TPS help XJR
#1
TPS help XJR
Hi
Having ongoing issues with my X300 XJR.
The symptoms are hesitation/surging when throttle opened to 3/4 then if you have the throttle on the floor the car kangaroos along the road and then eventually stalls if you let your foot off the gas.
I have checked the TPS output at the ECU pins. It is 0.62V at idle position and incidentally I have no idle issues, this does increase in a steady fashion as you open the throttle but at WOT it only reads 3-3.1V.
Would I be correct in assuming this is wrong.
The car has covered 126k miles and I have already ruled out coils and air flow meter (changed).
Having ongoing issues with my X300 XJR.
The symptoms are hesitation/surging when throttle opened to 3/4 then if you have the throttle on the floor the car kangaroos along the road and then eventually stalls if you let your foot off the gas.
I have checked the TPS output at the ECU pins. It is 0.62V at idle position and incidentally I have no idle issues, this does increase in a steady fashion as you open the throttle but at WOT it only reads 3-3.1V.
Would I be correct in assuming this is wrong.
The car has covered 126k miles and I have already ruled out coils and air flow meter (changed).
#2
The symptoms are hesitation/surging when throttle opened to 3/4
then if you have the throttle on the floor the car kangaroos along the road and then eventually stalls if you let your foot off the gas.
- My jag went thru some similar symptoms and hope it may guide you into fixing your issues:
The coils and injectors on my JAG were not getting the correct voltage signal. My jag had the engine harness connector not getting the sufficient connection due to corrosion. The engine harness connector was cleaned and contact enhancer was applied to the terminals. This stabalized my random idle issues and take off hesitation issues.
then if you have the throttle on the floor the car kangaroos along the road and then eventually stalls if you let your foot off the gas.
I had my O2 sensors cross connected due to the lack of quality control from one shop I used to go to. This was causing some aweful idles issues and hesitation on the go.
My fuel trim numbers were very high (+-30%). I had two leaks coming from the intake hose into the throttle body and my sparkplugs were oil fouled.
I purchased a new intake boot to fix my vacuum leaks and replaced my head and spark plug gaskets to resolved my oil fouled spark plugs.
I'm interest in knowing what you finally figure out as your root cause.My fuel trim numbers were very high (+-30%). I had two leaks coming from the intake hose into the throttle body and my sparkplugs were oil fouled.
I purchased a new intake boot to fix my vacuum leaks and replaced my head and spark plug gaskets to resolved my oil fouled spark plugs.
Hi
Having ongoing issues with my X300 XJR.
The symptoms are hesitation/surging when throttle opened to 3/4 then if you have the throttle on the floor the car kangaroos along the road and then eventually stalls if you let your foot off the gas.
I have checked the TPS output at the ECU pins. It is 0.62V at idle position and incidentally I have no idle issues, this does increase in a steady fashion as you open the throttle but at WOT it only reads 3-3.1V.
Would I be correct in assuming this is wrong.
The car has covered 126k miles and I have already ruled out coils and air flow meter (changed).
Having ongoing issues with my X300 XJR.
The symptoms are hesitation/surging when throttle opened to 3/4 then if you have the throttle on the floor the car kangaroos along the road and then eventually stalls if you let your foot off the gas.
I have checked the TPS output at the ECU pins. It is 0.62V at idle position and incidentally I have no idle issues, this does increase in a steady fashion as you open the throttle but at WOT it only reads 3-3.1V.
Would I be correct in assuming this is wrong.
The car has covered 126k miles and I have already ruled out coils and air flow meter (changed).
#3
#4
#5
#6
#7
I agree with Ross, the TP output seems low.
0.62v at idle is fine and you say there are no idle problems.
At WOT the output should be around 4.8v as I recall? If the ECM is only seeing 3.1v and the throttle plate is truly wide open, I imagine the ECM would be having a hard time reconciling the MAF with the TP and perhaps this could cause your symptoms?
Have you tried measuring the TPS output at the the TPS connector? There may be a wiring issue between the connector and the ECM. Doubtful but cheaper than replacing the TPS
0.62v at idle is fine and you say there are no idle problems.
