Automatic randomly stalling

Have a 2006 Jetta BRM 250K miles. Got it previous owner with a myriad of problems. Wouldn't start right away without a jump, wires everywhere were chafed or broken, had virtually no acceleration and would stall out every time the car stopped. It is definitely not related to cold weather.

Fixed wires, replaced cam, waterpump, EGR, head gasket, timing belt, fuel pump, air/oil/fuel/trans filters, cleaned injectors and replaced seals.

Now for my issue(s): Very occasionally (sometimes after 1K miles, 30 miles or 2 miles) I will start to lose power in acceleration to where pressing the gas doesn't make the car go unless I swap over to 'manual' and downshift then it will chug along for a bit but eventually still stall out. Sometimes it will happen when I'm coasting at a constant speed and other times it happens when coming to a stop and the trans starts to downshift. I managed to milk it pretty good today between 3 and 4. It started losing power in 4 so I dropped to 3 and rev'd high to get acceleration then shifted up and got a little of power but it kept fighting to die.

Every time after stalling out the motor will try to turnover but won't actually crank. I either have to let it sit or keep the key turned for like a minute or two constantly to get it to catch and fire up. Sometimes it will drive just fine for a long period of time but today it happened like 5 times in 6 miles.

NEED HELP!

I don't have a fancy code reader, just a basic one but no codes or errors are on the dash or show up.

Also, unsure if this is related, whenever I try to 'gun it' when in 6 to pass someone the car struggles and feels like it just chug chug chugs along to barely increase speed.

Without any info to go on I looked to change the flywheel for the potential culprit for the shifting problems. It was very loose and a pain but it eliminated my hard shifting and chugging when I try to floor it to pass someone in 6.

It did die once after this but it was more abrupt than before as I was trying to accelerate more. For this I looked to the tandem pump. I didn't notice any poor fuel mileage or anything chattering or loud. Just that when the car would cut out, it wouldn't start right back up thinking it either needed fuel or air but wasn't getting either. Also trying to start it again would greatly drain some fuel.

Also, went ahead and replaced the vacuum lines because they were a cluster of crap routing.

You will need to locate someone with a proper scan tool. There is a section in this forum for locating vcds owners. Most of them will gladly help a fellow tdi owner.

Without it is just throwing shots in the dark, and a generic obdii scanner wont cut it because that will just show the emissions related codes. There are way more vw specific codes that the generic scanner cant see. These cars have powerful on board diagnostics. Just need the correct tool to acces .

Not to dig up an old thread but did you ever figure out what was wrong? My Jetta is basically in same boat as yours and I’m at a loss as to what is wrong. Going to buy a scan room here soon but was wondering if you ever had any solutions? Thank you!

If you get a scan tool get the real thing at Ross-tech.com . Don’t bother with the crap eBay Chinese illegal clone junk.

Clean and check the grounds under the battery tray and immediate area. Those are a know issue with 06’s.

Sounds to me like fuel starvation. Assuming the fuel filter isn't neglected (these have a 20k mile service interval, and they are not kidding, PDs can clog fuel filters at 22k miles... seen it MANY times). Then go for the lift pump in the tank. You can take the back seat up and listen for it running. If it is dead, it may be that the tandem pump just cannot keep up. Tandem pumps rarely fail to the point they cannot pump fuel so long as the lift pump is providing a supply from the tank. Tandem pump failure mode is usually an external fuel leak.

oilhammer said:

Sounds to me like fuel starvation. Assuming the fuel filter isn't neglected (these have a 20k mile service interval, and they are not kidding, PDs can clog fuel filters at 22k miles... seen it MANY times). Then go for the lift pump in the tank. You can take the back seat up and listen for it running. If it is dead, it may be that the tandem pump just cannot keep up. Tandem pumps rarely fail to the point they cannot pump fuel so long as the lift pump is providing a supply from the tank. Tandem pump failure mode is usually an external fuel leak.

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I also had the same problem Oilhammer is mentioning, fuel starvation caused by a clogged filter, same symptoms as the OP. A friend of mine with a Passat gasser experienced the same symptoms, I have identified the problem to be caused by the control module located on top of the in-tank fuel pump, under the rear bench.

Wel, my rear bench isn’t in the car so I’ll listen to hear anything back there. Fuel filter was changed less than 2000 miles ago so I’ll look to test intank fuel pump first then go to tandem pump. Thanks for the help guys and yeah, I’m getting the Ross tech tool from USP that’s $200. Will report back with findings!

relumalutan said:

I also had the same problem Oilhammer is mentioning, fuel starvation caused by a clogged filter, same symptoms as the OP. A friend of mine with a Passat gasser experienced the same symptoms, I have identified the problem to be caused by the control module located on top of the in-tank fuel pump, under the rear bench.

Click to expand...

The gassers have a common failure point with the fuel pump control module. So much, they issued a recall. TDIs do not use those, however.

oilhammer said:

The gassers have a common failure point with the fuel pump control module. So much, they issued a recall. TDIs do not use those, however.

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Yeah, tried to hear for any activity near the rear seats today and heard nothing with my ear right by where the in tank pump is so that may be an issue

Here’s graphs of my MAF and idle RPM, can’t read much else with a generic Bluetooth tool. Will report back once I get the vagcom tool.