Hot Misfire - on Petrol and LPG

My car had a little bit of a fit last night.....

I've recently changed spark plugs (NGK items were fitted) new HT leads (magnecor) changed air filter and also cleaned the MAF Sesnor.

I've then had the adaptive values reset.

Everything has been fine until last night on my 9 mile trip home from work.

7 miles of this trip is down a dual carriageway, I'd been doing a steady 65 for most of this, driving without issue. As i pulled up to the roundabout at the end of the dual carriageway, the car started to misfire - it limped around the roundabout and for the next mile home. I switched between gas and petrol during this misfire period, and the misfire was still happening on both fuels.

Got in the car this morning for the return journey and no sign of a misfire at all?

In another thread I've previously stated that I've got doubts about my MAF sensor, so I'm going to order one from Land Rover today.

I've read eslewhere that coilpacks or the connection to coilpacks could also be a potential cause.

Anyone have any suggestions as to what to do next ? Thanks

Would check connection of leads to plugs and coil pack first.

I'll do that at the weekend in daylight - thanks

I checked the HT lead connections this morning - they were mechanically ok.

At lunch time , as I went back down the dual carrieage waye from work to fill up on LPG .....same thing happens - care starts to misfire as I pull up at the roundabout after 7 miles at a steady 65 mph.

So I pulled over, and switched off the engine.

Re-started the engine within 10 seconds, pulled away - and it was fine ?

Now I'm stumped !

bouncerdrum said:

I'll do that at the weekend in daylight - thanks

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check them when its dark as its easy to see leads arcing/tracking

Well the car got as far as Northallerton (from Durham) this morning and started to misfire terribly - so bad that I had to pull over and stop for a while because I thought I was going to do serious damage to the exhaust / cats.

I limped back to Durham on petrol with the car still misfiring subtly.

The car is going in to my local independant tomorrow for assessment.

Infuriatingly her indoors has been using it all day and it's never missed a beat - while I've had to drive to sheffield in her Scenic

I'll feedback what is found - hope the bill isn't too big this close to Xmas

Well, I've had the MAF sensor replaced with a genuine LR item, and the car has been in regular use for over a week now - So I'm thinking Happy Days !

However ..... I come to drive to work this morning - and it starts to misfire again ! it hasn't even coughed since the MAF was replaced !

So I pulled over, switched ignition off - re-started, and the engine cut-out. I waited about 20 seconds, re-started, gave the throttle a blip - and continued on for another 100 miles without incident

Hopefully this is an isolated incident .......

bouncerdrum said:

Well, I've had the MAF sensor replaced with a genuine LR item, and the car has been in regular use for over a week now - So I'm thinking Happy Days !

However ..... I come to drive to work this morning - and it starts to misfire again ! it hasn't even coughed since the MAF was replaced !

So I pulled over, switched ignition off - re-started, and the engine cut-out. I waited about 20 seconds, re-started, gave the throttle a blip - and continued on for another 100 miles without incident

Hopefully this is an isolated incident .......

Click to expand...

Check the security of the intake ducting and MAF multiplug.....could be a lose duct causing an airleak past the MAF, or the MAF plug not seated securely.

Hope you have a standard air filter and not K&N that use oil.

I've actually bought a K&N filter, but it hasn't been delivered - so the standard filter is still on the car.

bouncerdrum said:

I've actually bought a K&N filter, but it hasn't been delivered - so the standard filter is still on the car.

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The K&N will destroy the MAF, the oil from the filter coats the sensor wire.

Have you seen K&N's rebuttal of this 'urban myth' regarding the oil from their filter's destroying MAF sensors on Youtube?

They seem to have gone to a lot of trouble to 'debunk' the issue ......

Either way, I'm asking for a refund on the K&N filter as it still has not been delivered....so I'll stick with the standard one.

She's still driving ok ....fingers crossed lol....