Flat spot whilst slowing down

Anonymous · December 16, 2003, 12:14

I don't know if anyone's experienced this before, but recenty my '02 MR2 is acting strangely in deceleration. Whilst slowing down for traffic on the motorway without using brakes, I've noticed that my car "hangs" at about 65-70 mph before continuing to slow down. Although it's for a very short period, it is nevertheless noticeable. It is as if the ECU system is changing from a high speed engine programme to a low speed programme.

Is it me or is this normal?

Mart

Anonymous · December 16, 2003, 12:25

Try dipping the clutch and seeing if the revs drop or not.

Slacey · December 16, 2003, 13:09

No problems like that with mine... not heard of that affecting our cars before, either s:? :? s:?

Anonymous · December 16, 2003, 13:23

slowing down ! s:shock: :shock: s:shock: You dont need to do that in a 2

But i must say that when after driving for long periods of time on a motorway then the car dose act slitghy strange around town but i think that it's just getting its breath back s:wink: :wink: s:wink:

mph · December 16, 2003, 13:46

The more I think about this the more confused I get.

There will be a change in deceleration at the point the cam profiles change, but I'm undecided what all the side effects are.

s:idea: :idea: s:idea: You're moving from a point of more cross-over duration of valves being open to less so my thinking is that there should be an increase in deceleration. However that same thinking (that air could be being drawn from the exhaust side as the throttle body is closed) could mean a marginal increase in total air volume, and possibly fuel mixture if we think you're in closed loop. At the cross-over point, you could then be running slightly lean until the O2s catch up, but in between that time, you'd have a slightly stronger power stroke and so a slightly less deceleration effect, but then it'd be more than before as there's less/no overlap of valves.
s:!: :!: s:!: nonsense-quotient = high

Feel free to laugh!

Anonymous · December 16, 2003, 13:51

Quote from: "mph"Feel free to laugh!

s:lol: :lol: s:lol: s:lol: :lol: s:lol: s:lol: :lol: s:lol: s:lol: :lol: s:lol:

(only laughing as i didnt understand a word of it s:oops: :oops: s:oops: s:oops: :oops: s:oops: s:cry: :cry: s:cry: )

Anonymous · December 16, 2003, 13:53

Could this be aerodynamic ? Some parasitic drag effect of vortex swirls at a certain air speed ?

What difference does gear (3rd/4th/5th) make to this step speed ?

s:!: :!: s:!: nonsense-quotient = extreme

Anonymous · December 16, 2003, 14:22

Quote from: "Buster"slowing down ! s:shock: :shock: s:shock: You dont need to do that in a 2

But i must say that when after driving for long periods of time on a motorway then the car dose act slitghy strange around town but i think that it's just getting its breath back s:wink: :wink: s:wink:

Hey dave, remember you have 5 gears - I have six. I think my baby takes a little longer to get its breath back.

Anonymous · December 16, 2003, 14:26

Quote from: "krisclarkuk"
Quote from: "mph"Feel free to laugh!

(only laughing as i didnt understand a word of it s:oops: :oops: s:oops: s:oops: :oops: s:oops: s:cry: :cry: s:cry: )

OMG! That was incredible!

kanujunkie · December 18, 2003, 22:20

Do you reckon he's completly fluent in Bull S***
s:twisted: :twisted: s:twisted: