oakey

Well-Known Member
Full Member
1995 4.6 V8 210k
Only just failing emissions and suspect one cylinder is not firing properly. Not a full blown misfire, more like a not full fire on one cylinder.
Changed plugs leads and coil pack.
Suspect a burnt ish valve
Going to compression test then take heads off
Anything that I should do at same time?
 
They were a bit blackk but that was probably from being started just to move it
I had noticed the partial misfire a while ago when pulling hard.
Fails on hydrocarbons after the hi speed bit
 
Could also be a coating of soot on the cat surface o_O
The cat doesn't remove HC? That's essentially unburnt petrol
Could be an air leak.. somewhere, dying o2 sensor, dying maf, dying cam.. dodgy plug..
Need to narrow down is it just one or 2 cylinders, a bank, or all cylinders running rich
 
Thanks for all your replies
Before MOT I intended an Italian Tune up but had a heart attack so that didnt happen
Lambda sensor was changed just before MOT cos Nanocom said it was
 
My compression tester which I hadnt used for years, didnt fit. Need to make an adapter of some kind. Will see what results are this week I hope if allowed out to play
Thank you for all your good wishes
 

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