2011 TDI fuel system?

[J-Pipes]

Been having this random issue since I bought the car if it sits for a day or more. Seems like the majority of the time that it sits for a day or more, the next time I try to start it, its hard to start, cranks over many more time than normal before firing. I'm leaning towards it being fuel system related, and with the thread about the cp4/duramax lawsuit, it's got me thinking. My VP44 truck would do this when I had a leaking return line, causing the fuel system to loose prime. But so far I haven't found any leaks. I've been trying to randomly run some treatment/cleaner through the fuel, thinking maybe its dirty/sticking injectors, which has seemed to bump the mpg slightly, but still the random hard starts. Any ideas or insights appreciated.

Sent from my SM-G960U using Tapatalk

[J-Pipes]

Anyone? Just dont have the most confidence in the TDI forums. Kinda feels like asking the autozone counter kid super technical questions. Just not as confidence inspiring as the technical advice from here.

Sent from my SM-G960U using Tapatalk

[Beat68CST]

CP4 might be on it's way out...

Unfortunately had that happen to my now (EX) step-mom.
Literally rounded a corner and it died...

Bought a CP3 conversion, fully deleted it, picked up a solid 8-10mpg.

Them CP4's are junk, there's a reason the VW's have 2 lift pumps on em.

When I pulled the fuel filter screen on the CP4, there was a bunch of small fine aluminum particles, also check the FCA on the pump, it may show some as well.

[J-Pipes]

Thanks for the reply. Kinda what I'm worried about, that there's a issue in the pump that let's it slowly bleed of pressure of the system when it sets, thus needing extra cranking to fire up. Unfortunately my broke a$$ will have to just keep driving it, and hopefully if/when it goes, its within the next 90k miles that that is still supposed to be under warranty!

Sent from my SM-G960U using Tapatalk

[J-Pipes]

My random extended crank to start issue seems to be getting worse. If it is indeed the cp4 dying, does this sound right to you guys? Are they slow drawn out deaths, or sudden and catastrophic? Is this something the dealers can check? Plan to call and ask, just haven't had a chance.

Sent from my SM-G960U using Tapatalk

[Phil63]

How many miles are on it? How many miles were on it when you bought it? I believe the cp4 is covered under the emissions warranty.

[J-Pipes]

Originally Posted by Phil63

How many miles are on it? How many miles were on it when you bought it? I believe the cp4 is covered under the emissions warranty.

Yes it should be covered to 120k miles or 202? year. I bought it in may with 22k miles, have 32k on it now. Was serviced when I bought it, and I've done oil/filter and fuel filter myself again. Once running it seems fine, other than kinda scary egt's during regen, seen 1600+ the other night cruising flat on the freeway at about 75mph. Usually runs about 8-900 same area.

Sent from my SM-G960U using Tapatalk

[Empty_Pockets]

Not familiar with the tdi but check the crank n cam sensors. They can cause extended crank issues. Also the failed cp4s I've been around/heard of hardly ever show any signs of dying. They just die

[biggy238]

If they haven't changed the strategy, the ecm monitors the CKP and CMP at cranking. If the CMP isn't available, the ecm reverts back to the CKP for injection timing.
I think I damaged the tone wheel when I swapped cams, it always has a CMP Implausible signal code. Sometimes it will spin over without firing, I can let it off crank (key still on) and it will fire immediately. It takes several seconds to fire usually because of the monitoring process. Mine is an 05.5 so the strategy might have changed.

Sent from my motorola one vision using Tapatalk

[Red Sleeper]

Originally Posted by J-Pipes

Yes it should be covered to 120k miles or 202? year. I bought it in may with 22k miles, have 32k on it now. Was serviced when I bought it, and I've done oil/filter and fuel filter myself again. Once running it seems fine, other than kinda scary egt's during regen, seen 1600+ the other night cruising flat on the freeway at about 75mph. Usually runs about 8-900 same area.

Sent from my SM-G960U using Tapatalk

Mine showed similar EGT’s during regin mode. Both fans kick on full speed and the engine idles at slightly elevated RPM. When it would regin on the highway I would lay the hammer down as long as possible. Never exceeded 1700°.

[J-Pipes]

The egt's are suprising, I mean on one hand, it should be fine since that's how its designed to operate, but on the other, it seems crazy that this little stock 4cyl is running hotter than my dirty VP truck, that I thought ran plenty hot itself!

Biggy, I have no idea what the acronyms mean! But are you saying that you'd lean more towards it being a sensor issue rather than the cp4? To me it acts like my truck did when it had a leak in the return. It would loose prime of the system as it sat, then have extended crank times before firing. Although I have noticed or found any external fuel leaks on the car, thus making me think possibly the internals of the pump were getting bad, letting pressure bleed off as it sits?

Sent from my SM-G960U using Tapatalk

[biggy238]

I was just elaborating on checking the speed sensors.

