After all these years, my beautiful 1997 XK8 is having all kinds of problems so I'm seeking some input/advice to help steer my mechanic (certified, but not a Jaguar specialist.) I've been rather stunned reading about all of the problems so many on the forums have had with the early models because this is the most trouble-free car I've owned (and I've had her since May 01) - until last month.

Some of the recent history may be irrelevant, but I'll include it just in case it is not.

• Replaced power steering pump last month. Mechanic's team washed the car before returning to me
• The following day, drove fine but later in the day received an Engine Fault, Poor Vehicle Performance indicator and sent her back to my mechanic on a tow truck. Turns out they also cleaned the engine after they replaced the power steering pump. I am still fuzzy on the details, but they dried whatever needed to be dried. Car was returned to me running fine.
• About a week later, I heard a faint ticking noise @ the left front. Called my mechanic; he came over to take a look. The noise was coming from the new power steering pump. Replaced under parts warranty.
• Everything has been fine for a couple of weeks. Last Thursday I was low on gas and put gas in it at a station/brand I don't normally use (still a name brand gas.) Approx. 2 miles later experienced a severe reduction in performance, then the Engine Fault/Poor Engine Performance light came on. Parked the car and called the shop, thinking that perhaps I had gotten some bad gas.
• The next a.m. everything was fine (no lights, performance fine.) Took her into the shop to have the codes read. The bolt holding the back part of the air intake snorkel had popped off, so they bolted it down and cleared codes.Everything was running fine.
• The next day, the Engine Fault/Poor Vehicle Performance light came on again after about 20 minutes of driving. There was a brief surge after a few minutes, then back to barely moving. Pulled over and shut her down.
• Mechanic found a hole on the bottom of the air intake snorkel.This time the car threw several codes, including ignition coils and throttle body. He checked to see whether there was any water remaining from the engine cleaning situation; none evident. The coating on the wires to three coils was worn in a couple of spots; he taped those. Ordered and replaced the air intake snorkel. Took an extended road check and at the 20 min. point after the engine warmed up, experienced the same problems I had been having (engine fault/pvp, slows to a crawl but then an occasional surge back to full power)

After reading the forums, we've discussed throttle body and ECM as possible causes but he wants to narrow down further before we start looking at such expensive repairs. Any input/direction to narrow down the search? And...could washing my engine or bad gas have led to some of these problems?

 

Update: My mechanic said it is giving off codes for 4 coils; he also this we may need to replace the amplifier but is going to start with replacing the coils.

So the question is...what would cause 4 coils to require replacement at the same time?

 

Ever have the tensioners replaced?

Sounds like similar symptoms that another member had with an ECM circuit failure... they rebuilt it and it fixed the sudden loss of power. Other than that, I can't give you any advice. Coils are relatively inexpensive to replace, so try those and see if the faults still pop up. And as always, good luck.

 

Thanks. No, have not had the tensioners replaced because I was completely unaware of that issue until coming here last week!! That is now # 2 on the must-do list, because my baby has 90k on her...

My mechanic just called and it seems that all of the coil codes he is getting are for coils that run off the same amplifier. The coils are passing all other tests, so he's recommending we consider replacing the amplifier first. In the meantime, she is now running perfectly - he hasn't been able to get her to misbehave today, which makes me wonder whether this is as you suggested an ECM circuit failure.

 

Swap the amplifiers to verify. Anyone ever heared of a bad one?

 

no...
Has he pulled coils to make sure theyre not swimming in oil from leaking cam cover seals?
And at 90k replace plugs while out. If this was my car ide replace tensioner now with new spark plugs and any offending coils for affected cylinder. And yes you can get limp home by spaying water on engine. Most specifically knock sensors and mass air flow.

 

Excellent suggestion - will do.

 

I am 99% positive he has pulled the coils, but will double-check to be sure. I'm in total agreement re: the plugs and tensioners.

