the need to raise rpm before shutting down a warm engine?

 

I've never done this with a warmed/hot engine. I have the M-flash.
I think the card the dealerships are giving out now says that the raising of the rpm is for engines that are not warmed up.

 

better safe than sorry IMO

 

I have the M flash and, either before or after getting it, I have never revved the warm engine on shut-down. I have never had a flood or any other problem. There is no need for revving it when it's warm, IMHO.

 

I only rev the engine when it's not fully warmed. I've forgotten to do it many times also though, but haven't had any problems. I think the flooding issues have pretty much been worked out on the later build cars.

 

I was told the M flash would eliminate flooding so you should be able to shut it off cold, but i still try to avoid shutting it off cold.

 

I've never revved my engine to shut it off and I've even started it and shut it down within seconds--ice cold. I've never had a flooding problem, M-flash or otherwise.

 

Pre-"M" flash PCMs tried to immediatly rev the engine to 2500 or so when started cold. The result was, occationaly, the PCM tried to rev up an engine that wasn't actually -running-, resulting in a flood. The "M" flash causes it to wait a few seconds before reving. You can still flood the engine other ways (when very cold out, for example). The car still idles very rich as well, and that's just begging for a flood.

To answer your question, there was never a "need" to rev the engine before shutting it off. It was and still is a good idea - e.g. it hurts nothing, and -may- help to reduce flooding. I rev. it and shut it off letting it coast back down to 0 RPM. Oh, and I do that a lot - every time I test a new or refurbed Stage 1 box.

 

I went to WSB recenty at Laguna Seca and there was a Mazda Engineer standing in their booth next to a rotary engine. I asked him to tell me more about the function of the M flash. What he relayed was that the M flash now operates in such a way that it waits 3 seconds while turning over the engine before fuel is injected into the rotor housing. This eliminates the flooding issue.

 

M flash screwed my car up.........
My ROUGH idle is now worse.
Gas mileage is slightly WORSE.
When shifting at high RPM's I feel 3rd hesitate a bit when I fully release the clutch/floor gas.

Its just amazing to me the problems I have.

Oh....I put the MT90 REDLINE in......shifts are MUCH MUCH improved......but I still have that damn grinding from 1st to second..........

Jeff

 

I have the "M" flash. I have had several times where I have had to move the car to wash it. Didn't let it warm up, shut down, and has always started fine. Never did the rev before shut down. Prior to the M I did let it warm up on short moves and did the 3000 rev.The "M" flash had addressed the flooding issue. It is probably best to let it warm up though-just from a lubrication stand point- as the oil is not circulated until the engine is warmed up...