MANNYSBM

Hi

Can anyone help with an issue I am having and dealers are unable to diagnose?

When cruising at a motorway speed of 75mph with cruise control on and the revs are at approx 1750 I feel a noticeable judder/hesitation from the engine. It only lasts for a split second. It seems to happen as I go from travelling on a flat road, to going up a slight gradient.

It happens when I want to maintain that speed and revs by only lightly applying the accelerator - it will happen when there is a slight change in the gradient of the road so the system needs to slightly adjust how much additional power to give the car to maintain the speed.

The mpg needle will be at 50mpg, and then as the system applies more gas I feel it as it moves to towards the 30mpg marker on the dial. However, it only happens when applying the accelerator lightly. If I put my foot down as normal to speed up, I dont feel it happen

Dealer has so far thought it is a problem with the EGR valve needing some adjustment.

Can anyone help please?

Thanks
Manny

Anzafin

Have you got the error codes read? That might help.

- Antti -

dexteryout

I have the exact same problem, it doesnt do it all the time but I know what you mean, BMW dealers dont have a clue, would be gret if someone did

MANNYSBM

Hi

Dealers have advised that nothing came up on the diagnostics.

I initially thought it was a torque converter issue - but am stuck on how to prove/disprove this?

Would it be logical for the issue to even be linked to the EGR? and is there any adjustments available in the EGR?

Thanks
Manny

Anzafin

Here's few guesses:
- clogged EGR --> easy to remove, clean and reinstall by yourself
- clogged DPF --> usually causes a power loss though
- faulty MAF --> you can plug off the MAF wire and do a test drive. An error light will be caused but you can get it removed by dealer/independent/someone with the diagnostics equipment
- worn out engine support rubbers --> Check with a flashlight
- brittle injector wire harness --> remove acoustic cover and check the wiring

- Antti -

MANNYSBM

Hi

Thanks for the suggestions - is there an easy guide to follow for the egr and maf?

Thanks

Anzafin

Yes, here:

1) Remove the acoustic cover.
[attachment=173567:Imusarja01.jpg]

2) MAF locates in the red circle and you can see the plug connection as well in it
[attachment=173568:MAF.JPG]

3) Removing the EGR valve is possible without removing the whole intake manifold, but there are couple of bolts that may be funny to reach .
- open the 4 bolts indicated in blue (only one marked)
- remove the clip that holds the air intake tube (pink)
- disconnect the electric plug (yellow)
- open the bolt that holds the plug wire (purple)
- remove the clamp (red)
- remove the little vacuum tube that is connected on the side of the EGR valve (green)

[attachment=173570:EGR_valve_removal.JPG]

Now you can take out the EGR valve.

Also, now you can check the injector harness, it's the messy looking wires in the red circle.
[attachment=173571:Injectors harness.JPG]

- Antti -

Anzafin

This dirty EGR is from another member's car:


Another thing came into my mind. Have you removed the swirl flaps from the engine?

- Antti -

MANNYSBM

Hi

Thank you for the pics - very useful

No I've not removed the swirl flaps. I have read up about them and I dont know what to do - could that be affecting performance? My car is an Aug 2009 model so I'm not sure whether BMW will have changed the swirl flaps on these??

Thanks
Manny

Anzafin

They are the same. I could imagine if there's malfunctioning flaps inside, they could disturb the airflow to the cylinder and cause hesitation. Or then not.

- Antti -