Waxed and ready
Discussion
.....
Bah. Wish I could say the same. I spent almost the entire day today trying to figure out what was wrong with the 390. Basically: it wouldn't start.
Did full diagnostics on the fuel injection, had plenty of fuel, spark at each lead according to the strobe, injector pulses according to the oscilloscope, but would it fire? Would it hell.
Smelt of lots of petrol, so I began to think either the coil wasn't delivering a fat enough spark, or the ECU was overfuelling. Now bear in mind I'd MIG welded the exhaust the other day, without disconnecting anything (I usually do) and you can see I was starting to get paranoid.
In the end I rang Dexy, who 'volunteered' to bring his ECU over to try. In the meantime I was getting desparate for ideas, so I decided to check the compressions. Out with the first plug.. and it was fouled to hell. So was the second... and the remaining six. What the hell? This engine was rebuilt 6000 miles ago; it had new plugs about 1500 miles ago and has been running perfectly until the last few days when it's been getting progressively worse- rough idle, stalling for no reason. In the process of tracing the fault, I'd refitted the original AFM, tried a spare coolant temp. sensor, disconnected the throtle pot, checked the fuel rail pressure. I even stripped and cleaned the overrun valve in case it was sticking open, but it was fine.
So now I had 8 fouled plugs. I quickly checked the compression of two cylinders on each bank and they were all the same, so I threw the plugs in the sandblast cabinet, cleaned them up and refitted them. Turned the key and it started first time.
Now I don't think the valve guides have suddenly worn out, there's no cloud of smoke on startup like you'd expect if oil was running down the valve stems, so I can only conclude it's fuel fouling, which suggests overfuelling, maybe all that popping and banging on overrun isn't such a good thing after all!
I guess that when the strobe said the plugs were firing, in fact the HT was just shorting to earth. You'd think with my experience I'd have thought of that
So yes, with luck I'll be at the 'Fest, but with a spare set of plugs and some twiddling sticks...
Right, must go: got to apply some more cellulose putty to the stress cracks in the front spoiler... and it's after 2!
Ian
Did full diagnostics on the fuel injection, had plenty of fuel, spark at each lead according to the strobe, injector pulses according to the oscilloscope, but would it fire? Would it hell.
Smelt of lots of petrol, so I began to think either the coil wasn't delivering a fat enough spark, or the ECU was overfuelling. Now bear in mind I'd MIG welded the exhaust the other day, without disconnecting anything (I usually do) and you can see I was starting to get paranoid.
In the end I rang Dexy, who 'volunteered' to bring his ECU over to try. In the meantime I was getting desparate for ideas, so I decided to check the compressions. Out with the first plug.. and it was fouled to hell. So was the second... and the remaining six. What the hell? This engine was rebuilt 6000 miles ago; it had new plugs about 1500 miles ago and has been running perfectly until the last few days when it's been getting progressively worse- rough idle, stalling for no reason. In the process of tracing the fault, I'd refitted the original AFM, tried a spare coolant temp. sensor, disconnected the throtle pot, checked the fuel rail pressure. I even stripped and cleaned the overrun valve in case it was sticking open, but it was fine.
So now I had 8 fouled plugs. I quickly checked the compression of two cylinders on each bank and they were all the same, so I threw the plugs in the sandblast cabinet, cleaned them up and refitted them. Turned the key and it started first time.
Now I don't think the valve guides have suddenly worn out, there's no cloud of smoke on startup like you'd expect if oil was running down the valve stems, so I can only conclude it's fuel fouling, which suggests overfuelling, maybe all that popping and banging on overrun isn't such a good thing after all!
I guess that when the strobe said the plugs were firing, in fact the HT was just shorting to earth. You'd think with my experience I'd have thought of that
So yes, with luck I'll be at the 'Fest, but with a spare set of plugs and some twiddling sticks...
Right, must go: got to apply some more cellulose putty to the stress cracks in the front spoiler... and it's after 2!
Ian
streaky said:
Right, must go: got to apply some more cellulose putty to the stress cracks in the front spoiler.
Streaky
the missus is just doing the same her bikini line has been done and the clippings have been put into a sack just in case the pillows are too hard
......and i've just had a slap 
dickymint said:
her bikini line has been done and the clippings have been put into a sack just in case the pillows are too hard
[printscreen]
[blackmail]Muahahahhahahaaaa... you're buying the drinks all weekend then...?
[/blackmail]
Ian
Speed Matters | Wedges | Top of Page | What's New | My Stuff