Running issue and injector balance

On my old 1999.5 Golf Tdi that I sold to a friend I am having an odd running issue.

Occasionally it sounds like it has a misfire and runs rough. While it is running like this the injector balance in block 13 is way off. maybe +- 1.8, however, sometimes the car will come out of it and the injector balance will be normal or have a variation of +-.5. Also when you rev the car up it puffs blue, but it doesn't smell like oil.

Any ideas what might be causing this? Car still has good power and isn't using a ton of oil. Maybe a quart every 4000 miles. Timing is on and the car still goes good at under heavier throttle. Is it bad injectors or a bad pump?

Thanks for any ideas.

If they are within -2.0 to 2.0 they're within spec. But jumping around I don't believe is normal, is it the original pump?

Any codes?

Stuff jumping around like that suggest and IP issue, perhaps wiring.

+- 1.8 isn't, in my mind, acceptable (even though VAG says it is). Generally there's an issue when deviations are this high.

UhOh said:

Any codes?

Stuff jumping around like that suggest and IP issue, perhaps wiring.

+- 1.8 isn't, in my mind, acceptable (even though VAG says it is). Generally there's an issue when deviations are this high.

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Odly enough there are no codes (well other than egr, but that's deleted) I agree on the deviations, we are just trying to figure out why it's intermittent.

Pump is original as far as I know and it has 320K on it. Injectors bodys have been changed and have newer (20k) sprint 520s.

What is the IQ like at idle?

Swap around your injectors and see if the big deltas move with the injector(s) or stay with the cylinder(s).

Why were the injector bodies changed? Who installed the nozzles?

Injector bodies were changed due to large injector imbalance and a running issue. I installed the nozzles.

Injector imbalance issue is intermittent and doesn't appear to be related to a specific cylinder.

Fuel filter changed and ran a can of diesel purge through the car. The car ran good on diesel purge and did not smoke on the diesel purge. Weird.

Turbodude1 said:

Fuel filter changed and ran a can of diesel purge through the car. The car ran good on diesel purge and did not smoke on the diesel purge. Weird.

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Mine did that as well, had a struggling idle, like slow down shudder from he!!.
Took me years to find a nick in a wire, all good now. But it would smooth as silk on straight DP.
(not real typical, mine was #2 wire from IP to ECU, where it passes under the battery tray, near the starter.)

quantity adjustor codes?

Post #4, no codes.
Mine threw codes aplenty. A failing DMF can mimic the rough running and throws nary a code, as does a clogged exhaust, but that's very rare.

Thanks for all the ideas guys!! It's not a clogged exhaust as the cat is empty and the cat back is 2.5".

As a note it will smoke anytime you free rev it, even if the car is running smoothly.

Turbodude1 said:

Thanks for all the ideas guys!! It's not a clogged exhaust as the cat is empty and the cat back is 2.5".
As a note it will smoke anytime you free rev it, even if the car is running smoothly.

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I assume a failing turbo that smoked that much would consume a considerable amount of oil.

Is blue smoke at light throttle or decel a potential injector issue?