misfire on diesel

ZSZRANDRF900 · 14-05-14, 11:43 AM

hello, can anyone advise me?
My 54 plate MKII 115td ZR is being a bit of a tinker. it runs crap. miss fires occasionally and if i am cruising at 80-90 ( on german roads, obviously) it misses, then picks up, then misses and it all gets a bit tedious.
No lights come up, but the error code i am getting is for the MAF. so I have replaced the Maf, and the sub harness plug that connects to it, no difference. its done 98K and has had a bit of a hard life prior to me having it judging by the poorly re-fitted air box and MAF by the nugget i bought it from and the rear calipers and fraid cable suggested lots of handbrake turns, so i think he was a tw@t. any ideas what i can try?

ZS · 14-05-14, 01:22 PM

O2 sensor?

Otherwise, I'd look through the whole intake system for leaks and also check the boost pressure as it's possible he has wound it up and now it's over boosting...

peterzs · 14-05-14, 01:35 PM

You put on a new derv filter??

All boost pipes connected OK and no pin holes.

Bleed off pipes OK, no leaks from the injectors. Get someone to rev it up with the cover off, sometimes you get a bit of derv blowing by the copper seal. You had the injectors out??

Might be worth cleaning up the air intake bit that sits on top of the engine.

I'd change the derv filter first, what about the air filter, that been changed???

p_b82 · 14-05-14, 02:32 PM

also check all the earths, and the wiring in the tailgate to the brake lights for fraying.

when the brakes are applied it cuts the fueling, and dodgy/shorting wires will do the same thing.

ZSZRANDRF900 · 15-05-14, 11:18 AM

thanks for the advice guys. so far i have replaced the Air filter element, new air filter box, checked all sealed ok. will try to systematically check the rest out this weekend. thanks again

dida4g · 15-05-14, 02:12 PM

I've had similar issues before, new fuel filter every 6 months and I stick to BP fuel with a shot of Millers power ecomax.

Enright · 15-05-14, 02:33 PM

Always handy to have a fuel filter in reserve anyway - you'll need one sooner or later, so give it a go, and if it doesn't sort it then at least it won't do any harm.