Solved some K04 issues, but need help with another.

[BurgerGuy]

Nice to hear your trims are dialed in and most of your issues are resolved. My fuel economy has sucked since going K04 as well, but I found it's a result of the LPFP not being able to keep up. Upgrade on the way.

I have the Neuspeed outlet and throttle pipes on my FSI as well. I got the K04 outlet pipe and the bungless throttle pipe. Both went on without any problems, but the throttle pipe is less than a finger width from the fan. It does not make contact though. Also using an APR intercooler so fitment might be different. Are you using the Neuspeed muffler delete adapter (I am) in conjunction with the outlet pipe? Wondering if using whatever the CTS K04s outlet has might mess with alignment. Is the main reason I went with an OE/Borg Warner K04. Wanted to be able to use upgraded charge pipes without worrying if they would bolt up to the outlet of whoever's K04 kit.

 

[ROH ECHT]

Do you have this turbo outlet pipe? https://neuspeed.com/products/neuspeed-hi-flo-turbo-discharge-conversion-k04-480269

Forge diameter; I remember when I got mine there where two sizes. One for the S3 or ED30 IC and another for the stock fmic. Stock fmic; https://www.forgemotorsport.com/VW_...unt_Twintercooler_Kit--product--716.html#prev
On the Forge site, the hoses for the ED30 look to be tapered a bit where they would connect to the turbo outlet pipe and to the throttle body inlet pipe. S3/ED30; https://www.forgemotorsport.com/use...cts/Twintercooler-for-Golf-MK5-Edition-30.jpg
They have the S3 listed separate from the ED30 and the S3 hoses do no look to be tapered/reduced as that of the ED30. I think it may be helpful to give them a call; 407-447-5363. They may have helpful tips. I know people have used short lengths of smaller diameter hose placed onto smaller ports that then larger hoses would fit snugly over and clamped.

Breaking up at high rpm's; is usually due to interrupted or fouled ignition. If the red top Eldor coils(from Italy) are not for the R8 w/5.5 ohm resistance, they are likely closer to our oem 3.3 ohm resistance. If this is the case, the plug gap may need to be more open. If you do not see an improvement, I would begin there.

A picture may help me imagine something to work for the Neuspeed turbo outlet pipe fitment and to hose fitment.

 

[ROH ECHT]

Are you using the Neuspeed muffler delete adapter (I am) in conjunction with the outlet pipe? Wondering if using whatever the CTS K04s outlet has might mess with alignment.

Seems a difference in turbo outlet adapters could be easily remedied with a trimming of the upper outlet hose if they did in fact differ. Yes?

 

[RacerFreddy]

That's the thing, trimming most of these hoses would set the clamp on a bend of the hose, and I feel like that isn't secure nor good for the hose. The neuspeed pipe listed is what I got, I didn't use the turbo muffler delete piece because it doesn't fit a K04 nor is it needed, the CTS k04 has a straight outlet already.

I wasn't aware of an S3 ready set of hoses, maybe that what my first set were, but it doesn't matter the hoses fit fine, just want to clean up that bracket mount if possible.

 

[ROH ECHT]

Bracket mount...you mentioned it is held by one bolt, yes? Can you get a pic of that?

 

[RacerFreddy]

Not at the moment, I wouldn't be able to get a pic until the weekend.

I actually have it mounted down about 2 inches and towards the rear of the car using some stock aluminum with some holes drilled in. It spaced the pipe back away from the s3 intercooler enough to trim the forge hose to make it fit between the two. I will absolutely get a picture when I can of all those pipes. For the time being though, it works.

 

[RacerFreddy]

Update:

No pics, I'm not worried about my piping at the moment, it held up great all week through normal driving and some proper pulls. Gas mileage has improved significantly as well, likely got over 300 miles on a tank for once.

Fuel trims fully set in at -3% at idle and +7.4% under load, still higher than I'd like it to be, considering it was sitting under 3% after my fixes.

The car had two soft codes stored as of checking this weekend. The first was for the Diverter Valve, a code always thrown by it not knowing what the GFB DV+ is doing. P0249 or something along those lines, it's always in there.

