hey guys, on the clubs recent Dyno day.
my readout was this.
lacking in the power i was hoping for, as im still running the 3.0L auto ECU
i know im up for a aftermarket system and tune.
however
i was under the impression the readout was going to give a RPM vs KW/Torque read
but i got a AFR instead, so im assuming thats what the dotted line is representing.
but should it fall soo far as the RPM increases?
http://i304.photobucket.com/albums/nn177/lowridermagna/DYNO.jpg

if that is correct that is seriously dangerous and could cause some serious damage. i would suggest to get that checked.

jeeeeeez that is running lean. Be careful you don't push it until the problem has been isolated and fixed! After reading about Jason's 'donkey' engine leaning out a tiny bit in the midrange, I was made aware that anything below 11AFR is bad, particularly at high rpm.

thats what i was thinking, i hope this is not the case :confused:
funny thing is that they didnt mention anything to me when i got it printed

if im reading it correctly seems to me that your leaning out towards the top-end
could be costly in the long run

That AFR does not look right at all.

Im suprised your engine is still running - wait not anymore, read the graph the wrong way around :)

Umm looking at that printout its actually going very rich towards redline.

The lower the AFR numbers the richer the mixture

Would a rooted O2 sensor do this?

o rite!

Would a rooted O2 sensor do this?

It can, could also be a safe factory tune.

Hell my MPS goes into the high 9's AFR's when it gets up in the revs but thats beacuse its a safe rich factory tune

Yup definitely running rich so not really unsafe but using more fuel than needed and killing power up top.
A good retune with some timing advance and trimming of the AFRs will see more power and better fuel consumption.

:bowrofl: I guess maths and graph work in school came easier to some than others.

The AFRs are getting RICHER. Why? Factory settings to control heat, poor fuel, detonation etc. That's why there are products available that heat the fuel, so the fuel molecule expands and less molecules of fuel pass thru the injector to lean out the mixture without needing an ECU remap. Not accurate at all and says nothing for altering ignition timing.

Pretty normal NA dyno graph actually. Remember too that the dyno doesn't graph power runs for AFR terribly accurately. There is a delay between the rpm the motor is actually at vs the sample taken, analysed, graphed. That's one of several reasons load settings are held briefly during tuning - to get a 'true(r)' afr reading.

Looks pretty normal, starting at around 13:1 at lower revs and richening up like that is pretty standard for factory tunes, I don't see any danger.

People get too caught up on AFRs - different motors respond best to different AFRs, due to a number of factors such as shape of combustion chambers, intake port airflow characteristics etc. E.g I know of certain NA motors that are happy to run 13.5-14:1@WOT safely, while others need to be run much richer than that. What really matters is EGTs.

But as a general rule of thumb, for our motors IMO you want around 12:1@WOT for FI, and around 12.5-13:1 NA.

Also often you don't see rpm plots on dyno runs cos it can be a biit of extra work involved. But IMO peak power is occuring around 5200rpm, so you can work out a scale to a reasonable degree of accuracy from that.


Remember too that the dyno doesn't graph power runs for AFR terribly accurately. There is a delay between the rpm the motor is actually at vs the sample taken, analysed, graphed. That's one of several reasons load settings are held briefly during tuning - to get a 'true(r)' afr reading.

Interesting, this didn't appear to be the case when I was shown around a dyno/tuning software. The AFR meter read to 3 decimal places and only had a delay of a few milliseconds, from memory. Though this was a Mainline dyno, maybe what you said applies to some others, such as the DD dynos? I do remember the tuner having some rant about how much better the Mainline dynos are :P

Just love how certain members jump in and state "ooh not good, I would get that looked at" while having absolutely no clue what does not look good or what needs to be looked at.

All std mortors and tunes tend to go rich at the higer ends, this is to protect the car maker from having std engines melting down.

While I disagree totally with these "kits" to heat fuel given that the fuel travels so fast through the rail the "heating" would have 3 fifths of stuff all effect, the theory is there all be it un proven with some of these kits due to them not having been properly tested.

In so far as tune goes, lean = bad, rich can also = bad but not so much at high rpm like in the above example. Low RPM not so good as will wash the bores clean and lead to wear where as at high rpm the fuel barely touches the sides. (insert joke here)

Now back to running the Auto ECU, I assume you have done a manual conversion. I have done the same but used the Manual ECU also, had to change the ECU harness as this was also different where it plugs into the ECU but the rest of the plugs into either the body or other electrical all looked the same. May be worth a try if you can get a manual ECU and harness

my comment above was because I thought having a low number AFR meant it was running lean, and I know that a lean running engine at high RPM would probably melt. Now that I know its the other way around, running rich isn't nearly as bad

Umm looking at that printout its actually going very rich towards redline.

