Bang, bang.
What adjustments after Walbro on a CTSC?
- Thread starter Arshad
- Start date
dynomike said:
thats what I was thinking... what should it be? Not taking the measurement from o2 bung but from the tailpipe.
BRIDGEWATER ACURA said:
I don't think anyone could suggest a good reading from the tailpipe, since there is no calculation that can figure in your cats efficiency or inefficency. I'm sure most would concur with me and point you towards having a bung welded in before the cats.
There is no problem reading air fuel at the tail pipe after the cat. You have to remember how an o2 sensor works. An o2 sensor soley measures the amount of o2 coming from the engine. Cats do not add oxygen to the exhaust. They are there for the hydocarbons. I have done testing proving this theory. Took the same car measured air fuel before and after the cats and the results were identical. When I tune cars I try to put the o2 sensor in a bung rather than the tail pipe. I do this becasue the reactions of air fuel change are faster when tuning partial throtle and idle.
There is no problem reading air fuel at the tail pipe after the cat.
...
I have done testing proving this theory. Took the same car measured air fuel before and after the cats and the results were identical.
Hmm!! That's interesting info, and flies in the face of everything I've ever read! General consensus seems to be that you have to take the measurements pre-cat or it won't be accurate, and I've heard this from a lot of knowledgable folk. At the same time, what you're saying does make sense and I'm guessing a lot of the knowledgable folk are probably just reiterating 'known facts', and have not performed any empirical tests on their own to verify whether it's true or not.
That is simply not true - the purpose of the catalytic converter is to act as a catalyst* (duuh!) to promote the complete oxidation of the Hydrocarbons & Carbon Monoxide - in order to complete the reactions excess O2 must be used to complete the chemical reaction.dynomike said:
CO + 2HC + 3O2 -> 3CO2 + H2O
Note that a LOT of O2 is consumed to balance the reaction.
(add up the number of each element on either side of the equation & you will see this is a balanced equation)
Therefor the O2 level cannot be the same before & after the cat.
There is a secondary reaction which is to reduce the NOx compounds to Nitrogen and these will release some Oxygen, but that will be consumed by more of the CO conversion to CO2.
NOx + CO -> N2 + CO2
Here is an excellent tutorial on how a cat & O2 sensors work. Note particularly the graph of the O2 sensors O/P's pre & post cat on page 10
http://www.autoshop101.com/forms/h64.pdf
* catalyst - means it aids to help create the chemical reaction without actually being directly involved in it
i.e. none of the elements of the compounds of the cat end up in the reacted compounds of the exhaust gasses.
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I have read that the three way catalytic converter does not have a big impact on the exhaust gas composition when the air fuel ratio is on the rich side (ie. where we care when tuning under WOT). I don't have the time to find the references, try a web search. Sites that discuss the wide band O2 sensors and meters may have more detailed info.
Bases on your revised numbers, your A/F looks fine to me.
Onsoku said:
Oh. In that case wait for the experts to respond in this thread. From my limited knowledge, being around 11.8-12.2 is pretty much where you want to be.
If you are punching it in third, what RPM are you talking about "punching it" from?
NetViper said:
About 4k+. I always figured I'd have a problem being rich; but never an issue with being lean...or maybe it's timing...hell, I don't know except that it sucks not being able drive it the way I want to...back to GreenLight...
The Walbro does not overwhelm the stock fuel system.
I just installed the pump and fuel pressure gauge from Sos.
I have the following readings with stock engine.
At idle anyways!!!
Here are my readings at Idle.
45 psi with the vacuum hose attached to the fuel pressure regulator.
The manual shows 36-44 psi.
52 psi with the vacuum hose disconnected to the fuel pressure regulator.
The manual shows 46-53 psi.
Next is to install my used low boost whipple unit.
I have an older unit with the old-school check-valve & restrictor setup.
How old is that.....
I was also sent an E.S.M., not sure what to use.
Laterz, maybe under boost by then.
Trev
I just installed the pump and fuel pressure gauge from Sos.
I have the following readings with stock engine.
At idle anyways!!!
Here are my readings at Idle.
45 psi with the vacuum hose attached to the fuel pressure regulator.
The manual shows 36-44 psi.
52 psi with the vacuum hose disconnected to the fuel pressure regulator.
The manual shows 46-53 psi.
Next is to install my used low boost whipple unit.
I have an older unit with the old-school check-valve & restrictor setup.
How old is that.....
I was also sent an E.S.M., not sure what to use.
Laterz, maybe under boost by then.
Trev
boom boom
It was the install of the Cantreel AIS...too much air until the ECU adapted to it...all has been well for almost 3 years now with 70k+ miles since the install of the the CTSC.
160k miles and still running great!
So who on a low boost whipple isn't using a voltage doubler and or has placed a jumper on the fuel pump resister that is located in the engine bay just above the fuel filter.
Trev
Trev
I had exactly the same issues after the initial install of the low-boost autorotor. Cleaned the whole fuel system, even cleaning the tank. No better. Added the Apexi and could not get the thing dialed in. Finally, had to step up to the aem, 255 walbro, 550 injectors, etc. and it runs awesome now (albeit after a much bigger investment then originally contemplated).
My buddy had the autorotor, low-boost put on his NSX same time as my initial install by same mechanic. He drove off and the a/f's were dialed in. Go figure.
My buddy had the autorotor, low-boost put on his NSX same time as my initial install by same mechanic. He drove off and the a/f's were dialed in. Go figure.
with the apexi systems if you doing +- 5% adjustments it not a big deal.
when people start pulling 20-50% fuel thats running into trouble since at the same time your pulling fuel your also advancing the timing.
the knock system should kick in and prevent damage.
i have used the safc with great results but thats with additional upgrades such as meth injection which requires additional timing.
Here are my facts after the install of the Used 6lb Whipple unit on my 91 nsx.
I have the Walbro pump installed months ago.
I have the low boost comptech Rising Rate Fuel Pressure Regulator that comes with the 6lb low boost kit. - Mine is the blue Vortex unit.
I did not install the voltage doubler.
I jumpered the nsx fuel pump regulator so that the pump see battery voltage all the time.
On the dyno, we started with 46-48 psi at idle on the first run, it toped out at 84 psi.
Then increase it to 50 on the second, it topped out at about 86 psi.
Lastly 52 on the third and left it there. Went up to 90 or so.....
Fuel pressure ramps up nicely and gives me safe a/f readings.
So there you go for now.
Trev
I have the Walbro pump installed months ago.
I have the low boost comptech Rising Rate Fuel Pressure Regulator that comes with the 6lb low boost kit. - Mine is the blue Vortex unit.
I did not install the voltage doubler.
I jumpered the nsx fuel pump regulator so that the pump see battery voltage all the time.
On the dyno, we started with 46-48 psi at idle on the first run, it toped out at 84 psi.
Then increase it to 50 on the second, it topped out at about 86 psi.
Lastly 52 on the third and left it there. Went up to 90 or so.....
Fuel pressure ramps up nicely and gives me safe a/f readings.
So there you go for now.
Trev
