6n2 1.4tdi intermittent misfire to full misfire lumpy running

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train050
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Drives: 1.4tdi 6n2
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6n2 1.4tdi intermittent misfire to full misfire lumpy running

Post by train050 » Tue Dec 11, 2018 7:37 am

hi all, i have had a search but cant seem to find anything that is the same as this issue.
1.4tdi 2001 polo 6n2

What i have done
- clear fault codes
- change fuel filter

the car starts up no problem then when driven will feel like a misfire. it will do this maybe once every 30 seconds. within a few minutes it'll eventually get worse to the point its fully lost power and continuously judder and feel like its only running on 2 cylinders.

if i turn the engine off, then on again sometimes it'll do the same again. other times it will cure the problem completely.

there are no new fault codes and no dash lights.

does anyone have any idea what this may be and what the best order of parts to maybe replace are?

thanks in advance!

John24
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Drives: Polo 1.2 twist
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Re: 6n2 1.4tdi intermittent misfire to full misfire lumpy running

Post by John24 » Tue Dec 11, 2018 10:01 am

The first thing I would check is compression on all cylinders. Remove all spark plugs and take out fuses for the fuel pump and ignition systems. Put the compression test kit into each cylinder and crank for 8 turns at minimum. Report back with results.

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alexperkins
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Re: 6n2 1.4tdi intermittent misfire to full misfire lumpy running

Post by alexperkins » Sat Dec 15, 2018 1:57 pm

Could be a faulty/blocked injector, or a fault on the injector loom. I would test that and go from there

WilliamButcher
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Re: 6n2 1.4tdi intermittent misfire to full misfire lumpy running

Post by WilliamButcher » Wed Mar 13, 2019 1:13 pm

Same thing happens with mine,
First there was a full on broken spark plug after 93k or so miles
Got the spark plugs replaced but garage installed them wrong so still was not fixed, got them fixed the next day and engine was fine
After around 3k miles on brand new spark plugs it was misfiring again, so took it to the garage where they replaced the spark plugs
After 400 miles it started again but wasn't an actual missifre, just a judder at anything under 1200 revs.
On colder days it was horrible, with me needing to put my foot on the accelerator at idle just so it didn't stall itself, but then later on in the day it is fine
Now at around 98k miles it only judders at idle stopped at a light every 20 seconds or so, taking the revs back up to 1000 then back down to 850 or so (EMS kicking in I think)
Going to take it to a different mechanic to see what they say and failing that taking it to a VW garage as they will sort out the issue but understandably at a large premium.
Should be sorted in the next two weeks hopefully

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