The lower the AFR numbers the richer the mixture

i was going to say but i'm a bit behind the thread...

my 4AGZE ran well into the low 10's above about 5500-7800rpm.. alot of ppl just use an SAFC to

1. overide boost cut (factory 1 bar)
2. lean out the mixture a little

effectivley your doing both, but it's irrelevant to this thread anyway..

on road mapping of my 20V with 3SGTE (much bigger AFM) to check the AFR's worked out it was running a little leaner than factory.. which wasn't a bad thing.. and it made 128fwhp (20v with the same very minor breathing mods and stock AFM could only manage 116fwhp (before fitting the AFM mine made just under 115fwhp)

it very much depends on the engine.. and if it can run leaner to increase EGT's etc etc.. there is a fair bit of development to be had in the exhaust and mixtures and how they relate to one another.. after fitting some merge collectors to various 6-700hp ally headed small block's Vs pacemakers / press cone collectors.. they typically run lean, and you need to wind fuel into them, and alter the timing.. which usually results in almost 80-120hp gains from a new set of extractors and a retune..

that does look like its running lean in comparison to mine running on the same dyno (for comparing)
http://i335.photobucket.com/albums/m451/ih8hsv/21022009090.jpg

that does look like its running lean in comparison to mine running on the same dyno (for comparing)
http://i335.photobucket.com/albums/m451/ih8hsv/21022009090.jpg

Huh???

On the start both are similar, you are slightly richer but toward peak you are slightly leaner. Yours has a more steady fuel curve but does end up leaner in the end

Dont forget also, if the engine is running too rich you can start to lose power as well,,,,,

Look guys, if you aren't confident you know what you're talking, please refrain from posting. All these misguided posts just serve to confuse those trying to learn something. I can't believe in a thread about something as simple as reading an AFR line there are so many conflicting and misguided posts being made, this is absurd.

To summarise the basics:

- The larger the ratio the leaner the mixture is - e.g 15:1 is leaner than 10:1.

- Different motors work best with different AFRs, there is no set universal figure to aim for on all motors. But as a general rule of thumb, most motors work best somewhere around 11.8-13:1@WOT, when maximisng power/economy is the goal.

- Consequences of running too rich : poor fuel economy/power, accelerated bore wear to due to 'bore wash' in extreme cases. Also running overly rich can stuff up the O2 sensor and damage CAT convertors.

- Consequences of running too lean: engine-damaging detonation, loss of power. Serious detonation will destroy a motor in very little time.

- Factory tunes tend to richen up at the top end as a safety function to allow scenarios such as dodgy fuel.

- AFR curves on dyno plots only tell you AFRs @ WOT (Wide open throttle). E.g my car is mapped to run 12:1@WOT across the revrange, but at low load/throttle openings I saw it get run as lean as 18:1 on the dyno, from memory.

I don't wanto see any more crap posts in this this thread please. If you don't know what you're talking about, simply don't post. Do some research instead of spreading confusion/misguided 'info' which just confuses more people.

agreed..

have a look at this graph i captured doing road testing with a wideband.. you can see how lean it CAN get on cruise and part throttle.. vs WOT..

on part accel/cruise it's between the high 15's-high 17's... gradually as the load increases (road conditions, accel input, various other factors) it returns closer to what every one recongnises..the result we achived after playing with fuel pressure was 12.6-13.0 at WOT.. mind you this is kinda a dodgey way of tuning fuel in/out and the tuning was done by myself who i am very much a novice at on the road with a wide band O2 probe and a laptop :)... but the car cost me $500 with the 20v in it!!

cheers,

Umm looking at that printout its actually going very rich towards redline.

The lower the AFR numbers the richer the mixture

Yeah I had the same scenario when I converted to 3.5 using the standard 3.0L ECU. With a Unichip all the tuner did was pull back the fuelling for a final figure of 125kW at the wheels. So the OP's 121kW sounds about right (considering dyno variance).

Look guys, if you aren't confident you know what you're talking, please refrain from posting. All these misguided posts just serve to confuse those trying to learn something. I can't believe in a thread about something as simple as reading an AFR line there are so many conflicting and misguided posts being made, this is absurd.


