I've had a significant stumble, but I couldn't decide if it was the mis-wired TPS or dirty injectors.
I probably won't have time to work on it for a few days, but I'll let you know if it improves. I had it out on the road today for the first time. It idles great but stumbles on harsh acceleration. Slow acceleration seems fine. I didn't get to go far though, I found one of the rear brakes is sticking, so I have to get under there and find out whats going on.

 

youve definitely got them wired wrong. im pretty sure my wiring is right and that ive just short circiouted the TPS or the ECU somewhere.

 

M you should have 5V on one side of the TPS ground on the other and the variable comes from the wiper.

 

May I suggest a test to definitely decide if the feed to the TPS is part of the problem? Just so you can be sure, the ECU should produce 5v steady current to the TPS. On the yellow wire. This same yellow wire is branched to the Coolant temp sensor on the B bank thermostat housing, and to the air temp sensor on the B bank air intake trumpet. Check to see if you have 5 volts on these. If not, then the current from the ECU is part of the problem.

If this is so, check the pin output on the ECU, by carefully unwrapping the bundle of loom near the ECU plug and finding the yellow wire and testing it. If there is 5v there, but not downstream in the engine bay, you could splice in a new wire. Of course, the return wire from the TPS to the ECU could also be a problem, but one thing at a time!

On my rebuild, I managed to put a self tapping screw through the ECU/engine loom (on a perfectly post-rebuild previously running engine) where it crosses the (RHD) footwell, right at the end of the rebuild when I was fixing the wheelarch baffles! Found it eventually!

Greg

 

The three prongs on the Ford TPS are (A)=VREF, (B)=TP and (C)=SIG RTN
I may have A and C labeled wrong here, I'll double check my notes, but I know the TP is the center pin (B).
So the question is, which wire goes to what pin?

 

ive got no voltage to the TPS wire loom. ill check the ECU, im thinking the pins are 17, 20, and 21. ill have to check my schematic again.

 

in this case Red is the wiper for the TP so it goes on pin B no matter what. and if you check from pin B to pin C you should read high resistance at idle and low resistance at WOT. the green wire goes here. if you check resistance from pin B to pin A you should get low resistance at idle and high resistance at WOT. the yellow wire goes here.

 

update. im getting 1.5v at ATS and 3.5v at the CTS

 

im not getting any voltage at the ECU either. very little. certainly not 5v. max i saw was 1v.
its officially fried. MISH!!!!!

 

well the ECU is getting plenty of voltage fromt he battery, its priming the fuel pump, and the engine will start, run, and idle. but theres no voltage to the TPS.

 

I wish i was there for you, but i am in Costa Rica, until the first of april

 

could your EBAY department ship it to me?

 

It is at my garage, but you can find 6CU for cheap on ebay.

 

i cant find any 6cu's on ebay right now. i was looking at getting a 16cu but earliest estimated arrival on most is..... wait for it.... April 1st.

 

You could use this as an opportunity to go Megasquirt

 

never even thought of that.

 

Hi, as I said before, go download this book.
Kirby Palm's Jaguar XJ-S Help Book

Search for tps; comes up P305, will tell you all about replacements.

good luck
Pete

 

i downloaded the book, but havent read anything. ive already done the ford TPS swap. waiting on a 16cu from Jamey to replace my fried ECU. ive got a short in the rectifiers of the circuit board.

 

well...... ive put in my new 16cu. thank you JameyXJ6. im now getting 5v to the CTS. good sign. but no voltage to the IATS or the TPS. soooo im thinking the power wire for the TPS has a short, or the new TPS is bad.

 

this is bullshit. i checked all the TPS wires with an ohm meter and they all check good. checked the IAT wires with an ohm meter and theyre good as well. IAT isnt getting any voltage and TPS isnt getting any voltage either. WTF?!?

i checked pin 20 and 21 on the ECU, which is the 5 volt output for the IAT and its not reading any voltage at all. i checked pins 19 & 20 and theyre not reading voltage either. same goes for 19 & 7 and 20 & 7.

im really starting to lose patience with this car. im already sourcing an L67 and a 5 speed out of an F body.