i miss spoke...

i should have said...

cats will not effect how lean you are running as much as something placed infront of where combustion occurs...

better?

 

Actually, this would have been better:
'Intake mods will cause you to run leaner. Cats will not affect as much how lean you run since they are placed after combustion occurs.'
I don't know if the second statement is true.

 

JJ didn't I tell you that you were running lean..at lunch. Since the RT cats and the efu are the last things we do . It stands to reason that each mod adds to the leanest, till at the last, when it gets critical, by the time I hade my ECU done ,I had a 14.7 and higher A/F as a result of air intake, exhaust and Cat mods...I have the dyno sheets to prove it. It took TS three hours of testing and fine tuning on my car to get the new RT cat mapping you all will enjoy.

 

Jason is correct and should not have to admit that he is wrong. In fact, I would say that you are wrong here. Cats will not create a lean condition.

A lean condition occurs where there is too much air in the air/fuel mixture. That can occur from a CAI, a turbocharger, a supercharger or, perhaps a plenum. A lean condition will not result from something that comes after combustion such as a header or exhaust modification. Rather, it is usually an intake, or ECU/fuel management problem.

 

The only way to really know is by getting an A/F read out from the header O2 sensor...

 

I may be wrong so no flames.

If more air comes in, the A/F becomes leaner if the ECU does not compensate in fuel. So since the ECU does compensate the A/F should be near stock provided that the ECU can compenstate the required amount.

For example when my amuse muffler was fitted and driven for at least a week the A/F was measured again and showed that it actually was richer than stock.

BTW the A/F was measured from the rear of the exhaust

 

From my experience, high flow cats leaned my car up some. One way I could tell was from the lack of carbon build-up on my stock exhaust tips when the high flow cats were installed. The attachment shows my stock z and the addition of a high flow cats/y-pipe set up.

 

I just got my RT Cats yesterday and I have already flashed with TS and headers and TD exhaust. My readings were taken from Tadishi's test cat that he places in your car that allows him to do readings while on test drives. I did not have the RT cats when TS did my tuning and my intake plenum is stock. I ended up finalized with an 11.5 when done with headers and true dual.

I assumed that the cats would not cause me to lean out too much, even if I bumped to say 11.8 or 12 I was cool with that. So I bought the cats. I know Richard was at almost 14 with A/F (gasp) good thing he went there. His plugs were ash white not "black" because I called TS that day (Danny.) Richard also has the Crawford plenum and Nismo cams which do cause you to run leaner and I have documented this already.

TS told me this yesterday when I emailed , "Do not install them, they will add at least two points. This will put you at 13.5 which is too lean."

In the back of my I am thinking that TS wants to be safe and don't blame them. They had just done a Z with a Crawford (which brings in all kinds of air) and saw a 14 so I would be in just in case be safe mode too. So far they have a perfect record, mwhy chance it ya know? But I don't think they have ever done a car like mine with RT cats, blown etc. They have also NEVER done a Crawford/ATI and I wish they could because what an awesome setup that would be! So they are going on theories not proof.

So I may have to sell mine if it turns out to be true that it will place my procharged car at 13.5! My only recourse is another 7 hour road trip down there and a reflash (ugh.) Then 7 hours back!

Please keep this thread alive. This is my setup:

1. Stock intake plenum, NGK FR11 coppers or whatever they say.
2. ATI Procharger
3. Headers
4. True dual exhaust
5. Techosquare reflash to 11.5

6. Cat pipes placing me at 13.5 if I add them?

This has been bothering me so I went straight to the source. Tadishi is a man who does everything the safest way which is why I went there. Is the 14 he saw yesterday from the Crawford? I had a Crawford on my ATI and was 13.5 with stock exhaust. The Crawford and cat pipes is an excellent bang for the buck mod. More air in, and more hot gasses out FOR A GRAND. To me this is HP 101! But alas these dang computers! So now, my question after the background minutia is out of the way. Can a reflashed ECU at 11.5 really go all the way to an unsafe zone of 13.5 (two full points) by a cat change? Or is TS just being overly cautiuos because of all the recent termoil? Thanks in advance because I install mine next week and think it's a great mod. I bet Richards car just flys now with eveything he has done to it. I bet he is well over 300 RWHP N/A! Kudos to him and TS; and also Performance where I bought mine. I was counting my bolts too lol.

