Author Topic: Rough runnning after sitting or a while (Read 2269 times)

2.slowjetta · « **on:** May 27, 2008, 07:38:11 am »

I have a 94 Jetta TD, the engine was just rebuilt. It ran great for a while, but I had to replace the crank bolt since it had some wobble, everything was replaced with new parts and re-timed properly and it fixed the wobble and the car was good as new, except I now have a new problem, when the car sits for a long time (over night or all day at work) when I start it will run rough for the first few minutes and then it will be fine afterwards. If you try to drive in the period when its running rough the car will have a very mild buck, or loss of power then surge back to normal then a loss, then back to normal. I have check for air bubbles in the line and I don’t see any and there is no leaks on the IP that I can see. I’m fairly new to the Diesel side of VW’s , what else should I be looking for?

Possum79 · « **Reply #1 on:** May 27, 2008, 11:34:18 am »

glow plugs any good? What about compression and head gasket?

2.slowjetta · « **Reply #2 on:** May 27, 2008, 12:00:51 pm »

Glow plugs are about 2 months old and the head gasket is the same.
not sure about the compression, but it doesn't smoke and runs great when it warms up.
my timing advance lever doesn't work so it could just be that I guess, I just didn't think it would have that big of an effect on it.

Possum79 · « **Reply #3 on:** May 27, 2008, 02:21:04 pm »

I have a starting issue where its rough until it warms up then its great. Im pretty sure my glow plugs dont work though. if you cold start doesnt work it will change your timing more then likely which is a very accurate thing. If its off it can make it run like crap.

houseofdiesel · « **Reply #4 on:** May 27, 2008, 06:49:59 pm »

Make SURE your glow plugs work, check for power right at the glow plugs and if you have power jump them and check current draw with an meter (60 amp min). There are two types of systems, one with the metal fuse on the firewall and the newer version a large atc fuse above the fusebox.
If you glow plugs are in working order (not just new but getting power) and your timing is all set (timing belt timing cam/crank/pump in relation and pump timing for start of delivery measured with dial indicator) then look at your injection pump OR the drain back valve located under the rear seat area near the fuel tank in line. Have you tried running it off a gas can or jar of fuel directly? THis can eliminate the drain back or pump priming issue
Were the injectors new?
Greg

2.slowjetta · « **Reply #5 on:** May 28, 2008, 06:18:20 am »

would drain back really be an issue with no air bubbles in the lines?
No the injectors weren't new the were from the old motor.
I'll try the draw test when I get a chance.

jtanguay · « **Reply #6 on:** May 28, 2008, 01:47:33 pm »

Quote from: "2.slowjetta"

would drain back really be an issue with no air bubbles in the lines?
No the injectors weren't new the were from the old motor.
I'll try the draw test when I get a chance.

how many km's on the injectors??? a little feed pump to the motor can squeeze more life out. something like a facet fuel pump.

the timing advance mechanism really helps old tired motors start up when cold (-5 or below) if warmer than that you don't really need it, but it might smoke a bit all depending on how 'tired' the motor is.

2.slowjetta · « **Reply #7 on:** May 28, 2008, 01:54:48 pm »

450 000kms(ish).