TPS on DJet with 2056, Idle circuit Options

[thomasotten]

I have a 2056 cc engine running D-Jet. All new lines, harness, everything. The engine has 96 mm pistons and larger valves - 44/36. I had to tune the MPS away from the original factory settings or it was just running too lean. So I richened it up and it runs really well now, checked MPS and adjusted with an AFR gauge. Only worry is my ECU mixture knob has no effect. The throttle position sensor has been rebuilt and calibrated with a new board. I double checked and triple checked the calibration because I know that it won't go into the idle circuit, where the mixture knob has authority if the TPS isn't calibrated correctly. So, the next thing I tried was changing out the ECU. Still acts the same. Idle mixture knob has no authority. So I am wondering, is there something about adjusting the MPS that will cause the computer to never use the idle logic? I know it doesn't have any feedback that you get from an O2 sensor, but I am wondering if signals from the MPS can keep it from going into idle mode.

Thanks

[mgphoto]

Idle is controlled by the TPS, and the Pot on the ECU, it has to adjusted for proper function.

[914werke]

what is the problem you are addressing?
Too high an idle?
Have you smoked your engine to eliminate air leaks that would defeat idle adjustments?

[mgphoto]

TPS needs to be bench adjusted with the throttle body, the ECU “pot” is adjusted with the air screw for idle mixture, they seem to be very picky about this reading in England.
When your car was setup the technician who made the initial adjustments put a detent in the ring around the ECU knob using a soldering iron to indicate the adjustment position.
You need to have the ignition timing adjusted, then after the engine is warm, the air screw is adjusted for idle.

[thomasotten]

what is the problem you are addressing?
Too high an idle?
Have you smoked your engine to eliminate air leaks that would defeat idle adjustments?

The only problem I am addressing is that the ECU knob has no effect. The engine has all new vacuum lines and was smoke tested. TPS calibrated on bench. Question I have is if anyone has found if there are conditions where the ECU knob will have no effect, especially when MPS is adjusted for larger displacement engine.

[nordfisch]

Hi,
did you check the correct electrical function of the TPS?
It has to be adjusted not only on the bench, but on the throttle, too.

Check the continuity between the pins 17 and 47 with the throttle closed.
They have to be 'zero resistance'.



If you have no continuity, loosen the two screws of the TPS and turn it a little bit counter-clockwise until you can feel some resistance.
Fasten it in this position and check the continuity again.

If you still have no continuity, something in the TPS is wrong.

If you have found no problems at the TPS, you might have a problem with the harness.

Regards
Norbert

[Highland]

Curious when you say "bench test" does that mean as a TPS & throttle body assembly or just the TPS?

I've had no effect from the idle knob when the MPS is out of calibration at idle. The knob seems to be a very fine adjustment and if the MPS is too lean for instance, the knob won't do anything. At least that's my experience.

[emerygt350]

Yeah, check your adjustment. I have ended up adjusting them on the car for just this problem. Use a multimeter and make sure that last wire closest to the passenger is responding to the idle position.