Quote:
Originally Posted by blue62
Ike
I have experienced the same as you in regards to the torque curve around 4200 RPM under WOT or near WOT.
Every now and then it is like there is a little more power.
My car is a 2000S completely stock.
I thought that perhaps my MAF was going bad.
Or that my resonance flapper was hanging up.
But everything checks out ok.
The car runs great.
The only thing I could come up with is:
I can only get 91 Octane fuel.
So my thought is that the DME/ECU is holding back ignition timing to prevent pre-det or knock.
I think when I feel the little bit of extra power is when the ECU/DME is allowing a little more ignition advance.
Keeping my eyes open for some higher octane fuel to test my theory.
Thoughts????
|
Woody is right that in general the torque curves for the 2.7 and 3.2 don't start to peak until past 4k. I had never noticed the "kick" at 4200 before I did my intake and exhaust mods though. That's definitely interesting that your stock s does the same thing.
At first I wondered if it could be variocam switching over at different points depending on throttle and load but from everything I have been able to find that it always a fixed transition at 5500rpm. I posted recently about this topic but I haven't gotten any responses yet.
I have read similar comments about the timing but I'm not sure about it. I think that the base tune has ignition advanced to as early as stuttgart deemed "safe" and the only adjustments the dme will make is to pull timing if knock is detected. I've not seen any documentation that the dme will advance timing further if the fuel is higher quality. I've also not ever read that the dme will advance timing beyond the base map under specific circumstances such as wot or rpm threshold.
With that being said, you could be right that at a high enough rpm and load the timing becomes such that 91 will knock and then the timing gets retarded. I run 93 but it's the same tank that's been sitting since before I started all this work last fall, so I'll be curious to see what happens with the next fill up.
The other thing I wondered was the fuel maps in regards to open vs closed loop. Woody and I are running the 996 tune on 2.7 and 3.2 motors, respectively, and we should be encountering rich conditions when the dme flips to open loop mode. I would think that I should be so rich in open loop mode that it would probably hurt performance, where woodys probably wouldn't be effected much. I don't know of any way to actively monitor what mode the dme is running in though, unfortunately.
Sent from my POCOPHONE F1 using Tapatalk