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- 19 November 2002
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- 633
I have a 6lb bolt on whipple, I was just wondering what is the recommended setting for the FMU?
I have a 6lb bolt on whipple, I was just wondering what is the recommended setting for the FMU?
What is a FMU?
Fuel Management Unit
also (incorrectly) referred to as a FPR (Fuel pressure regulator), RRFPR (Rising Rate Fuel pressure regulator), or Boost-dependant FPR.
As boost increases, the FMU ramps up the fuel pressure at a set ratio (8:1, 10:1, 12:1, etc) dictated by the internal spring and/or diaphram.
a Fuel Management Unit is a (electronic)device
Stop fighting boys, we know what he means and he is wrong!!! lol
ffffanman said:I am no expert nor am I always correct, just trying to find the truths and spread the good word!
C-speed, have you seen many RRFPR's that vary each day or each start, mainly because they are older, like 10 years and the spring or what not can be worn?
It appears you have some nice experience under your belt!
Also have you ever seen the difference in changing the bleed type plug to a solid one. I can't believe how much faster the pressure rises.
I am actually talking about a little plug or plug with hole, just like a jet on a carb.
I found that they installed this bleed bolt or screw on the low boost whipple set ups. The high boost regulators do not have it.
I took the solid no bleed screw from a hi boost and put it into my low boost regulator and as I say, the regulator jumps up in pressure faster.
You must not have seen this or done this before.
But now you know!
Trev
i got try this any pic for reference and where do i find the plug? thanks Trev
Well , I have to agree with Crescent ( and anyone else who knows what they are talking about)
EVERY car is different, even the same model of car with the same mods!
you could start with the same approximate settings, but proceed with caution , you NEED a wideband, and you need some knowledge of what is going on.
There is a lot of widespread misconception the the "fmu" or "rrfpr" is a poor device , this couldn't be further from the truth, if it were then why would the "coveted" ctsc use it? even on their "hi-boost" kit? along with countless other commercially available sc/turbo kits , greddy/vortech/jackson racing/comptech/paxton - the list goes on.
So , what does all of this mean? One of the oldest sayings I can remember when dealing with cars? - KISS - keep it simple stupid.
Of all the turbo hondas I have seen (a LOT) the ones who have the most trouble are the ones running some kind of piggyback or standalone , larger injectors, etc...
DON'T get me wrong , these have their place, but for most people who want to run less than 10psi it is (IN MY OPINION) an unnecessary and potentially troublesome solution
Which brings me to the next topic, on a car with an engine as expensive as the nsx , why is no one running a knock control unit , like the one from J&S electronics? Wouldn't it be nice to actually see if it was detonating?
I have run these on hondas for years (more than ten) - In fact when I first turbocharged my integra in '97 , it was the second thing I bought, I ran that car hard on the stock motor for years .
Which brings me to the next topic, on a car with an engine as expensive as the nsx , why is no one running a knock control unit , like the one from J&S electronics? Wouldn't it be nice to actually see if it was detonating?
you guys know your things. so here's the question i have.
i am running a low boost whipple charger on my 96 nsx-T
i am thinking about doing the high boost set up, can you guys shine some light on me whats every thing that i will be needing, what fuel pressure i should set at what injectors i should be running or any thing that will make my life easier.
thanks
I
4. change the CTSC FMU to a 1:1 FPR, AEM makes a nice unit but there are many to pick from
If you are running the OEM ECU you are using a dual bank knock control system provided by Honda. This is a piezo transducer based system that uses a sensor to change the audible sound of knock into a voltage range that the ECU can understand. The factory ECU has a very aggressive knock sensor setup. On the OBD2 cars with a proper scan tool you can see the raw data from the knock sensor and the timing trims when they detect knock, very good tuning tools if you have an OBD2 car, if you have an OBD1 car you are sort of out of luck unless you add an additional knock sensor setup. These additional systems can be very difficult to setup.
If you are running the AEM ECU then you are in luck (sort of) as the AEM offers knock control using the original factory sensors if you know how to use it and set it up. Again this is not easy unless you have a frame of reference for what the knock sensors should be doing at any given RPM range and load range. I have seen a lot of tunes for the AEM and most (like 99%) do not have the knock control setup correctly or it is not even turned on.
Some tuners will tell you a proper tune does not need knock control, which is between you and your tuner to decide. I do know that the sensors are there to aid the ECU in keeping the engine alive when conditions are outside the norm. I also know that our stock cast pistons do not handle spark knock at all.
Dave
Just a quick note, you do not need to "replace" the Comptech FMU, just remove it from the system. The factory NSX FPR is already 1:1
The only problem with the stock knock control is , a) it is slow to respond(it does not really need to be very responsive on a stock engine b/c a small amount of detonation will probably not spike the cyl. pressure enough to cause immediate damage and ,b) the factory knock control doesn't have the ability to pull enough timing to stop the detonation from occuring at times. And ,c) an effective system needs to be able to pull timing based on which cylinder is pinging and put it back by the next rotation .
I think quite a few nsx owners have proven that the factory knock control is insufficient for use in f/i applications as evidenced by various blown head gaskets,pounded rod bearings ,cracked ring lands, ect.,etc..
I don't think the factory knock control is capable of retarding each cylinder individually - this is what is needed .
p.s. So me cracking open the timing pot and cranking in 2 more degrees on my 91 low boost whipple with 9.6:1 coated pistons was a good thing?
Boom