High speed coasting shudder

Dr. Dotgain

Veteran Member
Joined
Dec 29, 1999
Location
RI USA
TDI
2000 TDI GL 5-speed
I feel a shudder like intermittent fuel supply while coasting down from 75->72 mph (117 kph) in 5th gear. It feels the same whether it’s my foot off the throttle or the cruise control 'realizing' we’re going downhill. It seems more prevalent after an hour of highway driving and then doing a brief stint at Autobahn speeds. Replacing the fuel filter made no difference. I'm tending to think the fuel pump might be weak but basically operational. Is that diagnosis consistent with this other onetime occurrence: When the ambient temperature was 15 F. (-9 C.) it started fine but stalled at idle and failed to restart after going 4 blocks from home.
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Dr. Dotgain
2000 Golf GL TDI 5-speed ... 27,000 miles
 

Dr. Dotgain

Veteran Member
Joined
Dec 29, 1999
Location
RI USA
TDI
2000 TDI GL 5-speed
I just found Mickey's advice on another thread regarding the Vaseline lube for the temperature sensor valve in the fuel filter can. The dealer futzed around with that valve--even lost the clamp--left me with baling wire. Anyway, my point is that the one-time 15 degree stallout might have no connection with the 72 mph shudder which is what this thread is supposed to be about. Thanks
==========================
Dr Dotgain
 

Doug the bug

Veteran Member
Joined
Oct 18, 2000
Location
Barrie, Ontario
Hey wazzup Doc?
Seems like you and I have alot of the same symptoms. I went through the timing thing around the same time as you last fall. I have never had the stall thing happen but I do have a stutter when engine load is light with RPM in the 2500 to 3200 range. It hadn't been happening over the coldest months of this winter but now temps are between -15*C and 0*C and the last few days I have noticed it again.
I wonder if my TB is stretching again or it's temp related. Or maybe fuel? It would be nice to hear of someone having had and solved this one.
 

Dr. Dotgain

Veteran Member
Joined
Dec 29, 1999
Location
RI USA
TDI
2000 TDI GL 5-speed
Hey Doug,

Yeah seems we have clones --- smokin' buddies.

I think the cold morning stall was Mickey's O-ring grease thing. The fuel filter had been changed immediately before that problem occurred and it has not re-occurred since my Eastern European friend re-serviced the filter.

Re: "timing belt stretch," Is the injection timing driven by the cam timing belt?

What other characteristics besides the fuel injection timing adjustment do we share or have different?
...
5speed? (of course)
...
1.9 liter 90hp both
...
2000 Golf 2door German assembly factory vs 2000 NB 2door assembled in Mexico but do we share a common engine factory? Date of manufacture?
...
Do you get mediocre mileage? I'm a little disappointed when I compared with the rest of the TDI forum. I would estimate my fuel comsumption in mpg vs average mph is something like 46@60, 45@65, 44@70, 43@75, 42@80. (Sorry about the nonmetric dimensions.) The avg speed here is a sheer guess, but heavy traffic, highway construction, rain, and police presence do increase my mileage a bit.
...
5 mph shudder when braking to a stop, neutral engaged. You?
...
RPM at which peak torque occurs is specified as 1900 RPM but my torque curve as judged by the seat of the pants method seems like it peaks @ 2400-2600 RPM. You?
===================================
Dr. Dotgain
Y2k Golf TDI 90hp 155#' @ 1900rpm
GL 2dr 5sp 28,000 mi/yr Anniversary Feb 26
 

Dr. Dotgain

Veteran Member
Joined
Dec 29, 1999
Location
RI USA
TDI
2000 TDI GL 5-speed
I found these quotes in the many threads on slow speed shudder and the new Intermittent Rough Power Delivery thread. I collect them here because they represent possible sightings of high speed shudder.

On December 09, 2000 Driv'n EZ posted an observation of shudder under light power
demands:

"I get this when I have a very light foot on the go pedal,
whether I am increasing or decreasing speed. Almost like
coasting, as MBC3 described."

On February 09, 2001 Diesel Fan posted a similar observation,
and this in the absence of the slow-speed shudder (unless
he or she neglected to disclose a disengaged clutch):

"Driv'n EZ, I have the same problem that you describe.
A very light application of the go pedal will cause the shudder.
It is annoying. I have not really noticed it when coming to a stop
because the last 25 yards or so I usually take the car out of gear
and just roll to a stop with the shifter in neutral. I'll have to see
if I get the same symptom when leaving the car in gear. I have
also noticed that the shudder is worse on some days than on others.
...
Just got the car a week ago."

