Nothing like a few days off work to read up on other potential misfire issues. I keep thinking why would changing the shorter V belt for a longer one narrow the misfire range? Then I thought maybe the shorter V belt put a strain on the harmonic balancer causing vibration that the sensors pick up. See an article I found and an section from it. Diagnostic Dilemmas: The Misfire Code As a Symptom During the inevitable research involved in a case like this, I recalled a Nissan Pathfinder with a loose harmonic balancer that caused a similar false misfire coding problem. In addition, I discovered anecdotal evidence that rare factors like serpentine belts with an over-lapped splice and the occasional rough defective timing belt would cause timing deflections that might be mistaken by the PCM as an engine misfire. I did notice the rubber on the balancer looked tired so maybe the outer part has slipped causing vibration? looking at what I've changed the issue has to be something weird. I got the word that the battery checked out fine so the above could be a valid theory.
The balancers are relatively inexpensive. I changed mine about a year ago while chasing a misfire. Not sure it helped (we changed a couple of sensors too) but it was piece of mind...
seeing as it rains a lot in CR I think rain deer would be better LOL Bought a pulley today. So I'll replace the pulley, belt and alternator which should fix any vibration.
I'm back on it for 2016! Swapped the crank pulley and alternator yesterday. Started the engine, got up to the magic 3000rpm and once again the fault appeared! but hold on, it took longer for the fault to happen and now the fault range has reduced to 3000-3600rpm. Also now the error code is P0304 and not P0300. P0300 is multi-cylinder, P0304 is cylinder 4 , I confirmed that by removing the plug leads. So I swapped the leads as 1 and 4 fire together. same issue. I swapped the plugs but still the same issue. Tonight I'm going to swap the injectors from 3 to 4.
You're dedicated, Chris. I'll grant you that. Me...I'd have invested in some C4, a timer, and given that Coopah a decent "fare thee well" a long time ago. :devil:
I thought about it but then what would I do with my spare time?? Anyway I swapped the injectors around last night but #4 still had the error code. I did some testing and found code P0304 happened going up to 3000rpm and code P0300 happens when coming down from 4000rpm to 3500. The fault is now just now from 3000 to 3500. At this range I hear a lot of popping through the exhaust, so I put my stick on the throttle keeping the RPM just below 3000 then put my hand over the tail pipe. I could feel suck every pop so maybe a I have sticking valve on #4? A job for the weekend.
I thought sticking valve /valves had been discussed and checked but this has gone on for so long I tend to forget. The good news is that if'n this is the fix you're gonna have an almost new vehicle due to all the other things you have repaired. Also with all the knowledge you have attained along the way you will no longer be just a Midlands 5 speed wizard but an R50 wizard.
Part out your R50. God knows you have enough spare parts now! then, with all the money you get from parting out your non-functioning car...BUY ONE THAT RUNS!!!
Ah Yes I thought about that but R50's are not common here. Also there is the small detail of the roll cage etc. I imported this Mini as a 2 seater so getting another Mini from here would give me issues doing the technical test. Anyway I'm going to fix it one day and look back and laugh!
Ah yes the drama continues! I bought a valve spring compressor to remove the valves with the head on. I had to modify it slightly to work with the Mini head but in the end I got it to work. Anyway taking out 16 valves, checking and replacing them takes about a day. I didn't find anything bad, some exhaust valves had a slight resistance but nothing bad. I didn't find any wear, nothing to make me thing the valves were bad. Once I had everything back together I tried the 3000rpm test and sure enough the fault is still there. A while back I bought a cheap scan tool from China, never used it as it could not cancel codes but there is a nice little feature to monitor smooth running and misfire detection. I thought I'd run the misfire monitor. I get 0 for #1 #2 but #3 misfires per 200 cycles around 126 and #4 around 6 before going on 3 cylinders. So looking at that data my misfire cylinders are #3 #4 as noted in the error codes P0303 and P0304 and sometimes P0300. I changed the injectors over from 1,2 to 3,4 hoping to make the fault move. The misfire remained at 3 ,4 one strange thing is the engine went onto 3 cylinders at idle with #2 having the misfire just once after changing the injectors. Not being an electronics expert does not help me figure this out. I'll keep at it.