Misfire

[Stewart]

My 2003 petrol Alphard is misfiring but only in drive

idling and revving in neutral it is fine

any ideas ?

thanks

[Picasso]

Coil pack 

[Geralt]

Agreed. Coil(s) can't deliver required spark energy at higher loads.

 

Fortunately they're fairly easy to replace. You need OBD tool to tell you which cylinder is misfiring or use trial and error and disconnect each coil one by one until the problem remains static.

 

I had two stick coils go on my 1 series within a few miles of each other such is the manufacturing tolerances these days.

 

Edited September 20, 2023 by Geralt

[Mavill]

If your 2003 petrol Alphard is misfiring only when in drive and not when idling or revving in neutral, there could be several potential causes for this issue. Here are some ideas to help diagnose and troubleshoot the problem:
- Transmission Issues
- Engine Mounts
- Ignition System
- Fuel System
- Vacuum Leaks