2000 Cherokee Limited, 108k on truck, 19k on Jasper motor.... have been hearing a "high-pitched whistling" sound when I rev the motor and it increases and lessens based upon revs... seems to have worsened in the last week or so. Check engine light just came on....AutoZone pulled the codes... don't recall numbers exactly but low 300's and the print out stated cyl 2,3,4 intermittent misfire... also states it could be a vacuum leak. Based upon the whistling sound I am thinking that too.... anyone with any input/thoughts?

Regards,

JJ

 

I have the same year xj and have had similar issues in the past. The misfire could possibly be caused by bad spark plugs and coil pack. Check those for sure. Vacuum leaks usually will cause high idle.

 

Thanks for the input.... I will check those this weekend. Interesting in that it runs fine with the occasional rough idle when I start it... very infrequent though.