Engine Missfire 1994 XJ12

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Oct 25, 2007 | 12:36 AM

monahans10

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Engine Missfire 1994 XJ12

My XJ12 has 2 cylinders missfiring at idle, but comes alive at 40 miles per hour. The compression is 120 psi on the bad cylinders and about 160 on the good cylinders. -- side note one coil was burnt through and when I acquired it it only ran on 6 cylinders. After putting in new coil the engine had blue smoke out of the tail pipe and started running on 10 cylinders after 5 minutes and quit smoking. but 2 cylinders still are missing at idle. I've only put 10 miles since replacing the coil and plugs. It was suggested to drive this car 100 miles - to see if it the cylinders will come back alive at idle.

Oct 25, 2007 | 03:59 AM

Cadillac

Veteran Member

Joined: Mar 2007

Posts: 11,393

Likes: 649

From: Planetarium

RE: Engine Missfire 1994 XJ12

Welcome !
Sorry for this trouble .You can also post your other issues if you have on other forums like XJ40

Oct 25, 2007 | 09:42 AM

ken@britishparts.com

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Joined: May 2007

Posts: 2,533

Likes: 23

From: Houston, Texas

RE: Engine Missfire 1994 XJ12

I would take the advice. Sounds like the engine has sat for awhile. Get it up on the highway and blow the cobs out. Change oil and maybe use a little Marvel Mystery oil additive and put some miles on her. Bring her home and change the oil again. You will be amazed.