On February 23, 2001 Lance Allison posted another sighting, this one on a chipped 1998:

"I've been experiencing a strange problem that's
never happened in the past. For the past week or
so, my car has a slight (<25%) reduction in power
followed by a fast shudder. The shudder is different
than the one at low RPM that many here have. It seems
to come on the worst under light acceleration and
any RPM level. Speed doesn't matter either. I cleaned
the MAF and it cleared up for a few days, but is now
back (not as evident as before). On an aside, it was
rather wet this morning. Any ideas?"

Adding me and Doug The Bug, it appears that there are at least five TDI owners posting their observations.

==============================================
Dr. Dotgain
2000 Golf GL TDI 5speed 28,000 miles
 

Dr. Dotgain

Veteran Member
Joined
Dec 29, 1999
Location
RI USA
TDI
2000 TDI GL 5-speed
OK, take Lance's 98 Jetta TDI off the list; he claims the MAF was installed tilted 60 degrees of axis and the shudder went away when he verticalized it. I'm wondering if I could learn from Lance's anecdote. Maybe I should clean my MAF, or at least check its allignment.

Now there's only four owners reporting sightings of high speed shudder: Dr. Dotgain, DougTheBug, DrivinEZ, & DieselFan.

This is a forum? Seems more like a monologue. I will keep myself informed of my progress, but how will I remember to find out how I will have fixed it? Oh yes ... the bookmark!

========================
Dr. Dotgain
2000 Golf GL TDI 5-speed bone stock
 

Doug the bug

Veteran Member
Joined
Oct 18, 2000
Location
Barrie, Ontario
I must appologize good Dr.,
I have been out of town the last week. Business has taken me as far North as you can go by road in Ontario, Canada (Way past where TAzz lives).

All that excitement aside it sounds like you have done a fair amount of research on this topic. I have not looked at my MAF sensor yet either but have been waiting for my new Piper Cross from TAzz and plan to have a peak when I install that.
My car is a 2000 Jetta 5 speed manual...pretty sure it was manuf'd in Mexico. It continues to do that shudder this past week, again I only notice it when between about 2400 to 3200 RPM with very light, constant pressure on accelerator. If I am Accelerating to speed I will not notice it. If in gear and foot off pedal I do not notice it. Also in 5th I rarely notice it.
Mileage has been quite good for this trip approx. 1000 km for 50litres o'diesel. Generally power seems good. just that little something less than smooth with light pedal and light engine load.
Hope we can find some people who used to have this experience.
Regards

------------------
2000 Jetta TDI
Cool White with Road Salt Hi-lites
 

Doug the bug

Veteran Member
Joined
Oct 18, 2000
Location
Barrie, Ontario
Ah yes I almost forgot about the slow down shudder... I had it for awhile about 20k km ago (When car was at 30 - 35k km) it was quit frequent ...almost every stop for about 6k km now it is very intermittent in fact I would call it rare.
 

Dr. Dotgain

Veteran Member
Joined
Dec 29, 1999
Location
RI USA
TDI
2000 TDI GL 5-speed
Hi Doug,

Converted your fuel consumption to mileage 1000 km / 50 lit = 46.9 mpg. What was you avg speed?

I converted the range during which your slowdown shudder was observed 30-35 kkm = 18.6-21.7 kmi. I felt it right about there too.

I can't figure out why you do not feel the highspeed shudder in fifth gear, light throttle, 2400-2500 rpm, 116-121 kmph, 72-75 mph if you are feeling it in lower gears. Why are you not upshifting at 3200 with a light throttle if you are not in top gear? I tried your style first thing this morning, ambient temp 20* F, -7* C, cold engine, 3rd gear, 2500 rpm, and set the cruise control on a level boulevard ... Shudder-city! When the engine is cold I get a distinctly louder diesel clatter when applying a light throttle and no clatter when coasting under no throttle. The power demands from the cruise control was intermittent, so the clatter was going on-and-off and each time the floor pan was jumping around like a ... like a ... hmmmmmm ... like an orgasm on the mogul slope? Turned off the cruise and did it again using light throttle. Did it in fourth gear too. OK, here's my latest theory: High speed shudder is a type of control overshoot or hysteresis which occurs when the engine torque pushes the car to a speed higher than what the ECM believes is correct for the current throttle position, causing it to cut the fuel flow, slowing the car to a speed that is below what the ECM believes is correct for the current throttle position. And so on ...

