Technical Timing issue

[Pugglt Auld Jock]

Same with "phonic wheel reset/adaptation/whatever". It is one of the most useless features in the FES/MES programs.
It does almost nothing (cosmetic changes). It has nothing to do with the engine starting (or not). So forget about it for now.
Clueless people are fixated, obsessed with it (forums are full of "advice" like that: have you done The Reset, do the reset, you must do the reset, your car needs a phonic wheel procedure, learning, reset,...crazy). Engine won't start = phonic wheel reset. Rough idle = phonic wheel reset. Misfire = reset...

True. The engine runs fine - providing you've got the timing set right of course - even if it's comes up needing the reset. However the CEL will be lit so you'll fail MOT next time round. Also, if you're going to drive around with the CEL lit and ignore it then you may well miss that it's telling you something else much more important and maybe expensive to fix?

 

[GrandePunto PL]

The term should not be used here until the OP starts the engine. Then he can fool around with cosmetic touch-up (resets/adaptations etc).
Bad timing (so bad it trips the CheckEngine) has nothing to do with phonic wheel (assuming it is mechanically OK, installed properly).
It (reset/learning procedure) is also NOT a way to "fix" bad timing. By the way (with bad timing +/- one tooth) engine still must start.

Real goal is to have mechanically good timing, not fooling ECU, that timing is "better" (by using software tricks/resets)!
There is a play in the timing tools...and the phonic wheel (before you tighten the bolts)... Plus VVT (another can of worms).

Question: which position is the correct one? Where should I "freeze" the phonic wheel (torque 3 bolts)?

Performing a "phonic wheel learn reset" can do more "harm" than good. You don't know which way you're fooling the ECU.
Don't do it for the sake of doing it. Just because there is an option, doesn't mean you "must" use it (monkey see, monkey click buttons).

 

[Pugglt Auld Jock]

The term should not be used here until the OP starts the engine. Then he can fool around with cosmetic touch-up (resets/adaptations etc).
Bad timing (so bad it trips the CheckEngine) has nothing to do with phonic wheel (assuming it is mechanically OK, installed properly).
It (reset/learning procedure) is also NOT a way to "fix" bad timing. By the way (with bad timing +/- one tooth) engine still must start.

Real goal is to have mechanically good timing, not fooling ECU, that timing is "better" (by using software tricks/resets)!
There is a play in the timing tools...and the phonic wheel (before you tighten the bolts)... Plus VVT (another can of worms).
View attachment 466745
Question: which position is the correct one? Where should I "freeze" the phonic wheel (torque 3 bolts)?
View attachment 466746
Performing a "phonic wheel learn reset" can do more "harm" than good. You don't know which way you're fooling the ECU.
Don't do it for the sake of doing it. Just because there is an option, doesn't mean you "must" use it (monkey see, monkey click buttons).

I see what you're going on about. However there's always been "manufacturing tolerance" in mass production. If this were a performance engine I'd be very unhappy with this amount of variance but for a wee Fiat Fire engine? It's not going to worry me too much if I loose such a small amount of performance I'm not going to notice it or waste a few drops of fuel. I've noticed that that play exists but I have found that if you tighten the 3 bolts until they are just more than finger tight then most of that backlash play goes away - at least it did when I experimented with it.

The Phonic Wheel relearn doesn't "fool" the ECU into anything all it does is instruct the ECU to accept the existing crank/cam position sensor readings as ok and run with them. If the timing is incorrect doing a relearn won't sort it, it must be mechanically correct for that.

I agree with you that our OP needs to get the engine running before thinking about niceties like whether he needs to do a relearn. I do think it would be wise to get the cam timing correct - ie. not one tooth out - so that any poor running is then known not to be due to the timing being out. However I fear it may well turn out there's much bigger problems lurking in this engine from what was said back at the beginning of this thread.

 

[Pugglt Auld Jock]

I've noticed that that play exists but I have found that if you tighten the 3 bolts until they are just more than finger tight then most of that backlash play goes away - at least it did when I experimented with it.

Of course just because the play has been minimised by doing this doesn't mean the tools are correctly positioned, or that the phonic wheel is presenting it's timing aperture in the correct position in relation to piston position in the bore. However if you're going to go looking to eliminate that you're going to need to break out the crankshaft degree wheel and a DTI to read piston position. Unfortunately most of us just have to "play" with the "toys" we've got - Unfortunately it's an imperfect world damn it!