G
Geoff
I have 60 hours on my RV-8, Mattituck IO-360 (vertical induction) with Silver Hawk injection and two P-mags. After a few teething pains (to be expected), the thing runs great. The only outstanding issue is that when taxiing with hot engine, it starts to miss at low RPM settings after 3-4 minutes. This only occurs with a hot engine, on the ground, at low RPM, with ambient temperatures > 60F or so. I'm pretty sure this is due to fuel boiling somewhere in the lines, but I'm not sure what to do about it.
Here is some relevant information:
1) If this only happens on the ground with very little air moving over the engine, why would installing a blast tube to the mechanical pump make any difference? There wouldn't be much air miving through it...
2) Is there an easy way to tell where the fuel is boiling? Between the mechanical pump and servo, servo and divider, or divider and injectors?
3) At what temperature should 100LL be boiling? My under-cowl temperature probe is moveable, so I can put it just about anywhere to take measurements.
4) Has anyone tried putting firesleeve on the injector distribution lines? Do they even make it that small?
5) Should I just resign myself to the fact that a tightly-cowled engine is going to do this at idle sometimes? I never experienced this when operating similar engines in much hotter climates, but they weren't nearly as tightly-cowled as the RV-8.
6) Does anyone else experience this problem?
Any and all comments/ideas welcome.
Thanks.
Here is some relevant information:
- Engine only misses when hot, on the ground, low RPM, outside air temperature > 60F or so.
- Increasing the RPM to 1100+ makes the problem go away.
- Temperature under the cowl, at the top near the oil filler door runs about 50-60F higher than outside air temperature. So it's 110-120F in there when this is happening, although it might be cooler above the cylinders on the forward side of the baffling.
- Turning on the electric boost pump has no effect, so the problem is not occuring upstream of the mechanical pump.
- Adjusting the mixture (manually and/or idle mixture screw) has no effect.
- Every fuel line firewall forward is firesleeved except the lines to the injector nozzles.
- No gascolator installed.
- Hot starts are never a problem -- only idling when hot.
1) If this only happens on the ground with very little air moving over the engine, why would installing a blast tube to the mechanical pump make any difference? There wouldn't be much air miving through it...
2) Is there an easy way to tell where the fuel is boiling? Between the mechanical pump and servo, servo and divider, or divider and injectors?
3) At what temperature should 100LL be boiling? My under-cowl temperature probe is moveable, so I can put it just about anywhere to take measurements.
4) Has anyone tried putting firesleeve on the injector distribution lines? Do they even make it that small?
5) Should I just resign myself to the fact that a tightly-cowled engine is going to do this at idle sometimes? I never experienced this when operating similar engines in much hotter climates, but they weren't nearly as tightly-cowled as the RV-8.
6) Does anyone else experience this problem?
Any and all comments/ideas welcome.
Thanks.