If you are standing on it pretty good, then it's likely the Traction Control kicking in. Turn off the traction control and see if it still happens. But be aware, it might get out of control quickly.

 

also for smoother shifting there is a torque(power reduction) strategy used to provide that smoother shifting, and maybe thats what youre experiencing. Floor it a see if it stops. It should on full throttle with sport mode actrive. Otherwise alot is done to offer smooth, luxury car shifting and you may be experiencing just that

 

no it wont if you dont address the issue, But you also are due to have a recall 004 done if you havent already and this covers engine control module and trans control module updates and trans adaptations cleared depends on yrs and vin range for what is done. If not covered under the 004 for trans adpatation clear and programming of the trans. I would ask the tech to do it while hes doing the ecu, its only a couple more minutes after IDS is hooked up to do it. And clearing trans adaptations clear up the garbage the can creap into trans shift programming(its learns your driving style) and can drift causing weird problems with shifting. Not always, but its the first thing I do with a complaint like that

 

Greetings all! I want to start by saying I am a relatively new owner of a 1998 XJ8 which I really love. My previous jag was a 2002 X-Type. While I enjoyed the X-Type I always wanted the Big Cat so this is how I ended up here.

I have been following this forum since I got the car and have read many threads and posts regarding the hesitation and performance problems.

When I first got the car it drove okay, but whithin a couple weeks It would not accelerate smoothly especially under moderate to heavy accelration as when passing, taking off from the toll booth, etc. It seemed as if it was "hunting" for the right gear. I took it to the trans shop and they pulled the trans and found a cracked drum and othe rbad parts so I had to get the trans rebuilt.

After getting the car back from them, the car definitely shifted more smoothly, but it still has a lack of power and hesitation. I get no CEL at all or restricted performance indicatoars at all. Car idles very smoothly.

I replaced the spark plugs, fuel filter, air filter, part load breather hose (and cleaned the inlet as described in another post), replaced full load breather hose and cleaned the MAF. Disconnected the battery and let it sit for about 30 minutes to try to reset and computer or TCM issues there may have been. I have tried everything I can think of and everything I have read here that I could find related to the problem, but I can not get it running any better.

Sorry for teh long winded post, but I wanted to give as much info upfront for you guys so that maybe someone might be able to guide me in teh right direction.

Thank you all in advance for your wealth of knowledge and patience with us newbies!

 

I have a couple of questions to those who are reporting this problem. Is this issue while holding the accel pedal still? Or, when rolling into the pedal?

Have you cleaned the MAF and throttle body well? Have you used a tester to sweep the TPS's? (going to the sensor info on a hand held OBDII with engine off key in run position, and SLOWLY go from closed throttle to WOT and insure that voltage is smooth with both TPS) Have you checked that all the intake tract is completely seated and not broken in any area?

 

DBX,

I did clean the throttle body and plate very well. I also checked the air intake tract for any leaks or cracks. I found a small crack in the full load breather, which is why I replaced that hose.

I did not check the TPS(S), but that does make a lot of sense. I am not exactly sure how I can test them because I do not have an OBDII reader. Does anyone know of a method that would use a multi-meter that would get the same results? Not sure what I would be looking for there. Would I be able to take it in somewhere and have someone check them for me? If I was usre that was the issue I am confident I could easily replace them on my own. Any idea what one or two of those would set me back if I need them and where might be the best place to order them from?

Thanks again everyone for all of your help!

 

Afer doing some test on the TPS, I think one may be bad. I was told by Jaguar that the TPS for my throttle body are not availabe individually and I would need to replace the whole throttle body. I have found many on eBay for good deals, but one in particular got my attention. It was from a wrecked car and allegedy the TPS sensors were working fine when the car was wrecked.

My question is, does anyone know for sure if the TPS can be swapped out, or are they part of the throttle body and not removable/replaceable separately?

Thanks for your help!

 

I have seen the ignition coils being defective. My XJR had the exact same symptoms and after a replacement of the ignition coils AND the MAF acceleration was OK again.

(about the only thing on this P.O.S lemon that is ok)

 

Finally I have my XJ8 running like it should. I was able to determine that both TPS were not functioing correctly and that my throttle body needed to be replace. As I was seraching for parts on the net I found a local repair shop that exclusively repairs Jagaur automobiles. They had a throttle body for my car for a great price and also had very reasonable hourly diagnostic and repair rates so I decided to take the car in and have them do the work and look for any additional issues.

They hooked it up to the computer and confirmed that the TPS were bad and did the throttle body replacement in almost no time at all. The new throttle body made a big improvement however the car still did not have the performance that it should. They ran it for codes again but found nothing. Checked harnesses, etc. and still found nothing. Then the tech put it in the air and inspected the underside for damage or problems. What he found was that the fuel line running form the tank to the fuel filter was kinked, thus allowing good fuel pressure but not good volume. Apparently the previous owner had a fule pump replaced and whoever did it did not disconnect the lines underneath the car, but just stretched them out when they pulled the tank out from the trunk and kinked the line.

Once the fuel line was replaced, the car is now up to the level of performance that it should have and has a silky smooth idle, no hesitation, and goes like a bat out of hell!

 

I just wanted to confirm that what Brutal suggested worked for me. I had the same hesitation when accelerating from stand still. I saw this same fix elsewhere regarding the TCM software update and brought it in to have it done on Saturday. So far, it's worked 100%. It did cost me $400.00 to have it and the ECM done, but it alleviated the problem.

 

Can you please clarify what is meant by the TCM software update? Is that some recall? I have the issue for almost a year now and would appreciate any feedback. Thanks