Speaking of sudden fuel cutoff, when you use cruise control and you squeeze the accelerate switch does it take about 2 seconds before it takes effect like a rocket (compressing the springs in the seatback), and when you release the accelerate switch does it chop off the fuel supply so fast the springs in the seatback throw you forward? Reeeeeeeal refined
Do you have to press the coast button for about 5-7 seconds before the fuel supply is overly geeeeeeently tapered off? You call that refined or unsafe?
I usually give a slight touch on the clutch pedal and then hit the coast button. Do all A4 TDI cruise controls work like this?

Dr. Dotgain
2000 Golf GL TDI 5-speed one-year-old 28,000 miles (45,000 km)
 

Dr. Dotgain

Veteran Member
Joined
Dec 29, 1999
Location
RI USA
TDI
2000 TDI GL 5-speed
DougTheBug, DrivinEZ, & DieselFan,

Check out the "Vibrations may be the dealer's fault" thread. Did you folks ever notice engine oil was overfilled when getting free oil changes?

Dr. Dotgain
2000 Golf TDI
 

Doug the bug

Veteran Member
Joined
Oct 18, 2000
Location
Barrie, Ontario
I have only used the cruise control once or twice. It's something I just don't use. reminds me of a story I heard about a guy in eatern Canada who got a new camping van with all the toys...he set the cruise and then went in the back to make breakfast...
My average speed on that last tank would be hard to say ...various road conditions anywhere from 80 km/hr to 140.
The driving situation that most typically puts me in the 3000RPM range with light load on engine is for example someone ahead of me decideing to change into my lane while I am accelerating to speed ... this will cause me to lift off the accelerator briefly to watch while the driver ahead realizes what they have done. Some times they will correct halfway through the lane change and sometimes they won't know what they have done. In any case I like them to settle in to whatever lane they feel is most appropriate before I blow past them. Safety first of course. I will go check the thread you mentioned.
Doug
 

Dr. Dotgain

Veteran Member
Joined
Dec 29, 1999
Location
RI USA
TDI
2000 TDI GL 5-speed
The problem manifested itself as an obvious shudder at 1/4 throttle when turning 2500 rpm.


I demonstrated the problem to the Service Dept at Scott Motors East Providence, RI and they fixed it by installing a new Bosch VE fuel injection timing pump. After 3 days and 360 miles I can report I have no noticeable shudder at 2500 rpm so far!


Torque seems about the same, maybe slightly improved. Well, if it's really improved it should show up in the fuel economy numbers. My average over 34,000 miles is a somewhat disappointing 43 mpg or 18.34 km per liter.

Also I seem unable to create the "slowdown shudder" (10 mph or 16 kmph, braking, neutral engaged, clutch released), whereas before it was prevalent (and not too worrisome). While some say replacing the ECU fixes that, and some say replace the dual mass flywheel with another dual mass, and others say the replacement should be a Sachs clutch (w/springs) and a solid Corrado flywheel, I say (with some reservation) it's the fuel injection timing pump (unless that irksome devilish shudder returns)!

Hey! Anyone know if the new VE pump should be broken in slowly or can I just crank on it right out of the box? (Oops, too late)
 

gfs

Member
Joined
Jul 26, 2003
Location
Cleveland, OH
TDI
Jetta, 2010, black
Hey all. I've noticed the exact same thing lately...

"I feel a shudder like intermittent fuel supply while coasting down from 75->72 mph (117 kph) in 5th gear."

The only diagnostic I can provide is that I had a fuel gelling problem recently which caused me to crank the engine and the injector pump dry. It actually threw a CEL (dont remember the code) while I was cranking. After this, I noticed the shudder phenom. Fuel econ. remains stable.

I've got a 2000 Jetta, TDI w/130K - all OEM.

I hate to think it's the injector pump ($$$$) although it sounds reasonable... could it be indicative of a clogged intake ? - any optimists out there ?
 
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