About a week ago after driving < a mile a got my first Engine Fault Reduced Performance alarm. I gave it a little more accelerator and it starting running fine again. I took it to my mechanic, not Jag certified but a well seasoned SAE mechanic and had the computer scanned looking for any codes and we found none. Today again a got the same fault and again I got into the gas a little and it cleared OK. Both times this has happened I noticed it was running a little rough before the fault. Every once in a while it will run a little rough then clear up within 3-4 mile of <50mph driving. Looking for some advice. Thanks in advance.
97 XK8 53K miles

 

I had a similar problem that turned out to be cracked bellows area of the duct from the air filter box to the throttle body. It sits directly above the exhaust manifold and cracks from the heat. Causes the rich/lean sensors to go crazy and lock in a 'reduced performance' light. Would come and go.

Clean the bellows area well, use a heat gun to apply black plastic electrical tape and drive on. Duct is available for about $100.

 

Thank you and I'll look into this tonight.

 

Checked out the bellows and didn't find any cracks but did however find the hose clamp at the filter housing extremely loose and found one of the mounting flanges at the 90 where it enters the throttle body broke, so after JB weld does it's job we'll see if this helps. Regardless we got motion in the correct direction. Thanks again....

 

Try getting it scanned while the fault is present and engine running..

 

It happened 3-4 times today and took it to the shop but while I was there it ran fine. Was wondering why there would not be any stored error codes. Any additional info will be very helpful. Thanks again.

 

I have been down this road before! First be sure that you do not have an OBD trouble code! I do not have an answer for you but my information and related experience might help. Go to my web page and look at my experience with the Restricted Performance. Let us know what you find.

Good Luck!

 

Just got the codes......P0352, P0353, P0355, P0358 (all Ign. coil Prim/sec Cyl B,C,E&H) and code P01368 Ign module. Now trying to order Ignition Module but first need to get some numbers off the old one. My mechanic is going to do the replacement but first I have to fine the module here and get the number off it, can anyone tell me where it's at? Thanks again.....

 

One most important thing to do when you experience problems is to get the OBD codes… It is when you have no codes is when you have a real problem…

 

I got those same EXACT codes. It was NOT the ignition module. In fact, an easy way to test is just swap the wires from the left module to the right (and vice-versa) and see if the problem continues. Most likely it will still continue which indicates that the modules are fine. My problem turned out to be a couple of leaky transistors on the motherboard of the ECM/ECU. Try opening the ECM and look for any obvious signs of damage. The 97's are known to be the most problematic of all. If the ECM is totally shot the news is bad. A new one is $5k. There's some guy in texas who will rebuild/reprogram it like-new for $2500. The damage to mine was minor (as stated above) and so I had a local ECM repair place fix it for $150. Never had a problem since.

 

HELP !!!!
I put a NEW ignition module in and still have the same problem. I also swapped them and same problem....Is it my ECM? I haven't opened the ECM compartment yet, but are there any other possibilities?

 

I will be the first to tell you I have no idea where to begin. It all goes back to the ignition coil primary/secondary malfunction. This is an area I have little experience in. However, I would be looking for loose or bad connections first.

Gus

 

Told ya it wasn't the modules. ;-)

Open the ECM....can't hurt. You will need a special tool to get it out of its holder. Usually the problem is rather obvious upon close visual inspection (although not always). Look for any fluid leaked onto the board. Hopefully it's something minor like a bad transistor and not something more major like a fried chip.

I have never heard of a module or a coil/ignition wire go bad. There's no reason for any of the connections to become loose on their own. However, I've heard a lot about the '97 ECMs going bad...and those are the PRECISE codes that get thrown. Not so with 98's.

 

97JAGXK8 Is the ECM located (I have a 2000 XK8) on the passenger's side cubby? What special tool is needed? I've never removed the cover.

 

The ECM, at least on my '00, was in the covered box on the passenger firewall and didn't require anything special to remove. The ECM itself is pretty well sealed. It clearly can be opened but is not going to look the same after.

Perhaps, unless you have replaced components on a circuit board before, you should get one of the rebuild folks to try this.

 

Thanks everyone for the replies. I have removed the ECM and inspected all circuit boards and found no (visible) problems.....I have sent it off to ATE (Auto & Truck Electronics http://www.autoecu.com/) for re-build. Reasonable price. Does anyone have experience with ATE?

 

Your symptoms sound very similar to what I went through a few months ago. After learning the cost for a new or rebuilt from the dealer, I went hunting for more realistic (pricewise) alternatives and found ATE.

They rebuilt it and shipped it back promptly - and she has been running like a dream ever since. There were some frustrations with their payment processing system, but all was eventually resolved there.

 

That is good to know. I hope to have it back and up and running this week, we'll let you all know how it went. Thanks again to everyone for the help....

 

How did you get it open? I had to borrow a star-shaped tool from my jaguar specialist to open the plastic case. I was considering using a send-away company like ATE but I found a reputable local guy who was able to fix it and it comes with a one-year warranty. My understanding is that depending on the complexity of the repair, they may need to do a re-flash of the firmware/software. The small local shops usually don't have that capability. I assume that a place like ATE would.