340 camshaft position sensor fault

8 months 1 week ago #192328 by Harry
I am a newbie to F’s having bought a Steppie only in October last year. My previous ‘old’ cars have been Aussie GM machines and a 1929 Graham Paige.
I am therefore all at sea with ECU vehicles. At least I was as I am learning fast thanks in no small part to the links on this forum.
My Steppie was taken on a run of 5000 km soon after purchase. Went really well until the end 200m of a 60km thrashing down a wonderful twisting stretch in northern New South Wales (since burnt)
I thought I had broken the gearbox with coughing and spluttering and lack of power. Fortunately I was at the bottom of the hill and able to nurse the car along the straight stretches through the valley toward the coast. It got better and after I stopped to consult a map it started OK and only played up occasionally over the next few days. A free diagnostic on a workshop grade non Rover specific reader indicated multiple misfires and I was advised probably a fuel filter. This was consistent with the thrashing down the hill having stirred up crap in the petrol tank.
MG parts are not thick on the ground in northern NSW so I had to nurse the car home 2500km with an intermittent problem usually cured by a stop and restart and usually brought on by planting the foot to pass on the expressway.
Back home and new fuel filter did not solve the problem. Cheap OBD2 reader arrives and connected to Dash Command ap. Indicates 340 cam position sensor fault and random misfires. New sensor doesn’t solve problem. One thread indicates ignition as possible cause as cam position sensor is not a critical or even noticeable fault on its own. New plug leads and coil pack installed.
After all the above the problem has considerably lessened and it is now possible to drive 240 km with perfect smoothness. Still have cam position sensor fault showing up despite clearing and fitting new sensor
Wanted better performance from engine so Kmaps fitted. Much nicer running when gremlin not present but it still rears it’s ugly head every couple of days. Stopping and restart usually fixes this. Sometimes has to be done twice. STILL GET CAM POSITION SENSOR FAULT on bank A
Now have new crank position sensor from Rimmers.
Will fit on the 29th and let you know the result.
I think the crank position sensor is one of a number of contributing factors to my gremlin. The magnetic Hall effect sensors are degraded by heat and being an aluminium block the crank sensor would get hot quickly compared to being located in a similar position in a cast iron block.
I’ll let you know how I get on.
The following user(s) said Thank You: David Aiketgate

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8 months 1 week ago #192336 by talkingcars
I would be plugging in my www.pscan.uk to read live data to see what is going on.

Home to black MGZS180, yellow MGZS180, blue MGZR160, green MGF VVC and red MG Maestro T16.

MG - the friendly marque.

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6 months 5 days ago #192732 by Harry
All problems now resolved.
I have fitted a vacuum driven cruise control (minimum 3km over fine here is $A177 plus 2 demerit points). In the process I had to find a convenient vacuum source and I chose the manifold supply to the fuel rail pressure relief valve. This virtually fell off the manifold and could have affected the relief valve operation as well as providing a vacuum leak. Fixed this problem but visually all looked OK before I did the manual inspection.

About the same day I had my small handed mechanic replace the crank position sensor. All of these things led to slight incremental improvements but my gremlin still returned sometimes. PScan finally arrived and pointed to Lambda sensor one running sometimes at over 1 volt. Replaced it and gremlin gone. Still had cam position sensor as a come and go fault which turned out to be a loose connection between the new separate sensor and it’s supplied extension lead to the existing wiring loom. So much for buying cheap from the Internet. Replaced it with a secondhand unit from the wreckers and that fault gone too.

All is now well and happy camping.

Thanks for the advice re Pscan. It is certainly worth having

The following user(s) said Thank You: David Aiketgate, cairnsys

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