before/after ECU dyno results

[2003z]

Not sure what to think on this one, but still suspecting my exhaust is causing problems, especially after talking to techno. Need to find a stock one, cheap to put back on and see how it is.
Anyway, I got less than 1hp increase in peak torque and hp, but a 2-5hp increase throughout most of the rev range, and a small loss after 6200 rpm. Anyway, 2 charts follow, first is the whole dyno and second is a closeup of the main part.

dynorun.010 is last weeks baseline
dynorun.015 is after the ecu. Same tank of gas for both and similar weather conditions.

[2003z]

wide view of dyno

[jtree007]

I deffinately think it is your Exaust system.. I wonder where my old one is.....

[2003z]

I don't know what this graph is telling me, but shouldn't a/f be around 12.5? All 25 of my previous dyno's are in the 14-15 range.

[NSANY]

The interesting thing to me is the drop-off in HP/torque after the factory redline in the 2nd run. Looks like the engine puts out max power & torque well before the fuel cutoff.

What was Technosquare's reasoning behind the exhaust being a problem? Too wide-open? Not enough back-pressure?

[Chebosto]

did you reset the ECU before installing it and running the car a little bit before dynoing? it should take a little while to know what's on your car... those lines are REALLY jaggedity...

huh.. interesting..

your base line numbers, was that with stock or aftermarket exhaust?

[zax]

2003, I still have my stock exhaust... make me an offer. Actually I will loan it to you for dyno purposes if you want. Are you in town this weekend?

This is my next mod...maybe was, if your exhaust isn't the issue.

[2003z]

Originally posted by Chebosto
did you reset the ECU before installing it and running the car a little bit before dynoing? it should take a little while to know what's on your car... those lines are REALLY jaggedity...

huh.. interesting..

your base line numbers, was that with stock or aftermarket exhaust?

Danny reset the ecu before sending it back to me. I just did the learning steps 1-3 per his directions. Car had about 100 miles on it before dyno.


baseline was with same configuration, aftermarket exhaust.

original baseline bonestock has been the best dyno of all, with 242 hp and 238 tq., but had lighter wheels, which tested at 3hp difference.

[throbbing_Zon]

That's bad news for you. But I am not surprised in the least. I think that Nissan engineers tuned this puppy just as well as they could with the existing stock hardware. I'm thinking that the only things that will improve the NA setup is better exhaust such as the Borla, which I know will give you at least 10 hp, headers, plenum like the Crawford, intake, cams and all the other traditional stuff.
I don't mean to come down hard on Chebosto and TS but I honestly do not believe in the "ECU robs mod HP" theory. Especially when it comes to the exhaust. Their just is no sensor in the exhaust for the ECU to know anything about it. All their is is the 02 sensor for the cat's, and that's a whole different animal. What I do know is that air temp, humidity and air density will pay a major role in the ECU adjusting ignition timing and air fuel mixture. Someone needs to explain to me again and show me hard proof why the ECU will compensate for mods and keep performance down to stock level. I think it sounds rediculous and makes absolutely no sense to me what so ever. Besides, why would Nissan knowingly do that when they know they have their own performance affiliate in mind. I mean, it's bad for business for cryin' out loud!!! Prove me wrong and I'll eat my drivers license. I'm not spending $600 on something that don't do squat except raise the rev limiter, for that I'll pay $120 but no I'll wait and see what majic JWT comes up with. Flaming is OK, I can take it.

[SlamMan]

Wow, for all the hype surrounding the TS chip that incredibly unimpressive. I guess I will reserve judjment but thats not a good start.

The A/F graph seems totally wacked. There must be a good explanation for that.

[FairladyZ]

That chip is crap. Your A/F should be 12.9 all the way across your power band. As you can see by the dyno graph, the power is dropping like crazy and the best place to shift is at 6600rpms. So raising the limiter is useless, unless your trying to blow your motor.

Also raising the rev limiter in a stock car is asking for major problems. You will eventually blow your motor. Has anyone found out the spring rate of the valve springs and how much they can handle b4 you raise the limiter?

The drop off has nothing to do with the ECU, and everything to do with the design of the camshafts. Say the guy with the ecu raced a stock 350Z he would lose hands down. What you gained through the mid range you lose more in the top end.

