Troubleshooters unite! Few issues since engine build, input appreciated

[Quebster]

Hello fellow peoples. Thought I would post a few remaining issues I'm having with the car since building the engine in the hopes you all may be able to instill some knowledge upon me.


Current issues:

1. Issues starting, intermittent.
   • Engine will turn over several times as if there is no fuel in the lines. However, when I turn the key to ON, I hear the pump run and prime the lines, which would lead me to believe that the fuel IS there.
   • When the engine finally starts, I'll have a very rough idle/chase idle, and even if I rev the engine it will cut in and out, and typically die.
   • It will repeat this a few times, until finally it seems to "get over it" after a few tries and starts successfully, with no idling issues.
   • It also is more likely to do this if I have been driving the car hard.
2. After driving consistently hard on a road course, when I come off the track and idle, the engine will eventually begin to chase idle and eventually die. Observe:
   • https://www.youtube.com/watch?v=QtF-Tc0wQOQ&feature=youtu.be
   • This happened after all 3 sessions last Tuesday at Track Night
   • It's similar to the first issue described above so I think it's related
   • If I restart the car it will do the same thing, but it differs from the first issue in that it will actually idle smooth for a little bit before starting to chase idle again and die
   • When I would restart the car for the next session, it would turn over a few times and then be good to go
3. When the car dies from the 2nd issue, I get the following code:
   • P0087 - Fuel Rail/System Pressure Too Low
   • It should be noted that I have an aftermarket fuel pump and fuel pump controller (PR Stage 4 LPFP kit + Torqbyte) and MPI, but I had the first described issue while on completely stock fueling. I never pushed the car hard enough or went to the track while on stock fueling to know if the 2nd issue occurred while I was on stock fueling as well.
4. P038B - Cylinder 1 Pressure Too High
   • Finally, I get this fault code from time to time as well. It's a very strange fault code. I did get this while at the track this week.
   • Someone on FB mentioned this is due to the aftermarket Mahle pistons and the ECU needs to be recalibrated (something you can only do with professional software)

My thoughts:
The only thing I can think of after all of my troubleshooting is faulty OEM injectors. All of these issues share faulty injectors as a possible cause.

Spark plugs have been replaced, coil packs were replaced a year ago with the RS3 ones, so I'm fairly confident it doesn't have to do with plugs/coil packs. I'm also fairly confident it doesn't have to do with my Walbro 450 LPFP and Torqbyte controller since I was having the first issue before I installed them.


Thoughts?

 

[ITGUY]

what did you do to the engine? build wise?

 

[Wrath And Tears]

Let me look up your codes and spend some time with your issues.

Are there no upgraded injectors for our cars? I assume you are talking about the DI ones and not the PI ones?

Edit: Do this if you are able.

1. Check that the electric in-tank pump is producing 4 to 6 bar pressure with a mechanical guage.

2. Using a fully functional VW scan tool: Check measured value block 103 in the engine control module for specified and actual rail pressure. Check actual pressure and make sure that it is between 40-120 bar.

a. Perform output test for the N276 fuel pressure regulator valve and make sure that the ECM is sending a ground signal to the pump.

3. Test for constant power with key on engine off at pin 1 of connector T2dv of the high pressure fuel pump.

4. If the delivery pressure to the mechanical pump is correct, check the mechanical pump plungers and the fuel pump cam drive lobe for damage or wear. A worn pump plunger or cam lobe will understroke the mechanical pump and cause a low fuel rail pressure condition.

Main fixes are replacing the HPFP. Have you upgraded it? There are kits available. If you haven't, you should. If I missed that you had, my bad. Second fix is actually the fuel pump control module.

 

[Diggs24]

Is that cylinder actually high via compression check?

 

[GTI Jake]

Definitely sounds fuel related to me, can you log injector duty cycle and see what they’re doing during this issue.

I’m not very familiar with our scanning/logging but requested vs actual on injectors and HPFP if possible

 

[Wrath And Tears]

Definitely sounds fuel related to me, can you log injector duty cycle and see what they’re doing during this issue.

I’m not very familiar with our scanning/logging but requested vs actual on injectors and HPFP if possible

I think you can only get duty cycle, pressure (both low and high) and injector pulse width. As far as I know requested vs actual is only for boost. You can often also see the volts and amps for certain things.

...oh I guess Rail pressure is shown as actual vs specified.... durp good call Jake

Is that cylinder actually high via compression check?

