Still trying to solve my Z's throttle problem. Short story is that the TPS is pushing out 0.44V (checked with multimeter and replaced TPS), even on the plug into the ECU. Datascan shows the TPS voltage as 0.9V. As a consequence the car is not running well, high idle and very harsh gear changes. It also seems to sit at higher revs when cruising, but maybe that's another problem.

 

Anyway I've now swapped out both the auto box ECU and the main engine ECU and have the same readings, so whilst I'm happy that's 2 more bits ruled out I'm still left with my problem.

 

So I'm thinking there must be a short or something elswhere or possibly some other sensor into the ECU causing this, but all the wiring diagrams I've found just show the ECU as a black box, so I can't trace anything.

 

Has anyone come across this problem before and can offer any clues as to what's causing it. It's in the garage next week for new rear shocks and HICAS joints and I'll probably ask them about this, but I suspect they may have to hunt for the problem just as I am. So here I am sitting in the car typing this wondering what to do next :confused: :(

 

Gaz

Have you measured the voltage across the two pins of the tps or just from earth to the middle pin? Sounds like a possible earth fault somewhere....

Common problem caused by pressure cable faults, the shielding on the cables can also cause problems if it becomes disconnected as it will then produce back feed signals that voltmeters etc cannot discriminate between true readings and trace readings due to the low impedance of digital voltmeters, quickest solution is to rewire to the ecu as finding the fault inside the tightly wrapped loom is almost impossible.

 

Tempory drap a three core cable from the tps to the ecu and swap the cables over, hopefully the tps will then be setable, if however there is still a fault, other sensors will need to be checked as there is many common earth returns and supplies between them which can transfer faults from one area to another.

 

 

Know that sound a bit heavy but by slowly working through it you will eventually sort the problem.

 

Daveman

And then it fixes itself .................. but I know the problem will be back tomorrow or the day after :(

 

Thanks for the suggestions, I guess replacing the loom bit by bit might be the only way although it's a pain when it's intermittent.

 

I also noticed that when I have this problem the power light does not come on when I boot it. When the problem goes away and the car is running nicely the power light comes on as it should when booted. I wonder if I'm looking in the wrong place, maybe the issue is with the autobox loom ..... oh well, only time and lots of wire will tell.

 

Gaz