[stroud2010]

HI! i've got a 1998 beetle tdi ALH with 173k miles. I do all my own maintenance on it and am in the process of gathering things replace the timing belt (current one starting to show signs of wear).
There is also another issue with the car. At idle, and sometimes 1200 rpms or more, the car runs very rough especially when cold(below 60 deg. F). As it warms up, the "stutter" tends to get better, but it never goes away. I can usually get it to idle smoothly if I play with the accelerator pedal. Ever since i've had the car, its done this (i got it at just under 120k miles), but recently, its gotten worse, and worse. When I let the car idle, the rpms sometimes drop to 600! Sometimes sounds like its gonna die. Any suggestions?

 

[Seatman]

Hi, I've read that it can be something to do with fuel quantity delivery or something. Have a look here and see if it helps.

http://www.myturbodiesel.com/1000q/multi/IQ-adjust-hammer-mod-TDI.htm

 

[stroud2010]

thank you
It might be a while before i can get to a VCDS to check it out. When I do get a hold of one, i'll let you know!
I had another thought, I personally haven't looked at the intake track post egr. I have a feeling the egr valve is stuck or has limited movement due to carbon/oil mist build up, which is introducing too much exhaust gasses at idle. I don't know if the intake has EVER been cleaned. Could this be another possible cause to my stutter problem?

 

[Seatman]

The only thing I've seen about the inlet clogging is it can take the edge off the power, especially at higher revs. It wouldn't hurt to clean it though, it gets really clogged until there's just a little hole in the centre for the air to get in. Check out this for cleaning it.

http://www.myturbodiesel.com/1000q/a4/clean-intake-manifold-VW-TDI-carbon.htm

 

[stroud2010]

Thanks!

I know I have to do something about that egr because its weeping oil. I'll probably clean everything and replace the egr, and if its still stuttering, i'll have someone hook their VCDS to it and see what its doing. I'll have to hook it up to a VCDS eventually after doing the timing belt change, so i'll check out the fueling while i'm at it.

 

[chittychittybangbang]

The EGR can weep oil because the internal seal starts leaking and the oil that's present in the intake tract is getting pushed out. Check the injection quantity cold vs. warm once you can log the info.

 

[stroud2010]

Would increasing IQ raise the rpm at idle? Or is it stuttering because one cylinder isn't getting the right IQ? Because when I increase fuel with my foot, it still stutters, sometimes clear up to 1200 rpm. When I slowly take my foot off the pedal, clear down to idle, it usually idles smooth-- for a little while at least.

its weird

does OBDII work for this job?

 

[chittychittybangbang]

Iq should not effect idle rpm. Maybe it's something related to the cold advance solenoid on the injection pump. If so, it should throw a code. Many auto parts store should scan it for free.

 

[stroud2010]

I just went out and started the car. Its 30 degrees F outside and the car was, of course, running like crap. This time, I noticed the knocks were much sharper, and they were coming from the vacuum pump area every time it stuttered. its not a bent valve is it? =[

 

[chittychittybangbang]

Is this the original belt? If so, I wouldn't drive the car until the belt is replaced. It is way, way, way overdue if it's the original belt. The timing will drift slightly as the belt ages but it shouldn't cause your problem. If the injection pump jumped but the other sprocket are OK, it might cause a running problem but I've never purposely mistimed the engine like that to feel what it's like.

 

[stroud2010]

ok yikes jaw drops

I'm in college 50 miles from home lol

When we bought the car, the previous owner said it was recently replaced at like 114k miles... Which doesn't make sense because no kit offers over 100k, that i've seen anyway.... so idk sounds suspicious now.

A timing advance solenoid issue sounds like it could be something to do with it. When I rev the engine when its not stuttering, the rpm return to idle like normal. When the engine is stuttering and i rev the engine, the rpm hang for a little bit, and fall a little bit slower. Does this sound like its advanced?

