Why does it take so long for my RPM's to go back to idle?

9

93LINCMK8

Registered
When I rev my engine the RPM's don't return to idle right away, it takes too long, like 7-10 secs. What could be causing this, the TPS?
 
Well it depends on high how he is revving it in the first place. These motors are known for having slow back to idle speeds though in general.
 
I'm not sure why it does that but it sure makes these motors seem less "sporty." In my parents G35 you can rev it to 5000 and it drops back to idle in a second like a F1 motor lol...
 
I always hated that with my best friends 96 GT...sounded like it had NO power, where my 5.0 rev'd up/down like a motor cycle!
 
It's quicker to drop back to idle when I first start it up but when it gets warm it hangs up above 1000 for too long it seems. So there's nothing to be done for this?
 
You can try replacing your IAC and if that doesn't work your TPS... both really hard to get to on a 93 Mark VIII. You can also contact someone who burns chips for our cars if they can mess with the idle/rpm settings.
 
What does IAC stand for? Would a superchip adjust that automatically? I've been thinking about getting one for a while.
 
Last edited:
Idle air control valve and superchips are outdated pieces of crap. You are looking for an SCT chip (completely different than the old superchips), and it won't make adjustments by itself, you have to request a custom tune with whatever you want done.
 
SuperChips don't use a "stand alone" system so your cars ECU(computer) will eventually "re-learn"(aka adaptive learning) back to the most economical settings, there for cancelling out the SuperChip.

SCT chips(amongst other brands) are the way to go. I have a SCT 4 Bank chip which allows me to switch between 4 different tunes, plus the stock one. This style chip also bypasses the stock computer chip so it doesn't have the ability to "re-learn" anymore.
 
46callaway said:
Idle air control valve and superchips are outdated pieces of crap.
Click to expand...

IACs may be outdated, but they are still necessary for the car to operate. And it would be better to get a bad one replaced rather than adjusting the computer program to compensate.

Poor band-aid IMO.
 
J said:
SuperChips don't use a "stand alone" system so your cars ECU(computer) will eventually "re-learn"(aka adaptive learning) back to the most economical settings, there for cancelling out the SuperChip.

SCT chips(amongst other brands) are the way to go. I have a SCT 4 Bank chip which allows me to switch between 4 different tunes, plus the stock one. This style chip also bypasses the stock computer chip so it doesn't have the ability to "re-learn" anymore.
Click to expand...

You're behind the times J!

I've got an Xcal2 :wave022:
 
logres said:
IACs may be outdated, but they are still necessary for the car to operate. And it would be better to get a bad one replaced rather than adjusting the computer program to compensate.

Poor band-aid IMO.
Click to expand...

I think Max was just combining sentences on accident....the guy asked "what does IAC stand for" and also "would a superchip adjust....."

logres said:
You're behind the times J!

I've got an Xcal2 :wave022:
Click to expand...

Not MY fault my car has an OBDI system in it!(well...I did buy it, haha)

I'd rather have an OBDI car and do whatever I want to it, than have an OBDII car and have to try to "hide" all the modifications from the smog machine. ALL OBDII cars are plugged into the smog machine to verify nothing has been tampered, there are no codes, to verify atleast 5 of 7 readyness monitors are "ready", and to monitor all the vehicles sensors etc. My car doesn't get plugged into anything for its 2 year prostate exam :D
 
J said:
I think Max was just combining sentences on accident....the guy asked "what does IAC stand for" and also "would a superchip adjust....."



Not MY fault my car has an OBDI system in it!(well...I did buy it, haha)

I'd rather have an OBDI car and do whatever I want to it, than have an OBDII car and have to try to "hide" all the modifications from the smog machine. ALL OBDII cars are plugged into the smog machine to verify nothing has been tampered, there are no codes, to verify atleast 5 of 7 readyness monitors are "ready", and to monitor all the vehicles sensors etc. My car doesn't get plugged into anything for its 2 year prostate exam :D
Click to expand...

I am in CA, and I've never had a problem. Custom tranny, custom TC, modified shift points, modified lock-ups.

I've just never modified any of the ENGINE settings.
 
93LINCMK8 said:
So the IAC is the one that was described to me as having a "worm" gear inside that may be hanging up?
Click to expand...

Technically yes, I believe it is a linear DC actuator that opens/closes changing a metered opening on command from the PCM in a closed loop feedback circuit.
 
Engine Hesitates

Engine Hesitates

I'm having a problem with the engine hesitating upon acceleration. It's gotten better since I replaced the fuel filter but it is still very noticible. I also ran a can of injector cleaner through a tank of gas and that didn't help either. Any suggestions?
 
estridge48 said:
I'm having a problem with the engine hesitating upon acceleration. It's gotten better since I replaced the fuel filter but it is still very noticible. I also ran a can of injector cleaner through a tank of gas and that didn't help either. Any suggestions?
Click to expand...

Possibly TPS or ignition (old wires or coil packs).
 
You must log in or register to reply here.
Back
Top