ALH requested/actual pump timing issues

(no help in the vehicle specific forum, so I'm going to try here as well.)

My wagon recently developed an excessive smoking condition at anything above 75% throttle. After having my Malone tune installed nearly a year ago, I didn't notice anything like this. Over the last month or so, I began to notice this; new condition. I even swapped to a generic set of 0.205 injectors just to test and the condition doesn't get any better vs my PP764's.

I logged timing, actual and requested, and while actual does seem to track somewhat, I noticed at idle jumps all over and hits 0.0° often. This was just watching the two numbers on basic values. When watching those two items graphically via advanced measurements, the actual seems to stay at/near 0.0° BTDC and the requested is pretty constant at 3° BTDC (where I have it set.) (edit: days later, I noticed the actual timing appears to be stuck at 0.0°, not moving at all at idle, not trying to achieve the requested set point. The cold start valve indicates 44.4% for the most part unless its rev'd and then it'll only move slightly, but doesn't track requested much at all.)

IQ on the 764's was previously set at 6.5-ish and it didn't smoke this bad initially after the tune, now it does. Now I have the smaller 0.205's in and set at 6.0-ish and they smoke quite a lot.

I also logged boost pressure and actual almost always closely meets requested. Vacuum lines are all new, vanes are not stuck at all, move very freely. I don't think its a boost issue.

Does anyone think it might be anything other than the N108 valve which controls pump timing? I tested the resistance and this measured in the 'normal' range of 16.9ohm, but if the pump is really injecting at 0.0° BTDC... there would almost certainly be excessive smoke.

I've played with the wiring trying to get a reaction out of the N108 valve hoping to find a short in the wiring, but I can't see anything abnormal for at least 8" of chassis wiring. The wiring from the N108 valve to the pump plug looks normal too. However, when testing it, it definitely delivers an acceptable resistance as mentioned.

Any help is greatly appreciated.

PS: no fault codes.

Sounds like a worn out pump to me. Please verify the static timing on the cam/pump/crank. Make sure it didn't slip just to be sure.

I was wondering about the static (mechanical) timing myself. If that can be verified as advanced or retarded, it might shed a little more light.

If that is inconclusive, try graphing the timing while driving. It would be good to see what adjustments are being made in real time and whether (or at all) the adjustments can keep up with requested.

One factor in proper N108 operation is fuel pressure; there may be other causes than the N108 itself. JasonTDI is probably very close in a diagnosis that can be done over the net.

Good luck,

PH

I'll verify timing before I pull the 11mm just to make sure. I'll be shocked if its wrong, but stranger things have happened. For what its worth, the pump allegedly has about 120k miles. I can't believe it's faulty.

Jason: when you say 'worn out pump,' is there anything I can check to make sure?

No, you'd have to disassemble it.

It's off the car and I'm not opposed to finding the culprit inside the pump. Suppose it could be something simple in the pump?

I had someone 2-day air a used 10mm pump, spent a few hours swapping it over and it fired up as usual... and its exactly the same. Actual timing is essentially static at 0.0 and it only seems to jump a bit when I give it a rev.

I've done my best to wiggle/fiddle with the wires leaving the pump and running towards the battery/starter and it doesn't seem to make a difference. Can anyone lend a little more knowledge?

Just pulled all the tape/etc off the wiring all the way to the little plug on the driver's side. I tested the resistance across this wire and it's about 0.6ohm. Nothing out of line there and I wiggled the wire trying to get a short.

The N108 valve is essentially locked into 44.x% all the time, it doesn't move much at all. Very, VERY rarely anymore will the 'actual' timing or the value for the cold start valve change (that's the same thing happening on two different valves, two different injection pumps.)

I again changed the mechanical timing by a noticeable, guaranteed would move it off the graph, amount and it didn't move on the graph at all. It's stuck here:


Is there a fuse I'm over looking or something?

What actually controls the pump timing?

Case closed via the advice of a forum guru, aNUT. He lead me down the correct path of sensors. Huge thanks for this, aNUT.

The timing is calculated via the ECU from the crank position sensor and the needle lift sensor in #3 injector. Since I had a wonky timing situation, he essentially narrowed it down to one of those two OR wiring.

Long story short, I swapped the crank position sensors from the '01 and the '02. That wasn't the issue.

It was, however, the #3 injector. I swapped them out, switched nozzles and it runs like a top again.