2.1 mv missfire

[..lee..]

hi guys, what do you think of this....

engine is missfiring or seems to be, rev counter is kicking upwards, especially as i change up gear. ie revs to say 4500 when i know engine is only doing 2500 whilst dipping the clutch. at idle the needle flicks upward also gaining approx 500 to 1000rpm. have fitted another rev counter to confirm its not the counter itself. fueling is lean when cold also. i`m suspecting hall sensor causing the revcounter problem.

heres the story.

a few months ago the engine got really wet and missfired all the way home, not constantly but when loaded, turned out to be leads arcing when wet. easy fix i thought did plugs at the same time. seemed right for a while then had a few splutters and i also noticed the rev counter kicking a little.

changed cap and arm and coil checked connections on dizzy and coil and all seemed well for a while.

did about 120 miles up to the syncronaut wales event and drove fine all the way up. when the van was idling at the camp site i could hear it not right. tried pulling away and really, really bad missfire, just like ht breakdown thought i wouldn`t be able to do the event. parked up let every thing cool down and it was fine.

did the event, deep wading included no problems. drove home no problems.

now its started playing up again. engine earths good but not checked ecu earth yet.


thanks in advance lee.

[Aidan]

tacho gets signal from coil which is flashed by ecu, so I'd recheck coil impedences and ecu earth and lead impedances -
my misfire turned out to be corroded connector in lead, the cable was fine and gave correct readings but the crimped end was poor, only apparent when pulled the lead and engine note didn't change

[..lee..]

thanks aiden, will have to check that ecu earth. done a power balance without gas readings and it "seems pretty even". bloody p.i.t.a. busy spending on the wasser boxer when i should be consentrating on the tdi...

[melmelody]

hi,

i had the same problem a couple of years ago with my bus 2.1 mv in bratislava andonly had a few basic tools with me. diagnosed it as the dizzy or coil and then had to call adac who sent a slovakian mechanic we stripped out the dizzy to find the hall sensor had been bodged into plaace with a cable tie and a piece of wood wedged between it and the dizzy body.he went away and came back with a new bosch dizzy and we fitted it but still no go then we checked the coil and found that the insulating wax for a better word had melted from inside the coil.this was also replaced and the bus started up first time. i think what had happened was on the road from prague to bratislava the road was very bumpy and it must have broken the internal wires from the hall sensor to the dizzy and these were shorting hence thecoil going too but the symtoms were very much as you describe a very noticable missfire on an engine that normally runs very smoothly.i have kept the old dizzy as now i know you can get replacements i intend to repair it.good luck and hope you find that this is the problem