Over the past year, I've seen a few discussions around here about fuel mixtures getting too lean when a combination of modifications is done. I seem to recall the plenum/intake/headers/cats/exhaust combo being the point where an ECU tweak was needed. Now, I'd just like to confirm where this point is in the modification line.

I'm going to run new headers & Y-pipe, and considered going ahead and doing the cats as well (instead of waiting until out of warranty). I'm going to hold off on the plenum (or spacer) until I get closer to the end of warranty, and a drop-in filter and UT G-tube are the only thing I will be doing on the intake side before then. I know I'm not taking a balanced approach right now, but I will in the end.

My question is, will the addition of cats (with the headers and Y-pipe... ...and stock exhaust) pose a problem with the air-fuel ratio without me touching the plenum yet? I figure NO, but wanted to be certain.

 

I'll probably get flamed for this, but here goes.

Anyone who works for TechnoSquare or anyone who believes in their product will tell you that you need a reflash after the cats alone, or the plenum alone, or the exhaust alone. I've talked with Doug at Crawfordzcar quite a bit about this issue and his opinion is somewhat different.

He has ran the stock 350z intake (z-tube), crawford plenum, crawford headers, crawford cats and borla exhaust on his personal car and all of the guys cars in his shop and Doug feels as if the car is almost PERFECT w/o the ECU reflash.

The ONLY thing he wanted the reflash for was to increase the redline so that he could take advantage of the high hp output at 6600+rpms. (It's my understanding that Doug did all of this before TS had a package for the rev limiter bump alone.)

I asked him why he went through 8 iterations with the "Crawford Package Reflash" if he felt this way and his comments were very disturbing.

He said that TS actually "leaned out his car" at points where it previously was fine and made the car "overly rich" at other points. He would do a dyno, send the ECU back and wait for a reflash. He did this a total of 8 times and saw a 6-8rwhp gain (Doug told me that this gain was solely due to the 6600 rpm-7100rpm increase).

There you have it. A VQ35DE specialist that believes that the vehicle with all of the mods you listed doesn't need the reflash. Others have very strong opinions opposed to this, and this conversation could go on forever. The absolute best thing for you to do is to weld in a pre-cat bung before you do any mods and dyno the A/F curve. Do what ever mods you want to do now and then re-dyno. Compare the A/F curves and see what your results are. Just make sure to have Doug weld in a pre-cat bung on your h/f cats when you order them so that you can continue your testing.

Please post any and all data that you collect. Thanks!

 

Agreed. Only way to tell if you really need some adjustment of your ECU mappings is to compare before and after dyno curves and A/F ratios. Having a pre-cat bung is an excellent idea for wideband O2 sensors which will give you accurate A/F readings. If things are getting way off on your after dyno runs then yeah, you'll need to do something with your ECU whether its a reflash or you use some sort of piggyback or other managment system.

 

Let me add one more question onto GTRons original. Which ECU Reflash to you guys prefer? Technosquare or AlteredAtmosphere? The reason I ask is that they seem pretty comparable but AlteredAtmosphere's reflash costs $100 less.

 

Thanks neff! I'll throw a cup of water your way if it gets hot.

I was just looking for the general rule-of-thumb on this. Understood that additional testing/monitoring would be required for detailed A/F figures.

How about this one: Any noticealbe smell or visual difference in exhaust gas at the tips after replacing the cats?

 

My opinion - get the TS limited spec reflash to increase the redline and for the 100% throttle body opening feature... then use the piggy-back of choice to fine-tune the A/F ratios to your liking if your car is out of whack (mine wasn't the last time I dynoed - but it was before headers)

Too many problems popping up with the TS to have to worry about me being without my car for 3 days at a time up to 3-4 times to get the A/F perfect... I'd rather do it in one sitting on the dyno...

 

I'd say that's not too far off there Neffster. However, you are leaving out one very important elemant that is responsible for 90% or more of the power gained ... Timing Advance. A simple increase in redline will not have gotten it any where.

