Discussion
I've done an improvised leak down test. Using compressor charged to around 80psi, and a modified Tyre inflator thingy with adapter down into spark plug. All other plugs out and engine cold (I know it's supposed to be done hot but this evening is too warm)
Tested by rotating engine, holding on tight to torque wrench on crank and carefully finding the sealed point by pulsing air, rotating a bit etc. Once found cyl 1 5 and 6 (have checked those so far) all behave the same...at around 60psi into cylinder then release pressure I can get to point with no obvious audible leaks and can just about hang on to wrench! Leaks down to zero in around 5 secs. Seems to mainly pressurize the sump because after that small rotations cause audible leaks from any of the other cylinders.
I reckon that's an OK test...unless someone knows better...please.
Tested by rotating engine, holding on tight to torque wrench on crank and carefully finding the sealed point by pulsing air, rotating a bit etc. Once found cyl 1 5 and 6 (have checked those so far) all behave the same...at around 60psi into cylinder then release pressure I can get to point with no obvious audible leaks and can just about hang on to wrench! Leaks down to zero in around 5 secs. Seems to mainly pressurize the sump because after that small rotations cause audible leaks from any of the other cylinders.
I reckon that's an OK test...unless someone knows better...please.
Appreciate all the feedback guys. I have reset the adaptives etc, also tried running with no lambdas. All to no avail.
I have have also disassembled the ecu and all looks A OK. Have buzzed out direct from power transistors on ecu pcb to the coil pack connections and to injectors ...all nice low R.
Think I'll check the valve clearances one more time when properly hot.
I have a fuel pressure tester on the way and I'm also going to try and use one of the colortune thingys to see if there is evidence of mixture issues.
After that it's oscilloscope on each ht lead.
I have have also disassembled the ecu and all looks A OK. Have buzzed out direct from power transistors on ecu pcb to the coil pack connections and to injectors ...all nice low R.
Think I'll check the valve clearances one more time when properly hot.
I have a fuel pressure tester on the way and I'm also going to try and use one of the colortune thingys to see if there is evidence of mixture issues.
After that it's oscilloscope on each ht lead.
No change. I believe that pipe basically does nothing because the vacuum in the air box is never going to be enough to activate it. You'd need the suck from the engine side of the butterfly in the throttle body imo. Anyway good suggestion.
I also confirmed that map sensor is OK (which of course also doesn't see much change in the air box for the same reason)
I also confirmed that map sensor is OK (which of course also doesn't see much change in the air box for the same reason)
Just to pick this thread up again vs. the ECU one...
"I wonder if the fuel pressure regulator is playing up. Think about the full throttle and vacuum while the engine is running. I have experienced a blocked, partially, filter ( not in a TVR) and you will get a spot of normal running then run out of puff while the fuel passes the filter and builds pressure in the line. If this isn’t closing when it should it would be surely be dumping fuel? Still don’t get its function and purpose though. Hook the hose off then it is “blind” to the throttle position
Worth a shot
J "
@John: Agree...I'm wondering the same
Just for ref here are 2 waveforms captured on the coil primaries...all 3 coil drives doing the same kind of s***. Everything ive found implies that it's a lean misfire on all cylinders at random
"OK" fire
"Horrible" misfire (assumed)
"I wonder if the fuel pressure regulator is playing up. Think about the full throttle and vacuum while the engine is running. I have experienced a blocked, partially, filter ( not in a TVR) and you will get a spot of normal running then run out of puff while the fuel passes the filter and builds pressure in the line. If this isn’t closing when it should it would be surely be dumping fuel? Still don’t get its function and purpose though. Hook the hose off then it is “blind” to the throttle position
Worth a shot
J "
@John: Agree...I'm wondering the same
Just for ref here are 2 waveforms captured on the coil primaries...all 3 coil drives doing the same kind of s***. Everything ive found implies that it's a lean misfire on all cylinders at random
"OK" fire
"Horrible" misfire (assumed)
Finally found it after lots of experiments and some luck.
I have throttle body spindles linked by shaft couplers rather balance arms. Long story short...the coupler between 4 and 5 would slip slightly but only when hot! And yes, I had poked and wiggled all the butterflies very early on in the process to make sure they weren't loose...of course that showed nothing in the garage but out on the road butterflies 5 and 6 must have ended up slightly too closed under some random conditions making those cylinders run horribly but of course nothing much to hear up the engine end to give the game away (apart from the horrible flat shaky misfire). If it had gone lean it would have been popping and chuffing in an obvious way. I only found it because it finally got sooo bad that it was barely drivable and only then did I notice the problem once back in the garage with the airbox off.
So after a long journey and quite a few bits replaced it's back to normal. Thanks for all the suggestions.
I have throttle body spindles linked by shaft couplers rather balance arms. Long story short...the coupler between 4 and 5 would slip slightly but only when hot! And yes, I had poked and wiggled all the butterflies very early on in the process to make sure they weren't loose...of course that showed nothing in the garage but out on the road butterflies 5 and 6 must have ended up slightly too closed under some random conditions making those cylinders run horribly but of course nothing much to hear up the engine end to give the game away (apart from the horrible flat shaky misfire). If it had gone lean it would have been popping and chuffing in an obvious way. I only found it because it finally got sooo bad that it was barely drivable and only then did I notice the problem once back in the garage with the airbox off.
So after a long journey and quite a few bits replaced it's back to normal. Thanks for all the suggestions.
As part of my swapathon I changed the fuel pump and filter. The old filter was an eye opener...very much harder to blow through than the new one even though it was well within its service period. Didn't make any difference to the fault of course but might effect running at full throttle I guess.
The other thing that becomes apparent when logging adaptives is that the feedback loop makes diagnosis very confusing! A mixture fault in one or more cylinders on a bank makes the remaining ones on that bank also start to misbehave
The other thing that becomes apparent when logging adaptives is that the feedback loop makes diagnosis very confusing! A mixture fault in one or more cylinders on a bank makes the remaining ones on that bank also start to misbehave
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