Weird idle problem... almost a misfire? driving with choke

[mk2vr6]

Hey guys

I'm having this weird idle problem.  It can be equated to the way a misfire feels in a gas engine.  Now, it only does it on idle, or if im rolling around in 1st and sometimes 2nd gear at low rpms, you can feel it bucking a slight bit as if its misfiring, and especially when the car is just sitting there idling, clutch in or out, neutral.  As soon as I pull the choke out just a little bit, it goes away.

Any ideas what this might be, or what I can check to track this problem down?


Also, I was just curious as to what the consequences, if any, would be from driving with the choke pulled out a bit?  Typically I use it on cold starts, have the choke out for maybe 30seconds - 1 minute depending how cold it is, and then thats it.  I never drive with it on, but this weird misfiring has me pulling the choke in traffic just so the engine doesnt misfire and shake.  

Any ideas what this problem could be?  (on my 1.6L TD)

Thanks!

[Doug]

The "choke" is a mechanical advance to the pump timing. There is probably a plugged or faulty spraying nozzle tip on one of the injectors that is causing the rough idle. By advancing the timing the engine speed climbs slightly which tends to mask the roughness.

[mk2vr6]

I have also noticed that when the choke is not pulled, it will randomly puff some white smoke at times when the car appears to "misfire".

But when the choke is pulled, this goes away.  Does it still sound like a clogged nozzle tip?

[QuickTD]

Sounds like retarded injection timing, pulling the cold advance advances the timing and "fixes" the problem.

[mk2vr6]

Sounds like retarded injection timing, pulling the cold advance advances the timing and "fixes" the problem.

So would it be alright to drive with the choke pulled until I fix this problem?

And, what would a possible fix be for it?

[QuickTD]

The manual cold advance is only effective at low RPM, beyond about 1500rpm the pump is hydraulically advanced past the cold advance position, so it won't hurt anything.

 The real fix is to set the pump timing correctly using a dial guage. The procedure is in the manual and likely posted here somewhere as well.

[mk2vr6]

The manual cold advance is only effective at low RPM, beyond about 1500rpm the pump is hydraulically advanced past the cold advance position, so it won't hurt anything.

 The real fix is to set the pump timing correctly using a dial guage. The procedure is in the manual and likely posted here somewhere as well.

I just searched on here and no luck, and I also don't have the original owners manual, or did you mean like a bently manual?

Is it a DIY job?

[burn_your_money]

I just searched on here and no luck, and I also don't have the original owners manual, or did you mean like a bently manual?

Is it a DIY job?

It's in the Bentley. It's a pretty simple job if you have the tools. I believe the correct advance for a TD is 1.00 mm. If you dont have a dial indicator you can try making very slight adjustments to the pumps position, but idealy you need the dial indicator.

[rabbitman]

Yeah, the timing is definitely retarded. I thought my rabbit was to advanced so I timed it later and it missed just like you said. Sounded just like a gasser that runs rich, when I'd stomp the pedal it would sputter and then rev. When I moved the timing back it fixed it.