[SOLVED] Low power and boost, usual things checked, not sure what else to look for

[boostloading]

I have a 1997 Jetta TDI, originally had a 1Z (not AHU) engine and a couple weeks ago I dropped in a good running ALH with the stock wiring harness. Used the ALH IP swap wiring and figured out how to wire the crank position sensor myself, so it should be running like a stock 1Z. Engine is a bone stock manual ALH, 10mm pump with 0.184mm nozzles and a K14 turbo off an AAZ since my GT15 was worn out. I've been chasing down all the usual culprits for low power to no avail. Intercooler pipes all connected, N75 working, all lines routed correctly and not leaking, new line from intercooler piping to ECU and I replaced the section inside the ECU today too. I don't have VCDS to check but I unplugged the MAF to get a freeze frame on a normal scan tool and only saw 39 inHg manifold absolute pressure at 98.8% TPS and over 2300 rpm. Disconnecting wastegate doesn't do anything, and I don't have any black smoke. Only things I haven't been able to try yet are a different turbo or a different MAF. Going to talk to a local VW tech and see when i can get him to verify injection timing and quantity, though it should be fine since I was daily driving the MK4 the engine came from and it ran well. Any ideas?

 

[Abacus]

Throwing any codes?

This is where a Vag-Com really comes in handy since you can log each of the systems to see what isn’t working correctly. Sorry I can’t be of more help, but I don’t know swaps.

 

[boostloading]

Throwing any codes?

This is where a Vag-Com really comes in handy since you can log each of the systems to see what isn’t working correctly. Sorry I can’t be of more help, but I don’t know swaps.

No codes, which isn't helping lol.

Yeah, I'm planning to order an unlimited license hex net sometime soon, but it'll take some saving since I'm a broke college student.


Just spent about half an hour cleaning the MAF sensor with a ziploc bag of isopropyl alcohol. The filament was visibly cleaner after (looking in one end with bright light at the other) and I thought that might be it, but no luck. Took it for a drive, and got a MAF open or short to ground code. It was still plugged in, so I disconnected and reconnected it. No more code but the car was still slow.

I've been thinking about it for a bit, and the car has never run quite right since I bought it. It stopped running at one point very early on with the 1Z and I thought I had an injector issue so I replaced the nozzles with Bosio Sprints, and maybe those have been masking an underfuelling issue this entire time. Beginning to wonder if maybe it's an ECU problem. I think I know where I can pick up a spare ECU sort of locally to check.

 

[Abacus]

I highly doubt it's an ECU issue since they rarely go bad.

 

[boostloading]

Well that makes no sense. I decided to try a hammer mod by ear and feel since I'm impatient and still don't have VCDS, and it looks like my injection quantity was wrong. Not sure why, it ran fine in the MK4. Maybe a difference in fuelling curves proportional to boost, and having a bigger turbo made it really lazy. Runs really well now, still need to fine tune it but the idle is only slightly unstable so it'll do until I can get a cable or hex-net. May as well wait to fine tune until I can get my other injectors in anyway, since that will throw it off again. Just goes to show how useful VCDS would be lol.