04 PD - Runs rough when cold, dies when running hot

Hi guys,

Have an interesting issue at hand here and need some input from the experts.
My car is an 04 PD Jetta with 267K miles on it. All stock. 5 speed.
New turbo @ 160K and maintenance is up to date.

Symptoms:
On a cold start, if I try to drive the car right away, it runs rough and shudders. If I continue driving normally (shifting around 2,500 rpm), it runs really rough and sounds like it runs on 3 cylinders.
To fix that, I have 2 options:
1. Drive very gently and nurse it until the engine warms up to normal operating temps (nursing here means I accelerate gently and shift early, around 2K rpm)
2. Shut it off, remove the key and leave it off for 2 - 3 mins, then start again.
I keep doing this until the engine warms up to normal temps, then it drives with no issues at all.
If I try to drive it when it's on 3 cylinders, check engine light (CEL) will come on and it'll throw codes (more details below)

Up until last week, this cold start issue is the only issue I had. Once the engine temp was up to normal, it ran beautifully.

Last week, it started doing something else in addition to the cold start issue; while driving normally (engine at normal operating temps), the car would simply die. Just turn off. It doesn't matter what I'm doing, it happened while I was accelerating, sitting in traffic, or cruising on the highway. It just dies. The only common thing I noticed when it dies is that it's usually hot outside or I'd be sitting in traffic so there's some stress.
Once it dies, I have to let it sit until it cools down, then I can restart it again with no issues at all. If it sits for too long and the engine temp drops, then I have to go through the cold start issues detailed above.

If it dies, and I try restarting it before it cools down, I'll get the flashing Glow Plug light along with the same codes as the cold start issues (codes are highlighted below). The car would crank, but wouldn't start.

Codes:
Using Torque, the codes I get in both occasions are:
- P0203 - Powertrain Injector circuit - Cylinder #3
- P0674 - Powertrain
- P0727 - Engine Speed Input Circuit No Signal

If I drive it gently, nurse it up to normal temps and have an easy drive where it's cool outside, the car will run with no issues and the CEL will eventually turn off (the codes will remain stored though). Once I have any of the issues above (cold start or dies), CEL will come back on and I'll get these same codes.

Searching the forums, I found that there could be multiple remedies for these codes:
P0203: Open valve cover and clean wire to injector
P0727: check wires to cam & crank sensors

I've already replaced the Glow Plug harness. Wasn't sure about it, but I wanted to eliminate it as it sounded like it could cause many issues.

This weekend, I intend to:
Do the 2 things to remedy P0203 & P0727 as well as test the resistance on the glow plugs using the excellent Glow Plug 101 thread

I know the lift pump in the tank is good, as I just replaced it a couple of months ago and can hear it buzzing every time I turn on the ignition.

To my mind, the biggest suspect is the second fuel pump, under the hood. That issue where it does when it's running hot then runs fine when it cools down is a classical fuel pump issue (in gas cars) when the pump is on it's last legs. This being a pump that's original has me suspecting it.

What do you guys think? Any other ideas on what might be wrong?

Thank you for reading and sorry for the long write-up. Just trying to be thorough.

P.S: I found this link to a very nice PDF document that explains how the PD engine works. Don't recall seeing it in the stickies, but I found it beneficial in understanding how the engine works and is fueled.

Before guessing at parts ($$$) I would check the crank sensor wiring for frayed wires or such, and continuity (resistance) from the ECU plug through the sensor.
Wiggle the wires around the sensor and along the route it takes.
As long as the ECU is unplugged measure the resistance from the ECU plug to through each injector.
You will have to lookup what resistance the crank sensor is.
Good link BTW.

Check out the ross-teck wiki site for thorough insight for the DTC's.

Thanks guys, stepping out now to check the sensor wires and take some measurements with the ohm meter... More to come on my findings

Sent from my VS988 using Tapatalk

Ok guys - just came back in as it started raining...
Did the glow plug test, resistance is 0.7 ohms across the board. Check.

