Hello all, been reading this forum for a long time, first time post. I currently own two R52s, one R53 and one R50, been working on this cars for a few years and I thought I could fix anything on them... and then I was proven WRONG.

Bought this 2004 R50 with a blown CVT (shocking). I replaced the transmission with a tested unit from a salvage yard, reset the adaptations, ECU and it drives like a dream... until it doesn't.

When the car is cold it drives with no issues, but after about half an hour, it starts acting up. When stopped at a light it shudders and sometimes stalls, if I put it in neutral the idle comes up and the shudder stops but it won't rev past 2000rpm. Just as sudeenly the problem goes away.
If I'm on the highway and this happens, the RPM start dropping from 3K to 2K and it shifts up and down. Again the issue intermittently comes and goes. It does all this without triggering any codes or EML light

So far I've swapped (I have tons of spares and a parts car)
* Throttle body * Transmission speed sensor
* Fuel pump * camshaft position sensor
* MAP sensor * Purge valve
Also changed the fuel filter, air filter and plugs
It's driving me nuts and I thought I'd pick your collective brain because I'm running out of ideas... thanks in advance

 

My daughter has a 2004 R50 and it sometimes behaves as you describe. I have not found a solution, but I have noticed that if the CVT is misbehaving, switching into manual shift mode for a bit seems to clear it up. I am wondering if there are software updates for the ECU and transmission which may cure these problems?

-Jeff

 

I will try that, I never thought of sofware updates so is there a way to see its current version? It seems like a pesky wiring issue to me

 

I believe you can see each module software version in INPA. I don't have a laptop with it at the moment, but will check to see if the Schwaben/Foxwell scanner can retrieve software versions.