Have a 2001 XJR, hesitates. I saw the other thread, but don't believe the problems are exactly the same. First I noticed it was on a right turn, any normal right hand turn (sharp like onto another street) and heavy acceleration will produce hesitation (this does not happen or I am unable to produce it on a left hand turn). With sport mode off, heavy throttle will produce fuel odors. Now as of late, car appears to hesitate in sport mode around 3k-4k rpm...with full part throttle (about midway). If full throttle is applied, car will stop hesitation but still feels lacking in acceleration.

I have not yet replaced the fuel filter and will be checking the fuel line as in an older thread from here. There are no check engine lights on.

Anyone have an idea? Currently I am running a fuel injector cleaner through this tank of gas to see if that does not help a bit (if so, then I will go in for a full injector clean).

 

Well, the fuel filter would be a start. I assume the hesitation is not during an upshift. I would check the fuel line also. Also have you checked your plugs? These cars are notorius for leaking valve cover gaskets that allow oil to seep into the spark plug wells.

 

No, not just during an upshift. I had heard that about the plug wells, which has kept me from bothering to upgrade the plugs. Never thought about it already being too late, thought it was just if you upset the fine balance by installing new plugs etc...Is there a better gasket design (aftermarket) that you would recommend installing? I will check the wells for oil. Been not looking forward to the fuel filter as a self perform since I heard it was located under the car back by the rear drivers wheel.

 

No there is no aftermarket valve cover gasket that I am aware of. It is a very unique gasket designed to be held in place by retaining rings that are part of the valve cover bolts.

Fuel filter is located in a very awkward location. Not too bad if car is on a lift and you are using flared crows foot wrenches. I would not attempt to change the filter with regular flare wrenches unless you have very tiny hands or are a contortionist. If you are not familiar with depressurizing the fuel system, let the car sit for about 10 hours so fuel doesn't start spraying everywhere when you remove the filter and make sure you put out that cigar.

 

Have you tried cleaning your MAF ?

CRC makes a product for cleaning MAF´s that work realy good cleaned it on my car that was hesitating rfom time to tiime now it runs like a gem

 

Hey Jagga,

Nice to see your name appear again. Hope you are having a good summer.