sharkytm
Member
I've got an issue that I can't track down on my new-to-me MK3 AHU Jetta. It's had a ton of upgrades/maintenance done by the PO (also a TDIClub member), but on my drive home from his house, I started to lose power on the higher-end. It drives fine at partial throttle and at low RPM. Both the PO and I thought it was an exhaust leak, so I went home and dug into it. I tightened all the exhaust manifold nuts, verified the tubo nut/bolts, tightened EGR blockoff, tightened the intake and all boost pipes, etc... nothing leaking that I could see.
The actual issue was that injector #3 had come unseated from the head slightly, but I retorqued the yoke bolt to 20Nm and it's sealed again (I've got copper injector seal washers on order, and I'll probably change it the next time I'm doing work on the injection lines.) The PO did the nozzles a few months ago, and it must have backed out slightly. the yoke bolt was just more than finger tight.
However, I was running VCDS logs tonight, and here are the results: There's definitely a fuel problem.
The following graphs are of Measuring Block 015.
RPM in Red (0-5000 scale)
Actual injection quantity in green (0-40 scale)
Requested injection quantity in grey (0-80 scale)
VCDS Chart:
Excel chart of the beginning of that datalog chart, no split fuel scale:
So yeah... no wonder the car falls on it's face, the fuel can't keep up with demand. It's requesting 51mg/stroke, and maxes out at 23 right when you stomp the throttle, and slowly drops off. Leak, air in the fuel, clogged pickup, or a bad pump? The IP has a very slight leak, and I've got the seals, but I'm not keen on ripping it apart unless I have to.
Other stuff I've checked/verified:
Injector Balance is fine.
Injection Timing is still good.
MAF functional.
MAP/Boost sensor, and N75 frequency duty cycle.
First, Second, Third, paused, long third gear rip. I don't see anything hugely wrong here. It's showing 2260 mbar, minus 1000 for atmospheric, which is 18# in 3rd/4th gear.
Fuel filter was just changed before I bought it.
Tank is 1/2 full, same as when I bought it.
All vaccum lines were changed, boost piping is secure, and there aren't any boost leaks. It will hit 18# of boost at WOT in 4th, just doesn't have any balls.
Injection timing is good, and the IQ is low (extra fuel) at 1.8 mg/str. This thing should be leaving a haze with the fuel that high, but it's clean.
Upgrades/Specs:
Stock AHU, stock K03 turbo, 02A, 10mm pump, 205K miles
P150 intake, Race Pipe, no EGR
DLC1019 Nozzles, RC3 tune
Prior to the power loss, it'd spin the clutch in 5th. Now it basically drives like a stock MK3.
Thoughts?
The actual issue was that injector #3 had come unseated from the head slightly, but I retorqued the yoke bolt to 20Nm and it's sealed again (I've got copper injector seal washers on order, and I'll probably change it the next time I'm doing work on the injection lines.) The PO did the nozzles a few months ago, and it must have backed out slightly. the yoke bolt was just more than finger tight.
However, I was running VCDS logs tonight, and here are the results: There's definitely a fuel problem.
The following graphs are of Measuring Block 015.
RPM in Red (0-5000 scale)
Actual injection quantity in green (0-40 scale)
Requested injection quantity in grey (0-80 scale)
VCDS Chart:
Excel chart of the beginning of that datalog chart, no split fuel scale:
So yeah... no wonder the car falls on it's face, the fuel can't keep up with demand. It's requesting 51mg/stroke, and maxes out at 23 right when you stomp the throttle, and slowly drops off. Leak, air in the fuel, clogged pickup, or a bad pump? The IP has a very slight leak, and I've got the seals, but I'm not keen on ripping it apart unless I have to.
Other stuff I've checked/verified:
Injector Balance is fine.
Injection Timing is still good.
MAF functional.
MAP/Boost sensor, and N75 frequency duty cycle.
First, Second, Third, paused, long third gear rip. I don't see anything hugely wrong here. It's showing 2260 mbar, minus 1000 for atmospheric, which is 18# in 3rd/4th gear.
Fuel filter was just changed before I bought it.
Tank is 1/2 full, same as when I bought it.
All vaccum lines were changed, boost piping is secure, and there aren't any boost leaks. It will hit 18# of boost at WOT in 4th, just doesn't have any balls.
Injection timing is good, and the IQ is low (extra fuel) at 1.8 mg/str. This thing should be leaving a haze with the fuel that high, but it's clean.
Upgrades/Specs:
Stock AHU, stock K03 turbo, 02A, 10mm pump, 205K miles
P150 intake, Race Pipe, no EGR
DLC1019 Nozzles, RC3 tune
Prior to the power loss, it'd spin the clutch in 5th. Now it basically drives like a stock MK3.
Thoughts?