On my TA I have heads/cam. My cars original limiter was at 5700rpms. Now with my cam and LS1edit tuning I shift at 6600rpms. From 6000-6750 my rwhp styas at 380. So it is worth shifting at 6600rpms. Also with the heads I have lighter valves, stronger valve springs, etc.... If I didnt, I would break a spring, drop a valve, and blow my motor.

[NSANY]

The A/F bouncing all over is interesting. Some folks are adamant about a certain value that it "should be". Any reason behind that? (I'm asking because I don't know -- leave the flame guns at home.)

[Chebosto]

A/F with the Technos ECU should be set around 12.5 in the RPM band upwards after 3500 rpms.. 14.5 is a bit weird, let alone those jagged / skippy lines.

this is indeed not something Technos was looking forward to.. but a solution will be found.

sorry to have disappointed you Mike, but those are not typical results we have seen...

[NSANY]

In most modern cars, A/F ratios are highly dependent upon oxygen sensors. 2003z, you said you have a custom exhaust. When the work was done, were the two O2 sensors after the exhaust manifold eliminated, or are they still there? If they're there, are they working OK?

I can see erratic A/F mixing if the O2 sensors are either not there, or out of whack.

Just a thought.

[FairladyZ]

Originally posted by NSANY
The A/F bouncing all over is interesting. Some folks are adamant about a certain value that it "should be". Any reason behind that? (I'm asking because I don't know -- leave the flame guns at home.)

Thats a good question, thats just the way mine is aross the board. I dont know the answer to that, but I will ask someone who does. I told him about this baord maybe he will come in and tell us. :bowdown: This guy is the guy who tunes my car, prolly knows everything there is to know about cars (LS6's, LS1's, stangs anyways). :cool:

[2003z]

well, I have the data files from every dyno run I've done, from stock to modified and the a/f has always been in the 14s on my car. This is the a/f readout from my very first dyno when I was bone stock, so I didn't mess my 02 sensors up when changing exhaust, but that doesn't mean there isnt something wrong somewhere.

[FairladyZ]

This is what he said.

Paul,

All engines will differ slightly b/c of efficiencies within combustion, but
most late model EFI engines (and all the intensive research that has been done
to design cam profiles and head designs to aid the combustion process...
meaning "stuff that makes more power") will run best at ~12.7-13.0:1 A/F ratio.
This is for a NATURALLY ASPIRATED engine only!! To run this lean (the higher
the number, the leaner the mixture) will typically require 93 octane gas. For a
nitrous, turbo, blower engine the A/F ratio will have to be lower (richer).
At WOT, you want the A/F ratio to be ideal across the board typically,
otherwise you are losing power somewhere along the curve. Due to variances in
wideband meters (which can wear out if not serviced over time), a _completely_ flat
curve is almost never obtained. But that's ok. you just do not want big rises
and dips after going full throttle. If this happens, then there is a timing
problem or a fuel delivery issue.

As another point of reference, running high octane race gas (like 105 or 116
octane) you can run the engine leaner. For instance, on 93 octane my
supercharged Mustang liked the A/F ratio in the 11.8-12.0 range. But on 105 unleaded,
I could run it as lean as 12.8 or so... picked up 40rwhp in the process.

When you're NOT at WOT, you want the A/F ratio to be ~14.7:1. This is what
the O2 sensors are for. They keep the engine operating at this lean(er)
condition at idle and part throttle due to emissions issues.

Hope this helps some.

-Wes

[2003z]

this is what I have found out so far:
- My a/f ratio, from way back when I was stock, has always been ~14.5:1, before and after mods.

- The dyno facility compared other 350Zs and they were ~13:1 in stock form, then ~14.5:1 modified.

- The facility dyno'd a different car last nite, check that data and the a/f (Hariba Wideband O2 sensor) is reading correctly.

- The ecu flash should lower it to 12.5:1 but isn't for some reason. That is what we need to figure out.

[Chebosto]

just wanted to let everyone know. that we're working to resolve the issue with Mike.

sorry to have disappointed you mike, but im sure something will be worked out... i just dont think its the flash....maybe ill send you my ECU to try or something...

[350zdanny]

Damn that's pretty interesting. Could it have been a poorly done flash or something?

[FairladyZ]

Its called Nissan Engineers doing there job.

[SlamMan]

If that really is an accurate a/f reading that is VERY bad.

[spazpilot]

I always believed the ecu upgrade was a joke. I say get your money back reflash it back to stock and and wait for a twin turbo kit

[Michael-Dallas]

Wes knows his stuff. Is this the same Wes that works at Speedworks? :)

Michael.

