im Axle Specialists

Technical 04 1.2 8v Punto - problem with RPM sensor?

Currently reading:
Technical 04 1.2 8v Punto - problem with RPM sensor?

There will be 2 leads, but the third connection is likely to be the sheilding (rather like the outer on a co-axial TV antenae wire) (at least on the crank/rpm/tdc sensor).

FIAT's diagrams do show pinouts -- the MPI Sei (at least, the one with the micro ECU) is identical in most respects (but no canbus). There's a captured copy in the Downloads Library here. Wiring colours are probably/possibly different.
 
Update:

I bought a set of Sealey socket type bolt extractors - great kit that got the last engine mounting bolt with little fuss (should have bought them years ago!). 10 mins later I can see the cam belt but having read all the threads about appropriate markings I can't be sure, but think it might have jumped.

Pic 1 this is showing the cam pulley aligned with the notch in the engine.



Pic 2 This is where the crank pulley ends up pointing but I cant see any mark, just a little nib where the casing changes direction?



And finally these are the marks on the cam belt and pulley.



So what do you think has it jumped?

Dan
 
Last edited:
Don't turn the engine by the cam pulley. Never, ever. Turn it clockwise only by the crank pulley.





Any better? Note that the marks will - off the top of my head -- only line up every 2 crank revs anyway.

Jumps are usually caused by nothing more than an incorrectly tensioned belt.

But that's not going to cause the issue.
 
Thanks guys, and for the link, that one didnt come up in my search! now I normally do what I'm told ...... but what is the danger of turning the engine by the cam or rotating it backwards - I'm sure I've done it before! and certainly had engines rotate backwards when I've stalled on a steep hill.

PS When you turn it clockwise is it clockwise facing the crank pulley?

I'll give it a couple of turns to check the marks, if its still out, I'll get a kit. I assume there's no need to lock the crank so long as I'm careful?
 
Devondan said:
Thanks guys, and for the link, that one didnt come up in my search! now I normally do what I'm told ...... but what is the danger of turning the engine by the cam or rotating it backwards - I'm sure I've done it before! and certainly had engines rotate backwards when I've stalled on a steep hill.

PS When you turn it clockwise is it clockwise facing the crank pulley?

I'll give it a couple of turns to check the marks, if its still out, I'll get a kit. I assume there's no need to lock the crank so long as I'm careful?
Click to expand...

You risk undoing the bolt on the cam pulley, which on alot of engine they are free wheeled cams - ie the friction is what turns them, no pegs or anything
PLUS the cam does 1 turn to the 2 turns of the crank, its a double work load on the belt etc to turn it

And yes IIRC i turn it Clockwise when FACING the Crank pulley

No locking needed, if the alignment marks dont realign after the 2 turns, retime it again

ziggy
 
Devondan said:
Thanks guys, and for the link, that one didnt come up in my search! now I normally do what I'm told ...... but what is the danger of turning the engine by the cam or rotating it backwards - I'm sure I've done it before! and certainly had engines rotate backwards when I've stalled on a steep hill.
Click to expand...

I'll have to think about the last one!

But the cam is designed to be turned, not do the turning. On some engines you can effectively defeat the tensioner by turning anti clockwise (or, in the case of an engine which runs anti-clockwise, clockwise!).

Devondan said:
PS When you turn it clockwise is it clockwise facing the crank pulley?
Click to expand...

Yes.

Devondan said:
I'll give it a couple of turns to check the marks, if its still out, I'll get a kit. I assume there's no need to lock the crank so long as I'm careful?
Click to expand...

No need. These are non-interference engines, so you can just keep on setting it up till you get it right. Generally, parallax is your worst enemy, so try and look at the pulleys individually, head on, as it were.

The tippex marks may reveal an artful bodger!
 
I got over the parallax issue by using a small camera. I'll see if I can get a kit tomorrow
 
All lined up now,





But no difference, it turns over about 4 times then fires once and this repeats.

Continuity test next then a gallon of petrol!
 
The cam was at least 1 tooth out. Checking plugs is easy and a good idea (I'll do it after the continuity test) but remember it is firing on random cylinders - ie I cannot isolate which one is firing, there are sparks at the coils, and I have fuel to the injectors and a pulse to each one.
 
When I say random I mean not just 1 cylinder because I have disconnected each plug cap in turn and it still fires, this was also verified by the AA. I also removed two leads and it fired, replaced them and removed the other two - it still fired (I was looking for a failed coil pack). Also when the AA interrogated the ecu it couldn't tell what speed the engine was turning, the ecu reading kept jumping from 0 to 6-800 ish, hence the RPM error. The random firing could be because the ECU sends a spark when it picks up the engine speed. But that doesn't correlate with a spark at each plug that the AA confirmed, which is why I its a good idea to check. Remember I don't have a code reader.

It is possible that all cylinders are firing at a specific interval which strictly speaking means it might not be truely random but I have no way of telling. All I know is that all the cylinders are firing sporadically.

Bit of a mystery and becoming a PITA!
 
Last edited:
most aa men wouldnt know a red from a white
get a proper reader fiatmultiscan is ideal as it shows live data too
remember the ecu will still fire the coil if its down but the firing isnt enough to make a spark (but not under compression) and so you spend all day thinking its something else
cars dont you love em:D
 
Last edited:
The AA? I think you'll find I did, more than once! ;):):):)

Devondan said:
Ok recap:

Recap: My punto died while driving at about 70, I had serious power loss but limped to the french drain on one cylinder. Refused to restart but fired occasionally.

AA called - checked faults and said it needed a new crank position sensor.

New crank sensor bought and fitted still refused to start but fired occasionally as before.

AA called again, they checked that it has spark and injector pulse but ECU is still not saying it can detect RPM it its at 0 then occasionally spikes at 2-300.

Compresion tested by current draw, looked perfect. Cam belt intact.

Went out tonight to recheck, wiring looks fine and undamaged, engine still firing occasionally exactly as before. Disconnected crank sensor and it stopped firing completely, put it back on and its back to firing occasionally but not enough to start.

So if the wiring was broken it would not fire at all.

I understood that the ecu wont send a fuel and coil pulse unless the crank sensor is working - so what else could be stopping it from working and showing the crank sensor fault? I'm thinking ECU is there anyone who rebuilds them?

Any help appreciated
Click to expand...

By fire I mean the fuel mixture is ignited but just once, the AA did clear the faults - but I have no way of checking. The engine wont start so getting the EML to come on is unlikely to happen by just cranking.

Dan
 
Prob do the compression test at the same time, but it felt ok turning the crank over by hand.
 
You must log in or register to reply here.

Similar threads

T
  • Question
Technical 1.2 L 8v stutter at <1500 RPM
Replies
1
Views
459
George1982
G
M
Technical O2 sensor with P0136 fault
Replies
0
Views
28
maxispunto
M
B
Technical 1.2 8v in an '02 Punto - cam belt tensioning.
Replies
6
Views
305
boguing
B
R
  • Question
Technical Punto 2004 1.2 8V missfire/failure
Replies
14
Views
882
rkwheeldon
R
J
Technical Punto 1.2 8v Mk2 2003 Radio wiring issue
Replies
4
Views
647
JuupP
J
Back
Top