The only problem is ther is no codes logged. I pulled the connectors off the coils while running and seems to have a few cyl not working? This happens randomly with no dtc codes logged in the ecm? What to do?

 

The problem I’m experiencing is that the car will throw a yellow poor engine performance message with engine fault message on the dash. I disconnected some of the engine coils while engine running and it seems that 3 cylinder are cut out. It does this randomly sometimes the car runs fine and no codes or messages. How to tell if is a computer problem or actual engine problem.

 

I've merged your two similar threads and moved the question from General Tech Help to XK8/XKR forum. Members here with the same model will be able to help.

Graham

 

It could possibly be one of the ignition modules at the top centre of the firewall, but more likely to be the ECM as RJ237 noted in the old thread.

As pistnbroke states, it's almost always leaky electrolytic capacitors in the ECM that cause problems. If you are competent with a soldering iron (or know someone who is) it's a straightforward repair providing that the leaking electrolyte hasn't done too much mischief to the circuit board.

ASI used to be the go-to for repairs in the US, but the pricing strategy seems to have gone pear-shaped latterly. There is a company in So Cal that a member recently used to good effect. See this thread from NYN8IVE:
https://www.jaguarforums.com/forum/x...7/#post2387809

Separately, have the codes read, or try another reader. I believe that you have outlets that will do this for few/zero $$? If the car is reporting in the message centre, I'd be very surprised if there were no codes thrown, even if they appeared to be spurious.


edit: I see you have found the thread I linked

 

I strongly recommend a compression check. It's as easy as removing the spark plugs.
I bought my tester at Harbor Freight and the threaded hose end screwed right in to the spark plug holes with ease. It was so easy that I was embarrassed for not doing it earlier.
Luckily there was nobody around to laugh at me so I got away with that one. Until now.
Do all 8 cylinders and compare results.
It will tell you a lot, especially when you compare the spark plugs to each other while you have them out. Keep them organized so you know which came from where.
The electrodes should all be the same color. It might be time for new spark plugs anyway so you can install new ones.
Remember to put a little antiseize on the threads only. I use FelPro C5A.
You will find out if you have good compression and good combustion in each cylinder. If you do, you can feel good knowing that much. If not..........
Let us know what you find.

 

Good idea !! Will do and get back to all!

 

I took a pic of the insides of my engine Ecu on 97 jag xk8. It looks as though there is some residue or damage to the area around the capacitors. Any thoughts?

 

Typical leaked electrolyte. Luckily, it doesn't appear to have done any material damage to the circuit board.

If you're comfortable working with a soldering iron on multi-layered pcbs, then replace them all. There are seven:- I posted the Nichicon part #s and a potential supplier here:
https://www.jaguarforums.com/forum/x...6/#post1806456

Cost was around $5 or so in 2017.


Once the old ones are out, then you can gently clean the residue off the board with either or both of warm clean water (via a moistened rag) and isopropyl alcohol. This may remove some of the protective lacquer, but I wouldn't be overly concerned if so.

Ensure everything is properly dry before reassembly.

Might be a tad late with this, but please ensure that you disconnect the battery before removing/refitting any electrical modules.

Good luck!

 

Yeah I’ve heard there are some that tackle replacing the capacitors. I think I’m going to go the more traditional route although I truly appreciate the info. This site has been a tool box fool of good info.

I’m sending my Ecu to Module repair pro in van nuys ca. I’ll post what my experience was. I just shipped it today

 

We’ll I received my Ecu back from module repair pro. They changed the leaking capacitors on the Ecu tested it and returned within a week.
when I got it back I installed and now it runs rough at idle and when it gets to like 1500 rpm it smooths out and accelerates normally. I’m getting a random miss code 0333 and engine performance light in the message center. I checked the compression in all cylinders and they are close to 190psi. It’s hard to determine what cylinders are missing at or close to idle because it stay running without me raising the rpm. Not sure where to go next anyone have any ideas?

 

Compression is fine.

DTC indicates an issue with one of the knock sensors:



Unfortunately, they're not too easy to get to, but you can check the connectors (one each side of the thermostat tower) for 'goodness'

Is that definitely the only code you see?

 

On the XK8 & With a skinny 1/4” drive tool the knock sensors can be replaced without the need to remove other parts. The procedure is not so straightforward on the XKR’s, which is one of the few drawbacks of the R variant.

Z

 

It’s funny u say r u sure it was throwing the 0333 code. I did see a random misfire message and it did throw a code but I’m not totally sure it was 0333.

Anyways I fired it up again today and took it for a ride just to see if could make it to a repair shop. Under load with the rpm raised it seems to run ok but it definitely runs rough at idle and will die if I don’t keep the RPMs up. I’m really starting to wonder if the Ecu I sent out still has a problem. I did get a stability control / traction control message on the center dash with a abs light but no codes were logged? Very weird it’s really trying my patience! Anyone have advice?? I really would like to keep this car on the road it was passed down from my fiancé dad I have been working on it for sometime now and replaced the timing chains several items in the cooling system including the octopus hose. That wasn’t fun!! Now I have this electronic issue that is really testing me. Hope someone has some insite. I really don’t want to be a parts changer and with no codes it hard to know where to start! Thx in advance!!

 

You can't read abs codes with an ordinary code reader, they are Jag specific.

 

Thx for the info but I’m really trying to focus on the engine performance problems!

 

You did ask the question, and RJ is correct that ABS C-codes don't usually get picked up by a generic reader. It's probably not relevant to the rough running, however.

You need to ensure that whatever you're using to pull codes is reliable, hence my query whether the P0333 is the only one you're seeing. Could it be P0303 (misfire)?

If it's only one cylinder, then could be a bad plug/coil, multiple cylinders then possibly an ignition module, or it could be an air leak.

Without a better understanding of what the car thinks is wrong it's dificult to offer a steer.

 

Gotcha I’m going to go to my favorite auto parts store today and see what their scanner picks up!! I’ll let u guys know what I come up with!! Thx for the guidance!!

 

Very likely won't read ABS codes.

 

Not to read abs to see if their scanner will pickup any additional engine codes

 

Even an elm327 will read all those.