Could this be a timing issue? When I got the car it was not running (needed a turbo rebuild). I'm very impatient when it comes to buying a vehicle not running so I was checking everything out on it. I found the cam timing was retarded a tooth, so I fixed it. Could it be that the ignition timing is out far enough to mess up the idle?
Surging Idle????
- Thread starter Yeats5.0
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Ok, I took it apart - not much gunk. I went ahead and cleaned it up though. I put it back on and the idle stays high at around 1300 rpms but steady
Yes, as I posted earlier it does respond correctly to putting 12 volts to the different terminals in sequence. Both in and out. Very strange way to operate a idle air valve I think.
not sure on that one. Can you tell me the procedure? I will have to try that tomorrow night. I really appreciate the help - I'm used to mustangs
The idle will be high until the coolant temp gets above ~180 deg.
You will not be able to accurately set the timing until idle is at 650 RPM (spec).
To set timing, start at step 7:
http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?S=IG&P=19
The attachment may help you understand how idle is controlled
You will not be able to accurately set the timing until idle is at 650 RPM (spec).
To set timing, start at step 7:
http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?S=IG&P=19
The attachment may help you understand how idle is controlled
I just measured the ohms on the coolant temp sensor and it ohms right where it should be on a 60 degree day. I then went and drove it around and where it ohms would correspond on the graph to around 178 degrees which seems about right. The idle is solid at 1300-1500 no variation like before. Cleaning that idle air did help.
Re-check your ECU codes...want to make sure nothing is popping up after a drive.
Did you check the accordion hose for any leaks/tears?
Did you check the accordion hose for any leaks/tears?
no codes; is it normal that when you rev the motor the TEMS lights all come on then turn back off, except for the one on the far left, when it comes back to idle?
For the TEMS question, no clue here...don't have it 
Block off the brake booster line and the small fitting at the rear of the intake manifold.
If this has no effect, unplug the ECU temp sensor on the water neck and start the car.
Block off the brake booster line and the small fitting at the rear of the intake manifold.
If this has no effect, unplug the ECU temp sensor on the water neck and start the car.
tried both - no affect. Tonight when I fired it up it was idling smooth around 900. After a short test drive it was back to the normal 1300-1500
Ok...just to confirm, with the engine shut down you unplugged the ECU temp sensor in this pic:
There was no change in idle when you re-started the motor with this sensor unplugged?
Disconnect the vac line to the fuel pressure requlator. Idle should increase (so should fuel pressure)...check for vac at that line. Here's the TSRM page on the FP check procedure:
http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?Section=FI&P=71
There was no change in idle when you re-started the motor with this sensor unplugged?
Disconnect the vac line to the fuel pressure requlator. Idle should increase (so should fuel pressure)...check for vac at that line. Here's the TSRM page on the FP check procedure:
http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?Section=FI&P=71
no change disconnecting the coolant temp sensor. fuel pressure went up when I removed the vacuum line and the line has full vacuum. This car has an aeromotive fuel pressure regulator that is set up at 46 psi at idle. Will this cause a high idle? I saw the spec is 33-40psi.
That spec is with the vac line disconnected.
With the vac line connected, set the Aeromotive to 30 psi. Yes, high FP will increase idle
Depending on what injectors you're running, it may need to be less. I'm using 550 injectors and FP is set at 27 psi (vac line connected).
With the vac line connected, set the Aeromotive to 30 psi. Yes, high FP will increase idle
Depending on what injectors you're running, it may need to be less. I'm using 550 injectors and FP is set at 27 psi (vac line connected).
I started the car and reset the psi at idle with the vacuum attached. The idle rose to 1400rpms. I though you were on to something. Explain to me, if you don't mind educating me, why put on an adjustable pressure regulator if it negatively affects the idle. On a mustang thats how you richen the fuel.
Reset the ECU by pulling the EFI fuse and try it again with the FP at 30 psi (motor needs to be warmed up).
Setting FP is a "global" correction on this car...in that sense it is the same as most engines. Increasing FP will richen the mixture, decreasing FP will lean. The difference is the ECU controls injector duration...at idle it depends on coolant temps. This ECU first goes to start-up enrichment, then warm-up enrichment, then normal ops when coolant temps reach 176 deg F. That's why I had you pull the ECU temp plug so the default (fail safe) coolant temp value would be used by the ECU.
Idle and normal ops are subject to ECU "learned values"...when you make a change, you need to reset the ECU (pull EFI fuse) to put the values back to default.
This brings up another point...what temp thermostat are you running?
Was the car warm when you changed the FP this last time?
Setting FP is a "global" correction on this car...in that sense it is the same as most engines. Increasing FP will richen the mixture, decreasing FP will lean. The difference is the ECU controls injector duration...at idle it depends on coolant temps. This ECU first goes to start-up enrichment, then warm-up enrichment, then normal ops when coolant temps reach 176 deg F. That's why I had you pull the ECU temp plug so the default (fail safe) coolant temp value would be used by the ECU.
Idle and normal ops are subject to ECU "learned values"...when you make a change, you need to reset the ECU (pull EFI fuse) to put the values back to default.
This brings up another point...what temp thermostat are you running?
Was the car warm when you changed the FP this last time?
Don't know what thermostat its running, I'll put the efi fuse and try again. The car is probly in the 160 degree range.