Highway speed car jerks you forward ?!?!?! help ?!?!?!?

:Edit post:

I started this thread while on vacation in geargia!
I had a problem with my car jerking while driving/cruising down the road.
It appeared only to happen when I crested hills(under load trying to hold speed, going up the hill would seem fine, but at the peak the car would jerk you forward.

My friend explained it as "it almost feels like the car loses fuel, shuts off, and then cranks back up."
it made sense, but the rpms would not budge, and speed was not effected.

After short diagnosis, and 2pages of replies I changed my fuel filter.
Read my posts, the filter had been in the car since I bought(oct2008)

on the drive back to Florida, from Georgia, these "jerks" went from about 30 jerks in 3 hours,
to 2 jerks in the same time frame(30 jerks from fl to ga::replaced filter::2 jerks from ga to fl)

since this trip it has only happened a couple of times, twice coming back from georgia, and twice since then.

The most recent jerk was on the way to the beach, 5th gear at 45ishMPH.

I began thinking it was just the new filter letting in air for the first couple of jerks, now it has been TWO MONTHS and I still have this issue.

Can anyone help??

I have ideas as to why it's doing what it's doing, but don't want to get more confusion in my thread. Thanks for your time reading all this.


::: I EDITED THE ENTIRE ORIGINAL POST :::

fuel issue? ... how old is your fuel filter?, what is your IQ set at? any odd noises coming from your injection pump? any air bubbles in your fuel line while the engine is running?

also if you have vagcom, check your timing to make sure all is within spec...if you cant handly any of this find a local Trusted TDI mechanic

Okay so get this!

Fuel Filter has not been touched since I bought the car!
I've had it two years.

My idea, Between possible algaeing, and gelling, and a known bad filter(replace in a year and I haven't in two years)
guess it clogs it up and then sucks through


So I need this anawered.

I'm guessing it's stressing my injection pump, is it an issue driving around town and such?
Or will this cause more issues?

It is an issue, if it is clogged. You need to get it replaced to rule it out. Yes it is hard on your IP, if it is clogged.

You need to fill the filter up with fuel when you put the new one in. Fill it through the thermo tee hole. Sometimes you need to prime the system when replacing the fuel filter, which requires a hand vacuum pump (MityVac) or something similar.

Go see Scott Krout if you have any doubts.

What codes is it throwing? That will help a lot in diagnosing it.. swapping out the fuel filter is a good idea, especially if it hasn't been done since you've owned the car.. who knows how old it is..

Don't know the codes it's throwing.
Just CEL and FLASHING glow plug light(curly cue)

I'm in a small town, on vacation, there isn't a European specialist that I know of. Tha could run a vagcom.

I purchased a fuel filter through autozone(surprisingly they had on in stock)
I will install that soon.

Aside from that, the hoses into the filter appear to be dry rotted(on the rubber part). Could they be letting air in? Causing this issue.
It DID appear that there was small bubbles in the line while te car runs.
And it DID appear while the car was off there is not the usual bubble in the clear line.(usually that bubble is a half inch, now isn't a tiny bubble, practically non existent.

If I don't have mightyvac I can still prime it manually

Crack injector and turn the motor over til rag is wet, tighten.
Crack next injector turn motor over rag is wet, tighten and move to 3rd,
and then 4th.


I used this procedure when I replaced my nozzles,
filling up the injection pump with fuel as well.


Anyone else having this issue?

Scott Krout was mentioning diesel could gel up.
So I figure, if the filters bad and it's geling that could affect my issue as well.
He mentioned his car was running funky as well.


I'm near Macon GA if anyone can help I would buy you a case of beer!!!

getting the fuel through the injectors isnt the problem when putting a new fuel filter in, its priming it, it can drain your battery if its empty, takes a good while to fill it up cranking the engine.

you need to scan it for codes.. you don't need a european specialist, any code reader will do the trick, even the one at autozone. Besides, the majority of european specialists suck at TDI's anyway.. Just write down the code number and post it..

as far as filling the fuel filter manually, fill it up with fuel before attempting to start it. put some diesel in a bottle and fill up the filter, or fill it up with your favorite fuel additive. Don't install it dry and expect your battery and starter to be able to fill it. The IP will take a LONG time to suck enough fuel out of the tank to fill it up.. It'll start right up, run for about 4 seconds and stall.. Then you'll crank the battery dead trying to get it to purge even with the injector lines loose..

