Quote:
Originally Posted by serialk11r
I think you got your numbers wrong. The engine isn't tuned to run rich, at least not more than any other car, you just underestimated the throttle position that gets it into rich AFRs. At lower rpm the throttle position does not need to be very high to load the engine up. Try to get an AFR signal from the OBDII port to see how much throttle you can use before it starts running rich.
Also 3500rpm is way too high. Small 4 cylinder engines often have lowest BSFC point in the 2500-3000 range, the bigger bores on your engine mean the charge takes longer to burn and so for efficiency you want to run it slower, my guess is 2500rpm shifts would do the trick.
All that said I am not sure you will be able to do much better, everyone these days thinks big V8s get okay gas mileage since they are good freeway cruisers but they guzzle down the fuel almost just as fast in the city while you are going a lot slower.
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sorry I think I said it wrong. What I meant was the engine seems to run rich at cruising/idle loads even. it's also a short-stroke engine which loves to rev (in this case peak torque at 5000 RPM). The engine seems to stay stoich/closed loop below 3000 RPM no matter what throttle position. but ya 3500 is too much and i'm targeting 2500 RPM now.
I think it's mostly about smoothness with this car. Gently rolling on to the throttle and increasingly opening the plate but being careful not to spend too much time under high vacuum or crossing 2500 RPM. Accelerating in 6th or 7th gear or at low RPMs sometimes causes the torque converter to slip or unlock and i'm not sure if its a good thing for efficiency. it seems to accelerate in a locked state if I leave it in automatic and accelerate with traffic speed starting from 3rd gear. i think I will just use the torque app to monitor engine load and target about 70% MAP. Throttle position sensors don't seem to be too accurate on these cars.
Quote:
Originally Posted by Cobb
For almost all city driving in a v8 amg benz thats excellent fuel economy. Are you using premium fuel or the cheap moose piss?
Im sure you have no problems trading it for a 240 d - 300 td for more mpg and find one with 4matic for your winters.  |
i used to average 12 mpg at 20 mph avg speed. Starting from yesterday i'm averaging about 18.4 mpg at 30 mph avg speed (70% highway). I run 91 octane ethanol free gas. 94 here has ethanol.