttle stop. The instructions said a 0.010" feeler gauge until it dragged but I didn't have that so two pieces of standard paper sufficed, anyway that plus 1 and 1/2 turns.
3. I started the car cold with the IAC disconnected, and had someone just barely keep it running for 2 minutes.
4. I adjusted the IAC bleed out around 1 and 1/2 turns.
After this the idle was still quite low so I turned the throttle stop another 1/2 turn in like the instructions said, and the idle was good. I shut the car off, plugged the IAC in, started it, and it idled at 650 RPM. Perfect. Shut it off, unhooked the battery, and let it sit overnight.
The next day, I went to cold start it, and the RPM's shot up to 2000, and came down to around 800 in around 7 or 8 seconds. Fair enough, I haven't driven the car yet to judge it. I went for a drive and the RPM hang was awful. Way worse than before. The RPM's even jump up a little now if I don't wait long enough to push the clutch in after letting off the gas. Went home, flipped the plate around, same thing. Tried adjusting the idle down to where it was before, same thing. I set the idle as per the instructions perfectly, and unhooked the battery, and am now waiting for a couple hours for the car to be cold again to see what happens. Any ideas? The car has no vacuum leaks confirmed (smoke tested).
The main things I am looking for is:
1. What is the target TPS voltage when the car is idling? I know the TPS in the SN95 isn't adjustable, but I want to know so I can set my throttle stop accordingly, and I am also going to buy a multimeter to check out what the situation in the sensor is.
2. What is the computer's target idle RPM? AFAIK it is around 650.
3. Which way is the plate supposed to go? It is conflicting everywhere I look.
Thanks everyone.