checking Throttle feedback

[wycoller]

Find this can only be checked whilst engine running any jumpers i can insall to check this without running engine
buzzed out the wiring through to ECU and at underbonnet plug reading 6.3 K bible states 5k yet at the ecu the impedance measured at 3 and 25 drops to 2,6k should still read 6.3 or 5 k must be other sensors wired in parallel as buzzing out the cables indicates no probs in wiringwithin loom such as fuel temp etc i will investigate more, at idle output 0.44Volts. Looking at the reading i possibly have a dry joint somewhere on the track wiring as anybody else verified
Track resistance should it be 5k as in the bible.
next looking for electrical fuel pressure gauge to mount on my dash but cannot find matching magnolia face anybody any links to source
cheers jim

[blitzracing]

You dont need the engine running at all, just the ignition on. There are no other sensors involved, you supply 5 volts on one end of the TP (Make sure you have 5 volts or it will run lean), a ground wire (This is back to the ECU, not the same as chassis ground) and a wire to the wiper that should give a smooth transistion from less than a volt to a minimum of 4.6 volts. Resistance wise there may be some oddities on the type and angle swing of the TP, but the ECU just sees a voltage created by the variable resistance, so even if its 5 k or 6 k in total it does not really matter, as long as the voltage swing is correct from min to max. The ECU is smart enough to cope with some small variances.

Edited by blitzracing on Tuesday 20th July 12:17

Edited by blitzracing on Tuesday 20th July 12:22

[TVR Beaver]

Jim... I was told to check it at the Pot by one Co. and the ECU by another... I think checking it at the ECU sounds better.. this will be the voltage that the ECU see's and uses...
Good luck... hope you can get in!!

[blitzracing]

He right in so much the voltage will still swing smoothly on the back of the pot, even if the ECU connection is open circuit, but the ECU should pick this one up and generate a fault code and drop into the fall back mode.

[wycoller]

blitzracing said:

You dont need the engine running at all, just the ignition on. There are no other sensors involved, you supply 5 volts on one end of the TP (Make sure you have 5 volts or it will run lean), a ground wire (This is back to the ECU, not the same as chassis ground) and a wire to the wiper that should give a smooth transistion from less than a volt to a minimum of 4.6 volts. Resistance wise there may be some oddities on the type and angle swing of the TP, but the ECU just sees a voltage created by the variable resistance, so even if its 5 k or 6 k in total it does not really matter, as long as the voltage swing is correct from min to max. The ECU is smart enough to cope with some small variances.
Mark I have no power supply from the ECU to the Throttle sensor until the engine is running.With ignition on and imob de activated i have no voltage on Transmitter but as soon as crank engine then i have voltage to transmitter.
Understand what you are saying regard other sensors my observannce of the resistance of the track for the Throttle sensor would clearly indicate that when i check at the ECU plug ends ( disconnected from ecu that the wiring loop must be parrelleing in other sensors that why resitance of Throttle Track is not showing 6.3K at the ECU plug. The wiring diagram indicates at the pin out at the ECU plug i should still read 6.3K.So the wire loom is not as drawing
This wiring should not effect the Voltage feedback from the wiper i agree.


there must be some jumper i can install to power up the throttle sensor with just bthe nignition non

Edited by blitzracing on Tuesday 20th July 12:17

Edited by blitzracing on Tuesday 20th July 12:22

[blitzracing]

You have got me there, (it is a 14CUX isnt it?) The only supply that should be switched as you describe is the power to the AFM, Fuel pump and Lambda heaters and this is 12 volts not 5, and the correct 5 supply comes straight from the ECU, no relays involved, so it should not be switched (unless TVR did something wierd immobiliser wise). Ill drop you the Rover 14CUX manual.

[wycoller]

blitzracing said:

You have got me there, (it is a 14CUX isnt it?) The only supply that should be switched as you describe is the power to the AFM, Fuel pump and Lambda heaters and this is 12 volts not 5, and the correct 5 supply comes straight from the ECU, no relays involved, so it should not be switched (unless TVR did something wierd immobiliser wise). Ill drop you the Rover 14CUX manual.

Thanks mark yes it is 14 CUX i was a bit bewildred as i know that in the past the AFM is powered up once you have ignition on and Imob de activated and without even checking that power supply will be around 5 volts as its a standard sensor, I/O Voltage for 12 volt system which would suggest that the ECU is powered up as you say.
But i checked this 3-4 times, I opened up the ECU and was checking at the back off the PCB and was on the right pins for sure!!!!!! i have the proper needle probes for checking on the soldered connections of the PCB and had my mate crank engine up and sure enough voltage came on pin 20-25 (whilst i had my probes on the pin showing no volts at ignition on Imob de activated ). I,ll check again its not the first time i,ve cocked up like this having convinced myself that i,d done a proper check
Well the 14 CUX man will be a help cheers
I am rigging up to check my fuel pressure next i,ve a strong feeling this is where the prob lies.
Just noticed a bit of oil SC Oil around my Rotrex Oil Resevoir cap maybe time to change the oil and filter

[wycoller]

Okay throttle done Mark you were right checked with ignition on what can i say older i get more Fng stupid.
Full throttle 4.86VDC
Fuel preeure is low 32psi blips to 38psi at no load test idle to 5k but settles at 32 psi. removed vac line to fuel reg fuel preeure steady 38psi.
Possibly dizzie Vac diaphragm has gone as when sucking on line produces no change engine rpm.
looks like fuel pressure is cause of leaning off above 4k
I will be looking to upgrading
Fuel, pump filter Fuel lines and regulator any suggestions appreciated
I will also be installing a Fuel Press gauge on the dash in way of the Clock

[spend]

If your charger is achieving 6psi I think you should be expecting to see 41psi at the fuel rail. I would have thought at 5000rpm you'd have reached roundabout that boost.

[wycoller]

spend said:

If your charger is achieving 6psi I think you should be expecting to see 41psi at the fuel rail. I would have thought at 5000rpm you'd have reached roundabout that boost.

agree i have to up fuel pressure thats why i m asking for info on upgrades