The other was more troubling, I believe the code was P0087, it was rail pressure below threshold, intermittent. Which from my research is a PITA and very difficult code to diagnose and track down. I've been noticing my top end still has stutters, and it didn't feel as fast over 80mph the longer the period of time after my fixes I drove. My intuition says there is some fuel starvation somewhere after a certain RPM still, I at least know it isn't fuel trims or ignition causing the issue. That leaves the HPFP, related sensors, the devious rail sensor, the fuel filter, or the LPFP.

Breaking down those listed above, the HPFP is still rather new, I just changed the cam follower, and my cam is not in bad shape at all, although I very likely have an A revision cam just by my build date/VIN.
The thrust sensor on the HPFP I have replaced, I think twice, and the most recent one was when I changed the load of sensors to correct my trims. That's out.
The devious rail sensor I'm going to try a D revision part, the orange one, and see what effect that has while logging the car, I want to see what that sensor does to my idle pressures and go from there. This is my likely culprit.
The LPFP is original, but my duty cycle at idle is in spec, and considering while logging my car and viewing measure blocks I have never seen a great or concerning variation in spec vs actual rail pressures, I don't think my LPFP is struggling to keep up. I will watch this more closely this week while I have my laptop with me.
The fuel filter was changed when I did a full refresh on the car, about 40k miles ago now, so maybe time for a change. It was a mann-hummel filter with the 6.6 bar rating on it, so that should have been correct. This time around I have another one sitting around, a different brand, but should still be the 6.6 bar, maybe worth throwing that in while I'm at it.

At any rate that's all I can think of that would be left to trigger the code, mind you this is a soft code, the car never came up with a MIL from this, although I could feel it getting choked up and slower as time went on this week. The fuel trims still seem to be adding some fuel, likely when I stomp on the throttle, so maybe there is still a fuel delivery issue that the O2 is picking up on. It doesn't lean out under load, it never has. I just find it odd this creeps up after having all four injectors actually work properly for a week, and fuel trims have stayed in spec the whole time.

Feel free to toss in some other things I might be missing.

 

[ROH ECHT]

Update:

No pics, I'm not worried about my piping at the moment, it held up great all week through normal driving and some proper pulls. Gas mileage has improved significantly as well, likely got over 300 miles on a tank for once.

Fuel trims fully set in at -3% at idle and +7.4% under load, still higher than I'd like it to be, considering it was sitting under 3% after my fixes. Fuel adjustments may just be the tuning. Canned tunes will differ LTFT's. Not to mean there are no problems of course. There still may be something causing the addition. Especially if you noticed a better trim than 7% previously.

The car had two soft codes stored as of checking this weekend. The first was for the Diverter Valve, a code always thrown by it not knowing what the GFB DV+ is doing. P0249 or something along those lines, it's always in there. I don't think you should be having a constant P0249 code just because of the GFB DV+. I have never heard it will always code. I believe it is actually for the N75. Can you test the resistance across the two prongs of the solenoid? Should be 25 ohm minimum. If you see no problem there,, then there must be an issue with wiring to it elsewhere.

The other was more troubling, I believe the code was P0087, it was rail pressure below threshold, intermittent. Which from my research is a PITA and very difficult code to diagnose and track down. I've been noticing my top end still has stutters, and it didn't feel as fast over 80mph the longer the period of time after my fixes I drove. My intuition says there is some fuel starvation somewhere after a certain RPM still, I at least know it isn't fuel trims or ignition causing the issue. That leaves the HPFP, related sensors, the devious rail sensor, the fuel filter, or the LPFP. What are the pressures? It would be nice to see low and high pressure; specified and actual...on a graph preferrably. But some data to see is good.

Breaking down those listed above, the HPFP is still rather new, I just changed the cam follower, and my cam is not in bad shape at all, although I very likely have an A revision cam just by my build date/VIN.
The thrust sensor on the HPFP I have replaced, I think twice, and the most recent one was when I changed the load of sensors to correct my trims. That's out.
The devious rail sensor I'm going to try a D revision part, the orange one, and see what effect that has while logging the car, I want to see what that sensor does to my idle pressures and go from there. This is my likely culprit.
The LPFP is original, but my duty cycle at idle is in spec, and considering while logging my car and viewing measure blocks I have never seen a great or concerning variation in spec vs actual rail pressures, I don't think my LPFP is struggling to keep up. I suspect you will see a difference. In the higher, near redline rpm's the specified/target should remain 4 bar or more. Specified never drops below that. If the actual is dropping below 4 bar, post that data. You have to see data at near redline to get accurate data. If you then see the duty cycle at 92% yet the actual pressure drops below 4 bar...what does it drop to? I will watch this more closely this week while I have my laptop with me. Do you only watch? Or do you Log?
The fuel filter was changed when I did a full refresh on the car, about 40k miles ago now, so maybe time for a change. It was a mann-hummel filter with the 6.6 bar rating on it, so that should have been correct. This time around I have another one sitting around, a different brand, but should still be the 6.6 bar, maybe worth throwing that in while I'm at it.