Did the voltage check on the new harness I just installed; 7.5V once the ignition key is started, drops to 4.5V for a few seconds, then trails down from there to 0.5V. Glow Plug 101 thread said I should see 12V, the voltage never approached 12V in the 3 times I did the test. Test was performed with the coolant sensor unplugged, as the instructions specified.

What I don't understand is that if the voltage was indeed low, the glow plugs wouldn't heat up enough. So, the engine will have difficulty starting. This is not the case I'm seeing. The engine has no issues firing up at 2 - 3 cranks of the starter.

Checking the crank sensor wiring, everything looked good. All wires looked good. The only thing is that the yellow spout that holds the dipstick came off a few months ago, so my whole engine bay is covered in oil spray. I took out both sensor plugs and cleaned them thoroughly with electronics cleaner spray.

Looking up the codes on Ross-teck wiki, I couldn't find anything about 2 of the codes. Only P0674, and the recommendation was to check glow plug wiring, which I just did (finding the low voltage).

My next stop is to start looking at the injectors. To my mind, it would explain both issues I'm having.
For the engine to die suddenly, one of the 3 vital ingredients has to be missing (air, fuel & spark). Diesel engines don't need spark, so it's air or fuel. So, I'll lift the engine cover and take a look at the injectors.
One more thing I noticed is that the fuel lines from the pump under the hood are a little cracked. Nothing looked wet with fuel, or leaking, but it may have something to do with my issue. We'll see.

Keep you guys posted with my findings, and would appreciate if anyone would comment on the low voltage I'm finding at the harness.

Thanks!

Check this thread over in the 101 subforum as some of what you're experiencing sounds like it's also happening for this guy...

http://forums.tdiclub.com/showthread.php?t=473685

I'm not clear on the glow plugs but I know there are different voltage plugs.
They pulse the voltage to get the effective voltage that the glow plug needs from the 'plug trigger control module. (or such)

Oil in the connectors pins would not be good.

You need a meter and wire diagram to test the wires for continuity and shorts.
With engine vibration the insulation over the wires could be cracked and that covered with the sheathing.

Is there a clear fuel line going from the fuel filter to the pump or such?
With the car running there should not be bubbles in it.
In reality I don't think many do not have any.
I have some tiny bubbles.

@OlyTDI
Awesome thread! Does sound exactly like my cold start issue. He hasn't stepped up to the 'dies when warm' part though
I'll take a look at the fuel temp sensor tomorrow morning, it makes perfect sense that it would be a culprit in my case.

Will keep you guys posted.

Sent from my VS988 using Tapatalk

wonneber said:

I'm not clear on the glow plugs but I know there are different voltage plugs.
They pulse the voltage to get the effective voltage that the glow plug needs from the 'plug trigger control module. (or such)

Oil in the connectors pins would not be good.

You need a meter and wire diagram to test the wires for continuity and shorts.
With engine vibration the insulation over the wires could be cracked and that covered with the sheathing.

Is there a clear fuel line going from the fuel filter to the pump or such?
With the car running there should not be bubbles in it.
In reality I don't think many do not have any.
I have some tiny bubbles.

Click to expand...

You're absolutely right about the oil on the connectors; I cleaned them all with the electrical contact cleaner and they all look brand new now. Cleaning the whole engine bay is my next step once I get the car running properly again.

Haven't taken the time to test every connection today, but what you're saying makes sense. Reality is that the car is 13 years old now. Wire sheathing does crack, and I'm feeling I'll start replacing harnesses for the coming months as the connections & wires deteriorate. Last year it was the alternator harness that needed replacement. This year, there's this issue.

Haven't looked at the clear fuel line yet; tried looking for it while under the hood today but all the lines I saw were black. Will trace the lines from the filter to the pump tomorrow to see where that clear line is, and if it has any bubbles.

My gut feeling tells me my issue is around the fuel temp sensor, but it won't hurt to check the fuel line as well. Thank you for the suggestion.

Will report back once I do my trace tomorrow morning

Thanks guys!

