Hello there..i have big issue with my jag…it’s a 2004 s type v6 3.0…. last couple of months iv been trying to figure out this misfire. 1st It started with the “Restricted performance”. When I changed cylinder 1 coil.. it went off…I was really bad...i have changed all the spark plugs and cylinder 1 and 3 coils passenger side. Changed the passenger Cat converter as well..but it feels like a little leak in the exhaust when I 1st start up the engine.. Now the engine idles so smooth. Check engine light is on. Giving me P0171 & P0174. When Im driving 30mph-50mph. it hesitates with a huge vibration. When im taking a ramp. It’s worse.. Rpm goes to 1700 to 2500 and it just keep going up n down until I get n to the highway…n my tranny wont shift smooth. It shifts hard first 3 gears..but low Rmp it will shift smooth..when im on highway doing 70 mph car runs so smooth. But I noticed rpm jumps a little bit n come back to where it was…like 2500 to 2700 n comes back to 2500.. it happens every 5 mins… I changed the knock sensor as well..coz I got an error code n after replacing that it went off.. im just tired of this car..i don’t know where to start and im low with money… do you’ll think it’s a vacuum leak? MAF? What it could be..im worried coz tranny shifts hard… what options I have? Please help me …

 

Some line breaks would really help.

Hard shift is likely due to engine fault(s). You need to fix. Look up other threads about LTFTs.

 

sir what is LTFT? what some line breaks?

 

When all else fails try Search and my footer (signature)

 

LTFT = Long Term Fuel Trims. A diagnostic reading from your OBDII reader. Look up other threads about LTFTs using the Search feature. JagV8 and others have posted extensive info on why and how LTFTs are important regarding P0171 & P0174 codes and Restricted Performance.

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These are line breaks

Line Breaks = paragraphs; spacing in your post. It's difficult to read a post that has no paragraph breaks. Many of us can't help you out because all that text jumbled together is just too difficult to read.

Just trying to help you out.

 

The post (below) from Rick may help.

https://www.jaguarforums.com/forum/s...ics-faq-52720/

 

Your original post is hard to read and most give up with trying to help because of that.


Any misfire on any car with coil-on-plug design means it is time to replace all of the coil packs. This is especially true on the Jaguar 3.0 where one bank of the cylinders is covered by the intake manifold. Basically, how many times do you want to pull the manifold off to service the coil packs.


I have been buying aftermarket coils off eBay for around $65-$70 for all six, shipping included. No problems. Of course, install new plugs all the way around, too. You also need to service a very troublesome vacuum elbow on the crankcase breather under the lower intake manifold where the injectors sit.


There are may write-ups here about this issue. Start with what I have recommended before going further.