Misfire and cold start issues

[Tim 7-33]

Had a run out yesterday c25 miles, all good, last part single track 1 in 4, parked at the top on a grass verge. Walked 3 hours, back in the car, down the 1 in 4 and on to the flat there was a very definite misfire. Wouldn’t say it got worse but wasn’t great but did get home. Fired the car up tonight to investigate and would barely run, indeed stalled if left to idle. Nothing visibly loose or mechanically damaged. Very strong fuel smell. I suspect low speed up steep hill on a v hot day meant under bonnet temp got very high by the time I parked up but surely nothing would have cooked? Looked at a few threads on here but nothing seems to quite match my symptoms. Any thoughts? 96 500 by the way. Thanks, Tim

[sixor8]

The 100A fuse on the chassis starting to fail on my car caused it to run rough, over fuel and stall. It came off in one piece but fell apart when I touched it, corroded through.

[Belle427]

Just make sure you do not have an actual fuel leak too from the rubber hoses if the smell is strong.

[NiaLaurie]

I had similar sounding issues that gradually worsened over a year or so, so not a sudden as yours. It was the temperature sensor that goes to the ECU. Having the incorrect temp being indicated led to massive over-fuelling and petrol smell form the exhaust, and it would not idle until hot.

Its a cheap part to replace, and I have heard some people say that they get it replaced every year.

Good luck.

[Tim 7-33]

Hi NiaLaurie. To update I swapped out the coolant temp sensor for the ECU and tick over and warm up back to normal. Unfortunately the rain was too biblical to go for a test drive but I have some confidence that has done the trick. Many thanks for the advice.

[NiaLaurie]

Tim

Glad it worked. Its surprising how much a little item like that can affect the performance.

My other big step forward was to replace the injectors on our '94 4L Griff. The Rover ones were really old tech and worn. I could have had then refurbished but took advice and replaced them with modern Bosch jet pattern ones. Wow - better performance than when new. Mind you, not a cheap undertaking for eight of them and the fitting!

Cheers