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amrrashad said:

Haven't looked at the clear fuel line yet; tried looking for it while under the hood today but all the lines I saw were black. Will trace the lines from the filter to the pump tomorrow to see where that clear line is, and if it has any bubbles.

My gut feeling tells me my issue is around the fuel temp sensor, but it won't hurt to check the fuel line as well. Thank you for the suggestion.

Click to expand...

If you don't see the clear line easily then the PD engine may not have it.
Others may comment on it.

1st thing cold in the AM when you test the fuel temp sensor it should be about the same temp as the coolant temp.
Also you shouldn't have to start the car, only turn the key on.
Once you have the temp start the car and the fuel temp should rise.

Cold start issues

If your car starts....no way it's glow plugs...sounds like a fuel issue, when was the last time you changed you fuel filter and or air filter...start simple and work in to the hard stuff...vag-com will definitely help!

wonneber said:

If you don't see the clear line easily then the PD engine may not have it.
Others may comment on it.
1st thing cold in the AM when you test the fuel temp sensor it should be about the same temp as the coolant temp.
Also you shouldn't have to start the car, only turn the key on.
Once you have the temp start the car and the fuel temp should rise.

Click to expand...

Agreed. I checked all connections yesterday but couldn't find anything staring at me. No clear fuel lines either. Mine were all thick black lines.

I'm thinking I need VCDS, it's the only way to see what the ECU is seeing and make some real progress. Otherwise, it's a big guessing game. Hoping I'll find one of the local gurus who can help me out.

Geobmx4life said:

If your car starts....no way it's glow plugs...sounds like a fuel issue, when was the last time you changed you fuel filter and or air filter...start simple and work in to the hard stuff...vag-com will definitely help!

Click to expand...

Yes, I agree. It sounds like a fueling issue to me too. Both filters were changed earlier this year.
Agree on VCDS; I'm going on the forums now so look for a local guru who can help.

Car is driveable, which is a good thing. Want to solve this issue before it gets any worse and I'm not able to drive it at all

Thanks guys!

A quick update on this thread...
With help from a very generous VCDS owner, who turned out to live in the next town over, I was able scan the car for codes...

8 faults found:
16706 - Engine Speed Sensor (G28)
P0322 - 000 - No Signal - Intermittent

19463 - Camshaft Position Sensor (G40)
P3007 - 000 - No Signal - Intermittent

17058 - Cylinder 4 Glow Plug Circuit (Q13)
P0674 - 000 - Electrical Fault

18076 - PD Unit Injector; Cylinder 3 (N242)
P1668 - 000 - Electrical Malfunction - Intermittent

16502 - Engine Coolant Temp Sensor (G62)
P0118 - 000 - Signal Too High - Intermittent

17055 - Cylinder 1 Glow Plug Circuit (Q10)
P0671 - 000 - Electrical Fault - Intermittent

17056 - Cylinder 2 Glow Plug Circuit (Q11)
P0672 - 000 - Electrical Fault - Intermittent

17057 - Cylinder 3 Glow Plug Circuit (Q12)
P0673 - 000 - Electrical Fault - Intermittent

I'm thinking the codes on the Glow Plug Circuit were thrown when I was testing out the circuit last weekend, so there's no need to do anything there.
The PD Unit injector on cylinder 3 is interesting... will leave this one till the end, although I have a feeling this is the one making it hard to run on cold start.

My course of action for now is:
- Change out the Cam position sensor, crank position sensor (Engine Speed sensor) along with the coolant temp sensor
- Clean out the oil residue in the engine bay on all electrical connections as well as whole engine
- Reset the codes

Let me know if there's anything else you think I'm missing

Thanks

Before you start throwing $$ into parts you might not need do more testing.

If you have the Bentley manual maybe start measuring continuity to the crank, cam, and other (non glow plug for now) codes.

To many things wrong at once, I'm skeptical they all went bad at once.

Maybe even check the ECU grounds under the cowl and the one under the battery tray.

