Help!!!!!I'm going crazy !!!!!!
Forgot to mention, think of the "BISS" adjustment as cracking the throttle blade just a hair bit to allow for some air to bypass the TB..... you may wonder then why do we need to do this if the IAC can do it....well its another knob or control over areas where the IAC is out of range.
Hope that helps!
Hope that helps!
Thread Starter
Newbie
Joined: Jan 2010
Posts: 11
Likes: 0
From: woodbridge
This is how it works, when the throttle is closed, the only way for the motor to stay alive is by actuating the IAC via ECU to provide the necessary amount of air to allow for the engine to idle at a set rpm. So for every rpm target (900, 1000, 1100 rpm) the IAC should correspond to the correct needed amount of “steps” or openings you can say to allow the motor to “breathe”
When the rpm oscillates or hunts, the ecu will run a PID control (I think its PID type in mitsu) to correct the oscillation. Depending how aggressive or “lazy” the PID was tuned, you may feel a delayed response or aggressive swings like you are describing…. Jumping to 2k…etc
If we think the tuning is all correct, then the other thing that could throw things off is the BISS adjustments or a leak which u ruled out. You mentioned that you put on a new throttle body, its possible that the BISS on the new TB needs some adjustments. If you are familiar with what I am describing and can adjust it in your garage while this oscillation behavior is occurring, then you could resolve the issue.
IAC typically will relearn its locations (Park..etc) especially after a battery disconnect, when the key is turned on but while the engine is off. I think it takes a 2 secs or so to complete this learning. Someone could confirm.
Do you have access to another IAC valve that you could test?
GL!
Ps. Biggie is on the same track....
When the rpm oscillates or hunts, the ecu will run a PID control (I think its PID type in mitsu) to correct the oscillation. Depending how aggressive or “lazy” the PID was tuned, you may feel a delayed response or aggressive swings like you are describing…. Jumping to 2k…etc
If we think the tuning is all correct, then the other thing that could throw things off is the BISS adjustments or a leak which u ruled out. You mentioned that you put on a new throttle body, its possible that the BISS on the new TB needs some adjustments. If you are familiar with what I am describing and can adjust it in your garage while this oscillation behavior is occurring, then you could resolve the issue.
IAC typically will relearn its locations (Park..etc) especially after a battery disconnect, when the key is turned on but while the engine is off. I think it takes a 2 secs or so to complete this learning. Someone could confirm.
Do you have access to another IAC valve that you could test?
GL!
Ps. Biggie is on the same track....
Thread Starter
Newbie
Joined: Jan 2010
Posts: 11
Likes: 0
From: woodbridge
This is how it works, when the throttle is closed, the only way for the motor to stay alive is by actuating the IAC via ECU to provide the necessary amount of air to allow for the engine to idle at a set rpm. So for every rpm target (900, 1000, 1100 rpm) the IAC should correspond to the correct needed amount of “steps” or openings you can say to allow the motor to “breathe”
When the rpm oscillates or hunts, the ecu will run a PID control (I think its PID type in mitsu) to correct the oscillation. Depending how aggressive or “lazy” the PID was tuned, you may feel a delayed response or aggressive swings like you are describing…. Jumping to 2k…etc
If we think the tuning is all correct, then the other thing that could throw things off is the BISS adjustments or a leak which u ruled out. You mentioned that you put on a new throttle body, its possible that the BISS on the new TB needs some adjustments. If you are familiar with what I am describing and can adjust it in your garage while this oscillation behavior is occurring, then you could resolve the issue.
IAC typically will relearn its locations (Park..etc) especially after a battery disconnect, when the key is turned on but while the engine is off. I think it takes a 2 secs or so to complete this learning. Someone could confirm.
Do you have access to another IAC valve that you could test?
GL!
Ps. Biggie is on the same track....
When the rpm oscillates or hunts, the ecu will run a PID control (I think its PID type in mitsu) to correct the oscillation. Depending how aggressive or “lazy” the PID was tuned, you may feel a delayed response or aggressive swings like you are describing…. Jumping to 2k…etc
If we think the tuning is all correct, then the other thing that could throw things off is the BISS adjustments or a leak which u ruled out. You mentioned that you put on a new throttle body, its possible that the BISS on the new TB needs some adjustments. If you are familiar with what I am describing and can adjust it in your garage while this oscillation behavior is occurring, then you could resolve the issue.
IAC typically will relearn its locations (Park..etc) especially after a battery disconnect, when the key is turned on but while the engine is off. I think it takes a 2 secs or so to complete this learning. Someone could confirm.
Do you have access to another IAC valve that you could test?
GL!
Ps. Biggie is on the same track....
Newbie
Joined: Sep 2014
Posts: 17
Likes: 0
From: Watertown,NY
have you try to spray carb cleaner? you said you used a smoke test to check for vacuum/boost leaks? idk if that would be the best way to tell. they don't usually put out much pressure . i think around 3-5 psi . sounds like an intake gasket leak
Thread
Thread Starter
Forum
Replies
Last Post
E-SPEC INDUSTRIES
Evo X Dyno Results
51
Sep 1, 2015 11:14 AM
SilvrEvoIX
Evo Engine / Turbo / Drivetrain
10
Apr 27, 2010 01:01 PM
EvolutionTime
Evo Engine / Turbo / Drivetrain
5
Mar 26, 2010 07:03 PM