P38A New crank sensor not working?

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Musicmaker

Musicmaker

Active Member
Posts
346
Location
Glasgow, Scotland
HI
I have fitted a new crank sensor to my 1998 P38a diesel autobox as per Wammers's instructions. Still no joy. Engine starts but idles very fast and the engine management light remains on. Dodgy sensor?
 
Musicmaker said:
HI
I have fitted a new crank sensor to my 1998 P38a diesel autobox as per Wammers's instructions. Still no joy. Engine starts but idles very fast and the engine management light remains on. Dodgy sensor?
Click to expand...
Possibly a dodgy sensor, or the bracket has been moved so the clearance is incorrect. Diagnostics is the way forward.
 
Thanks. The bracket has not moved. The AA report was Rpm sensor comparison not ok. Going to double check the wiring loom under the inlet manifold and no 4 injector incase a wire has been damaged after I replaced the glow plugs.
 
Please bear with me as sensor's are not my strong point. The injector light on the dash is still on. I've checked the resistance on both sensor's giving a reading of 1.247 ohms. Also waved a penknife at the base of sensor registering 0.5 volts. It seems to me (correct me if i am wrong) that the sensor voltage isn't going where its supposed to. No 4 injector?. Thanks. Billy.
 
Musicmaker said:
Please bear with me as sensor's are not my strong point. The injector light on the dash is still on. I've checked the resistance on both sensor's giving a reading of 1.247 ohms. Also waved a penknife at the base of sensor registering 0.5 volts. It seems to me (correct me if i am wrong) that the sensor voltage isn't going where its supposed to. No 4 injector?. Thanks. Billy.
Click to expand...

Number four injector sends a point of injection signal to the ECU. CPS sends TDC signal to the ECU. ECU then modulates timing solenoid to adjust position of timing device to set point of injection at TDC. You need diag on it.
 
Did it do this before you changed the sensor, did the new CKP seem exactly same dimensions as the original?
Engine management suggests No4 sensor, I think if you unplug it BECM will take nominal figure - does that make difference?
 
Thanks Wammers, that kind of makes sense. Yes same symptoms as old sensor and new sensor exactly the same dimensions. If I unplug no 4 sensor, do I start the engine and will it damage the BECM? Anyway, thanks for the input so far, much appreciated. Talk about learning curves...thankfully this forum exists
 
Musicmaker said:
Thanks Wammers, that kind of makes sense. Yes same symptoms as old sensor and new sensor exactly the same dimensions. If I unplug no 4 sensor, do I start the engine and will it damage the BECM? Anyway, thanks for the input so far, much appreciated. Talk about learning curves...thankfully this forum exists
Click to expand...

If you unplug number four injector and CPS is not working it should not run at all. May fart a bit though. When did MIL lamp decide to come on? Did you remove manifold to do heater plugs ? If so make sure you have not trapped injector lead under manifold.
 
Musicmaker said:
Thanks Wammers, that kind of makes sense. Yes same symptoms as old sensor and new sensor exactly the same dimensions. If I unplug no 4 sensor, do I start the engine and will it damage the BECM? Anyway, thanks for the input so far, much appreciated. Talk about learning curves...thankfully this forum exists
Click to expand...
BECM has nothing to do with it it's the EDC and no it will not damage anything.
 
wammers said:
If you unplug number four injector and CPS is not working it should not run at all. May fart a bit though. When did MIL lamp decide to come on? Did you remove manifold to do heater plugs ? If so make sure you have not trapped injector lead under manifold.
Click to expand...
Around 2 weeks ago the MIL lamp came on after I heard a metallic clatter under the car. The revs shot up ticking over at 1200 revs. I removed the inlet manifold to replace the glow plugs. It did take at least 3 cycles to start. I put this down to cold weather and Britpart plugs. Having said that, I'm now wondering maybe a wire is trapped allowing more air into the inlet. Mmmm
 
Musicmaker said:
Around 2 weeks ago the MIL lamp came on after I heard a metallic clatter under the car. The revs shot up ticking over at 1200 revs. I removed the inlet manifold to replace the glow plugs. It did take at least 3 cycles to start. I put this down to cold weather and Britpart plugs. Having said that, I'm now wondering maybe a wire is trapped allowing more air into the inlet. Mmmm
Click to expand...

Air going in is of not importance. But a trapped grounded wire would be.
 
This car definitely needs diag on it, he needs to find out why the MIL lamp is on. The mechanical noise he heard could be the chain jumping the crank sprocket. Lots of work to do if it was.
 
Last edited:
The AA guy thought that the timing chain might have stretched and slipped a cog. Hope he is wrong. Would this show up on diagnostics. If so I'll get it booked in, but don't have time or money to fix this at the moment.
 
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