Engine ran fine on LPG, no power now on petrol

Need technical Q/A then you're in the right place

Moderator: martauto

Post Reply
User avatar
flashBE
E30 Zone Newbie
E30 Zone Newbie
Posts: 26
Joined: Wed Feb 29, 2012 11:00 pm

Fri Aug 02, 2013 11:48 am

Hi guys

As I already said in another topic, I removed an LPG installation from mijn '84 320i for various reasons. It had been running on LPG for 3 years. It started on petrol and then automatically switched.

I never tried manually switching it to petrol when the installation was still present because I thought there was no switch (found one eventually) so I'm not 100% sure the lack of power is caused by some residue wiring or parts from the installation, but I don't think so. I removed anything obvious.

Symptoms:
- It ran fine on LPG
- It starts pretty good
- A little rough idle
- No power whatsoever
- In fourth gear it goes to 3000 RPM and no further, in fifth the RPM almost don't go up
- Very poor fuel economy. 20-30 liters on the meter

What I tried:
- Drained the fuel and put fresh fuel into it
- Agressive injector cleaner
- New fuel filter
- Other spark plugs
- Fiddled with the ignition timing

What I'm investigating right now:
- The blue plug doesn't give a reading, so I think it's broken. But other people with an early M20B20 also don't get a reading and theirs runs fine. Could it be that the plug causes such big engine problems or not?
- Could it be that the injectors are so badly clogged up?
- What's this pressure switch for?

Image
Image
Image

It looks like it has been messed with. There an extra resistor soldered between one of the 2 pins.

Thanks guys
User avatar
flashBE
E30 Zone Newbie
E30 Zone Newbie
Posts: 26
Joined: Wed Feb 29, 2012 11:00 pm

Fri Aug 02, 2013 10:28 pm

Problem solved

I was looking at the wrong blue plug. There's another one next to the first injector.
My injectors were very badly clogged up

Image
Image
Post Reply