I need to go back and read more on the complaint.

Sent from my motorola one vision using Tapatalk

[J-Pipes]

Well after the car sitting for a few days over Christmas, the tiny, incorrect, battery died, put in a new batter, and had a heck of a time getting it to start. Total crank time in the minutes easily, and missed badly for a solid 30+ seconds when it did fire. Going to drop it off at the dealer tonight. See what they come up with.

Sent from my SM-G960U using Tapatalk

[bracker8040]

Originally Posted by J-Pipes

Well after the car sitting for a few days over Christmas, the tiny, incorrect, battery died, put in a new batter, and had a of a time getting it to start. Total crank time in the minutes easily, and missed badly for a solid 30+ seconds when it did fire. Going to drop it off at the dealer tonight. See what they come up with.

Sent from my SM-G960U using Tapatalk

What was found?

[J-Pipes]

Oops, should have updated this. Nothing really, found a bad glow plug, which also functions as a cylinder pressure sensor apparently. But it still has the same random extended crank issue. Even did it when the guy went to start it and pull it out of their shop. I would really like to try a changing the tune, but it's just not in the cards at the moment. Was really hoping the firepunk crew was working on something for these cars, but was told no chance a few weeks ago when I dynoed the truck.

Sent from my SM-G960U using Tapatalk

[mhuggler]

Originally Posted by J-Pipes

Oops, should have updated this. Nothing really, found a bad glow plug, which also functions as a cylinder pressure sensor apparently. But it still has the same random extended crank issue. Even did it when the guy went to start it and pull it out of their shop. I would really like to try a changing the tune, but it's just not in the cards at the moment. Was really hoping the firepunk crew was working on something for these cars, but was told no chance a few weeks ago when I dynoed the truck.

Sent from my SM-G960U using Tapatalk

I'm not familiar with that fuel system, but there should be a check valve, or something acting as a check valve somewhere in the return fuel system. I'd say to replace it and see what happens; you don't have to have an external fuel leak to loose prime.

[J-Pipes]

Yeah they kept talking about some little valve or something, but said it checked out fine. I'll probably be calling them before too long anyway, all week when I would leave for work, itd wind up to almost 2k rpms, first gear I think, and start missing for a few seconds holding rpms steady, then smooth out and shift to the next gear. Parked in the garage, probably 50+ degrees in it, and had run for probably a couple minutes by this point as well.

Sent from my SM-G960U using Tapatalk

[J-Pipes]

Another update, might have finally got it fixed. Dropped the car off again Saturday morning as the hard start seemed to be getting more common. This time it finally did it while they had it hooked up to monitor it, said the rail pressure relief valve was opening and loosing rail pressure. They had one in stock, got it installed and I picked it up around 4. Definitely seems better, sounds smoother, perhaps I was having what I've heard called fuel knock? Also felt a little stronger on the drive home. Hoping this was it, and possibly picks up a little fuel mileage as well. I've honestly been a little disappointed with the mpg's of this car, been consistently 38-40 all winter. Solid 4-8mpg less than my previous 6spd jetta would do on identical trips.

Also asked them if there were any mods that could be done without violating the warranty. Said an intake is about it, and even then its still questionable. Would kinda like to try one to see if it picked up anything, although I kinda doubt it'd be noticable with everything else being stock. Maybe I'll get to try something if I can ever get my truck "fixed"!

Sent from my SM-G960U using Tapatalk

[biggy238]

My 05.5 PD does 38mpg but I'm also the size of two humans so it is what it is I guess.

Sent from my motorola one vision using Tapatalk

[Badbrad3701]

Originally Posted by J-Pipes

Another update, might have finally got it fixed. Dropped the car off again Saturday morning as the hard start seemed to be getting more common. This time it finally did it while they had it hooked up to monitor it, said the rail pressure relief valve was opening and loosing rail pressure. They had one in stock, got it installed and I picked it up around 4. Definitely seems better, sounds smoother, perhaps I was having what I've heard called fuel knock? Also felt a little stronger on the drive home. Hoping this was it, and possibly picks up a little fuel mileage as well. I've honestly been a little disappointed with the mpg's of this car, been consistently 38-40 all winter. Solid 4-8mpg less than my previous 6spd jetta would do on identical trips.

Also asked them if there were any mods that could be done without violating the warranty. Said an intake is about it, and even then its still questionable. Would kinda like to try one to see if it picked up anything, although I kinda doubt it'd be noticable with everything else being stock. Maybe I'll get to try something if I can ever get my truck "fixed"!

Sent from my SM-G960U using Tapatalk

My 2011 Jetta been doing same thing think I'm gonna change that. My car has that fuel knock a lot worse than my wife's car so hoping this fixes it. Ever had your car going down highway and car just cuts out for sec then right back to normal?