Beemergeek
New member
Hi guys as the title says I'm having a misfire on 5 & 6. The problem started easter friday when I drove to JHB for a family outing. The car drove fine all the way maybe I was even going over the speed limit with no hassles.. I said maybe 
Got to our destination and parked the car. When we got back the car just refused to start. I thought it was flooded as it was smelling a bit rich for a while so I tried kickstarting. Car still wouldn't start. Removed the spark plugs and cleaned them. Still nothing. Checked whether the fuel pump was running. Swapped computer boxes with my old one I kept in the boot just in case. Still nothing. So I decided to just leave it with the battery terminal removed for 5 min. still nothing. Left the car for another 30mins... nothing. After a further +-1 hour I tried and low and behold the car started... on my way home the car would hesitate every time I drove up a hill. Tried tps, spark plugs and coils on 5 & 6 only, maf and exhaust cam sensor and a spare fuel pump (which should be good)with known good units one by one with no change.
Stripped timing case cover and checked timing all still within spec so I couldn't have bent valves. No over reving so I couldn't have dropped a valve either. Interesting thing was my valve clearance wasn't within spec but the car ran fine all the time. There is less clearance which is the opposite of what is normally the case as the shims are supposed to wear and the clearance should increase. I checked it with engine stone cold. BMW spec for S50b30 both exhaust and inlet is min0.28mm & max 0.33mm For e.g. #5 inlet tested 0.20mm on the one and 0.10mm on the other. #6 tested 0.20mm & 0.22mm both on inlet and exhaust. Could this be my problem and how does the tolerance get tighter?
I'm @ the stage where I want to test for compression but none of the off the shelf testers thread in the spark plug wells. Does anyone know where I can get an adapter or a complete unit that works on bmw. I use bosch Y5ddc plugs.
Got to our destination and parked the car. When we got back the car just refused to start. I thought it was flooded as it was smelling a bit rich for a while so I tried kickstarting. Car still wouldn't start. Removed the spark plugs and cleaned them. Still nothing. Checked whether the fuel pump was running. Swapped computer boxes with my old one I kept in the boot just in case. Still nothing. So I decided to just leave it with the battery terminal removed for 5 min. still nothing. Left the car for another 30mins... nothing. After a further +-1 hour I tried and low and behold the car started... on my way home the car would hesitate every time I drove up a hill. Tried tps, spark plugs and coils on 5 & 6 only, maf and exhaust cam sensor and a spare fuel pump (which should be good)with known good units one by one with no change.
Stripped timing case cover and checked timing all still within spec so I couldn't have bent valves. No over reving so I couldn't have dropped a valve either. Interesting thing was my valve clearance wasn't within spec but the car ran fine all the time. There is less clearance which is the opposite of what is normally the case as the shims are supposed to wear and the clearance should increase. I checked it with engine stone cold. BMW spec for S50b30 both exhaust and inlet is min0.28mm & max 0.33mm For e.g. #5 inlet tested 0.20mm on the one and 0.10mm on the other. #6 tested 0.20mm & 0.22mm both on inlet and exhaust. Could this be my problem and how does the tolerance get tighter?
I'm @ the stage where I want to test for compression but none of the off the shelf testers thread in the spark plug wells. Does anyone know where I can get an adapter or a complete unit that works on bmw. I use bosch Y5ddc plugs.
