Technical Multijet with new injection pump.

[DaveMcT]

MES does the same job as any PID. It's pretty useless beyond that IMO. I'm frankly sick of the programmer thinking that gets in the way of actually diagnosing the car. The same issue makes very wary of alternative software. I refuse pay money to be forced to guess what the programmer expects me to do.

This morning, Mike came over with his Toughbook kit. It has near enough the same options as MES, but it is usable and gives better graphs. Data rate looks about the same so probably limited by the ECU.

The smoke has magically reduced (obviously the "help" arrived). But the hunting, especially at low throttle and low speeds is obvious. Theres also an intermittent diesel knock again at low speeds. These alone tell me an injector is dribbling. Driving, with that going on is a bad idea.

We considered doing a leak-off test but would it add value or more confusion? I mean the bad injector might have the highest leak-off, but the dribbling might reduce the leak-off rate.

Mike's kit showed Injector #1 was showing a significant negative adjustment value (-0.2 to -0.3 while others were near zero). However we were not able to detect which one that is. Unplugging any injector put all correction factors to zero. Thanks Fiat.
Edit - I have thought of a way to work it out. Pull #1 or #4 injector connector and switch on engine. MES should show which one is disconnected.
However, replacing all four makes more sense. Just bite the bullet.

 

[DaveMcT]

Update

I pulled the injectors and sure enough the one (#1 to be exact) with the largest correction factor was dribbling. The tip was wet. The one I replaced last year with a used injector was dry but that leaves two potentially close to following the dribbler. I bit the bullet and bought a set of new injectors. Not cheap but I do not intend to sell the car any time soon. I'm glad I did because getting a set was hard going.

That's given an immediate improvement. No knock, no hunting and almost instant starting. The pulse just above idle is a bit bumpy but it will probably improve as the ECU settles down.