03 stype 4.0 Hello...After my car ran hot because of a failed resevoir top, I took it for a test drive after replacing it and it ran fine. But after about 10 minutes of driving it started to miss really bad. Ran the codes and had a exhaust leak thats always been there because I can hear air coming from the black round thing on top of the left side of the engine. Not sure what the name is. But whats really bothering me is that all the cylinders but two have a misfire...2 and 7 are the only ones firing right. I replaced the plugs still runs like crap...Just want some suggestions before I throw alot of money at the wrong things...thanks

 

What kind of coils did you replace the OES ones with? OES Jaguar coils or aftermarket coils? Aftermarket coils suck about 95% of the time. When changing the coils was there oil in the spark wells? If so, you must change the spark plug gaskets, along with new cam cover gaskets...

Take a pic of the black round thing and post it - I think you might be referring to the crankcase ventilation hose - if you are you probally have a crack and air leak - if that is the case the car will run like crap until it is replaced but I'm speculating w/o seeing a picture.

You could have a coolant issue somewhere - hate to say it but it could be the headgasket - did you replace with the proper rated cap - 120 or 140 kPa? I believe 03 and up require 140 kPa expansion tank cap...

Check connections at each coil for a snug fit and check connections at the fuel injectors as well for a snug fit - often when coils are changed the fuel injector harness is touched and those injector connectors that the locking tabs snapped off will not fit snug.

Just some thoughts...

 

I meant vacuum leak not exhaust leak...but crank case ventilator sounds about bout right. I cant post a pic right now. Its round and sits on top of the valve cover and a big vacuum line runs from it to the air intake assembly. up by the throttle body. i believe. I didnt replace the coils just the plugs... I didnt think that that many coils could go out all at once suddenly like that and cause that many cylinder misfires. Like I said before It was driving fine and it instantly started jerking putting all in one split second.

 

no oil on plugs...there were actually in good shape....its about 105000 miles on the carr

 

Plugs don't all go bad at once, either. Coils are more prone to cause misfires than plugs. Any vacuum leak needs fixing first or it'll mask almost any other problems.

 

A split in the crankcase ventilation hose would be classified as a vacuum leak as it leads back to the intake duct.

 

Ditto to all who posted. U have a vaccume leak. The crankcase ventilation line will be the largest vaccume line leak on the motor. B sure this is ok or she will lean to the point of toasted cats, etc. Also check for leaky injctors.

 

Just a quick clarification. You have a 2003 it should have the updated 4.2L and NOT the older 4.0L engine?
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4.2 it is

 

what do you do if those tabs do snap off??

 

Which tabs?
Generally, fix / replace.