210 variable speed

If the concern is that oil on the pre-filter would clog the pores of the paper filter and restrict air flow, then it should be an easy check to see if this is an issue. Restricted airflow would make the fuel mixture burn richer, which would be visible as black carbon deposits on the spark plugs. This would be for carbureted engines like a 425, though I'm not sure what happens with an EFI engine (e.g. 445)..... whether the mass airflow sensor provides the info to compensate and adjust fuel mixture or not.

The conventional wisdom with oiling the pre-filter is that very fine particles get stuck by the oil in the cleanable pre-filter. I believe this is to extend the use of the non-cleanable more expensive pleated paper filter, rather than any concerns for preventing premature engine wear. If you find it necessary to clean the air filter really often, I would think you would want to rely more on the cleanable pre-filter rather than less.

Regarding the original problem, not sure what you're environment is, but perhaps mowing in less dusty conditions might help like in the morning (dew) or a day after it rains.

NOT trying to be a "Know It All" here - Just thinking this might be a good place to seg-way into the future of fuel injected lawn and garden engines .

The 445s' Kawasaki engine uses MAP(manifold absolute pressure),which is a speed / density system , to direct the fuel management . MAF system is not involved , and not present on this engine . The speed density system correlates the manifold pressure as "load" , and together with the engine speed reference input , directs the computers output to the "duration" signal (how many milli-seconds to hold the injector open) . This engine is "open loop" programmed , meaning that the fuel curve is preset in the computer and does not change , and therefore does not have an oxygen sensor feedback involved.

That being said.., The Mass Air Flow system (MAF) , is much more sophisticated , and actually measures the air flowing into the engines . Some use a "hot" wire to do this , and some are a damper valve that swings to calculate air flow . This system will most likely be seen only in cars [which will have either MAP or MAF] , or in some cases , can utilize both together (rare).

Kohler EFIs' use a "closed loop" system with a single wire (not heated) oxygen sensor input to trim the prom (programmable read only memory) chip in the fuel management ECU , and is more than likely MAP directed (not 100% sure), rather than the more expensive , and sensitively delicate - MAF system . For good reason .., we probably won't see MAF systems on lawn mower engines , as they are very delicate and probably would not stand up to the rigors of this industry - in general .

Welcome to the future everyone , where lawn mower engines will soon be as complex as the older car engines in the 80s' used to seem to us , but only until we learn what makes 'em tick . Some will grasp this new (old) 'tec stuff , and others will be at the mercy of others to figure it out (just as always) , but I have to know the whats'what when it comes to this stuff to feel comfortable .

Sorry for the long diatribe here on fuel injection .., just thought I'd share what I know personally , before the old carburater(sic) goes the way of the DO-DO bird , as it has in automobiles.

Dave

Hey David, Thanks for taking the time to do a write up on the distinction. Continuing the digression... since I'm guessing Jay is going to grow more grass to help his issue ;-)

A while back, I was looking for a MAP sensor for my 445 and went through a bit of sticker shock at the JD prices (~$275 if I recall). Looking around e-bay I could find physically identical looking Denso MAP sensors for Honda and others in the $29 range. However, none that matched the exact Denso part number 100798-2910 (still have it written down from my search). While I can imagine how the output profile is intended to match my FD620D engine, I was not able to find any information that might give me some insight into finding a potential close match for 1/10th the price, or alternate supplier for the exact Denso part.

I have always appreciated the simple mechanical nature of carburetors, though in hind site, EFI seems like a much simpler system, despite it's reliance on multiple pricey sensors.

The only negative I have is that I regret being bound to what feels like high monopolistic prices on EFI components that 445 owners are subject to. I think one could spend upwards of $2k to replace all new EFI specific components that are unique to a 445. Some of the components are virtual black boxes that some will swap in a working component to determine if the old one is faulty. Without a return policy, it can be a really pricey diagnostic technique. I'm lucky to have multiple 445 engines to swap parts should I get into that situation. I wonder if X485 and X728 owners suffer the same sticker shock or whether there are alternate suppliers with shared EFI related components. The 445 EFI module is about the size of an iPhone, probably has 1000 times less processing power, a million times less memory, but costs 6 times as much. Too bad there isn't a 445 EFI app for an iPhone (yet) ;-)

Fortunately those components seem to typically outlast everything else and so are likely to be among the last to go.