My motor is a slow revver...always has been. It's perfectly normal on the rev-up...but it takes an eternity to fall back down. It's like the computer hangs it at 1300, then 1100, then finally lets it drop back to 800. What's the cause of this...or is it a problem? Car runs great...just got it running again earlier today. It's just irritating to start it, and have to wait 10 seconds before I put it in gear because if I don't, it'll stall out or chirp the tires if I give it extra gas.
Trick for quicker revs?
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BlackFox5.0
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Sounds like an IAB problem, try cleaning it with carb cleaner.
The IAB is the long clyndrical piece at an angle on the TB, and has a single plug on the end of it... take it off, and clean the insides of it out...
The IAB is the long clyndrical piece at an angle on the TB, and has a single plug on the end of it... take it off, and clean the insides of it out...
What do the plugs look like? Any evidence of a rich condition? The reason I say that is that a common reason for high idle is innadequate air coming into the engine...OR what the computer is interpretting as a rich condition. How old are those O2 sensors? Engine coolant temp sensor? Engine air intake temp sensor? EGR valve or position sensor? These things, if sending a false or dampened signal may create idle issues.
Sometimes if you try to pull the codes, a few will show up, even without the check engine light coming on. Some sensor functions slowly fade away, others just fail and trigger the "check engine light".
The hanging, high idle is most likely a closed-loop issue from the IAB, EGR, or O2 sensors. The cold-start stall problem is likely a separate issue because it is in open-loop until the O2 sensors warm up.
Something you mentioned...cleaning the IAB every few months...why? Is it really getting that dirty? It shouldn't. Maybe once every few years with normal driving. Perhaps you've got some smog equipment issues that is spewing a little too much crud into your intake (like a rich condition). Oilly crud in the intake plenum and runners restricting air flow? Very common. PCV valve or screen plugged up? Very common.
Needless to say, there are many things to look at.
Sometimes if you try to pull the codes, a few will show up, even without the check engine light coming on. Some sensor functions slowly fade away, others just fail and trigger the "check engine light".
The hanging, high idle is most likely a closed-loop issue from the IAB, EGR, or O2 sensors. The cold-start stall problem is likely a separate issue because it is in open-loop until the O2 sensors warm up.
Something you mentioned...cleaning the IAB every few months...why? Is it really getting that dirty? It shouldn't. Maybe once every few years with normal driving. Perhaps you've got some smog equipment issues that is spewing a little too much crud into your intake (like a rich condition). Oilly crud in the intake plenum and runners restricting air flow? Very common. PCV valve or screen plugged up? Very common.
Needless to say, there are many things to look at.
Good points above, let me add this too:
Set your TPS voltage to right below 1V, say .998 is where I set mine. Also, see what happens if you move your throttle screw. Probally do this and then set the TPS. If it is in too far, it will hang your throttle open, so the IAC will not be controlling the idle air as it should but the throttle will be open, but the computer will leave the IAC open where it should be, causing a hanging idle.
Set your TPS voltage to right below 1V, say .998 is where I set mine. Also, see what happens if you move your throttle screw. Probally do this and then set the TPS. If it is in too far, it will hang your throttle open, so the IAC will not be controlling the idle air as it should but the throttle will be open, but the computer will leave the IAC open where it should be, causing a hanging idle.
Plugs are light to dark tan. The car has been tuned to run richer than normal via an AFPR, since I have modified intake/heads and stock injectors. I clean it so often because I clean the throttle body fairly often.....it gets light buildup from the PCV return that I like to clean out. I usually do the IAB because it's right there, and it's not like it's going to hurt it by cleaning it.
O2 sensors are maybe 8 months old. Coolant temp sensor, maybe 10 months to 1 yr old. Intake temp sensor, where's it located? Throttle position sensor is around a year old, and the EGR valve is maybe 3 months old. Basically, every sensor I'm aware of, I have replaced. The PCV valve is around a year old also, and the screen was replaced because the old one...well, there WASNT a screen in it at all before.
The I had the upper intake off earlier today....the upper and lower look to be very clean inside. Only a few runners on the lower intake had discoloration (black-ish).
As far as ignition goes: Fairly new spark plugs, MSD 8.8 Superconductor wires, MSD cap and rotor that are 8-10 months old, and the distributor gear and pickup coil were both replaced. The coil is an MSD Blaster TFI.
And the stall problem, it's not cold start. It only happens because the idle hangs and if I need to get it into gear fast, dropping it into drive from like 1300 rpms will stall the car.
O2 sensors are maybe 8 months old. Coolant temp sensor, maybe 10 months to 1 yr old. Intake temp sensor, where's it located? Throttle position sensor is around a year old, and the EGR valve is maybe 3 months old. Basically, every sensor I'm aware of, I have replaced. The PCV valve is around a year old also, and the screen was replaced because the old one...well, there WASNT a screen in it at all before.
The I had the upper intake off earlier today....the upper and lower look to be very clean inside. Only a few runners on the lower intake had discoloration (black-ish).
As far as ignition goes: Fairly new spark plugs, MSD 8.8 Superconductor wires, MSD cap and rotor that are 8-10 months old, and the distributor gear and pickup coil were both replaced. The coil is an MSD Blaster TFI.
And the stall problem, it's not cold start. It only happens because the idle hangs and if I need to get it into gear fast, dropping it into drive from like 1300 rpms will stall the car.
The TPS was set quite a while ago, and the idle speed has been tinkered with frequently since. How can I set the TPS voltage? I have a digital multimeter, but I'm electrically retarded and have no idea how to use it. And also, I lose the probes for it somewhere...all it has is alligator clips. 
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