One for the gurus... :)

[bimmaman]

When I'm stationary and give the throttle a little blip, the engine revs up nice and fast but if I'm moving at more than about 3mph and blip the throttle, the engine revs much slower. Why would this be?

[schrodingers-cat]

Not being a guru i wouldn`t have a clue but i`d imagine someone is going to throw a witty suggestion that its the weight of the truck your pulling as opposed to blipping the throttle when standing still. Me i`m just using this to get my amount of posts over the paltry 300 mark

[IanB2]

I'm guessing the driveline load is what slows the engine's response. What you haven't told us is if you are driving an auto or standard, and if you are in gear or neutral when doing this if standard.

[bimmaman]

Yeah sorry - it's a manual. When I'm stationary (ie, at the lights), it doesnt matter if I'm in neutral or just have the clutch in - I can sit there like a boy racer revving the engine freely.

If I'm moving, and press the clutch and then rev the engine, it just revs much slower. I can't explain it any other way really... Thinking about it, I haven't tried putting it in neutral while rolling, so might try that later.

I'm guessing its supposed to be like that, but I just don't know why.

[IanB2]

Yeah sorry - it's a manual. When I'm stationary (ie, at the lights), it doesnt matter if I'm in neutral or just have the clutch in - I can sit there like a boy racer revving the engine freely.

If I'm moving, and press the clutch and then rev the engine, it just revs much slower. I can't explain it any other way really... Thinking about it, I haven't tried putting it in neutral while rolling, so might try that later.

I'm guessing its supposed to be like that, but I just don't know why.

I've got an auto, so I can't replicate your symptoms, but many manual cars use the VSS signal to tell if the car is moving or not, and it affects certain aspects of how the engine runs. For example, I noticed that one of my old manual cars would idle higher with the clutch in or in neutral (didn't matter) while moving, than when it was at a rest. I suspect the engine wouldn't want to be at low idle when it could be expected to leap back into action at any moment. What you are experiencing is likely the same kind of thing.

If it isn't a problem, don't make it one.

[bimmaman]

Haha, I'm not trying to make it a problem, I'm just curious is all

I tested it again last night, this time putting it in neutral and the same thing happened. Just seems odd to me :/

[IanB2]

Haha, I'm not trying to make it a problem, I'm just curious is all

I tested it again last night, this time putting it in neutral and the same thing happened. Just seems odd to me :/

Just buggin,lol.

To clarify my theory, an auto tranny vehicle ecu knows when it's in "park" because the gear selector tells it so, and things like idle speed, etc, change as a result. In a manual tranny vehicle, there's no "park" position, so it uses the VSS to tell if the vehicle is stationary or not, and the ecu reacts differently as a result.