So close I can smell the diesel...

So I've been working on my second AHU to Sidekick swap. Things have gone well so far, despite being a bit short on time to work on the thing...I ended up having the harness done by Fast Forward, up in Canada. Time comes to start the thing and it just cranks and cranks. I vac'd diesel into the pump and have fuel leaking out of the injector lines when I open them to crank. Last night I put Vagcom on it and pulled a few codes. There were several codes that initially could be cleared, but one that comes back immediately: Quantity adjuster, limit reached.

The engine is an AHU that's got a ALH pump on it. In the wiring swap, I had FF change the IP harness to the ALH style. I'm not sure exactly where to go with this, so I've been checking the T10 IP connector to ECU pins.

Here is what I found:

T10 connector pin # ------- ECU pin #
1 ---- 29
2 ---- 7
3 ---- 52
4 ---- no connection to ECU, maybe ground?
5 ---- 23
6 ---- 4
7 ---- 63
8 ---- 53
9 ---- 51
10 ---- 23

My question is, the Quantity adjuster pertains to activity in pins 5 & 6. Can someone confirm that the above is connected properly?

Further info:

pin 5 to 6 in IP harness yields between .5 and 2.5 Ohms

The needle lift yields between 80 and 120 Ohms

pin 9 to 10 yields between 15 and 16 Ohms

All of these values are within range based on what I found searching.

Vagcom shows 180-200 RPM while cranking. Should be ok.

I pulled the valve cover and checked that timing wasn't 180 out. Lobes up, as they should be. Cam locking plate went in, pin went into the pump in the proper orientation. Cranks, cranks, cranks.

I got my Vagcom up and running 100% and it only shows one code: Quantity adjuster, upper limit. It shows this without any cranking.

Should I swap out the IP? I bought it as a freshly rebuilt unit from a forum member about two years ago. It sat in my garage since.

So I managed to stretch the Fast Forward harness out to the IP of my 2002 Jetta. I then ran Vagcom and guess what - no QA code. So this points strongly to the pump...

Anyone have a spare laying around?

Kind of a bummer, cause I bought this one freshly rebuilt from a forum member. Has an 'A' stamped onto the top of it and sealing paint on the bolts.

Popped the top off the pump and manually moved the QA arm. It was a bit tight, but loosened up after just a little movement. I think this was caused by sitting in the cabinet for four years. She runs great now!

Now getting into limp mode. Boost gauge goes to 8-10 psi and then right down to 0. Sounds like a lot of hissing until I let it return to idle then it's good to go again. Back to 10 psi, falls flat, repeat. Tried a different N75, same result. Any ideas?

I think if it was an intercooler pipe leak it would be easy to find as it would blow all the way off...

Pulled turbo, actuator moves as it should at 8 psi. No problem here.

Bypassed the intercooler, same result. 10 psi then falls flat to 0.

I consistently get a MAF code, which I had the tuner eliminate with Malone tuning. I think this is the problem and the cause of limp mode.

Any thoughts?

Sounds like it may be a tuning issue an worth contacting mark.

Wastegate is opening for some reason. Have you confirmed your N75 routing?

I've contacted Mark and it looks like he made a little error in the tuning. The MAF delete was not deleted properly and it throws a code each time and I'm hoping that is the same thing causing the limp mode.

Funny thing, when I was trying to diagnose the N75 I unplugged everything and gave it a run. It did the exact same thing (whoosh of air and boost quickly down to 0) but only at 5 psi instead of 10. So I'm pretty sure the whoosh of air is the result of the ECU killing the fueling under boost and having the air come back out the intake or something to that effect.

I examined the wastegate with the turbo off the car, it is in perfect working condition.

Received new chips from Mark. Car behaves exactly the same. Produces MAF error code too.

So now...

New N75
Tested wastegate
Tested intercooler system
Checked turbo

I don't know where else to go!

Log of poop:

May as well throw up a pic of the patient...



