Right, took it upon myself to check all the electrics in the car hoping to get to the root cause of that mis-fire - I hope there's something useful below...

Here's what I've found - all done with ignition off and ECU disconnected.

-All connections between sensor connector and ecu are 100%.
-Reading between pins 24 and 25 (ECU to ignition amp), I have 24Kohm, which is way above the 1000 to 1500 it should be.
-Pins 11 and 30 (ECU to TPS full resistance), I am reading 412ohm which I think is ok.
-Pins 30 and 17 (ECU to TPS moving contact), I read 437ohm at idle, 0 on full throttle.
Before you ask, I have also taken the TPS off to take the measurements.

Would I be right in assuming that there is a problem with my TPS sensor and possibly the ignition amp too ?

I have been experiencing mis-fires on wide throttle and boost. New leads and grp A coil didn't make much of a difference. Plugs are NGK9's, 800 miles on them, gapped to .65mm.

Thanks for your feedback. I will crack it (one day).

 

 

is it a 4x4 or a 2wd - as they have different readings(opposite) for the TPS

 

Dave,

Its a 4x4 .

 

cool
,
so with the ecu plugged in but the shroud removed so you can access the contacts with the connector plugged into the ecu.

turn ignition on and across the 2 pins (sliding contact - 30 and 17) you should ajust the TPS so that it gives a reading of between 0.2 and 0.25 volts. this should increase to just under 5 volts at full throttle (without the engine running).

note how linear it is (by the smoothness of the bar graph on your fluke or the motion of the needle on a proper meter)- as they can wear and cause odd spurious readings around the part throttle positions as they wear the most there.

 

yo may have to disconnect the actual ignition amp and go accross the pins of that rather than the ecu loom , you may be seeing resistane across other things aswell.

a new ignition amp is not too expensive though..... mine did fail on my 4x4 saph .

 

Froq

See my post in Technical Help in case there's anything in there that might help you.

Ive got a Misfire when on WOT and Boost.

So far ive not managed to trace the problem. If you look in my post you'll see there are loads of things ive checked to no avail.

I'd be interested if you cure yours.

Good Luck.

 

Dave, surely, if the TPS doesn't give the correct resistance, the voltage on the ECU with ignition on will be wrong too. Or have I got the wrong end of the stick again

 

it will be - but i know that thats what the voltage readings should be .... the voltage is related to the resistance - ohms law anyone...

 

I have taken my TPS off and opened it Cleaned it thoroughly and put it back in.

Is the TPS for a 3 door, 2wd and 4x4 the same thing ? Or do they operate differently ? I have a feeling that the documentation I found was for a 3 door...

Now, the car idles rough when cold, then fine when hot IF the ISCV is disconnected. As soon as I reconnect it, then engine races to 2500 rpm or so.

 

you readings are ok for a later type 4x4 tps,and as far as i,m aware you allowed between 300 to 600 ohms at closed throttle and between 40 and 150 ohms at full open throttle but being at zero ohms full open i dont think is a problem but you could fine adjust it and see if it makes a difference , the earlier types just opperated more or less in reverse.but with ignition on its not a bad idea to get voltage readings aswell to be double sure.
when you reconnect the iscv you said it races to 2500 rpm but does it go back down to normal levels is a few seconds?

 

Thanks velocity, that clears up a few things, looks like the documentation I have I relates to a 3 door which explains why things aren't reading right.

When I checked the TPS (inside) yesterday, there was no way that the measurements I got in the documentation could be given by the TPS, hence my question on the difference between 4x4 and 2wd.

I will check the voltages tonight on the ECU and made triple sure the TPS it setup ok, then take it from there.

When I plug the ISCV back in, the RPM doesn't drop at all, stays there... That could be down to the TPS not being quite right though.