Hi there, I have an F reg Rascal van. I haven't used the van much since I bought it, but on a recent long motorway run (about an hour into the journey) the van started to stutter / hesitate when accelerating through the gears, from about 1000 rpm upwards in all gears. Once cruising at about 50 mph in 5th it runs fine and doesn't seem to lack power, but as soon as the speed drops the engine stutters when accelerating back up to top speed. Stopping and re-starting the engine can make the stuttering dissapear for a short time (a few mins), but then it appears again.
I serviced the van not long after buying it:
I changed the cambelt, spark plugs, fan belt, oil filter, air filter, gearbox and diff oil, adjusted the valve clearences and swapped the distributor points and condenser for electronic ignition. I haven't changed the fuel filter yet though, and I haven't touched the carb at all nor the coil or HT leads.
I re-timed the engine to 8 deg BTDC, the dwell angle is fine, both the mechanical advance and the vacuum advance seem to be operating correctly, the mixture and idle have been adjusted and the CO2 emissions seem fine.
Generally the engine appears to be in very good condition - no leaks, always starts first time and returns good economy of about 31 mpg.
I don't particularly recall this problem occuring before the service, but then I haven't been on a long journey before I serviced it.
"Stopping and re-starting the engine can make the stuttering dissapear for a short time (a few mins), but then it appears again." seems to indicate a fuel system problem to me, perhaps take it for a run and look at the colour of the plugs to see if it is running weak or rich.
I haven't had time to check anything yet, but I did drive it for about 20 minutes yesterday and it ran fine (it had reached operating temperature).
I will take it on a longer drive to see how long the engine needs to be run (and how hot it needs to get) for the stuttering to kick in.
Is it possible that a dodgy coil could work ok when cool, and start to fail once hot? Do coils get significanctly hotter on long motorway runs than on shorter (but still long enought for the engine to reach operating temperature) journeys?
If the coil is faulty, can it be checked by measuring the resistance of both windings? Perhaps when the van is running ok compared with when it isn't?
I think I will start by changing the HT leads and the coil. As for the old points, I threw them out! I can probably get old of a new set though.
bit of a long shot, but I had similar symptoms after I serviced a petrol landrover I owned, it was fine 50 mph+ but chugged and stuttered at low revs. I put the old plugs back in and it ran fine again. They were brand new, gapped fine, clean, well known make, just didn't work properly.