At WOT the output should be around 4.8v as I recall? If the ECM is only seeing 3.1v and the throttle plate is truly wide open, I imagine the ECM would be having a hard time reconciling the MAF with the TP and perhaps this could cause your symptoms?
Have you tried measuring the TPS output at the the TPS connector? There may be a wiring issue between the connector and the ECM. Doubtful but cheaper than replacing the TPS
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#8
#9
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You should have two cables: pedal to traction control unit and traction control unit to throttle body. The adjusters are on the cables themselves. You'll see 'em.....just follow the cables themselves.
Someone has posted the official adjustment procedure but I've never been able to get my head around it. I just slacken the adjusters and then tension them until most of the free play is removed. You'll know you've gone too far if the engine speed increases.
I've long been suspicious (but never really investigated) that an old/worn/malfunctioning traction control unit itself can cause a drag/interfernce/loss of motion on the cable to the throttle body. I've had to adjust mine a couple of times as excessive slack develops...almost as though the cable are stretching.
Years ago I was battling a high idle problem (which can have several causes) and fixed it by slackening, exercising, and readjusting the cables. I *think* the TC unit was somehow sticking or binding.
Cheers
DD
Someone has posted the official adjustment procedure but I've never been able to get my head around it. I just slacken the adjusters and then tension them until most of the free play is removed. You'll know you've gone too far if the engine speed increases.
I've long been suspicious (but never really investigated) that an old/worn/malfunctioning traction control unit itself can cause a drag/interfernce/loss of motion on the cable to the throttle body. I've had to adjust mine a couple of times as excessive slack develops...almost as though the cable are stretching.
Years ago I was battling a high idle problem (which can have several causes) and fixed it by slackening, exercising, and readjusting the cables. I *think* the TC unit was somehow sticking or binding.
Cheers
DD
#10
Right I found the bulletin adjusted the cables and now I have the full range on TPS now which is good, 0.62 - approximate 4.54v.
However I still have my fault so was barking up the wrong tree. The car still try's to stall when you put your foot down but I believe it is when the first stage of the kick-down kicks in and the gearbox goes to grab a lower gear so now believe I have gearbox issues. I had box issues over Christmas and have changed the fluid a number of times and all seemed ok for a while
However I still have my fault so was barking up the wrong tree. The car still try's to stall when you put your foot down but I believe it is when the first stage of the kick-down kicks in and the gearbox goes to grab a lower gear so now believe I have gearbox issues. I had box issues over Christmas and have changed the fluid a number of times and all seemed ok for a while
#11
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The ECU retards the timing at the moment of each gearchage....I wonder if there's a glitch in that function?
Also, is the problem rpm sensitive? The #2 fuel pump turns on at 3000 rpm. I not sure what would happen if it doesn't. A lack of power would be expected, at least. Not sure if such a fault would account for the specific symptoms you're experiencing.
Just spit-balling here. Others will chime in with better advice
Cheers
DD
Also, is the problem rpm sensitive? The #2 fuel pump turns on at 3000 rpm. I not sure what would happen if it doesn't. A lack of power would be expected, at least. Not sure if such a fault would account for the specific symptoms you're experiencing.
Just spit-balling here. Others will chime in with better advice
Cheers
DD
#12
The ECM communicates many things such as throttle position and engine speed etc to the TCM, perhaps they are now out of sync in some way? It might be worthwhile trying to do a 'drive cycle' and see if that improves things.
drive cycle.pdf
If not, then you might want to disconnect the TCM and inspect/clean the pins. Also might be worth checking that the kick down switch under the accelerator pedal is working correctly.
Doug makes a fair point about the 2nd fuel pump though I wouldn't expect that to cause a stall at speed but who knows?
#14
#15
Well later thy day I actually got some fault codes and related to shift solenoid B being jammed, so now have on order from the US a pair of shift solenoids, not using the car until I've put them in, on the plus side work have supplied me with a hire car for my longer work related trips and getting by using my lovely little 1970 mini in the meantime!
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