Westerhuis
Active Member
Hi all
I posted a question about the torque on intake gaskets earlier. I found that the bolts were not very tight as part of an effort to find out why my engine runs a bit rough (intermittently) on low RPM. It feels like it misses a beat every few seconds are so, when the RPM sits between 610 - upper 700. If I increase the RPM a bit it starts to run smooth.
How do I approach trying to locate what might be causing the fault? Few things about my set-up:
Mattituck IO-360, with dual PMags and vertical induction. Pmags connected to an EI Commander. Car plug conversion, and I have installed eight new spark plugs a few weeks ago. I did an Ohm check on the HT leads and one lead has a slightly higher resistance than advised, and I have a new one on order. I have a Dynon D700 EFIS with EMS. App. 560 hrs total.
Initially I suspected an issue with my PMags but having spoken with Brad at EMag, I am less and less sure it is the mags. I have been testing them fairly extensively and they seem to produce their own power when expected, and when the engine runs a bit rough in the lower range, I get the impression they are receiving battery power, or at least to not kill the engine. At lower RPM I am below the RPM that the mags produce their own power (from app. 950 on my set-up,) so they need battery power to operate.
There is nothing on the engine monitor (I have individual CHT and EGT readings for each cylinder) that indicates that one cylinder is not 'firing' or at least all the temps give me a fairly consistent reading across all four cylinders. The roughness feels the same when running on either mag exclusively.
I checked the inlet manifold to see if there were air leaks, hence my post earlier, but again, if there was I would expect it to show on the affected cylinder. I did tighten the bolts a bit and the hose clamps to see if that made a difference. It didn't.
What else could I do to try and find the problem? I made a little video that shows the slight 'surging' when running idle and you see the RPM fluctuate by 40 rpm or so, when this happens. I don't think I can post the video here. I would like to add that when I increase the RPM the engine runs smooth and I have had no issues in flight with the engine sounding great and all the readings looking correct.
Thanks
Roger
I posted a question about the torque on intake gaskets earlier. I found that the bolts were not very tight as part of an effort to find out why my engine runs a bit rough (intermittently) on low RPM. It feels like it misses a beat every few seconds are so, when the RPM sits between 610 - upper 700. If I increase the RPM a bit it starts to run smooth.
How do I approach trying to locate what might be causing the fault? Few things about my set-up:
Mattituck IO-360, with dual PMags and vertical induction. Pmags connected to an EI Commander. Car plug conversion, and I have installed eight new spark plugs a few weeks ago. I did an Ohm check on the HT leads and one lead has a slightly higher resistance than advised, and I have a new one on order. I have a Dynon D700 EFIS with EMS. App. 560 hrs total.
Initially I suspected an issue with my PMags but having spoken with Brad at EMag, I am less and less sure it is the mags. I have been testing them fairly extensively and they seem to produce their own power when expected, and when the engine runs a bit rough in the lower range, I get the impression they are receiving battery power, or at least to not kill the engine. At lower RPM I am below the RPM that the mags produce their own power (from app. 950 on my set-up,) so they need battery power to operate.
There is nothing on the engine monitor (I have individual CHT and EGT readings for each cylinder) that indicates that one cylinder is not 'firing' or at least all the temps give me a fairly consistent reading across all four cylinders. The roughness feels the same when running on either mag exclusively.
I checked the inlet manifold to see if there were air leaks, hence my post earlier, but again, if there was I would expect it to show on the affected cylinder. I did tighten the bolts a bit and the hose clamps to see if that made a difference. It didn't.
What else could I do to try and find the problem? I made a little video that shows the slight 'surging' when running idle and you see the RPM fluctuate by 40 rpm or so, when this happens. I don't think I can post the video here. I would like to add that when I increase the RPM the engine runs smooth and I have had no issues in flight with the engine sounding great and all the readings looking correct.
Thanks
Roger