Thank you very much Chisolm. I really appreciate the addition of some constructive comments to help out everyone's' understanding on this subject. It certainly pays to have someone with experience and superior knowledge on the subject and provide educational input. Its what make this forum worth its salt. You and a handfull of other people, keep up the good work. :clap:

Chrisholm...

A couple people (myself included) made a simple mistake when looking at the graph.....not particulary a major problem, as its a forum and was pointed out by someone paying closer attention.

If everyone goes along your way of thinking of not posting if not 100% certain, then this forum would have next to no posts and be painfully boring.

While its great that some people that have a fair bit of technical knowledge post - going off at members for a simple mistake is getting beyond a joke on this forum :)

Chrisholm...

A couple people (myself included) made a simple mistake when looking at the graph.....not particulary a major problem, as its a forum and was pointed out by someone paying closer attention.

If everyone goes along your way of thinking of not posting if not 100% certain, then this forum would have next to no posts and be painfully boring.

While its great that some people that have a fair bit of technical knowledge post - going off at members for a simple mistake is getting beyond a joke on this forum :)

First of all, you spelt my name wrong, about 50% of people seem to :P

Look maybe that post came off a bit harsh than intended - I wasn't "going off" at anyone, just trying to point out that people need to take a bit of care to not post conflicting/incorrect information, bcos it can make something that should be quite simple to understand confusing.

I do think a few members here are sometimes making posts for the sake of it, and just sprouting stuff off the top of their head without proper understanding of what they are saying, or bothering to check info before they post. Nothing personal, but this really degrades the quality of these forums and tends to cause confusion for some members, and I wanted to point this out as politely as possible.

Not saying I'm by any means perfect, no doubt I've posted crap at times here in the past :P


Thank you very much Chisolm. I really appreciate the addition of some constructive comments to help out everyone's' understanding on this subject. It certainly pays to have someone with experience and superior knowledge on the subject and provide educational input. Its what make this forum worth its salt. You and a handfull of other people, keep up the good work. :clap:

Cheers mate, to me that's the main point of these forums, we all share with each other with the pursuit of overlal benefit to everyone :)

I swear I was copying your name letter for letter :P

All good, your post just came across rather condescending more so than harsh. My main point is if people dont post and get things wrong, while it may be confusing, they (myself included) wont ever learn. Hell, even with this thread I'll know to be more careful when reading an AFR graph and not mixing up my ratio's :)

I swear I was copying your name letter for letter :P

All good, your post just came across rather condescending more so than harsh. My main point is if people dont post and get things wrong, while it may be confusing, they (myself included) wont ever learn. Hell, even with this thread I'll know to be more careful when reading an AFR graph and not mixing up my ratio's :)

Your point is very valid, getting things wrong is a a good way to learn in the end - though you need to find some kind of balance. My intent wasn't to come across as condescending, but I guess it was a given it was gonna seem that way to some given the nature of the post. Cheers mate.

thanks for the help guys, i knew when i did the conversion that it would run rich and needed to be tuned, but the car is drivable, just lacks low down power and very easy to stall,

Yeah I had the same scenario when I converted to 3.5 using the standard 3.0L ECU. With a Unichip all the tuner did was pull back the fuelling for a final figure of 125kW at the wheels. So the OP's 121kW sounds about right (considering dyno variance).

yeah, well on the same dyno, another 3.5L AUTO with similar Exhaust, pulled a 127KW
so im hoping with a new ECU, i could fix up the afr's and advance the ignition timing, (say tuned to RON 98)
and mine beging manual, im hoping for 140KWs

Over the last few months i have learnt a lot more about dynos. And i still have a long way to go before i fully understand them lol They are a good platform for tuning an engine and getting your car driving the way you want. Power figures vary immensely from dyno to dyno and don't really mean much.

One thing i did notice with my own car is how much of a difference AFR trimming can make. Not talking just about WOT 4th gear AFR but trimming or smoothing out of the AFRs acorss the rev range in different gears. My car picked up 10kw across the rev range just by leaning out the AFRs a bit across the board. Car is much more drivable and powerful but at the same time returns the same fuel economy as when i was N/A auto.

Main thing is to find a tuner who knows what he's talking about and takes the time to explain things, you'll be amazed and what you'll learn from this alone.

