1.9 runs rough between 1800 and 2850 rpms when hold steady

[lyle]

Any help is appreciated,
I have a 97 jetta 1.9 turbo diesel  aaz  166000 kms runs rough when i hold the accelerator steady at any rpm between 1800 and 2850, if i accelerate hard, it runs great no sputter but if i level it off and try to hold 2750 (100 km/hr ) it sputters and bucks. I had vw put a new timing belt  and crank bolt on 2 months ago i also put a new fuel filter on 1 month ago.
 The problem seems to be more noticable now that it is getting colder outside if any one has any insight??

[vixentd]

check with the dealer re the torque on the bolt to make sure it had the extra 90 degrees or so. The new bolt does not mean you do not have the crank shaft pulley problem. If the crank is worn at all, then the pulley will move regardless of new bolt or old, and put it out of time. If that is the case then the motor could go asap. I would have them take off the bottom pulley again and check for any wear on the keyway on the crank.  

Usually this does not occur under the conditions you have mentioned but could.

[QuickTD]

The timing sounds a bit retarded. The load dependant timing cuts out at 2850 and is reduced somewhat under power, that explains why the problem goes away at higher rpm and under acceleration.

 The reason for the retarded timing could be any number of things, restricted fuel filter, improper timing from the timing belt change etc. But history has proven that the most likely suspect on a 1.9TD is worn crank pulley key. I would have it checked out right away.

[lyle]

Thanks for the reply, I talked to vw about getting the car in to check the crank pulley, they assured me they inspected the crank pulley when they changed the belt and bolt. He did mention there  was a service buuletin out on those models which involved rewiring the glow plug relay from the fuse box and relacing the coolant temperture sensor,so for kicks i unplugged the black and green coolant temperature sensor,my sputter disapeers, hmmmm I am going to take it to vw on tuesday to have the other things checked but just found it interesting how this sensor could do this.

[QuickTD]

Unplugging the coolant temp sensor will keep the glow plugs on for a long time, for a full 3 minutes after the engine is started. This will mask all variety of injection timing related problems by keeping a good source of ignition present at all times. A 1.9TD will run well with massively retarded timing if the glow plugs are on. Make sure your test drive is longer than 3 minutes or your test is totally inconclusive.

 Another function that may be controlled by the temp sensor is load dependant timing. If the engine never appears to warm up (coolanrt temp sensor unplugged) the load dependant timing solenoid may never turn off. In this case the timing will stay in the advanced condition at all times and problems related to retarded injection timing will again be masked.

Get the injection timing checked, that is your problem. It may or may not be related to the crank pulley problem, but it is too retarded.

[addautomotive]

I am displaying some of these symptoms as well... I'm quite sure my timing is a bit retarded. I have also noticed that my idle is a bit rough - with an occasional sputter - and there is a bit of blue smoke at idle. If I pull out the cold-start just a wee bit, both of these symptoms go away.

The PITA with the AAZ is setting the timing... I like to set it "by ear", but on my car (96 AAZ) the adjustment is all don on the pulley; the IP doesn't move.

[lyle]

I replaced the coolant sensor and the flutter is all but gone,now when it  is warm it has a slight hesitation at about 1900 rpms, above that it is 100% we drove 590 kms today and it worked great. never got a chance to take it to vw yet for the glow plug relay problem.
 Quicktd...
   Thank you for your input, i am going to take it in to a diesel shop next week to get the pump timing checked, i think you are right that it is out some. i will keep you posted as to how it turns out.

[lyle]

got the bulletin from vw today, for these symptoms remove wire # 13 on glow plug relay and secure end of wire with heat shrink and tie back into harness, i did just that, eveything works 100% now. if anyone would like a copy of the bulletin let me know i will email it to you

[Master ACiD]

i had that problem once. it turned out to be a leaking valve cover gasket and a leaking intake manifold gasket. turns out the valve cover gasket was leaking oil, which got ingested into the intake manifold via a leaky intake. the engine would just rev on its own every 5 or 10 seconds at idle and then quiet back down on its own again.

took me a while to figure that one out.