limp mode ?

Hi all.
A few months ago my F VVC went into limp mode, would only rev to 5500rmp, bought a cam sensor as suggested by SAWS tuning when i sent live data to them.
bought a lucas cam sensor for £23, fitted all was good. 2 weeks later back to 5500rpm, checked faults with Pscan and nothing, nothing before either. advice given that the VVC mech was sticking and needed to be stripped down. spoke to a well known MG mechanic who said they had never heard of a sticking VVC mech and suggested to replace the cam sensor again but buy off Rimmers so I did. back to 7100rpm happy days, tonight 2200hrs, back to 5500rpm but earlier in the day was 7100rpm. again Pscan, no faults and no change in the cars driving except lower revs.
Any ideas please, pulling my hair out and didn't have any to start with....

And before Cobber gets in with something better, isn’t limp mode age related?

nah, been doing it for years lol

Limp mode……… I believe that there are little blue pills for that

If you have changed sensors and it was ok for a while, change back to the old sensor and try again, if all is good for a while until it happens again I would suggest a wire fault that is intermittent, the act of changing is allowing the connection to re-make, once warm again and the pvc coating get soft the wire breaks again, well that's my thoughts at least, I have had this happen but not VVC related.

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I have just done a fast run.
Cam requested at idle is 225 & measured is 220, at
550rpm requested is 270 & measured is 216.
water temp 70 & oil 42.
I will have to do some swapping and continuity testing when it stops raining.
Values shown are for anyone knows what they mean lol.

To me this is pointing to an issue with the VVC solenoid or the timing of the cam for it.

It's obvious the ECU is requesting it but the car isn't getting it or the sensor is not reading it correctly.

But as the sensor does appear to be reading a signal as previously said it could be a wire faulty or a faulty ECU.

Have you another ECU to try first?

If these all check out I would be checking the VVC solenoid.

yeah my thoughts too but i dont understand why Pscan doesn't find a fault when it clearly is one, even an interruption in volts

pscan only reports the error codes that the ECU provides to it.
If the ECU is not storing and reporting an error code when you think it should, I'm afraid there's not much that pscan can do about it.

okies thanks, i didnt know thats how it worked.
oh well old skool detective work it is lol