Hello everyone,
I have just bought an XJ40 with the 3.6 litre engine and have a problem. The problem is that the car idles in a very "lumpy" way and misfires consistantly on number 5 cylinder. The exhaust is also a bit fumy but it passed the MOT test yesterday and didn't fail on emissions.

I have done the following: Replaced the plugs (when I got the car, the plug in number 5 had faild completely, with the porcelain section loose and bouncing up and down as the engine ran).

Switched around the ignition leads to prove that they are not faulty. The distributor cap is new.

Switched around the injector connectors to 5 and 6 to prove the injector supply.

Removed the injector rail and swapped injectors 1 and 5. Proved the injectors but connecting to a battery and blowing through them - worked ok.

Removed and cleaned the crank sensor.

Carried out a compression test - all pots about the same reading.

Now I'm out of ideas! Cylinder 5 still seems to do nothing - when you pull the plug lead, you can hear the spark, and when I disconnect it, there is no difference to the engine.

Any ideas?

Thanks.

 

You said the distributor cap was replaced, but did you also do the rotor? I'd try that to begin with...

Scott

 

When you had the fuel rail off,did you clean it as it might be plugged up,as it seems that its not getting fuel

 

Thanks. I checked the fuel rail when it was off, and it was clear and clean

 

Yes points would be a place to start, they do wear, measure the gap? also, can you remove the plug and place it in the cap resting it on the metal of the cylinder head and watch for the blue flash as the engine runs, failing that a ring strobe to check pulse?

Coil and ignition amp to test next I guess, not my field this motor....

 

Hi.

You could try to check the ignition amplifier and its connector. Try to clean it properly and make sure the retainer clip holds it in place.

There has been reported that engine movement can under certain circumstances pull the ignition amplifier partly out of the socket and cause problems as mentioned.

Solved my idle and stalling problem.

 

Whilst looking on the internet, I came across an article which stated that some early 3.6 AJ6s suffered from inlet manifold gasket failures which led to leaks and therefore bad idling and running.

I removed my own inlet manifold and ta-dah the gasket had failed around inlets 5 and 6 and was mainly hanging out at the bottom of the manifold.

What to do? The gasket was non-existant around ports 5 and 6 so it was time to improvise - with Hylomar Blue gasket cement. A good bead around both inlets then reassembled the whole thing - now it purrs like it should...but for how long...?

Looked on a well-known internet trading site but no-one is listing a gasket so I'll see how it goes.

 

Hello. I'vr had a simillar problem in my friends car. The cause was the 3rd fuel injectors o-ring. New one costs 40 pln thats about $12. Quite a lot of money for a piece of rubber.