Lifting off problem, map or sensors ?

[jimbom30cab]

Hi.

When I'm cruising and lift off the throttle allowing the car to coast in gear, the car slowly reduces in speed like you'd expect a BMW to do - for the first few seconds.

and then it rapidly slows like the engine's been switched off.

Always returns to idle fine and there are no vacuum leaks at all.

325i 1987 2.7 conversion DME 1.3 .

I was thinking about it and have a theory.....

When moving the ECU senses the car is moving and once the throttle is closed it uses the ICV to give a smooth coasting experience or the map keeps putting fuel in. This is happening for a couple of seconds and then it's like someone turned off the injectors as the engine breaking is much much more pronounced.

So to me it feels like one of the sensors or the map isn't quite right.

Anyone also experienced this?

Thanks in advance.

[Brianmoooore]

then it's like someone turned off the injectors as the engine breaking is much much more pronounced.

That's what's happening, and is what's supposed to happen. Injectors are switched off on over run.

[jimbom30cab]

Thanks Brian. I wonder why there is such a pronounced change from initial coasting (nice and smooth for a couple of seconds) to rapid engine breaking coasting (quite dramatic).

I've just done a re-build so it could be anything !

Thanks,

[Carmo13]

Maybe a sticky accelerator cable?
Then again, maybe not

[jimbom30cab]

Thanks guys,

Occasionally when it returns to idle, the revs drop really low and then pick up again before settling at idle.

Very odd

[BenHar]

Sticky TPS?

Ben

[jimbom30cab]

Thanks Ben, i will try that.