TDIJetta99 said:

you need to scan it for codes.. you don't need a european specialist, any code reader will do the trick, even the one at autozone. Besides, the majority of european specialists suck at TDI's anyway.. Just write down the code number and post it..

as far as filling the fuel filter manually, fill it up with fuel before attempting to start it. put some diesel in a bottle and fill up the filter, or fill it up with your favorite fuel additive. Don't install it dry and expect your battery and starter to be able to fill it. The IP will take a LONG time to suck enough fuel out of the tank to fill it up.. It'll start right up, run for about 4 seconds and stall.. Then you'll crank the battery dead trying to get it to purge even with the injector lines loose..

Click to expand...

I was under the impression the scanners could not read all the codes, just some. If we run back into town I'll go get it scanned.

So fill the filter with fuel, install all lines, and crank.
What else is it going to need to get everything out of the line and running smooth?
Sorry, your paragraph made me think as long as I fill the filter it should be fine.

you should be fine as long as you fill the filter with as much fuel as you possibly can.. That's the way I do it 95% of the time and it works out fine.. after you fire it up, just make sure to let it run for a few minutes before shutting off to make sure all of the air is purged out.. Best thing to do is take it for a quick drive..

If the engine light is on, then you'll get the important codes with a generic scanner.. Sometimes it won't read some of the secondary codes (the ones that don't trip the engine light), but if it's running funky and the light is on, it'll tell you something.. It's most likely setting codes for the quantity adjuster inside the injection pump. It's common enough for a clogged fuel filter to set QA codes.. You'll know right away if the fuel filter was causing the running issues when you put the new one in..

Thank you.

The car runs fine! Just the "rare" skip.
So I don't know if I'll notice it right away.

replace the filter, prime it properly and drive and see if this helps at all over a few hundred miles. I would also get the codes pulled by someone with vagcom

After replacing the fuel filter, if you still get random hesitation, maybe check the fuel sender to see if you have the restrictive check valve. Here are a couple of links:

http://forums.tdiclub.com/showthread.php?t=205619

http://forums.tdiclub.com/showthread.php?t=68872

well, without codes, EVERYONE is guessing.. Go to autozone and get the codes scanned and post it here..

THE ORIGINAL POST HAS BEEN EDITED FOR UPDATE!!

IF YOU ALREADY READ, PLEASE REREAD MY NEW/EXISTING ISSUE!!



Didn't want to start a whole new thread for the same problem.

This post is to bump my thread to the top.

Gotta get some new ideas.

Why are you ignoring everyone telling you to check your codes? Help us help you.

Haha, OOOPS. Forgot to mention that part, I check them.

Gave me::

injector #3 Something about bad connection.

And

EGR. Bad ground connection

Cleared codes and they never returned, was told if it doesn't return then it probably just flashed the codes cause of the jerking.(in the period my car has been doing this it only flashed the code ONCE, reset it within acouple of days and hasn't returned)

I checked the codes over a month ago so I can't remevmber what numbers they flashed.

It might be your crank sensor, it seems like you have a fuel problem when it fails. It will throw a code and your glow plug at the same time. It will crank and run for a while and then do the same thing. It does need to be read with a vagcom to be sure.

Will vagcom still read codes even though I no longer have a cel and flashing glowplug light??

I know my temp sensor is bad, or going bad.
I was driving acouple days ago, after driving for a while, the temp is just jumping all over, no heat on or ac, was at 190, then jump to 0and come back to "about" 100 an back to 0 and up to 190.

It only gave me that particular problem once, but it has been Consistently acting funy on startup. Crank up the motor, drive, when it gets 3/4 to nrmal operating temp, the temp sensor would drop back down to 1/4 to normal operating temp, and without stopping, it would imediatly go back to 3/4 to normal operating temp and then creep to 190, normal operating temp.


