S-Type Misfire
 

I Have just purchased a S-Type 2005 2.5 Petrol. Has been running good for a week. All of a sudden the engine management light popped on and I am experiencing a misfire when engine is at running temperature. Popped it on the diognostic machine and wss showing errors on coil pack 4 which I changed. However hasn’t changed a thing. I’ve checked all the wiring even just as a matter of call swoped all the coils about. The issue stays with coil 4. Iam now at scratching head mode. Anyway one gave any suggestions. Please and thanks

Welcome to the forum Mellison,

I've moved your question from General Tech Help to S-Type forum. Members here with the same model will be able to help.

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some information about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

What actual code(s)?

BTW you can get the workshop manual (free download), look up the code, and then follow specific guided tests.

+1 on having the DTCs read and posting them here.

Here is a link to the Workshop Manual:

http://jagrepair.com/images/AutoRepa...M-Workshop.pdf

Attached is the cylinder numbering scheme for the AJ-V6 engines. Be sure you're looking at the correct cylinder.

Check to see if there is any oil in the spark plug well as that can cause misfire(s). Also check to make sure the electrical connector for the no. 4 cylinder fuel injector is plugged in correctly.

As others have already suggested, please post the exact fault code you are getting. It will start with a letter (typically P) followed by 4-digit number. Is it P0304? If so, that is a misfire detected on cylinder #4, and you are on the right track.

Since you mentioned a misfire, you are legally required to listen to my canned speech on the subject. This has become a drinking game, where all forum members must down a shot every time I get up on my soapbox:

If the computer has set a misfire code, please be aware "misfire" wasn't the best terminology that could have been used. Misfire sounds like an ignition problem, at least to me, meaning the fuel and compression were there, but for whatever reason, the required spark was missing or weak. This might lead an aspiring mechanic to troubleshoot the daylights out of a perfectly good ignition system. I do not care to discuss how I know this.

In OBD-speak, misfire simply means one or more cylinders is putting out low power compared to the others. Pretty much anything affecting the output of a cylinder can set a misfire code. It can be low compression. It can be a valve not opening fully. It could be a clogged fuel injector. And yes, it could be an ignition problem, too, but don't overlook the other possibilities, too. [/soapbox mode off]

But for starters, I'd suggest new spark plugs since you've already swapped the suspect coil. Resist the temptation to make a bunch of other changes at the same time. If a new fault is accidentally introduced, you'd have a bunch of extra work to undo each step to figure out why.

I was thinking P0354