 

[Seatman]

If you had a bent valve it would be a regular miss and knock. Random knocking can be caused by a fuel problem. Try using a long wooden stick, a screw driver or metal bar and put one end at various points on the rocker cover and the other end to your ear. Usually top end noise is more tappy sounding. Maybe your vacuum pumps making a racket. I don't think you're gonna really get anywhere though until you get the car hooked up. (Other than driving yourself nuts lol)

 

[stroud2010]

well you're definitely right about that! lol

 

[stroud2010]

Just did timing belt service. While i was at it, i cleaned intake and turbo, removed head to get it cleaned right, and to put new valve seals in it (cheap preventative precautionary measure that was suggested by my parts store/machine shop[of course]). I got the injectors cleaned and set. When I FINALLY got it running... see below... it ran much smoother and didn't stutter as much, but it still does occasionally. so we've pretty much got it narrowed down to the IQ, RIGHT? I'm waiting on my vag cable to come in at the end of the week.

STARTING
After sitting for a week with no injectors or injector lines on the pump, there was a bunch of fuel laying on the floor. My pump completely drained along with probably a percentage of fuel in my filter. This made start up really hard. someone suggested pressurizing the tank to us, which sparked a memory in my dads brain. Working on all the older diesel tractors on the farm, he would shoot some air into the fuel tank to pressurize the fuel system and force the air out of the pump(prime it). Well, we tried this but it did not produce results. the pressure in the tank was relieved by the relief valve, and when the relief valve couldn't keep up, the tank started making noises that were suggesting to me that it wasn't very happy. We installed an in line electric fuel pump though, and this worked much better. It primed the whole system and the car fired right up.

 

[chittychittybangbang]

FYI, you can also loosen one of the fuel lines at the injector and wrap a thick rag around it. The pump is self priming but it takes forever for it to bleed out. When the rag is wet the car should be ready to start.

 

[stroud2010]

yup
thats what we were doing
it just kept bubbling and bubbling and bubbling. eventually we had the starter smoking!
btw it seems as though 30 seconds off for the starter isn't enough time

after the electric pump was installed and cycled a few times, the air bubbles went away and the old faithful of fuel came spraying... i put dad in charge of the line nut... by mistake. I guess he just liked to see fuel spray all over the place. lol hope my coolant lines got wiped off enough... anic:

 

[stroud2010]

I finally got my timing set thanks to Growler :thumbsup

while he was in there he saw that the IQ was around 3.2
he bumped the IQ up to 3.8 and It hasn't stuttered since.

Question...
this will reduce my power output?

it doesn't seem to have quite as much kick in the 2k to 3k rpm range as it did before i did all my work on it (timing belt, intake and head cleaning, and vnt cleaning).

I kinda thought these maintenance procedures might have the opposite affect

 

[chittychittybangbang]

Not really but it can affect "throttle" response since it's slightly changing the fueling. Just step on the pedal harder

Did he have any comment on the piston protrusion or other issue you've been having?

 

[stroud2010]

Piston protrusion didn't come up seemed to have slipped my mind
he also had another guy in line behind me and I had a 3 hour drive home! :eek

the accelerator pedal doesn't 'really' feel different
but i drove it for two months with retarded timing... so who knows really...
but I've always(and still do) notice that no matter what rpm range I'm in, the accelerator pedal seems to not change ANYTHING after it reaches a certain point in relation to the floor. in other words, i'll push it down and it'll seem to reach maximum acceleration before the pedal touches the floor. there's probably about 3 to 4 inches of useless pedal travel approaching the floor.
is this normal? or is this where my low power is coming from?
I know any other vehicle I drive, the closer to the floor you get, the more work the engine wants to do.
my dad's powerstroke is drive by wire also, and its just unbelievable when that pedal is even close to the floor, and when you push it to the floor, it does MORE!
but that's made by ford, and my car is made by VW, so I realize that two completely different teams of engineers developed them.

it just doesn't seem right to me that there's that much useless pedal travel :dunno

 

[chittychittybangbang]

Can't say, it's not like that on my car. 3-4" is a lot of travel but keep in mind you only have 90 hp.