When the car dies do you notice if the tach and speed MPH drop down also?

wonneber said:

Before you start throwing $$ into parts you might not need do more testing.

If you have the Bentley manual maybe start measuring continuity to the crank, cam, and other (non glow plug for now) codes.

To many things wrong at once, I'm skeptical they all went bad at once.

Maybe even check the ECU grounds under the cowl and the one under the battery tray.

When the car dies do you notice if the tach and speed MPH drop down also?

Click to expand...

I'm skeptical as well, but then, I haven't changed any of those sensors since I bought the car 8 years ago with 120K miles on it. Today, it almost has 270K miles, so I was thinking it maybe time for them to be replaced.

In case my original thread wasn't clear, the cold start problems started first, a few months ago, following by the engine suddenly dying while driving a couple of weeks ago. So, there was kind of progress.

And now that you mentioned it, I do remember the speedo & tach dying when the car died on the highway last week. The tach diying makes sense, because the engine died. But the speedo? Why would it drop to 0?

I have the bentley manualy; will lookup the continuity tests and do some more testing... maybe the problem is smaller than I thought.

If you have any comments on the speedo dying, would appreciate the input

Thanks

Correction, car died yesterday on my way back from work. Speedo was working.

When the engine cut out; tach died, and the glow plug light flashed a couple of times. Wouldn't start, but would crank.
Left it to cool down, then it caught right up.

All I had to do to make the engine die is to rev it up a bit between the gears; nothing too crazy, somewhere between 2.5 & 3k rpm for a couple of shifts is enough to induce enough stress to make it happen.
As long as I shift around 2k rpm, and accelerate gently, car will run all day wothout a hiccup (as long as it's warm)

OK, sounds like relay 109 is working OK.
Not an expensive one anyway.

I'm starting to wonder if you have bad wiring, frayed or cracked inside the outer sheeting.

Like the other thread linked above, I found that my harness is spliced in a couple of places from fixes prior to my ownership.

Bought electronics cleaner spray today and will be using it extensively in the area to clean all the wires from the oily residue.
If that doesn't work, then I'll start replacing the sensors, one after the other, starting with the crank. That's the one that seems to make ECUs go crazy and report errors like the one I'm seeing

amrrashad said:

Like the other thread linked above, I found that my harness is spliced in a couple of places from fixes prior to my ownership.

Bought electronics cleaner spray today and will be using it extensively in the area to clean all the wires from the oily residue.
If that doesn't work, then I'll start replacing the sensors, one after the other, starting with the crank. That's the one that seems to make ECUs go crazy and report errors like the one I'm seeing

Click to expand...

Now I'm wondering if one of the repairs missed something not in the area or the harness itself is just deteriorating?

Crank sensor problem should only throw 1 code.
If its cheap you could give it a try.

I would test it for continuity.
I didn't find specs in the Bentley with a quick scan.

Got the Bentley manual today and will be doing some continuity testing over the course of this week.

Deteriorating harness is definitely a possibikity given the splicing that's taken place and the fact that the car is 13 years old

Will keep you posted

Dipstick holder

Bought electronics cleaner spray today and will be using it extensively in the area to clean all the wires from the oily residue.

You can get a dipstick holder for around $7 at fixmyvw.com

Happy to report that I've been able to fix both issues that my car was having.
It was the crank position sensor.
Cured both issues as soon as I put the new one in.

Thank you all for your help and advice

Another quick update to this thread; shortly after changing the crank position sensor, the cold start problems resurfaced, and wouldn't go away. The car would basically run on 3 cylinders until it warmed up, then I would just park on the side of the road, shut it off, start it, and it would run perfectly.

After doing some research, I performed the injector wire loom repair/hack in this video:
https://www.youtube.com/watch?v=L5vmJ1_-Nrw

Also cleaned the connections with electrical connection cleaner, so make sure the contacts are good. Everything looked clean, no rust anywhere and the wire loom looked to be in perfect condition.

Car works perfectly now and is happy to rev through the whole rpm range without any hiccups.

Thanks again everyone