Modern engines coupled with advanced management systems will allow safe and efficient operation at relatively high AF than old school thinkings and implemenations. You'd be surprised with some of the numbers seen in top-tier racing (i.e. F-1, Champ Car and even NASCAR ... no joke!). I can't give the exact figures as I'm under NDA. AF is sometimes being overly emphasized for Natural Aspiration application. One need only to be close to a paricular target AF value to achieve greater than 95% potential. Being reasonably too rich (or lean) will not have a large impact on power loss. By simpy richen AF from the seemingly lean OEM figure down to say ~12.8 (ideal) alone, you wouldn't have observed a *dramatic* power increase (or decrease). What is beneficial by lowering AF down to say 12.8 is the ability to dial in even more timing advance w.o. running the risk of excessive detonation or pre-ignition. The end results is again being able to use as much timing advance as possible for maximum power output. Naturally, fuel stability (octane) is also a big part of the equation.

BTW ... I still believe running 7100rpm is a bit wreckless for '04.5 and earliers. Not with stock valve springs and seats at least.


So, to TS or not to TS??? If ya got the cash spend it ... if not, don't sweat it too much either.

 

Clint,

I read your comment and respect your opinions quite a bit. Maybe I either didn't understand your post well enough or you misunderstood mine.

What I was trying to say is that when Doug Crawford dynoed his 350z it was still making horse power when the vehicle hit the rev limiter. By increasing the rev limiter by 500 rpms, Doug's car made an additional 5 (or so) hp AFTER 6600 rpm's. Doug never said (or at least it was my understanding) that the area under the curve between ~2000 rpm's and 6600 rpm's changed one bit due to the TS ECU reflash when he was done with the reflash (timing advance or not). Initially it changed FOR THE WORST and he had to send the ECU back and forth eight times before he got the reflash back to the stock condition. Feel free to call Doug and speak with him, he's a cool guy and will let you know if I misunderstood him.

At your dyno day, your car proved to be the best and highest output vehicle and you did not have this reflash. The guys below you did have this reflash (if memory serves correctly). This alone would make me believe that the reflash doesn't do an awful lot with these mods.

Do you have data (independent data not data provided by TechnoSquare) that shows a clear hp or tq gain between 2000 rpms and 6600 rpms as a result of the timing advance by lowering the A/F curve (i.e. feeding the car with more fuel)?

BTW, AA simply purchased the rights to sell the Technosquare reflash. It is the EXACT SAME reflash according to AlteredAtmosphere's posts on my350z.com.

 

Clint,

What are your thoughts on using one of these to assist in tuning? A buddy of mine was telling me some good things about this product.

 

Neff,
Hold your thought ... I'll address your concerns after work this evening. I'm currently swamped with meetings at work.


dklau33,
I haven't any personal experience w. the Zeitronix unit, but have heard good things about it. Looks fine to me too. It appears to offer the best bang for your bux on the market. The narrow band signal pass through would come in handy, so you can use the oem-bung for the wide-band. I'd be interested to see how well that worked in actuality (hope they got the interpolation right). The only thing I would thing is some patching job to get that going.

If however, you're looking for even more product depth and expandability at some premium, then look no further than the unit by Innovate Motorsports. You'll be able to daisy chain input modules that'll support up to 30 inputs (next software and firmware update). It'll have the ability to log actual ignition timing, duty cycle, built-in acceleratmeter, MAP sensor and much more. The telemetry software is to die for (very similar to the ones I've used in racing developments in the past). It also has the ability to daisy chain multiple digital AEM/GReddy-like round guages that are fully programmable to display any channel and colors out of a palette of 65,500 . Neat! I was able to convince Gurgen to get a full setup. You should hit him up for a demo. SoCalTed's also recently got the setup.

In either case ... the minimum you'll need is wide-band AF and simulaneous RPM logging for tuning.

 

With a reflash, if the rev limiter becomes increased, can this damage the engine? I'm new to the mod thing so be gentle...lol