According to VW repair manuals this is what you need to check for that fault code, assuming it is unrelated to the first.

 

[GTI Jake]

I think you can only get duty cycle, pressure (both low and high) and injector pulse width. As far as I know requested vs actual is only for boost. You can often also see the volts and amps for certain things.

...oh I guess Rail pressure is shown as actual vs specified.... durp good call Jake



According to VW repair manuals this is what you need to check for that fault code, assuming it is unrelated to the first.

Im just kinda spitballing here lol, we’ll get him figured out though I love troubleshooting but very rarely do it on cars

 

[Quebster]

ITGUY:

Engine has rods, bearings, pistons, ARP head stud kit, valve spring kit. BOSS600 turbo, Walbro 450 LPFP and multi port injection, Torqbyte fuel controller. It's the Stage 4 LPFP kit so it replaces all lines, adds a return and a FPR. FBO otherwise.


Wrath and Tears:

The stock HPFP combines the FPR doesn't it? No I have not upgraded it, there isn't really a point in doing that if you have MPI. I see HPFP is a valid possible cause.


Diggs24:
No, it isn't. Compression is within 10PSI through all 4 cylinders, though it is a bit low. The Mahle pistons don't have the exact same compression ratio as stock though.


To Jake and Wrath, as far as the logging aspects, I'll have to try to log. The problem is this seems to be quite inconsistent, and does it at very inconvenient times. Like leaving somewhere with the wife.. at least issue 1. So I never have the luxury to pull out the tablet and try to set up the logs with the wife breathing down my neck!



There was one random time I got this fault:


P2294 - Fuel Pressure Regulator Valve (N276) - Open Circuit

It was a one-off though and hasn't happened since. On that note, I also currently get this fault all the time:


P0413 - Secondary Air Injection System Valve (N112) - Open Circuit


Possible electrical issue? I've double checked all connections and everything looks solid. Open Circuit sounds electrical, but I think I read that it can still be a mechanical fault too. I'm not concerned with the P0413 SAI BS... But mentioning it here for the sake of thoroughness.

 

[Quebster]

Oh and yes I'm talking about the stock injectors, the DI ones. MPI ones aren't active at idle.

 

[GTI Jake]

The SAI fault could very well be the cause. False or un-requested lean mixture could make it dump extra fuel and run rough/stall. But I’m not 100% sure where the extra SAI air is injected honestly so this is just speculation

 

[Quebster]

Well, the SAI fault started happening fairly recently in the grand scheme of things and I had problem 1 and the cylinder over pressure fault a good while before the SAI fault started.


I'm honestly not sure how it impacts the engine after it's warm, 613B6 (my tuner) said it shouldn't have any impact.

 

[Wrath And Tears]

Oh and yes I'm talking about the stock injectors, the DI ones. MPI ones aren't active at idle.

Good to know about that. Are there rodent in your area that would have access to your car? Have you seen evidence of rodent activity in your car? It's possible they could have chewed threw some wires and caused some issues (although probably not fully through, but enough to expose them and cause some issues).

Rodents are the number one cause of strange electrical issues. If for some reason the fuel pressure sensor is messing up occasionally, due to wiring or actual failure, could cause other codes. It would also explain the SAI code.

Just spit balling here. A pinched wire can be fine most of the time, until it shifts and loses connection. That kind of thing.

edit: Jake has the SAI correct down below

 

[GTI Jake]

If it’s working properly it wouldn’t effect anything after cold start, but given it showed up late to the game I’d count it out as well

 

[Quebster]

I was thinking along the same lines due to both the HPFP and the SAI valve being in the same area and linked with the same wiring harness. I did my best to trace everything (but didn't remove the outer shell from the big groups of wires) and nothing looked damaged. Connectors looked ok as far as I could tell... I'll triple check next time I'm working on the car though.

 

[Wrath And Tears]

I was thinking along the same lines due to both the HPFP and the SAI valve being in the same area and linked with the same wiring harness. I did my best to trace everything (but didn't remove the outer shell from the big groups of wires) and nothing looked damaged. Connectors looked ok as far as I could tell... I'll triple check next time I'm working on the car though.

If you have a DMM, it never hurts to check to make sure you have proper voltage to the sensors and all that. Even better.... but far more painful is to check the resistance (Ohm) the lines, make sure none are open. It does require finding the corresponding wires where they plug into the ECU.

Edit: This is all in the sake of eliminating electrical issues as a culprit.