Underhood:



The M-TDI

Is that a 4770 adapter and CAT setup? Thats on my to do list if so. Thats a nice motor setup ive been tryin to find a tracker for something like this. Did you just make an adapter plate to use the ALH on factory tranny/transfer? What clutch flywheel setup?

The fuel filter adapter is a NAPA part, can't remember the # off hand...As for the rest of the swap, I used an Acme kit that mates to the stock Zuki 5 speed. Clutch/PP come from Clutchmasters. Flywheel comes from Acme.

I decided to hook up the glow plug light today and found that it gets a constant 5v from the ECU while the key is on. Shouldn't it get 12v for a moment while the plugs heat then go off?

EDIT: Glow plug light works as it should. Thought the ECU provided 12v when in fact it grounds.

Driving around now the only code I get is a 'warning lamp' fault and a alternator load signal fault. Nothing that pertains to the drivability problem.

The glow plug and check engine lights are funny. The ecu supplies ground to turn the light on, however when the light is off, the connection floats as opposed to going to 12V to them the light off, so if you connect an LED, it will dimly glow, however if you use a bulb for a light you won't have this issue due to it's resistance, if you are using an LED, or a 1k resistor in series and parallel with it and you won't have an issue.

This makes me want a tracker or a sammy with an ALH in a weird way...

New ECU. Same result. New pump, same result.

Fcuk.

I'll offer $100 to the guy who can diagnose this thing.

This isn't a fuel starvation issue is it? looking at your log the map seems to nose dive before the ordered value comes down, maybe put a fuel pressure gauge on, or a clear hose and look for bubbles?

+1 on that possible fuel starvation. Sounds silly but are the fuel feed and return lines crossed? I've made that mistake myself.

I dont think it is anything fuel supply related. All new hoses and a big CAT filter, everything is oversized. I also pulled fuel through the pump with a mightyvac and it seemed to do it well. Not sure how else to test the system.

The IQ drops to 0 even if the ECU has no idea whats going on with boost (boost to ECU and N75 disconnected)

Maybe I should look into a fuel line vac gauge...

Got a fuel line vac gauge on the thing. Reads approx 8 inches of vacuum at idle, doesn't change much with RPM. Nothing changes.

Ae you guys all just grounding your (1) clutch and (2) brake switch wires??

I learned tonight that I can replicate the cut out issue just by revving the engine in neutral. It acts and sounds just like it is hitting a rev limiter.

Also learned that leaving the three clutch and brake switch wires ungrounded does nothing.

Disabled the cruise with Vagcom too.

Also grounded the Vehicle Speed Sensor.

8" sounds like alot of vacuum .... maybe others can chime in in this

I looked around and there were a few guys with vac gauges from their veggie conversions that claimed even 15" was still within reason for the TDI...I think it's normal...

Is it possible that this engine needs oil pressure sensors connected to fully operate?

mannytranny said:

Is it possible that this engine needs oil pressure sensors connected to fully operate?

Click to expand...

not at all .... the ecm doesn't care if the engine is destroying itself

crazee idea, but try running without anything hooked to the inlet side of the turbo... i've heard of collapsing intakes preturbo causing similar issues ... EDIT!... looking again at your logs you MAF is dropping in relation to boost .. as boost climbs MAF descends, am i reading this wrong?.... when i run map/maf logs the maf climbs in relation to boost ... accordian inlet hose between the airbox and hard pipe looks a little flimsy too but i'm not standing right in front of it either

Hi Jim,

I'm running a MAF delete tune from Malone...I can't quite figure out why it logs like that, but maybe it's just a nuance of the delete tune? Malone thinks its ok.

I'll disconnect the air filter to the turbo and give it a whirl. The thing makes such a whooshing sound you could swear that there is a leak in the intercooler system somewhere. I have no idea why...I pressure tested the intercooler circuit to 40 psi.

Thanks!