 

Brute,

Thanks, Amen on the coils. And I washed exactly one AJV8 in my life, and ruined exactly two knock sensors in the process.

 

the reason i know this is not that i dont wash them, i do, i just stay away from certain areas. But whenever you get coolant leaks/blown hoses on the front of the engine, many times either right away, or sometime down the road, you end up with knock sensor codes. Sometimes you can clean the connectors and it wont come back, but more often than not they need to be replaced

 

This has not been a good morning! My mechanic replaced the amplifier and all was working fine through extended test drive so it appeared that the problem was fixed.
However, this morning, we're back to square 1. and he is now getting additional codes that were not present before, including a fuel pump code.
He is reluctantly concluding that it is the ECM. Local Jag dealer wants $7000 for the part or $2500 for a rebuilt one.

Two questions (well, maybe three)-
1) I am not sure whether my ECM has been reprogrammed under the service action that is out there (late 2004 is when the dealer's shop lost my business). Sounds as if this would be the first step to check on and have done, correct?
2) I gave him the # for Coventry and suggested he call them first. Any other recommendations for alternate sourcing or rebuilding? I've found a service on Ebay that rebuilds your own unit for $389. They seem to have overall positive feedback; anyone on here use them?
3) Other thoughts?

Thanks!

 

Put this under "other thoughts":

Have your guy inspect the ECM connections for corrosion, I recently read of an XK8 with major problems which were traced to this point. If your ECM pins are badly damaged, the unit may not be rebuildable: at least that's what BBA Remanufacturing told me, when I called about a customer's XJ6 ECM that had one pin rotted off.

Bring your car to the dealer, have them check for open recalls/ service actions, and pay them to diagnose any additional faults found. You can always say no thanks, I'll drive the car home and bring it back if I decide not to sell it as is, or when I save up some money to authorize the repairs you recommend.

 

Thanks, I've asked him to check for corrosion while I make some decisions here. The jag is my only car so I've been renting a car for several weeks now.

I'm thinking that once we get her running again it is time to retire her to #2 car position and buy something else for daily use or find her a good home as is and buy a newer (04-06) XK8.

It's funny how I flip flop on that from day to day. Had pretty much made the decision to buy a newer one, but they are very scarce right now!

 

Here's an update:

Had the ECU rebuilt by the place that lists on Ebay. My car was running well yesterday and the engine fault light was gone during an extended test drive yesterday.

At the same time, we had them rebuild the ABS module, because that has been an issue for a few months (ABS light and stability control fail message.) Following installation of the rebuilt ABS module, my mechanic is now reporting the following issues:

• Check engine light is back on . The code given is 1637
• ABS light is on
• Brake light is on
• Speedometer is inoperative
• Incorrect part fitted message

 

I'm going to take a guess that the last four are all related to the ABS module. Not for sure though.

I wish you had tried to clean all of the wheel speed sensors first, they get pretty mucked up with brake dust and OFTEN causes the light and DSC faults.

P1637 has to do with the ECM or ABS

 

I got my car back today - hooray!

Code P1637 has to do with communication between the ECM and the ABS module -- and that was the cause of the speedometer being inoperable as well as the engine fault, abs, brake light and "incorrect part fitted" error messages we were getting.

The place that rebuilt the modules (Auto ECU) was very helpful and sent over a step by step diagnostic process. The problem was that 2 of the pins on the ABS module were bent during the reinstall process.

She is running smoothly now with no error codes and no warning lights.

Thanks, everyone for all of your help. Now to find someone local (S. Florida) to replace the tensioners...

 

Ahh, feels good to remedy the situation, doesn't it. I congratulate you on your patience and prudence.

Good luck on the ol' tensioners. Preventative maintenance that will give long life to your car, and make it more appealing when (or should I say IF) you ever sell the car.

Check out the regional section of the forum, maybe post a thread there; there's quite a few guys from that area, that may be able to recommend a shop to do that very work.