At any rate that's all I can think of that would be left to trigger the code, mind you this is a soft code, the car never came up with a MIL from this, although I could feel it getting choked up and slower as time went on this week. The fuel trims still seem to be adding some fuel, likely when I stomp on the throttle, so maybe there is still a fuel delivery issue that the O2 is picking up on. It doesn't lean out under load, it never has. I just find it odd this creeps up after having all four injectors actually work properly for a week, and fuel trims have stayed in spec the whole time.

Feel free to toss in some other things I might be missing.

There's more replies ↑, expand is required.

If you later feel you have tried everything and still have the rail pressure code. You may need someone to intercept the rail line with a gauge and see if the gauge pressure matches reported. This determines if the rail sensor needs replacing. Or you just replace the rail sensor and hope...

 

[BurgerGuy]

I'm with ROH on his most recent reply. I live monitored rail pressure, LPFP pressure, and duty cycle via Polar FIS, but didn't really see until I logged the car that the tank pump just isn't cutting it. When I log now, I just hit go and drive. Turbo mode is important to capture more data. Throw in a couple WOT pulls in 3rd gear @ 2000rpm to redline. You need to see more than just spec/actual values for fuel though. Things like:

• Engine speed
• Lambda (spec. & actual)
• Throttle valve angle
• Pedal position
• Injection timing
• LPFP (spec. & actual)
• Rail pressure (spec. & actual)
• LPFP duty cycle

 

[RacerFreddy]

Here's the rub, the code hasn't come back as of yet, and the fuel trims are better once again at +5.5%. A number I am very good with, so maybe a one off bug or the system wasn't ready to see high boost at first and read lower than usual pressure, not sure, but for now issues resolved itself.

However, after sitting the weekend, the car had a failed start on Monday afternoon. It started, and sputtered out, it wasn't particularly cold, but that's a first. It's startup speed varies a lot day to day, but that one caught me off guard. Likely I didn't let prime long enough, I know the relay on the pump works when opening my door, so it wasn't that. I do need to change my fuel filter, it's been awhile.

Dunno, overall not too concerning it always starts eventually and that is all that matters.

 

[BurgerGuy]

Man, +5.5% ...some day. Really anything inside +/-10%. As for your failed start, I try to wait at least 5 seconds before turning the engine over once turned on to accessories. If I just go to crank it, the car tries and tries to start then finally gets going, but it has not sputtered out on me. Glad you sorted the trims though.

 

[ROH ECHT]

My fall back or go to for intermittent "long or hard" cranking is to do this test;

Many people think it is a normality for these is due to it being cold. I say so because of the number of posts on many MK5 GTI forums people telling others it's normal and you just need to prime it over and over. But it usually means there's a bleed off of feed fuel pressure happening after priming.

 

[RacerFreddy]

With a returnless system there can't be a bleed off of pressure unless one of two things is present. A leak, rail or injector etc, or the fuel pump primes but fails to maintain pressure once the key turns. Is my thinking there correct?

I know I don't have a leak, have never smelled gas in the engine bay, the only fuel smell comes from the exhaust in the past.

 

[ROH ECHT]

Yes, correct. Bleed off on the LPFP side would be from the retention valve inside the LPFP(which I just checked mine today) or could be from the regulated filter as well. On the High side; it would be injectors only, because if the FPRV leaked it feeds back into the low side.

 

[RacerFreddy]

Well this weekend I'm going to change my fuel filter anyways to start. I may look into replacing more fueling components if codes ever come up, but for now I'm happy.

I did some pulls last night and it feels pretty good. A full fourth year pull from 60-100 was smooth, minus one misfire hiccup, which is an unbelievable improvement compared to before. In the cold weather it really struggled to keep misfires at bay, but even at 34 degrees it was very happy.