05 C3 after replacement alternator

[citronut]

after a customer of mine had a replacement alternator fitted to her 05 1.4 8V C3

it has acquired a random misfire on all cylinders,

the fault code are
P0300
and
P1336

the first one i think is a ling standing code which no one seems to be able to get to the bottom of,

the second one on a gooogly search says it could be various items at fault, like crank sensor, lambada sensor or the car,

anyone have any ideas,

i did a resistance test on the crank sensor off the car which reads 500 ohms, were my Autodata software says it should read 450

[uncle buck]

Had a simular problem a lot of years ago on a mk3 astra.

It had a misfire that we just couldn't get to the bottom of, an auto electrician that was there to do a job on a different car had a quick look at it and after connecting various meters etc to it said it was the Alternator. We had checked the voltage from the alternator which seemed fine. Anyway the Alternator was changed and lo & behold the misfire was gone.

The auto electrician had gone by the time the Alternator was changed ....Wish I had took more notice or maybe even quizzed him to what it was he was testing.


Cheers.

[Mandrake]

Had a simular problem a lot of years ago on a mk3 astra.

It had a misfire that we just couldn't get to the bottom of, an auto electrician that was there to do a job on a different car had a quick look at it and after connecting various meters etc to it said it was the Alternator. We had checked the voltage from the alternator which seemed fine. Anyway the Alternator was changed and lo & behold the misfire was gone.

The auto electrician had gone by the time the Alternator was changed ....Wish I had took more notice or maybe even quizzed him to what it was he was testing.

He was probably measuring the battery voltage on an oscilloscope looking for AC ripple - a failed diode (among other things) in the alternator can cause far more ripple on the charging voltage than there should be - although what a "normal" figure for ripple is on the average car alternator I'm not sure. Ideally you would measure it directly on the charging terminal on the alternator but you could also measure it at the battery posts, although the ripple reading will be smaller there.

http://www.pvv.org/~syljua/merc/TooSeptST07.pdf" onclick="window.open(this.href);return false;

Interesting that enough ripple can cause an intermittent misfire though! I really ought to check mine for excessive ripple as I was chasing an intermittent misfire for a long long time and although it seems pretty good now I'm not sure that it's perfect...

[uncle buck]

Thanks fo that.....every day's a School day


Cheers.

[citronut]

whoooops i must had miss typed the P0300 into the gooogly search, as it comes up relating to a misfire now,

had another guy/freind check it out with his all singing and dancing Bosch analyer, which says its the cat at fault