Hi, I have a 1996 discovery TDI diesel. It has a missfire on no4 cylinder. It has injection , has compression etc. The injector has a wire off it which i gather is the reference for injection. the circuit is good through the sensor. the engine check light does not come on but if i disconnect the wire the engine runs the same but the check light comes on. the smoke out of the exhaust is gray/white. I have checked under the rocker cover and the top end all appears to be ok. Any help with this would be much appreciated.

 

Are you loosing engine coolant?
It sounds to me like either a blown headgasket or a clogged/bad injector.

 

You lucky bastard, i would give my left ******** to have this problem.

Cause it would mean i had a working rebuilt 300tdi.

 

no, no coolant loss. I have removed the injector and pop tested, all ok,

 

Sorry that I dont know enough about these diesels to be of much help.
Have you tried a UK Land Rover forum?
If that injector wire is bad that would defiantly do it.

 

Sounds like an air leak. Have you bled your system? Start at the fuel injection pump and work towards each injector. Bleed the tank side of the pump first, then the injector side and up to each injector. The seals dry-rot and cause air leaks mostly from moisture. Make sure you clean each injector fitting real good, and then re-seal. Sometimes they leak at the top of the fitting where the tube enters, because of debris.

 

With the engine running, have you cracked open #4 injector. Does the engine still run the same?

 

Thanks for the advise. I checked with the local dealer and he said my compression reading of no4 was good (240psi), which to me seemed too low, i checked the others 400, 390, 400 psi. so i removed the head. no 4 piston is about 1/8 inch lower than no1. suspect bent rod. may have got water in it and had a lock up?. will pull off sump and remove piston and check and let you know,

 

Be sure to check out that cylinder liner real good for defects too.