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High LTFT K04 BPY

BurgerGuy

Go Kart Champion
Location
Charlotte
Car(s)
'07 K04 GTI
Got it. I'll just watch it from the MFD once the engine is off then. FPRV is new so unless it was installed incorrectly or faulty from VW it should be fine.

Just realized I can't math. I did 14.5 instead of 14.05 which would be .956 (basically 96% :p) in the ECM. On lambda monitoring, the idea here is that, while taking the 10% ethanol value into consideration, if the value is higher than 96% it indicates more O2 or unmetered air in the mixture, yes?
 

ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
Yes...it means a more air is sensed and is a bit lean.
 

BurgerGuy

Go Kart Champion
Location
Charlotte
Car(s)
'07 K04 GTI
So I checked rail pressure after turning off the car. It took quite a while to get up there, but the highest I saw it go was 119 bar. Is it possible that the outside temperature cooled the engine quickly enough to prevent the fuel rail from reaching 130 bar or higher? This was at the end of the day and it was cool out. Would say it took about 30m to get up there.
 

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ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
Is it possible that the outside temperature cooled the engine quickly enough to prevent the fuel rail from reaching 130 bar or higher?
Yeah, it is possible. Not sure if the low pressure should be at 7 bar though. I might need to see what mine does next time I drive it. If mine doesn't rise to 7 bar as yours...then it might be the FPRV leaking into the low side a bit. Of course...when yours is running, the hpfp can make up for this. But it could make for a low distribution from the injectors when operating and why the addition. What is the temp when you did this? Typically this works when above 80°F. Not sure when it will warm up here again. We will be in the low 60's for the high temps until later next week.
 

BurgerGuy

Go Kart Champion
Location
Charlotte
Car(s)
'07 K04 GTI
It was much cooler than that. Probably mid-60*Fs. Also, the low pressure side was 7.5 bar just before I snapped the picture. I had been monitoring it for a few minutes and it dropped to 7.0 right as I took it.
 
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ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
I will try remembering to check mine when I've returned from a trip to town this week and report. We will be mid 60's this week here.
 

BurgerGuy

Go Kart Champion
Location
Charlotte
Car(s)
'07 K04 GTI
It was about 75F today. Pressure rose much more quickly this time and reached 129 bar before dropping to 126 after sitting on 129 for a while. Guessing the FPRV cracked once it got close to 130 bar.
 

ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
Yeah...it shows the injectors and fprv are holding pressure as it builds to the limit of the valve.
Injectors can be lacking in their delivery as well. I've seen videos of R-Tech checking the volume dispersed. And a set of four can vary in their volume. There's a shop nearby that do injectors...going to stop in and ask if their cleaning and pressure testing include the screen as well. If so...I may take those I just removed in for a refurbishing. Here's one vid where two are lower than the other two. There's another vid, couldn't find it, of a set of four and two of the four were even low than those in this vid:
 
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ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
I wish there was an R-Tech here. Here they've modified S3 injectors to produce approximately 30% more volume than stock S3 injectors....at 9:20;
 

BurgerGuy

Go Kart Champion
Location
Charlotte
Car(s)
'07 K04 GTI
There's a shop not far from where I am that uses the same flow testing machine shown in the vids you shared. Even if I installed brand new ones earlier this year you think it would be worth getting them checked?
 

ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
Not sure. I just installed new injectors myself in June...and I too think about this equal flow issue.

I'm going to ramble on a bit; Mine is at +7%...and I can only think it is due to wear. Only, I replaced all of the fueling bits; both pumps, both sensors, control module, and injectors. The PCV is good, the MAP shows between 272 to 280 g/s each data pull, and the thermostat is new so I doubt the temp is triggering a fuel additive. But I haven't checked compression since before I rebuilt the head. Even though it was smoking from the pinched ring in 2016, but it still had 191 to 195 psi in all four cylinders before the rebuild of the head. I can't imagine it is worse now with the rebuilt head and new rings. I've smoke tested it and all is sealed. I hate to settle, but I almost feel I need to settle and say it is wear. I've replaced the B1S1 O2 not so long ago but this could be causing it. I know coils can fade. All four were replaced at one point due to an open campaign many years ago...and I replaced one in 2013 or 2014 when I ran the DM tune. Maybe it just needs four new coils. I just want better mileage like it once did. I have to baby it all the time to average 28 mpg right now. If I drive it how I normally did in the past, it barely makes 23 mpg now...and when I drove it however I wished to in the past it would average over 27 mpg.

