From Sitting Bull, Dundee.

Due to Covid I only took my Mondeo for one longish trip last year. After about 30 miles the engine appeared to develop an intermittent misfire, missing a few times then running ok for some time,then missing a few times again, and so on. Seemed to be at light throttle openings in the higher gears , not on accelerating or overrun. It also did the same on the return journey. Since then (10 months ago!) this has not happened again during my routine trips around the local area. However I repeated the previously mentioned annual holiday trip this week, and the misfire reappeared, again just a few misses now and again on low throttle at 50 to 70 mph. During short runs in between arriving at our destination and leaving there were no issues. I ran my basic code reader before making the return trip home and it showed CMDTC P0087:23-68 fuel rail system pressure too low. I cleared this DTC, but despite having the 'misfire' problem again on the return journey, when I ran the code reader at home there were no DTCs shown. Forgot to say that the engine management warning light does not come on. Does anyone have any ideas as I am now reluctant to drive up North again until this is resolved, and because the fault seems to only appear on longer trips I,m not sure how a garage would approach diagnosis. Thanks

I'm no expert on this but is it serviced regularly? What's the mileage of the car? as the fuel filter should have been changed last year on the 9 year (112500 mile) service.

I'm thinking you've got a split in one of the hoses. Main culprit is the hose from egr as that gets the most punishment. 

On 8/7/2021 at 8:52 PM, sitting bull said:

From Sitting Bull, Dundee.

Due to Covid I only took my Mondeo for one longish trip last year. After about 30 miles the engine appeared to develop an intermittent misfire, missing a few times then running ok for some time,then missing a few times again, and so on. Seemed to be at light throttle openings in the higher gears , not on accelerating or overrun. It also did the same on the return journey. Since then (10 months ago!) this has not happened again during my routine trips around the local area. However I repeated the previously mentioned annual holiday trip this week, and the misfire reappeared, again just a few misses now and again on low throttle at 50 to 70 mph. During short runs in between arriving at our destination and leaving there were no issues. I ran my basic code reader before making the return trip home and it showed CMDTC P0087:23-68 fuel rail system pressure too low. I cleared this DTC, but despite having the 'misfire' problem again on the return journey, when I ran the code reader at home there were no DTCs shown. Forgot to say that the engine management warning light does not come on. Does anyone have any ideas as I am now reluctant to drive up North again until this is resolved, and because the fault seems to only appear on longer trips I,m not sure how a garage would approach diagnosis. Thanks

 

Hi did you get the problem solved iv the same on a s max