So my jag has been having an intermittent shut off issue when i deccelerate. It also would have an issue of high rpms(Up to 4000!). I was stumped as to the reason, so i posted up my issue and got some great answers! Since that time i have replaced the egr valve and thoroughly cleaned the holes it attaches to, i have replaced the iac valve and cleaned all connectors, i replaced the throttle body, a couple of fuses and checked all the relays. Nothing! It would still happen! So i gave up and took it to JagPro in long island, and i had high hopes. but not even the pros could figure it out! So i hooked up my scanner to the car and drove it and discovered something odd. When the car was running fine without issue the absolute throttle position would be at 0.0% when i didnt push the gas pedal in, however when the car was running with the problem it would be at 11.8% with out me touching the pedal. This has led me to believe that the TPS is faulty and needs to be changed. I never changed it and would like a confirmation if anyone knows that this is the issue.
Side note- when i disconnect the tps and check the computer, i get a reading of 8.6% and it doesnt change when i hit the gas.

Thanks GUys!

 

Hi.
Yes, when a TPS goes wrong, an ECU seems to be in a safe mode and rev up when engine idling. You have to have the engine set up at a dealer when you change a TPS, but I remember there was a post that someone explains how to change a TPS without being set up.
Hope this helps

 

Thanks JapThug! I looked it up on the forum, people speak about slotting the holes for the tps. I think i'd rather just have it calibrated, any idea what i should say specifically when i get to the dealer and how much it would cost? thanks in advance!

 

Actually, I live in Japan, so I don't have any idea how much it will be there. Up in here it cost like 8000yen, which is about $100, that means it is about 1 hour job or something like that. Somebody will chime in.

 

So i changed the TPS and now im getting a reading of 10.6%-11.0% and the car is still shutting off when i deccelerate. i wont deny it tho, it seems like its dying less, however the idle is still dropping below 500 rpms. Any other ideas? Im dying to get this car fixed already, this issue has me sick already! I didnt take it to the dealer yet as the tps doesnt seem to be calibrated, or does it?

 

You need to have an engine setup done at the dealer which will orientate all 4 02 sensors, throttle position and verify proper kickdown switch setup under the gas pedal. past that i would slightly turn the mechanical throttle blade screw alittle more open say 1/8turn. When you say shut off, is it a electrical shut shut down, air or you arent sure

 

Hey Brutal. thanks for the info. and when it shuts off i am not sure if its electrical or not, the idle drops below 500 rpms and the voltage drops along with it and the engine shakes slightly and turns off.

 

i would think its not electrcal since its not an abrupt shutdown. But more a petering out from low rpm. this on decel is manytimes because the throttle shuts quickly and the IACS(idle air control solenoid) doesnt keep up the air flow bypass needed to keep engine running. I would again try opening the mechanical throttle opening a 1/8 turn at a time and this is free. just remember where you started. If you open so much that the idle is higher, that can be fine too as long as its still in the range the IACS can control by closing more and returns to a normal idle. You might fix your issue with this by changing from a more electrical idle control(iacs) to a mechanical one(throttle blade setting) This is a good start and may or may not be the issue, but based on you info. I would try this first. Then i definitly would have and engine setp done. I can do my own at work and fixed several roughness idle issue over the years with this on my own car.

 

Thanks so much brutal!! i will try what you said! hopefully this corrects the issue.

 

As per your instructions brutal everything is working great now!!! Im taking it tomorrow to get an engine setup done at the dealer. Thanks again! Damn tps and adjustment is all she needed...I think

 

Brutal is one of the greatest assests to the forums
He always helps members and I also appreciate your thanks to Brutal

 

Brutal is the best! Thanks again so much!!!

 

So should we change the thread title to best jag tech did figure it out without even seeing the car?

 

Lol! Yea the best jag tech figured it out and didn't even see the car!!! Thanks again brutal!!

 

That was a nice proposal by norri

 

Hey brutal the car is running 100% in my opinion, is it absolutely necessary that i goto the dealer and have the setup done? My fear is that the dealer will mess the car up since the dealer i would be taking it to is not good for service at all, or so ive read! Manhattan Jaguar.

 

retract my previous statement, im going to the dealer and doing things right!