If I were seeing misfires in a single cylinder...I would have its new injectors tested. I may just try new coils and a B1S1 O2 to see if these change the trims. I can tell you what made the hugest difference in my trims was a small leak I found at the MAF seal in the p-flo intake during a smoke test. The leak was minor, barely saw the smoke coming out, but once sealed the LTFT off-idle went from near 18% to below 8%. Maybe I need to smoke test it again just to double check it all.
 

BurgerGuy

Go Kart Champion
Location
Charlotte
Car(s)
'07 K04 GTI
You raise a valid point with the MAF seal on the intake. What's the torque specs for those bolts? I wrenched mine down pretty tight, but didn't over do it. Running Unitronic's intake which is a similar design to the P-Flo with full metal tubing between the turbo coupler and filter.

Next step for me is to smoke test. Will rule out anything I haven't changed yet as well as the new PCV valve although the blow test passed. Vacuum looks good on the boost gauge as well. Sitting at ~21-22 in. Hg. now. If vacuum is good then that really means I'm looking at a potential fueling issue or bad sensor(s) elsewhere. I have no problem replacing the O2 sensors, but that's a lot to shell out on a hunch.
 

ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
You raise a valid point with the MAF seal on the intake. What's the torque specs for those bolts? I wrenched mine down pretty tight, but didn't over do it. Running Unitronic's intake which is a similar design to the P-Flo with full metal tubing between the turbo coupler and filter. Mine were tight as well. It was just a matter of manufaturing dimension I believe. Torque is unknown to me. Nearly all of the 6mm bolt torque is 7 lb*ft...those are even smaller. But yeah, the smoke test showed smoke trickling out of it.

Next step for me is to smoke test. Will rule out anything I haven't changed yet as well as the new PCV valve although the blow test passed. Vacuum looks good on the boost gauge as well. Sitting at ~21-22 in. Hg. now. The vac on mine always looked fine as well. If vacuum is good then that really means I'm looking at a potential fueling issue or bad sensor(s) elsewhere. I have no problem replacing the O2 sensors, but that's a lot to shell out on a hunch.
I understand...I suggest a smoke test before replacing more parts.
 

clockwise33

New York Giants Fanatic
Location
NJ
Please forgive my brief thread-jacking:

I have been chasing a slight issue with my car all summer and I think this thread may have helped me get closer to a solution.

Background: 2006 GTI with K04, IE HPFP, APR tune v1.3 rich fix, MK6R (CRZA) rods and pistons.

Issue: The car runs perfectly, pulls very hard and smooth to red line, makes 305whp on Virtual Dyno. The issue is that I consistently see more timing pull (4.5deg max) in cylinder 2 than other cylinders. Also the piston crown is wetter and the spark plug is darker on the same cylinder. Compression is exactly the same on all cylinders.

Testing: After seeing ROH ECHT suggest to monitor rail pressure after shut down, I performed the test and got the following: Drove about 20 minutes, shut down and monitored actual rail pressure with VCDS. The reading started at 49.9 bar and immediately started falling. Pressure had dropped to 15 bar within about 5 minutes.

Question: Does this result definitively point to a leaking injector? Could it be anything other than an injector?

Thanks,
Matt
 

BurgerGuy

Go Kart Champion
Location
Charlotte
Car(s)
'07 K04 GTI
Did the engine reach operating temp in 20 minutes? The gauge in the cluster is a bit misleading as it will show 190*F, but the computer will say the engine temp is still just 160*F. That plus outside temperatures will determine how quickly rail pressure rises as a result of heat. It seems you may be on to something though.

To answer your question, ROH said it could be leaky injector or FPRV. Mine cracked at 129 bar, then dropped to 126 bar. Unless there's a problem with the HPFP or the rail pressure sensor itself is leaking I can't think of any other way for pressure to escape the fuel rail.
 
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