Could the bad temp sensor be causing this jerkIng effect?

There can be stored codes, even if you have no CEL.

The temperature sensor will vary fueling, and can cause a change in motion. It is as if you had a sudden decrease or increase in fueling - maybe 10% change.

If the jerk is as if the car shuts off fuel completely and then immediately restores fuel that is probably an intermittent wiring issue on the crank sensor. This is pretty violent, a jerk, not just a surge.

There are actually two temperature sensors in the same housing. One feeds the engine controls, the other the instrument cluster. So an erratic instrument cluster temperature gauge does not necessarily mean your ECU is seeing erratic temperatures. You can run a log with VCDS and tell for sure.

The VCDS would show an erratic crank sensor problem very clearly. You see downward spikes on RPM that are much more rapid than what happens to the car speed. I saw a good example of this just yesterday. It did have a code for intermittent crank sensor. We cleared it and drove it two miles. During the two miles we had at least 100 jerks from the intermittent crank sensor, but surprisingly the code was not reproduced. The VCDS showed the sudden drops in rpm very well.

Since the difference (between crank sensor and temp sensor) is subjective, and you know your temperature sensor or wiring is bad, I would definitely start with a temperature sensor change.

The temp sensor is about $20, the crank speed sensor about $65, if memory serves. Both are easy to install on your car.

When you post the codes, post the numbers, not just vague remembrances of the wording.

If you want long distance help, you have to provide details to work with.

"I feel ya" on posting the number of code and not my ****ty discription, I just didn't have them available.

Temp sensor just got replace,by me, afew minutes ago. Filled the coolant back with distiller water and took it for a quick trip.(32$ @dealer for parts .)

I spoke with "Keith", I don't know his username. But I found him on the trusted guru page. I moved from jax to tampa, so Krout is no longer my local guy.


Keith had a similar issue, his was wiring to the injector. He kept replacing injectors and it never fixed the problem. Til he found the wires messed up(he said a long line of diagnosing on his end)

my only concern is the fact, in Georgia is did it 50 times in just afew
miles. And then I replaced the fuel filter, and now it's only happened 3 times in about 1200 miles. But GET THIS! I found a fuel line to fuelfilter that could have been pinched! It was not secured tightly in the snap in clips, it was snapped half way in.
Could that very simple issue have cause my 3 hicccups?

What is the crank sensor?
The three plugs just above the CTS?? Those three plugs are all kinds of deteriorated!

Those three plugs are coolant heater glowplugs on your Mk IV manual transmission engine.

They are not important to you at all, in FL, as long as they hold the coolant back. Just tape the wires up so you have no shorts to ground.

The crank sensor is between the oil filter housing and the joint between the engine and transmission, really close to the flywheel.

Cool. I'll look into the crank sensor.
Searching on here sure didn't tell me nothin...

I have afew things to diagnose anyways........
Money money money....

Would a code 17978(vcds) immobilizer fault cause a problem like this? I have an intermittent surge/hesitation that turns on the glow plug light (no check engine). That is the only code stored, aside from a right side mirror heater (because it burned out the grid). I haven't tried to graph a reading of the crankshaft sensor, it happens so infrequently.

BUMP!!

Got my car hooked up to vag again this month(febuary) and got no codes at all!!

My timing was right on the line(top line) of being more performance.

My IQ was HALF of what it should have been!
If I remember the numbers correctly, I was around 1.4, and 3.0 is normal(correct me if I'm wrong on the normal side)

checked abunch of random things. No signs of why it should be surging.

It has happened twice this year. Once in January, that's why I got it hooked up, and once just afew days ago.



After surging this week, I parked the car, let it run, popped the hood and noticed microscopic bubbles coming through the clear hose.

The following day after driving(no surge) I parked, left it running, popped the hood, and NO tiny air bubbles coming through.

I'm guessing my problem is somewhere air is getting into the line, and it's so rare that I cannot properly diagnose it.
Let's hear some issues!