Misfire/down on power
Misfire/down on power
Author
Discussion

mb450

Original Poster:

429 posts

229 months

Monday 29th October 2007
quotequote all
Hello everyone

I'm sure this will turn out to be something simple but need some pointers.

My 450 had it's MOT today - flew through it no problem (phew)

Picked it up this evening and it was fine, on part of the journey home I thought I'd give it a bit of stick and this is where the problem comes. It was fine up until 4000(ish) rpm then it was all hesitation and surging.

I thought maybe a bit of crap got sucked up from the tank as it was running very low - so stopped and fulled up.

Off I went again - tried the same thing and got the same result.
I didn't notice until pulling onto the driveway but the dash lights were flickering ever so slightly and in the time it took me of open the garage the temp gauge went totally insane (having been at 70-75ish - it was jumping about between 50 and off the scale).

Any one any ideas - I've had a quick poke about to see if anything is loose - wonky ht lead flapping about or anything like that - but everything seems in place.

350Matt

3,912 posts

309 months

Tuesday 30th October 2007
quotequote all
Check to see if the alternator is working , as its sounds like the battery is flat, try the 100A fuse first


Matt

mb450

Original Poster:

429 posts

229 months

Tuesday 30th October 2007
quotequote all
I'll check the 100A fuse when I get home. The alternator has just been replaced (90 miles ago) could be duff though.

I did check the coil-->distributor lead this morning. Pulled it out and there is some charing round the distributor end and wasn'tas firm as I expected - I wonder if it wasn't seated properly and had worked it's was loose?

I'll reset the ECU tonight and take it out for a blat see what happens.

:-)




350Matt

3,912 posts

309 months

Tuesday 30th October 2007
quotequote all
Test the alternator by measuring battery voltage with the engine off, then measure it again with the engine running, the voltage should slowly increase with the engine running

Matt

mb450

Original Poster:

429 posts

229 months

Wednesday 31st October 2007
quotequote all

Didn't get to go out last night - work intruded - but did get half an hour to poke about in the garage.
I reattached all the HT leads and plug extenders.
Checked the spade connectors on the coil.
And the airflow meter connector.
100A fuse looks ok.

I did as suggested and tested the alternator. Voltage when I got to the car was 12.5 with the engine running it went up to 14.3

The lights seemed solid and didn't flicker.

Hoping that it was just a loose ht lead - will try to get out and test it tonight

mb450

Original Poster:

429 posts

229 months

Thursday 1st November 2007
quotequote all
All good - no problems

woohoo