Zetec Crank Position Sensor

[Sam M]

Hi, long time lurker.  Originally from the UK, I sold my 7 when I moved to Germany in 2015.  The itch never goes away though and I bought this 7 a couple of years ago on a whim, aware of a certain level of work needed to restore it to its former glory, but not appreciating it's not as easier to make time when you have 3 kids and some property. So earlier this year, after 18 months of failing to make time or find motivation, I admitted defeat and took it to a shop.

 

The work is nearing completion but the crank position sensor is weak.  However, the sensor is not the standard Ford one and points at a 60-2 trigger wheel rather than the standard 36-1.  Does anyone know if this was typical on US Zetecs?  Or recognize the type of sensor?

[11Budlite]

That has to be an aftermarket CPS. Perhaps it's a CPS that's used with the MegaSquirt ECU? The stock Ford one is located at the back left side of the block and reads off the flywheel. See attached photo.

[Scott_]

Seems to me that before replacing anything, the shop should put a scope on the sensor and check the air gap. I’d also have them pull the sensor and see if there are any identifying markings on it.

 

I’m fairly confident that 36-1 was Ford’s standard trigger arrangement for the Zetec, and the sensor and external trigger wheel in your photo certainly don’t look like the original Ford.

 

If you can establish whether it’s a Hall-effect or VR sensor, finding a replacement should be straightforward. But I’m curious what the shop means when they say the sensor is “weak.” Is the signal amplitude low, is it dropping out, or is the ECU having trouble recognizing it?  Ultimately, what matters is whether the ECU is receiving a clean, reliable signal of sufficient amplitude.

 

What kind of ECU do you have? If it’s a programmable aftermarket unit, I’d suggest having the shop find and download the appropriate software and connect a laptop. Depending on the ECU, they should be able to monitor engine speed, crank synchronization and other sensor inputs in real time. That might tell them (and you) quite a bit before they start replacing parts.

 

Also, have them check the trigger wheel for runout.   if it was damaged that could affect the signal.  Just a thought.

 

 

Scott

 

 

[pethier]

3 hours ago, 11Budlite said:

That has to be an aftermarket CPS. Perhaps it's a CPS that's used with the MegaSquirt ECU? The stock Ford one is located at the back left side of the block and reads off the flywheel. See attached photo.

My Caterham S3 has a 1995 Ford Contour Zetec.  Although it is running on a MegaSquirt ECU, it does indeed use the sensor at the back of the block.

 

I don't know a lot about these things, I do know that the location of the sensor (and perhaps the sensor itself) differs a little between the manual- and automatic-transmission cars.

 

I can't imagine why a location other than at the ring gear would be an improvement, but maybe someone can explain that to me.

[Sam M]

5 hours ago, Scott_ said:

I’m fairly confident that 36-1 was Ford’s standard trigger arrangement for the Zetec, and the sensor and external trigger wheel in your photo certainly don’t look like the original Ford.

 

If you can establish whether it’s a Hall-effect or VR sensor, finding a replacement should be straightforward. But I’m curious what the shop means when they say the sensor is “weak.” Is the signal amplitude low, is it dropping out, or is the ECU having trouble recognizing it?  Ultimately, what matters is whether the ECU is receiving a clean, reliable signal of sufficient amplitude.

 

What kind of ECU do you have? If it’s a programmable aftermarket unit, I’d suggest having the shop find and download the appropriate software and connect a laptop. Depending on the ECU, they should be able to monitor engine speed, crank synchronization and other sensor inputs in real time. That might tell them (and you) quite a bit before they start replacing parts.

 

 

Thanks Scott.  It's definitely not standard as it's a 60 tooth with 2 missing teeth design.  The shop inspected the flywheel through the standard CPS mount hole, and it looks like there are no trigger teeth on the flywheel, so looks like that's also a non-standard component.

 

The car came with a Megasquirt, but it was not an MS-3 Pro as per the advert, and the wiring was a bird's nest.  So a Haltech Nexus has now been fitted.  It will be going onto a rolling road once these issues have been resolved. The weak signal comment was 4th hand, as the dyno guy had remoted in to help diagnose (so with live data feed), and it was his recommendation to replace the sensor.  

 

Part of the issue is that there are no part numbers/marking on this sensor, and so I have no reference for the target air gap etc.  I will ask the shop if they can experiment with this a little, but at Bay Area hourly rates, replacing the sensor with something that has a known spec might actually be more cost effective!

[Sam M]

6 hours ago, 11Budlite said:

That has to be an aftermarket CPS. Perhaps it's a CPS that's used with the MegaSquirt ECU? The stock Ford one is located at the back left side of the block and reads off the flywheel. See attached photo.

The block has the mount hole in this position but the flywheel does not appear to have the trigger teeth, so looks to have been replaced at some point.