I recently had my 1/03 build MCS s/w upgraded to 3.6. My impression:

No more stumble at initial start-up

DSC is less intrusive. It cuts the power less and for shorter duration. I used to be unhappy about having ordered it, but now I'm not.

Does anyone else have an opinion of the change? It would be interesting to know what all the differences are. The tech said my mileage would improve. Its too early to tell but I would be curious to know if those dynoing and checking a/f ratios notice any significant changes.

 

I had mine done as well(May 2002 build ) The upgrade fixed the cold start issues, the yo-yo effect between 3-k rpm in 2nd, is better but not gone. For some reason is does feel stronger, especially at the bottom end, but then the weather is colder and that will add some power feel.

 

As far as the cold start issues, are you talking about when the ecu seems to get all screwed up and the "EML" and "Service Engine Soon" lights come on? This just started happening to mine, and I can't say how THRILLED TO PIECES I am about.

 

My "Service Engine Soon" light was on for a while and when I brought it in for service after a couple of weeks the problem was diagnosed as a bad thermostat. One was ordered but not installed yet. Check your engine temp. If it's not coming up to temp then you may have the same problem. I've never had a thermostat go bad on me until now. Maybe this is a problem area with the car. I had noticed before service that the engine wasn't warming up as much as it did before and the heater was slow warming up. I should not have assumed the thermostat could not possibly go bad this fast. Ironically, I had the s/w upgraded at the same time as diagnosis and the light has gone out and has not reappeared yet. Reprogramming was 12/19/03

 

I'm still with the V35 software, but had my thermostat replaced at the last service apt. I was having the same troubles. The Service Engine Soon light arrived and I thought it was due to a loose gas cap. Then after driving on the highway for over an hour and the temp gauge was still not at "op temp", I knew something had to be up. I'm looking forward to v36. Let us know if your problems return.
The car seems to have an amazing ability to "adapt" back into its old habits.

 

I had my 12/02 build MCS upgraded to version 3.6 and it has made a big difference. The stumble is gone, and the car is a lot smoother. I'd say it's about 80 percent better.

I should also mention that the coolant tank was also replaced, and the discolored coolant, which also smelled bad, was replaced. I guess it runs hot. Other things that they replaced included: driver's lock, gear shift console, adjusted Xenons up, tightened parking brake, and replaced gas cap actuator.

 

I don't have the stumble or yo-yo but I am having my JCW upgraded to version 3.6 next week. I will make some notes at that time as it may or may not make any difference.

My check engine light has come on in the past for 2 reasons: gas cap and also an oxygen sensor which the dealer replaced under warranty. The oxygen sensor was a result of minor flooding after Isabel. My car has reverted back to it's old ways now and no more problems :smile:.