Technical Adjusting spacing of crank sensor?

Currently reading:
Technical Adjusting spacing of crank sensor?

firecolour

Spanners at the ready
Joined
Aug 21, 2012
Messages
169
Points
71
Couple of issues trying to start recently and it may be the crank sensor. I've cleaned the connectors in the plug but noticed it sits a few mm away from the toothed wheel. The manual says it should sit 0.4-1.0mm from the teeth and too far will cause signal problems.

The book also says not to disturb the mounting plate as it's factory set re the angular displacement from the teeth etc. the sensor is fairly cheap to replace but I wondered how the spacing was adjusted since it seems to just sit in place with a fixed flange against the mounting plate.

Nothing seems to have moved.

Symptoms are occasionally car won't start (from hot or cold), just turns over with no spark. Leave 5 mins, try again, all works. No problem with misfiring or any stalling once it starts.

Any ideas team?
 
If there was a problem with the position of the sensor surely the engine would not run properly when it was going either? I used to have issues with bad connection but never replaced or moved a sensor so not sure about that.

If they're starting to fail, rather than completely had it, then they can cause intermittent issues, which will normally be when the engine is warm and be ok on cold startups.
 
Back again with this issue. RAC man called out one night a couple of months ago. He unplugged the sensor cable where it lies on the top of the wheel arch. Plugged it back in and the car worked.

Now, on a regular basis, the car won't start after standing idle for a few days. There is no spark at all. Unplug that lead, plug it back in, and it starts immediately. The connections are secure and clean so I wonder if the act of resetting the plug is doing something in the ECU?

Has anyone got a spare crank/RPM sensor they will sell me so I can swap this and see if it's an intermittent sensor.
 
Now, on a regular basis, the car won't start after standing idle for a few days. There is no spark at all. Unplug that lead, plug it back in, and it starts immediately. The connections are secure and clean so I wonder if the act of resetting the plug is doing something in the ECU?
Yes, Roofus has done exactly the same to me a couple of times now, same connector, just reseat and he's away again. Weather's getting colder and damper at the minute though, I was wondering if there's just some damp getting in the connector? Not made any moves to investigate yet though so watching with interest.
 
I was wondering if there's just some damp getting in the connector? Not made any moves to investigate yet though so watching with interest.

I don't think it is damp. Not only is it bone dry around there, I cleaned the connector and it's been happening throughout the warm dry summer we've had.

From the manual, the ECU can substitute any of the inputs with a preset to run the engine in limp mode except the crank RPM sensor which doesn't (couldn't) have any preset the ECU could use. My guess is there is little or no signal from the sensor during cranking so there is no spark as the ECU doesn't "see" the engine turning over so it won't start.

The puzzle is why unplugging and replugging this fixes it. The RAC man knew this immediately from his "faults with a Fiat Panda" guide so it must be common.
 
I don't think it is damp. Not only is it bone dry around there, I cleaned the connector and it's been happening throughout the warm dry summer we've had.

From the manual, the ECU can substitute any of the inputs with a preset to run the engine in limp mode except the crank RPM sensor which doesn't (couldn't) have any preset the ECU could use. My guess is there is little or no signal from the sensor during cranking so there is no spark as the ECU doesn't "see" the engine turning over so it won't start.

The puzzle is why unplugging and replugging this fixes it. The RAC man knew this immediately from his "faults with a Fiat Panda" guide so it must be common.

Possibly breakdown of the connector / wiring causing a change in resistance :confused:
 
An update to this thread. Since Vern sent me a replacement sensor and it was changed, the car has started without fail, so if anyone else has this intermittent starting issue, then the crank sensor is certainly worth looking at. Bear in mind the RAC man already had this in his ancient book of Panda faults so he was onto something. A fiddle to get the old one out as it felt like it was welded in, but new one went in easy and car has been 100% since.
 
Back
Top