This is my first Post so humble apologies upfront if I haven’t got used to how the Forum works yet. In advance of asking for your help I have ‘searched’ my topic and the results gave me things to check and having done that I still have the same issue so I would appreciate your advice please.
My issue is a familiar title ‘Misfire/poor running’ which for now I am treating as an electrical problem and having tried a few things already (listed below) I am next looking to either fit a new distributor or, swop out the ‘vane and pick-up unit’ in the existing one. But I have also had it in mind that it could be a mechanical or fuel issue, or, a combination of all 3! Finally, there are gaps in my understanding of how the LT/HT system works on my Van and that will be my first question below. But first up, a quick van intro - we have a 1984 1.9 W/C (DG engine code) with electronic ignition and she is normal aspirated. Our van is LHD and from the Westfalia factory it spent the first of its years in Sweden – I mention that just in case for that market there were set-ups/parts included for the expected climate. We have owned the van for the past 14 years and, apart from one collapsed spigot bearing and a perforated clutch pipe, through servicing it regularly we have had very few issues so have been very lucky.
Original issue and symptoms – after about 50 miles I could feel through the seat a ‘hunting’ started which then became an unhealthy misfire and finally a full-blown backfire followed by cut out. Tried roadside checks but no improvement so AA Relay back home.
Summary of what we have done so far:
Fuel and Mechanical checks completed - checked fuel pump and fuel filter etc were good and the carb was not full of grit. Completed a compression test on all 4 cylinders and for 175000 miles the readings were good – I wanted to make sure I didn’t have a valve seat issue leading to a hot spot pre igniting the fuel. I also checked the rocker settings just in case one had loosened off leaving a valve closed etc.
Ignition-Earth checks: The engine to chassis earth strap is good and tight. I have also checked, cleaned and made good the ignition system earth wire – Control Unit to engine block. The ignition timing was a couple of degrees off but following reset the running improved slightly but misfire still there.
Ignition parts changed so far: I have swopped out the following one at a time to see if any got rid of the misfire - Coil, HT-Lead set, distributor cap, rotor arm and plugs. I also bought in an ignition ‘Control Unit’ which, after fitting it the issue was still there and because the mounting holes to the heat-sink plate are not the same as the original then for now I have retained the original Unit.
- according to the Haynes manual apart from the Ignition Control Unit there is also an ‘Idle stabilising unit (ISU)’ which in my case I cannot locate in the engine bay! Am I just not seeing it or does anyone know if the ISU unit is only fitted to certain models?
- Given the items I have swopped out so far would anyone agree that the next logical step would be to tackle either a new distributor or the vane and pick up unit? Or do you have another route I should follow?
Nigel and Katie G