[2003z]

everyone says my car should be pinging at 14.7:1, but that is the ideal af mixture for economy, so why should it be pinging??????

from how stuff works:
A gasoline engine burns gasoline in the presence of oxygen (see How Car Engines Work for complete details). It turns out that there is a particular ratio of air and gasoline that is "perfect," and that ratio is 14.7:1 (different fuels have different perfect ratios -- the ratio depends on the amount of hydrogen and carbon found in a given amount of fuel). If there is less air than this perfect ratio, then there will be fuel left over after combustion. This is called a rich mixture. Rich mixtures are bad because the unburned fuel creates pollution. If there is more air than this perfect ratio, then there is excess oxygen. This is called a lean mixture. A lean mixture tends to produce more nitrogen-oxide pollutants, and, in some cases, it can cause poor performance and even engine damage.

[peptidbond]

Looking at those graphs, I do not see erradic A/F. The scale of the graph makes it seem erradic, but you are still holding within .15. I would not say a variance of .15 peak is that great, especially when it does not place you in a dangerous lean condition or a wasteful rich condition. However, the fact that the TS ECU did not bring you down to the high 12's is a problem that needs to be fixed.

[Gruppe-S]

I'm not an engine tuner by any means, but the eratic A/F upon closer inspection doesn't look that bad, it probably depends on the system reading hte A/F. Many of the WB02's do not respond rapidly to changing a/f conditions (especially after prolonged use), and thus the peak & troughs. But like peptibond said, the variance is pretty tight.

The main concern is the high a/f reading on the car. In my experience, typically on the VQ35 the car does run fairly lean in WOT, in the high RPMs, I generally see high 13's on the dynojet meter in both stock and midly modified form (but never in the 14's).

As for 02 tuning (closed loop mode) most cars run open-loop at WOT, so the fuel map changes based on 02 readings by the ECU should not be occuring. What might be happening is the car is shifting to high detonation maps because of aggressive timing advance. That would explain the lack of HP gains as well as the extremely lean A/F (it depends how the reflash modifies the Nissan maps), although this is generally only a problem with piggy-back ECU's, not reflashes. Furthermore, traditionally speaking, most power is obtained through the "leaning out" of fuel maps and fuel enrichment will have the ooposite affect so I wonder why the reflash results in a richer A/F.

My personal opinion is that the 350Z with its extremely sophisticated ECU/ECM setup is designed so that the traditional advance timing + leaning fuel mixture will not suffice in making power in the car... Another recommendation is that all you guys that choose to run aftermarket engine management (piggy back or otherwise) invest in some form of knock-detection. :)

Gary

[Rogue350z]

Good first post Gary!!

[2003z]

my research into the matter has led to some of the same conclusions as peptid and gruppe=s. The car does indeed run in the open-loop mode at WOT, as well as
decelleration and accelleration
high-load, high speed operation
malfunction of O2 sensor 1 or its circuit
insufficient activation of heated O2 sensor 1 with low coolant temp.
High coolant temp
warmup
shifting from N to D in automatic, and
when starting.

Additionally, it truly isnt an erratic reading, as mentioned above, just at the high end for a WOT application.

Technos is sending me a new ecu very shortly, as soon as it clears customs, to check if the problem is what we think it is (a very simple one, but dont want to comment til I get the replacement).

[Zcarnut]

Whats up 2003Z!
Remember me in NC?
Im not at the Nissan store anymore but I bought a blue Enthusiest 6MT in April for myself. Your cars looking hot!

[2003z]

Originally posted by Zcarnut
Whats up 2003Z!
Remember me in NC?
Im not at the Nissan store anymore but I bought a blue Enthusiest 6MT in April for myself. Your cars looking hot!

Hey Scott! Welcome to our forum! Thanks
Mike

[NSANY]

Any further progress with Technosquare? Has it all boiled down to the A/F mix that won't drop? Curious to see what progress they may have made.

[MaxHax]

err,

so was this resolved?

[2003z]

hello, a quick checkin from aruba as we await the snorkeling trip. I should have a replacement ecu waiting when I get home on monday. We think they may have put the fi/nos program in instead of the correct one, plus with my abnormally high a/f ratio, they are writing a special code for me with a little more fuel.

[2003z]

looks like wednesday. had to come back to the internet cafe to let the kennel know we are extending our trip by 2 days. Aruba is awesome!