 

Hey
I've got a NISMO CAI and exhaust.
Is my car running lean ? Do I need to upgrade the ECU ?

I know lot's of guys with a CAI and most did not upgrade the ECU.
Hell I doubt most of us know that might have to be done, does it?

 

I have the larger 380cc injectors. I believe I am the first larger injector ATI install Tadishi has done so perhaps he forgot about that part. The stock car that was lean on the A/F had stock injectors right? The performance Nissan car with RT Cata and Cams had stock injectors right? Wouldn't my larger injectors change this A/F theory if not included in the hypothetical (yet to be tested setup?) I am thinking even if I was at 12 I would be ok with that with larger injectors. Thoughts?

 

Put the cats on drive it down (you'll need some breakin miles on the cats) and have TS reflash the ECU for $150 and dyno with A/F before you go home to make sure everything is just perfect.

I bet you'll be at 375whp

 

I was thinking that but Tadishi doesn't do Dyno's just tuning. I am keeping this as a last resort for now. I hate dynos.

 

Does anyone have the A/F page that lists the exact numbers in text form that comes from a Dyno (rather than the graph?) It's hard to read the small graphs.

 

Your fine with that I wouldnt worry.

 

Jason's statement:
"Cats will not effect how lean you run since they are placed after combustion occurs."

Hfm, I'm sure Jason appreciates you jumping to his defense, but his statement above is wrong and he acknowledged it in his own way. You, however, have missed the point.

Your statement:
"In fact, I would say that you are wrong here. Cats will not create a lean condition."

Show me where I said the cats will create a lean condition?


The cats will lean the mixture but not necessarily create a lean condition. To understand my point, you have to make the distinction between leaning the mixture, which the cats will do, and lean condition, which "occurs where there is too much air in the air/fuel mixture."

 

I'm sorry, I must have misunderstood. It sounds to me that we agree that cats wont create a lean condition. Frankly, I don't know whether cats can lean the air/fuel mixture. I don't think they can however, if that's what you were referring to, then I have no business calling you wrong on that subject because I don't know the answer to this specific distinction. Maybe you can educate me here.

 

I think you're basically correct; the ECU senses the changes through the mass airflow and O2 sensors. But this system clearly does not work perfectly. Air/fuel mixtures vary from Z to Z.

 

So then here are my plans:

1. Install the RT's.

2. Put 200 miles on them off boost.

3. Go to Motor Sports Dynamics and have them do a (gasp) Dyno and A/F test with wideband right here in Sacramento.

The owner Henry is highly respected and actually had lunch with Tadishi of Technosquare at SEMA the other week. If I am too lean I will then schedule an app. and drive down to LA and reflash. Hopefully I will come out ok (plus I will finnaly have a dyno number for my sig.)

It seems like there is too many variables etc and I have come along way. It is worth it (peice of mind) tto do this final step and be finished (except for my Edge Racing Converter and B&M tranny cooler.)

So of course I will have pics and updates soon for all.

 

I'm no expert, so correct me if I am wrong, but wouldn't a rich condition (not lean) make the plugs turn black as you say? Black for fouling? I have never heard of a lean coindition causing this condition on a spark plug. Also, isn't the top of the threadds on the plug where most people put dark colored anti-sieze compound on the plugs? I pulled my plugs out on my car, and they were black and fouled a little, maybe due to the rich condition of the Z at higher RPM? Right now with all my mods, my plugs are black and red? So are my O2 sensors? What does this mean? I was thinking that it could be from the red oil from my aftermarket air filter? Otherwise car runs great without any problems.

 

I may be wrong, but won't increasing the exhaust flow with headers, high flow cats, or dual exhaust create a more lean A/F ratio because more air is being drawn into the combustion chamber due to the higher flow of the exhaust? Isn't this basically how turbos work? If you do nothing to add more fuel to the mixture the condition will be leaner than before the exhaust mod correct? Now, how much of a difference the exhaust side modifications are making can only be known by measuring the A/F ratio after each mod without adjusting the fuel delivery. Has anyone personally followed these numbers? I would also assume that the more you modify the intake side combined with the exhaust side, you will create an even more lean A/F ratio if fuel delivery is not changed, which is what I would assume happened with the Performance Nissan car. Hopefully TS can get enough cars will all types of modifications to have a good "starting" map for all of us who do not live close to a shop. That will hopefully reduce the number of times the ECU will have to be sent in for remapping.