PDA

View Full Version : Soft rev limitor on PFC



souljourner
09-15-2009, 06:06 PM
Hey guys,

I run the PowerFC on my S14 and I've always wanted to have the soft rev limiter (spark cut instead of ignition cut).

PFC does not have built-in soft limiter so I came up with an idea:

What if you set your timing map so that at your desired reline, you simply reduce the ignition timing massively? to like -5 or -10?

Would that have the same effect as soft limiter? I haven't given it a try yet but seems to make sense with my very limited knowledge so far.

lets discuss :)

John

srs14
09-15-2009, 07:12 PM
you said spark cut istead or ignition cut. they are one in the same. the pfc has a fuel cut rev limiter.

as for editing the map for it. thats a horrible idea because if you hit that part of the map while driving regularly then you hit the rev limiter.

Bee-r (sp?) makes a ignition cut rev limiter, i think thats how you spell it. why do you want ignition instead of fuel? lauch control?

souljourner
09-15-2009, 07:54 PM
you said spark cut istead or ignition cut. they are one in the same. the pfc has a fuel cut rev limiter.

as for editing the map for it. thats a horrible idea because if you hit that part of the map while driving regularly then you hit the rev limiter.

Bee-r (sp?) makes a ignition cut rev limiter, i think thats how you spell it. why do you want ignition instead of fuel? lauch control?

Hey thanks for correcting me. I meant ignition cut instead of fuel cut.

I want it for a rev limiter for safety rather than for launch control. From my understanding, fuel cut could potentially cause knock as the engine runs lean. Soft cut pretty much limited the engine rev due to loss of power. The downside of soft cut is the high EGTs potentially damaging turbos and downpipes.

steve shadows
09-16-2009, 12:10 AM
The PFC Rev limit is fine as it is.

Why is this an issue?

You can set it at any level you would like using FC Logit or other commander sw

Kingtal0n
09-23-2009, 04:49 PM
Hey thanks for correcting me. I meant ignition cut instead of fuel cut.

I want it for a rev limiter for safety rather than for launch control. From my understanding, fuel cut could potentially cause knock as the engine runs lean. Soft cut pretty much limited the engine rev due to loss of power. The downside of soft cut is the high EGTs potentially damaging turbos and downpipes.

you are better off with a real fuel cut

set it where you want it like steve said and leave it alone
this is not the sort of thing you mess with for "fun" and if you need a 2-step get an MSD DIS-4 or something like it that has one

Bucum
09-26-2009, 05:26 AM
From my understanding the spark rev limiter can break the engine. Unburn fuel gets in the hot manifold and turbo. Fuel ignites and pushes valves which hit piston.

Allthough spark limiter is much cooler because you get cool flames.

ericb382
09-26-2009, 03:14 PM
Not sure how the PFC is set up, but can you control at which RPM fuel is cut, and at which RPM fuel starts getting added back in again seperately? If so, just set these two parameters closer together

Napalmsticks
10-20-2009, 10:32 PM
Seriously, is this possible? I have a BEE-r on my car and just broke a valve in half and dropped half of it into the engine....:p Forged internals here I come!

From my understanding the spark rev limiter can break the engine. Unburn fuel gets in the hot manifold and turbo. Fuel ignites and pushes valves which hit piston.

Allthough spark limiter is much cooler because you get cool flames.

Napalmsticks
10-20-2009, 10:39 PM
Also, does this work? Just bought a PFC and after hearing this I am gonna ditch the BEE-r...

Not sure how the PFC is set up, but can you control at which RPM fuel is cut, and at which RPM fuel starts getting added back in again seperately? If so, just set these two parameters closer together

ericb382
10-21-2009, 12:56 AM
Like I said, I'm not sure how the PFC is set up, but on my bikirom it I set the two values about 100 rpm different so I had a "semi-soft" rev limit...

Napalmsticks
10-21-2009, 07:41 AM
Pretty good idea. Once I get the car running again I will have to try that out.