Alternator Leading to Misfire on 2?

tuizner

tuizner

A2OC Donor
I only just last week bought into the A2 family with a 2000 1.4 petrol AUA and just over 100k. I can say its been an interesting few days.

So - I have a misfire on cylinder 2. Typical ( in as far I have read ) issue in that it happens generally on idle.

Have replaced plugs and coil, cleaned throttle, played musical chairs with the leads, replaced injector 2 (electric plug came off on removal). Compression test shows really high in all 4 (14 bar). I thought the replacement injector did the job but then on a run out it comes back - quickly followed by the battery light o the dash (with power steering and then ABS failures). Battery changed but issue came back within 5 minutes. So the Alternator (or other elastictrickery) isnt doing its job. Alternator on order with a new belt. Question to the experienced - could the alternator have been causing the misfire (or helping it with the damaged cables on the injector 2?).

Will find out in a few days when i replace the alternator but thought I would post it as I didnt see the alternator side of the elctrics being mentioned in the other posts I saw about misfire (no doubt its out there somewhere - but the posts on misfire tend to look at the high voltage end rather than the low).

Engne flush and lifter treatment to come in case its a sticky valve and the alternatr was just coindcidence.
 
Unlikely to be the issue, but have you checked the earths, particularly that linking the engine block back to the chassis, and the starter motor earth? I agree that suspicion towards the charging circuit or the alternator itself appears to be warranted based on the latter part of your first paragraph.
 
Thanks for the help.

Starter earth looks fine (havent taken it off but all looks clean and attached). Cannot find a strap linking the engine block back to the chassis but wil look when I do the alternator.
 
tuizner said:
Thanks for the help.

Starter earth looks fine (havent taken it off but all looks clean and attached). Cannot find a strap linking the engine block back to the chassis but wil look when I do the alternator.
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There is no earth strap from engine block to chassis just the one from the chassis to the starter, although members quite often add their own separate earth strap. Difficult to tell state by inspection without removing and examining mating surfaces, also deteriorates unseen under its protective cover.

Andy
 
If you need it these pictures will help find the chassis end.

Earth tag below NS light?

Hi, Can someone tell me the exact location where the large Earth tag connection is supposed to be below the passengers side headlamp? Cause it looks like I don't have one. I have an intermittent misfire and I'd thought I try this mythical creature first. Photos would be good! I...
www.a2oc.net

Andy
 
this engine suffers from air leaks and also from sticky engine valves and valve lifters
The ECU monitors the number of misfires and after (from memory 400 misfires) it kills the injector on the cyclinder with the misfire to protect the cat.
also the EGR is know to be a problem and can and does cause misfires

I personally chased a misfire on a 1.4 AUA for months, changed just about everything and made no difference until I changed and adapted the EGR

The car would always start on 4 cyclinder from cold and as it warmed up would start to shake as it dropped onto 3 cyclinders
It was always cylinder 2 that VCDS reported as being the misfire
I emptied a can of some product (cant remember what it was called) to free up stuck valves/valve lifters about the same time that I changed the EGR, so I can't be 100% sure if it was the treatment in the oil or the EGR.
A compression test pre and post oil treatment reported 14bar per cylinder, but this was done when cold and at the point of the misfires starting, but engine temp would be cooling all the time to remove the 4 plugs and run the compression test on each cylinder, hence I still partially thinking the issue was a sticking valve/valve lifter, but could equally be the EGR
Enough said once I had it running misfire free I was not going to swap back in the old EGR and readapt it to prove if the EGR was really the culprit.
Interestingly VCDS would not adapt the EGR (full register copy of VCDS) but ODIS picked up the need to adapt the EGR when I scanned the car with ODIS and adapted it first time. Car ran a lot smoother with the new EGR

hope this helps
Paul
 
Thanks Paul - and again for the wiper arm.

I am getting a P0135$10 error (O2 sensor heater bank 1) also but I think maybe this is an effect of the misfire rather than the other way around.

EGR added to the list (plus a leakdown and a leak test) along with a knock sensor which I also read might be a cuplrit.

Anyone ever tried to clear the carbon off the valves? Looks difficult with the intake location.
 
tuizner said:
Thanks Paul - and again for the wiper arm.

I am getting a P0135$10 error (O2 sensor heater bank 1) also but I think maybe this is an effect of the misfire rather than the other way around.

EGR added to the list (plus a leakdown and a leak test) along with a knock sensor which I also read might be a cuplrit.

Anyone ever tried to clear the carbon off the valves? Looks difficult with the intake location.
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If the lambda heater is not working, then the air fuel ratio is likely to be way out. The ECU uses the lambda reading, to get the mixture spot on, which will be when the O2 level in the exhaust, measured by the lambda sensor, is at a minimum.
So I'd fix that first.
Mac.
 
Alternator changed. Not too bad to do. Thought maybe it had helped but 4 minutes in when the engine had warmed up - back to misfire on 2... No O2 heater sensor fail yet.

EGR on order. Will look into the O2 heater sensor. Just got my kkl obd from gendan ( bargain at £20) so can vagcom tomorrow
 
tuizner said:
Alternator changed. Not too bad to do. Thought maybe it had helped but 4 minutes in when the engine had warmed up - back to misfire on 2... No O2 heater sensor fail yet.

EGR on order. Will look into the O2 heater sensor. Just got my kkl obd from gendan ( bargain at £20) so can vagcom tomorrow
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The eBay KKL leads work OK, not sure any advantage with Gendan lead, which is nearly three time the price.
Mac.
 
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Just to close this down for future refence - the issue was the cam housing - either leaking air (was previously sealed with silicone!), tappets (cleaned and reset), or oil leaking into the cylinder???

Either way, once cleaned and reseated using hylomar blue the misfire has cleared - 200 miles now free of issues (and the engine running much quieter with the cleaned tappets)

Thanks all for input
 
tuizner said:
Just to close this down for future refence - the issue was the cam housing - either leaking air (was previously sealed with silicone!), tappets (cleaned and reset), or oil leaking into the cylinder???

Either way, once cleaned and reseated using hylomar blue the misfire has cleared - 200 miles now free of issues (and the engine running much quieter with the cleaned tappets)

Thanks all for input
Click to expand...
Glad you didn't give up, enjoy your reward.
Mac.
 
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