Your point is very valid, getting things wrong is a a good way to learn in the end - though you need to find some kind of balance. My intent wasn't to come across as condescending, but I guess it was a given it was gonna seem that way to some given the nature of the post. Cheers mate.

Now you can see my frustration a lot on these forums.

The ideal AFR is 14.7:1. This is not set for performance or anything but is the ratio that std fuel burns best at. This is in the initial training of any mechanic. Then things go hairy from there depending on the motor, the type of induction, exhaust etc etc

For an example you do not want a hot rotary going richer than about 12.5:1 unless you want to loose power and fowl plugs really bad.

10:1 in a magna on WOT is obviously a safety thing Mits and most likely a lot of car makers would use as the combustion will be cooler and should not cause wash off at that rev range.

But back to what Chisholm initially said, please do not post you "facts" when you do not know what you are talking about. To make it easy for the noobs, the first number is the units of air, the secon is the units of fuel thus 13:1 is 13 parts air to 1 part fuel

Now you can see my frustration a lot on these forums.

But back to what Chisholm initially said, please do not post you "facts" when you do not know what you are talking about. To make it easy for the noobs, the first number is the units of air, the secon is the units of fuel thus 13:1 is 13 parts air to 1 part fuel

Yep and mine too, hence why i dont post up alot of the time cos it just seems to be too hard to "inform" people of the facts/truths.

hey hang on a minute, before this gets too far OT, some of us still need to learn and understand this sort of thing myself included. Other than reading up on the internet (where the facts may or may not be true anyway), how else are you supposed to learn without study and qualifications? i posted up what I thought to be true, not because I was being a know-it-all. If you believe something is wrong, please correct me/us but don't tar everyone with the same 'know-it-all' brush. Isn't that half the idea about public forums anyway?

There is no issue at all with ppl asking questions, that is how you learn. But when people post things as fact not knowing that is what cofuses people.

fair enough

hey hang on a minute, before this gets too far OT, some of us still need to learn and understand this sort of thing myself included. Other than reading up on the internet (where the facts may or may not be true anyway), how else are you supposed to learn without study and qualifications? i posted up what I thought to be true, not because I was being a know-it-all. If you believe something is wrong, please correct me/us but don't tar everyone with the same 'know-it-all' brush. Isn't that half the idea about public forums anyway?

And did i do that? NO i posted the correct answer to the dyno printout, that is all.

Jason my post wasn't aimed at you

hey hang on a minute, before this gets too far OT, some of us still need to learn and understand this sort of thing myself included. Other than reading up on the internet (where the facts may or may not be true anyway), how else are you supposed to learn without study and qualifications? i posted up what I thought to be true, not because I was being a know-it-all. If you believe something is wrong, please correct me/us but don't tar everyone with the same 'know-it-all' brush. Isn't that half the idea about public forums anyway?

My issue wasn't with people wanting to learn stuff, I encourage this. My issue was with people posting incorrect information while sounding like they know what they are talking about (delibrate or not). This creates confusion among the less knowledable members who are trying to learn, as they don't know who to believe. It's also a little frustrating for me and some other members cos we have to waste time correcting false information/clearing up the confusion.

Basically if you aren't confident you understand something properly, you should word your post in a way that says something like "I'm not sure but I think X could be true. Is this the case?". As opposed to something like "Yep X is true", which implies you are sure and know what you are talking about well.

There's plenty of good information on the net, you just need to look for it (i.e not rely on AMC as your main source of info:P ). For starters these forums are pretty good for getting into the technical stuff a bit more, and you come across all variety of cars, not just one particular brand/model :

http://www.performanceforums.com/forums

cheers for the link chisholm, will check it out

thanks for the help guys, i knew when i did the conversion that it would run rich and needed to be tuned, but the car is drivable, just lacks low down power and very easy to stall,


yeah, well on the same dyno, another 3.5L AUTO with similar Exhaust, pulled a 127KW
so im hoping with a new ECU, i could fix up the afr's and advance the ignition timing, (say tuned to RON 98)
and mine beging manual, im hoping for 140KWs

I was still running a hacked up (dodgy quick cut n shut to extend the collectors to compensate fro the larger deck hight of the 3.5) standard 3.0L exhaust bar a catback. So with extractors and a proper tune 130-140 should be achievable. I had it tuned to 98 RON fuel too, but only managed 125kW. Felt allot better then that on the road though, the mid range torque of the 3.5 made day to day driving allot better :).