Rough idle

A while back i was getting rattling a noise from the exhaust and intermittent loss of power, when i removed the exhaust, there doesn't seem to be anything within the cat, i could see right through to the 2nd lambda sensor. I removed the two shields the outside of the cat as they were loose.

It was fine for a bit , but in the last week or so i have noticed that the idle feels a bit rough and some occasional loss of power.

Then as I was driving to Bristol on LPG there was a lurch and the red light on the LPG unit started flashing three times a second, the manual says this is fuel mixture running rich.

I haven't been driving the van for a while, but now i have started driving it again i still get a lumpy idle, seems okay when at speed though. And still occasionally a loss of power, I have replaced the air filter and checked the plugs and they seem fine.

The engine warning light has stopped appearing since I replaced the air filter, but the saved codes are

P0105 (MAP),
P0130 (O2 Sensor Bank 1/sensor 1),
P0133 (O2 Sensor Slow response sensor 1),
P0136 (O2 Sensor Bank 1/sensor 2

Anyone got any suggestions?

You could have a vacuum leak possibly.

A faulty map sensor.

Or a buggered lambda sensor.

Disconnect the batter for half an hour and drive it again - this will make it forget all of its learnt fuel correction value.

Report back!

Disconnected the battery for half hour, then drove it...

Seems slightly better when I first start it up, idling sat still but by the time i get to the next set of lights and stop the lumpy/rough idle is back.

Checked the MAP sensor with my multimeter...

3.6V with the ignition on, it then drops and slowly increases back to 2.4V when I start the engine.

Next trick is to unplug the front lambda sensor - disconnect the battery and try again.

Report back!

Thanks for your help so far...

Unplugged the front lambda, disconnected the battery and drove for a bit. The rough idle when stopped at lights seemed to have evened out a bit, could still feel something there but very slight. Drove on for a bit and the gas was getting low so I switched over to petrol, rough idle came back, so I plugged the lambda back in. and it smoothed out again.
I then filled up and switched back to gas and it remained pretty smooth. Not sure if that can rule out the sensor?

Do you have a misfire - e.g. it misses on the same cylinder every time.

Listen to the rhythm, and if in doubt disconnect a coil pack at a time to work out which cylinder isn't firing.

It does not occur with regular spacing. In fact, sometimes u can barely feel it and I think it has stopped only for it to come back really rough later on. I disconnected each coil pack in turn but couldn't pin it down to any particular cylinder. I am on my second rusty fuel tank since I bought it, could there bebm with the fuel lines?

Hi, still having issues with this rough idle, occaisionally the van will cut out and it is a struggle to start it again, usually happens for the first few miles, especially when slowing down approaching roundabouts. only two codes appear now...

P0130 (O2 Sensor Bank 1/sensor 1),
P0133 (O2 Sensor Slow response sensor 1),