hi guys, this is my first jag, i'm usually a mercedes guy, but i got a good deal and i bought a 2000 stype 4.0 with 80,000 miles. it starts up fine, after about 15 minutes, it starts to misfire. i changed all plugs and coils, i even moved around the coils to see if one was bad. after it starts to mis, if i shut the car off and start it right back up, it runs fine again...for about 15 minutes and the whole thing starts over. please help me....

 

Good Morning Romeo... Lots of knowledgeable folks on here. To be honest, an issue like that could be a lot of things. More than likely something small like a sensor or vacuum leak. Do you have a code scanner that captures codes and live data? It would be helpful to check for pending or stored codes and post data from the scanner from when it runs rough.

 

Romeo, go over your plugs and coils again. Look for something awry. Your misfire can likely be a bum/cracked plug/coil leaking spark.

 

hi, thanks for your help. my friend plugged in a scanner once and it said misfire on #2 and #6 i believe. i changed around the coils and got the same result. if its a sensor. any idea which sensor it is?

 

run some bg 44 fuel injection cleaner through the car first in the tank. if youve already swapped coils and plugs around then you need to look at the injectors. if the additive in the tank does nothing. I would pull all 8 injectors and send them to be cleaned, rebuiilt and performance checked. I send mine here
www.injectorrx.com
theyre $18 each for a complete service and youll know for sure if any are bad or act up in their operating range. He'll let you know and send a before and after flow chart for each injector. this includes, new orings, and baskets in all the injectors. or you can swap injectors too, but if i was going to that much trouble I would just have them serviced.

 

hi, thanks a lot for your advice. i didn't even know they have a service like this! i ended up searching for injector cleaning places, and i found a guy who does them for $16!!
fuelinjectorman.com

 

Fuel filter?