Surging Idle????
- Thread starter Yeats5.0
- Start date
That's with FP at 30 psi and vac line connected?
Drop FP to 27 psi.
You might want to drive the car to allow the ECU time to "re-learn"...but, that idle is still high even for default values.
What injectors are you using?
Can you accurately read coolant temps? Try pulling the ECU temp sensor plug again, then start the car with it unplugged. See if there is any change with the lower FP.
Drop FP to 27 psi.
You might want to drive the car to allow the ECU time to "re-learn"...but, that idle is still high even for default values.
What injectors are you using?
Can you accurately read coolant temps? Try pulling the ECU temp sensor plug again, then start the car with it unplugged. See if there is any change with the lower FP.
No idea what injectors are in it. be nice if they were big ones! I have a Snapon Modis scanner, not sure what info it will give me on something that old, it being obdI and all.
I edited my above post 
Sorry for all the small shit details, but it's kinda painful with me not being there!
Sorry for all the small shit details, but it's kinda painful with me not being there!
If there is no difference with the ECU temp sensor disconnected, coolant temps are not the problem...it's default is 80 deg C. That's where warm-up enrichment terminates.
jdub;1146125 said:
I would expect no less. You are diagnosing blind! I pride myself of being a descent tech - I think I have covered everything but you never know. You obviously have an expansive knowledge of these cars and I appreciate your time.
No change with the coolant temp unplugged. check engine light does come on though. That curcuit must be complete at least.
No problem...I can tell you have a clue
Ok, what I understand is the idle is steady at 1400 RPM, FP at 27 psi, no vac leaks, no tears or leaks in the accordion hose or PCV/ISCV hoses to the TB. All correct?
The CEL with the coolant sensor unplugged is normal...it will set a stored code...you need to clear it.
Ok, what I understand is the idle is steady at 1400 RPM, FP at 27 psi, no vac leaks, no tears or leaks in the accordion hose or PCV/ISCV hoses to the TB. All correct?
The CEL with the coolant sensor unplugged is normal...it will set a stored code...you need to clear it.
Even though the Idle Air Control checks out good. I'm wondering if it might be my problem. Plus I need to get the check valve for it anyway.
I will clear the code
I will clear the code
The ISCV could be it, but not likely...and, yes you need that check valve
Can you hear it step open when the motor is shut down?
Drive the car with the current settings and see what it does.
Timing is the next thing to look at.
Can you hear it step open when the motor is shut down?
Drive the car with the current settings and see what it does.
Timing is the next thing to look at.
Should I be cautious when I drive this after lowering the fp, This car has dynod at 373hp at the wheels. I have two timing lights, neither one is at my house - one is 30 min east with my mustang project - the other is 30 min west with the mustang I typically drive everyday. I guess I'll have to find one somewhere tomorrow.:nono:
A long shot, but perhaps you should check the dashpot:
http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?Section=EC&P=8
It shouldn't be a factor since it appears the TB plate is closed at idle (engine dies when you pinch off the ISCV/PCV hoses).
Do you have a wideband O2 gauge/display?
My motor is at a similar HP level at 27 psi FP with a SP61 turbo. I hope you have 550 injectors
Do you know if it has a Lex AFM installed?
http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?Section=EC&P=8
It shouldn't be a factor since it appears the TB plate is closed at idle (engine dies when you pinch off the ISCV/PCV hoses).
Do you have a wideband O2 gauge/display?
My motor is at a similar HP level at 27 psi FP with a SP61 turbo. I hope you have 550 injectors
Do you know if it has a Lex AFM installed?
Ok went and drove it again, still the same idle. Here is another observation from driving it. This car is very jerky! You cannot maintain constant throttle around 1500rpms. There is a place in the throttle that when you play with it - it seems like when you let off just a little bit it is like turning the key to shut it off. Maybe the Idle air slamming shut! Give it just a hair more throttle and it is back to normal. This issue seems to be right around the same rpm as were the idle is riding at the time. Maybe the tps is jacked up. All the terminals checked out good. The car has an old school SAFC with knobs - maybe it is messing up the throttle signal to the ecm. Any thoughts?
It has a Wideband O2, only hooked up my laptop once just to make sure it works. I have not been driving it very hard just because of this issue. Want to make sure everything is right before turning it up!:naughty: I've been looking for a Lexus AFM, this car used to have one. The guy I bought it from had already sold it off. Got an extra? The junk yard wants 100 bucks for one. Probly worth it, but I don't have the injectors either, so I'll wait for a deal and just keep the boost down for now.
Got an extra? The junk yard wants 100 bucks for one. Probly worth it, but I don't have the injectors either, so I'll wait for a deal and just keep the boost down for now.Oh yeah, I forgot to mention. I have not been able to hear or feel the IAV make any kind of noise after shutting down the motor. All I can hear is the fuel pump (walbro).
The SAFC could very well be part of the issue...thing is, I'm not familar with it as to how the knobs control the different aspects of what it does. I do know it modifies the AFM signal to the ECU.
You might want to contact the previous owner and determine what you have for injectors. If you have a wideband O2, pay attention to your AFRs...you should be very close to 14.7 at idle and cruise. Under boost, 11.5 is good...you don't want to go over this AFR or you risk killing the motor.
The Lex and 550 injectors go hand-in-hand...pushing those kind of HP numbers on the stock AFM/injectors is pushing it quite a bit. Keeping off the boost is a very good idea
No...I don't have an extra Lex. You might want to consider dumping the old SAFC for a Maft Pro.
You might want to contact the previous owner and determine what you have for injectors. If you have a wideband O2, pay attention to your AFRs...you should be very close to 14.7 at idle and cruise. Under boost, 11.5 is good...you don't want to go over this AFR or you risk killing the motor.
The Lex and 550 injectors go hand-in-hand...pushing those kind of HP numbers on the stock AFM/injectors is pushing it quite a bit. Keeping off the boost is a very good idea
No...I don't have an extra Lex. You might want to consider dumping the old SAFC for a Maft Pro.
There is a good deal locally on a SAFC Neo. What do you think of these? I will check on the injectors later today, but I'm pretty sure they are stock. I will be driving it to the alignment shop today, so I will watch the AFR's close and see what is up. Thanks for your help!
Just replaced the TPS and the IAC motor and have the exact same symptoms. This is getting frustrating, it would be different if I knew some background on what has been done to the car. I unplugged the AFM and the car idles low and rough, but it is low! Maybe the AFM or the SAFC is messed up.