A few thoughts on engine/auto trans performance

[wildturkeycanoe]

Lately, as the new engine beds in nicely, I have noticed something curious about the power output from the engine.
One day I will be driving home from work and it feels like the power has disappeared, like there is very slow response from the accelerator and the economy is appalling. Yet, the very next day she pulls like a mule with barely any throttle. What can make it behave so randomly? Air temperature has a lot of influence, I know, but even on subsequent identical days in terms of weather, the car behaves like chalk and cheese. No error codes, but vast difference in the amount of pull it has going up hills and acceleration from a standing start. The same drive home can return fuel economy anywhere from 13.9L/100km to 11.5L/100km. That is on a 30km journey, 80 zone+ with only 4 sets of traffic lights.

I have found also that planting the foot will not make it speed up any faster, but instead makes it accelerate more slowly as the transmission kicks down and the engine just sits in the medium to high rev range. Then if I back off it kicks up a gear and the torque can be felt pulling the car along again. It feels like the auto gearbox is shifting down too easily, instead of letting the engine torque do its job. I hate fly-by-wire. If I only use a quarter or 1/3 throttle, I can feel the engine grunt trying to move her along much better than with wide open throttle and the auto gearbox doesn't feel like it is slipping half as much, with revs dropping down to a nice 1900rpm. Totally counter-intuitive, when more throttle means less get up and go. I have done a half transmission oil change, but should probably do another to see if the fluids are a bit old and if it might help this situation.

Last but not least - traction control and wet weather! It's horrible when the engine cuts out when you are half way through an intersection and a car is about to T-bone you, but putting the foot down does absolutely nothing. It is downright dangerous and should be removed from all vehicles. I prefer to have the wheels spin and to keep inching forward than for the whole car to come to almost a complete stop thanks to traction control, then wait for a good four or five seconds before it decides to get going again. I'm going to have to do some overtime and spend money getting the ECU remapped to avoid the in-built throttle response lag - worst feature ever designed, thanks Mitsubishi.

[RHKTriton]

I've got a manual ml and that 'syndrome' of get up and go some days and others a bit lazier does occur sometimes.

In your case, I'd start by giving the MAF Sensor a clean and put a bit of twist on the connector pins.
If your getting big changes day to day, poor connections or dodgy sensors would be first port of call, ultimately the ECU uses lots of inputs to calculate how much juice and consequent power it let's you have.


The new autos get lots of comments about less than optimal shift points. The Trimatic in my Commodore years ago would hold a gear unless you planted the loud pedal past about three quarter.

A problem with all the electrickery getting into vehicles is, it seems, that boffins, who probably aren't drivers, apply all their theoreticals that don't always reflect real situations.

The Trimatic, a VN work car and my old Vito all performed as 'point and shoot' - put the foot down and they took off.