Thread: V8 Compression Test

The mis fires happen at all revs..so far no difficulty in starting whether hot or cold.
I checked the battery and it holds 12.44 when the engine isnt running.

I also double checked my readings and they vary from 120psi to 137psi.(I havent worked out the % as yet...I thinks its just over the 10% mark)

This coolant temp sensor'theres just the one on the engine?

Originally Posted by ******

could be valve stem seals. I'm going through it at the moment, no noticeable oile usage and no smoke but burned out plugs and sooted up to buggery. All this with only 34k on the clock.....
Maybe try some heavy duty engine cleaner and see if it helps? May be a low cost winner..

Usually you get smoke from start up when the engine hasnt been start for a feew hours.
The oil seeps thru the valves and sit in the pot,so when you start the engine it burns that on start up and clears up after a few minutes....

START SIMPLE! Start with a replacement rotor - even if it is a borrowed one just to try. I was stunned at how badly my 3.9 ran with a non-genuine rotor after only 5000km.

"What can be done with fewer assumptions is done in vain with more."

On a similar theme, can someone tell me what the spark plug gap should be for a 3.9?, my Haynes manual makes no mention of it..

Cheers,

W/M Manual says: 0.84 - 0.96 mm.

not sure where the mention of the rotor came in to it,I havent mentioned the rotor.(rotor is the orginal)
What I did do is check the destributer cap for cracks to ellimunate tracking within the cap....

But very usefull info to say the least.

Ill be trying all these fresh ideas this weekend when I have a chance.(damn work require my body )

did these engines run the cold start injector.....?
if it has a cold start injector...simply unplug it and see if it fixes the problem......





you could also try.........pulling the engine fuse.....
(if its in limp mode...it richens the mixture up something drastic.....
to avoid burning the engine due to lean running......)
pulling the fuse or disconnecting the battery may reset any faults present.....

Originally Posted by Bully

not sure where the mention of the rotor came in to it,I havent mentioned the rotor.(rotor is the orginal)
What I did do is check the destributer cap for cracks to ellimunate tracking within the cap....

But very usefull info to say the least.

Ill be trying all these fresh ideas this weekend when I have a chance.(damn work require my body )

I raised the rotor button - the aftermarket versions develop cracks in them causing shorts or lack of constant spark that result in sysmptoms very similar to what you originally mentioned. On cranking can show up as HT to the distributor but no spark to the plugs - however the engine may still fire and run at higher revs and the spark jumps around inside the distributer.

It is only the aftermarket rotors that have the problem - they usual last about 3-6 months before they pack it in - it doesn't kill the engine but makes it run like **** - something like the symptoms you suggested.

Gazz

Just something to check - do the easy things first.