A pal of mine has a P reg 2 litre with a/c & the car has been suffering from jerky running/misfiring at about 2000 rpm, below or above that OK. He's paid for the diagnostic check at Ford's & no fault found. Changed the HT leads as well, plugs next.
We have also been looking at some Mondeo specific forums & the number of people suffering same or similar problems is staggering. Most common advice is don't waste your money for the diagnostic check. Annoyingly the authors don't come back with their solutions
Also advice given for possible causes is quite exhaustive.
There has to be a specific root cause for this problem. A few of the people could have written my pal's problem as they say it went wrong after a service & a cam belt change.
One unique thing that happens to his is that if he unplugs the connectors to the electric fans the problem goes away, well, I know I've already told him.
Any ideas on the fault, it seems hundreds of mondeo users are waiting
Cheers Bert
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My Dad had a Mondeo with this problem from new.
Over the two years he had the car Ford could not find a solution.
Fortunately it was a company car and he was happy to live with a misfire for 2 years.
New HT's solved the probelem for 500-1000 miles.
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Parp, Parp!
Note: All Toad posts come with an implied smiley.
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There has to be a resolution to this problem, I had a look over the shoulder of one of the lads at a local fast fit centre who was struggling with the same problem (I am expecting the telephone call any minute!)and so far they have thrown a new MAF unit at it plus the obligatory plugs and leads. It appears that the Mondeo wiring suffers a lot from chafing around the battery and coil areas, and coils seem to be unreliable. I'll look into it and keep you posted.
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He has changed the Exhaust Gas Pressure Differential Sensor now, no change in problem.
We have seen on another forum about the water thermostats on Mondeos having short lives. His seems to be stuck open, according to the gauge, watching the gauge on initial warm up. The needle stays on the top part of the white section only going up when stuck in traffic. He is to change the stat this weekend.
Another tip received was to unplug the EGR & see if the problem went away. By unplugging the EGR the engine will not control emissions but it may point to that being at fault if the jerkiness stops.
Changing one thing at a time & then going for a test run.
Will post again next week with any results.
Cheers
Bert
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Is it when the aircon is switched on or all the time?
My Mondeo is rough and sluggish when the aircon or heated front screen are on, I suppose it is just the amount of power they need.
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My dear wife has a Mondeo and there is little change in engine speed when the air-con is switched on. It has never misfired in 54,000 miles as far as I am aware.
I mentioned this misfire forum problem to a local garage owner last night and he said it can be caused by not using semi-synthetic oil. Failing to see a connection, I asked how could that be?
He said that if the wrong oil is used, it gives off gases which then enter the cam-chamber and seep out to contaminate the spark plug insulators which are deep set.
If correct, this may be the reason why changing the plug leads fixes the problem for a while as the gunk on the spark plug insulator would be displaced and perhaps a source of tracking removed.
To test his theory, it would be sufficient to remove the spark plugs, check for signs of tracking, clean and refit.
Please report any positve results. I see no harm in trying this approach.
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No report back from my pal today.
When the A/C is switched on he can feel that but the problem persists with or without it. The oil used has been mentioned to him, it definately had synthetic oil before the service. the service was carried out by a Ford garage fitter, can only assume the correct oil was used to refill.
Bert
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this problem is almost always down to tracking on the plug leads on cylinder 3/4. Look for black marks down the side of plugs and on the inside of the leads. Change the leads and reduce plug gap to about 40thou (shows my age doesn't it)
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Well I did get 'invited' to look at the Mondeo at the fast fit centre. Arrived at it cold and immediately noticed the cam belt slapping away at the belt covers. Set about changing the belt and discovered that the lower front guide was knackered and the exhaust cam was 1 tooth out. Shame because the belt was not very old but the tippex marks everywhere showed it to be a cowboy job. So far so good, car drives a lot smoother, watch this space.........
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All
First thing he did was the renew the stat, the engine temperature now rises to the R of NORMAL & stays there. Next he changed the plugs to NGK. Went for a test run & two further journeys & the engine ran smoothly, a success then.
Next morning he came to work & the jerkiness had returned, a very unhappy bunny, also the cooling fans continued to run on, as per original message. He disconnected the plug connector to stop them. Drove home with them disconnected & returned this morning the same, no jerkiness from the engine.
So, how quickly does the spark plug tracking take to build up & why does unplugging the fans stop the jerkiness.
We know our way round a wiring diagram but we are missing something.
I will pass on all info but the new plugs did cure it for a while.
Cheers
Bert
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Sounds like it is a combination of things. Perhaps the plugs/leads had a bad connection that exaggerated the jerkiness.
My Mondeo fan runs occasionally when the car is at normal operating temperature. Perhaps they are supposed to do that.
Perhaps the drain of power by the fan considerably reduces the spark and causes jerkiness.
The fan sounds like a red herring
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In response to Bert's original question about the 2 litre jerkiness at 2000rpm, I have exactly the same problem on my M reg 2 litre Mondeo. After swapping out everything like plugs, leads, air filter, the problem persisted. Took it to a Ford dealer (first time in 4 years!) for a half hour on the test rig. Their diagnosis, failed EGR valve. Not replaced yet as they didn't have one in stock. Car now running very smoothly as I've disconnected the plug to the EGR pressure differential sensor. So at least it points to the EGR circuit as the culprit.
Apart from increased NOx emissions is there any point repairing it ?
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He is now going to try running with that sensor unplugged to see what happens.
Also another strange electrical problem has reared it's head, the interior fan now only works on setting number 4. The engine cooling fans are still running all the time.
Cheers
Bert
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The interior fan problem is probably the fan speed resistor unit, if the first element fails, they all don't work apart from maximum. Back to 'jerkiness' some post seems to have disappeared from this column, there was a letter about earth points behind the headlights last week. More importantly, I believe there is an earth point beneath the power steering reservoir, which is possibly the earth point for the ECU. Definitely a candidate for clean up plus a smear of petroleum jelly to help in the future. Good luck.
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Success, well partial anyway.
The interior fan resistor to be replaced.
The engine cooling fans & their running on even when the engine is cool. As mentioned by Andrew of Tune Up, they are controlled by the ECU. The signal to the ECU is from a SECOND sender unit mounted near the thermostat housing, the other doing the temp gauge. The first one has a variable resistance according to water temperature, the ECU monitors this & will put a voltage to the relays when required, the fans have 2 speeds & the ECU will switch to the high speed if the temperature continues to rise. It looks like this sender unit is breaking down. The resistances can be measured, so when the fans start to run on their own again the resistance will be measured & compared to normal. For the past couple of days they have been behaving themselves.
Same process with the EGR, when it starts to play up again he will stop the car & unplug the sensor.
Cheers all
Bert
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Is the air-con on when the engine cooling fans are running constantly ? The engine cooling fans are wired to run constantly when the air-con is switched on. If it is on, switch it off and the fans should shut down about 20 seconds later. Regarding the misfire, I was advised by the dealers to apply white silicon grease to the inside of the plug caps to aid them being pushed fully on and to prevent any condensation that was trapped, in the cavity where they fit, entering the connection.
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kith
Thanks for that, I believe he has sorted everything out.
Since then he has had a water pump bearing go, this gave a strange whirring noise from under the timing belt cover on engine overrun. Again all sorted now
Thanks
Bert
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