V8 efi missfire on 1 and 2

[doodsdad]

Hope someone can help?
                                       I've got a 3.9 V8 efi that has got a missfire on plugs 1 and 2. I have fit new plugs/leads/dizzy cap and rotor arm but still the missfire is there. When i remove the plugs they are very sooty.also when i rev the engine it spits out a sooty residue out of the exhaust. can the timing be altered if so how. I live in Leeds west yorkshire if anyone can help I'm willing to learn
 
cheers Lee

[Range Rover Blues]

No.s 1 and 2 are the front cylinders in each bank, so it's odd they are theones misfiring.  The sooty plug makes me thing it's not an ignition problem, if they weren't firing the plugs would be wet.  It's not the timing either.

Is it carb or EFi? I suspect it's over fuelling at the fornt, it could be just coincidence it's those 2 cylinders or it could be related.

[Crispywombat]

...sell it and buy a disco

[doodsdad]

The rangy is efi. We have been tinkering today to try and find anything obvious. The only thing we found was when we put the timing strobe on HT lead No 1 it was only fiering intermittently. We took the plug out gave it a good clean and checked the gap. When it was replaced it seemed to run OK for a short while,the strobe flashed more frequently but when it was revd high the strobe stoped and then came back as the engine slowed down. I have been told it could be the cam but I don't want to start stripping the engine if it could be something else.

[doodsdad]

Crispy you know you would rather have a rangy bobtail [-X

[Crispywombat]

 :scold:

[Rossko]

Check the magnetic pickup airgap inside the distributor.  Bit like checking points, but much easier with plastic feeler gauges! (because of the magnetism)

Look for metal debris stuck to the magnet or rotor (rotor meaning the lumpy shaft, not the rotor arm).  Check for worn dizzy bearings, how much wobble is there in the shaft.

[doodsdad]

Cheers Rossko
                       Ill have a look tomorow and let you know what i find :-k

[Range Rover Blues]

That's interesting, because the firing order is 2-1- so it could be damage or contamination on the magnetic input.

Not sure wht the strobe would do if you had dodgy plugs :-k

[Crispywombat]

:scold:

I'd rather have my tail bobbed than my bob tailed... :whothedaddy:

[TwoSheds]

Sooty (to me) suggests rich - possibly leaking injectors?

Just a thought...

Rog

[Range Rover Blues]

Leaky injectors or ignition misfire, either way it's an obvious symptom that something is wrong.  If it's EFi then the fuelling is totally separate and the baknks fire LH and RH so it's one fo each :-k

I still think a ignition problem is most likely, cyclinder 1 follows 2 in the firing order, so something like a bent dizzy, contamination etc that is disturbing the air gap on the magnetic pick up.

Or pehaps yet another s**t dizzy cap