ToothDoc

Anybody care to explain how PPE and Sikky conditioners work? I have PPE headers and all I know is that the O2 sensors after the cats are intercepted and modified.

The A/F sensor in the cats try to maintain stoichiometric ratios of fuel and O2 and the secondary O2 sensor is supposedly there to monitor cat performance.

Does the car's computer purposefully run rich/lean cycles to check response. In theory, if the cats are working correctly, the secondary O2 should read the same voltage all the time?

I tried to google/youtube/etc, but I'm a little confused. Any help would be appreciated here.

ToothDoc

If the A/F sensor is the only sensor responsible for the air/fuel ratio and the car tries to keep stoich, I'm confused why headers cause the car to run richer and hence a decrease in fuel efficiency? I do notice that cruising at 60 mph, I no longer get 30 mpg but only 28. I also did notice more carbon deposits on the A/F sensors after headers vs. before headers.

Not looking to make anything, but just wanna know..

BTW, I started thinking after reading about mrSlayX info regarding stock headers with the cats busted out making as much power.

I'm thinking why can't we modify the stock exhaust so we can replace the cat portion with test pipes and have a "cat" vs. "no cat" switch that'll put the O2 simulator in series or not. I like having no cats... but for only 1% of the time (when I'm at a track).

ToothDoc

Another thing is that PPE and SIKKY seem to have different methods of working. PPE going to modifying the secondary O2 approach and SIKKY - I don't know how they work, but they have totally different wiring.

I'm curious... I'm actually considering buying a SIKKY conditioner to see what happens to my IS-F. Anybody have a SIKKY conditioner for sale or know where I can get one?

Defratos

I dunno much about what the Conditioners do exactly but I never had to install it on my car when I installed PPE headers (this is probably due to the fact that my car is GCC spec and I believe we do not have strict regulations here on emissions) so never had a need to actually install it.

So far the car is running fine.

Biggu

iTrader: (12)

the boxes are essentially a resister to fool the car into thinking the O2 sensors are reading in the desired range for the air/fuel mixture.

Defratos

^ So in theory since I don't have the box installed it'll mean my O2 sensors are reading actual air/fuel mixture.....could this result in added power compared to you guys who have this installed?

imp0rted1

I was curious about the same thing .. MrSlay can you comment?

Cronic

iTrader: (1)

Is the main concensus that the SIKKY O2 fix is better/more consistent than Ppe fix?

darbs242

iTrader: (5)

The boxes simulate your rear o2 sensor signal. Your front (primary) o2 sensors read and adjust your air/fuel. Your rear (secondaries) o2 tell the ECU that your cats are burning the extra fuel correctly as to not put raw fuel into the atmosphere. So the simulators from PPE and SIkky copy the single of the oem rear (secondary) o2 sensors making your ECU think your cats are in place and your CEL stays off for failed cat codes. Without a simulator, the sensors would read the same as the fronts and the ecu would think a cat has failed. If its effecting gas milage I would say thats because its using more fuel too keep up with the airflow you increased by adding headers... which the combo of better airflow and more gas makes the power you paid for by adding the headers.

RCB

iTrader: (18)

Same here.....
I don't remember ever seeing anyone post dyno results with catless stock manifolds. If there is a thread somewhere please direct me to it. I would like to see the curve with stock manifolds, no cats and exhaust.

flowrider

iTrader: (9)

^^^^I asked the same question in another thread:

I took his explanation with a BIG grain of salt.

Lou

lobuxracer

iTrader: (2)

Not quite. Fuel economy in steady state operation should be unchanged unless the A/F ratio is off target. There could be a lot of reasons for the A/F to be off target when the OEM headers are replaced with a cat-less system. I'd bet the same problem would exist if the OEM cats were gutted. Keep in mind, all the fuel and timing calibrations in the ECM are based on the OEM configuration. Changing anything in that configuration could impact the A/F targets by changing pressure ratios in the exhaust and subsequently the ability of the A/F sensors to accurately measure what is going on.

Also keep in mind, the front O2 "sensor" is a wideband and the rear is a narrowband. The ECM has A/F target tables for the front O2 sensor and it is able to accurately measure A/F ratio whereas the rear narrowband is only capable of detecting stoichiometric A/F. And yes, without any doubt the ECM runs a test cycle to determine the catalyst's efficiency at random intervals, so fooling the ECM is a bit of an art. It's not like the old days where you could just build a simple circuit and have it work reliably for years to come. Also, NO, it is not just a resistor, it can't be a passive device at all.

ToothDoc

That's what I'm confused about. As the car runs tests at random intervals, how would a simulator that only intercepts and modifies the secondary O2s know that the car is running a test unless the simulator gets a signal from the A/F sensors and then based on that signal, modifies the secondary O2.

I would imagine a true simulator would get voltages from the a/f sensor and when a "test" cycle is performed, it would have to modify the secondary O2 signals to reflect the random tests.

Just thinking out loud.. scratching my head…

lobuxracer

iTrader: (2)

Yeah, me too. I don't have one to take apart.

imp0rted1

lobux and toothdoc,

if the ecm is randomly sampling the narrowband post cat-converter, what would prevent us from using a device such as a "spark plug antifouler" aka spacer to dilute the exhaust stream?