Best technique for clearing a fouled plug

Pmerems · #1 04-28-2014, 02:08 PM

Attention all Yoda's out their with vast experience in clearing a fouled plug during runup.

What is your best proceedure? I have a IO-360 engine.

Tried to go for flight yeasterday and during the runup I experienced a fouled plug. I tried a few attempts at a high RPM (2K) setting and leaned but it would clear. I am typically very careful about leaning during taxing both prior to takefoof and after landing. However my previous flight ended with a very long 2.5 mile taxi back to the hangar and most likely didn't lean properly during the road trip before I shut down the engine.

The engine monitor worked great to determine which plug was fouled but I had to remove the lower cowl to remove and clean the plug. Did an oil change while I had the cowl off so the morning wasn't a total waste.

So back to my question, what is your best time tested precedure for clearing a foulded plug during runup?

Any help would be appreciated.

Joness0154 · #2 04-28-2014, 02:21 PM

I usually lean very aggressively on the ground to prevent this in the first place, however if I do get a fouled plug:

RPM 1700 and aggressive leaning for a minute or so. If that doesn't do it, 2 minutes. If that didn't do it, back to the hangar. You don't want to run at a high enough power that detonation becomes an issue, so be aware of that.

Pmerems · #3 04-28-2014, 03:28 PM

When faced with the fouled plug I leaned for max RPM any more then that the engine RPM drops (as expected). So how do you define aggressive leaning?

Thanks,

Don Patrick · #4 04-28-2014, 04:15 PM

I fly a Bellanca Scout with the Air Cadet League where we typically are doing 8 take-offs and landings an hour with the towing of the gliders.

We have pretty extensive procedures for all sorts of things and one of the items in our checklist is for fouled plugs.

When doing the run-up, we set the RPM at 1800 and then check each mag. If the RPM drops too low on one mag, the procedure for us to unfoul the plugs is to go max RPM for 15-20 seconds, then back down to 1800 and check the mags again.

Worked like a charm yesterday.

We use to do a burnout at the end of the day where the engine would be leaned to peak at 1800 for 60 seconds and the idle and mixture cut-off. That usually cleared most of our issues, but that procedure has since been canned.

Cheers,

Don

N941WR · #5 04-28-2014, 04:21 PM

With the dual electronic ignition and auto plugs, I have had not fouling issues in almost 600 hours and I don't lean my engine on the ground. (I know, I know, I should.)

Do others with EI have issues with fouled plugs?

Walt · #6 04-28-2014, 04:26 PM

Quote:

Originally Posted by Pmerems

Attention all Yoda's out their with vast experience in clearing a fouled plug during runup.

What is your best proceedure? I have a IO-360 engine.

So back to my question, what is your best time tested precedure for clearing a foulded plug during runup?

Well you may not like this but.... the only real way to clean your plugs are to take them out and do the job

BillL · #7 04-28-2014, 05:23 PM

Quote:

Originally Posted by Walt

Well you may not like this but.... the only real way to clean your plugs are to take them out and do the job

+1, Sorry.

Joness0154 · #8 04-28-2014, 05:41 PM

Quote:

Originally Posted by Pmerems

When faced with the fouled plug I leaned for max RPM any more then that the engine RPM drops (as expected). So how do you define aggressive leaning?

Thanks,

Keep leaning until she starts to run rough and slightly enrichen at that point.

jbDC9 · #9 04-28-2014, 06:10 PM

Quote:

Originally Posted by N941WR

Do others with EI have issues with fouled plugs?

Nope! Dual P-Mags running NGK BR8ES plugs for 1100 hours, never had a fouled plug at run up. I lean on the ground a good bit, just in case...

skylor · #10 04-28-2014, 06:16 PM

I had this happen just the other day. First time in 280 hours, and wouldn't you know, it just had to happen when giving a demo ride to a new RV-7 builder...

Anyway, I left the engine at runup RPM (1800) for a minute or so, leaned as far as I could go without the offending cylinder dropping out. I could see the dropped plug during the leaning exercise because that cylinder was running with a high EGT while it was firing on just one plug. After a minute or so, it still hadn't cleared, but when I pulled it back to idle for 30 seconds then repeated the runup it was clear. The problem hasn't returned in the five flights since. Also worth noting, I had cleaned and regapped the plugs during condition inspection just a few flight hours prior.

This is on an IO-360 angle valve.

Skylor
RV-8