Classic "How are my AFR's", log plots included

[skid542]

Well I'm getting my car running again for race season which means I need to continue evaluating my AFR's and my tune. It seems to run pretty well but some areas are a little rich and some are a little lean. I do plan on getting everything where it's all an even 11.2 AFR anytime pressure is above 2-3 psi.

I know I need to work on my enrichment values - I have two, TPS and Boost enrichment. My VE table probably also needs a little work.

However, what I'm looking for now is some input on the safety of my current tune. Is it acceptable as is to run around on and Auto-X? My EGT's seem like they're high but I've heard of higher too. My probe is mounted about halfway up the up-pipe and everything is ceramic coated with White Lightning from the boys back east. I also run a skid plate so airflow over the pipes is also limited to what's coming through the radiator.

I have a total of three 'pulls' that were all taken during the same half hour drive. I've attached just the relevant section of the logs for each pull below.

I have a screen print from the Zeitronix software so you can see all the values in relation to each other and then I have Excel graphs of RPM, AFR, and EGT at a higher resolution so you can see actual values.

So yeah, blast away! I'm open to all input as I'd really like not to burn my motor down .

Many thanks in advance.

Pull 1




Pull 2




Pull 3




Pull 1








Pull 2








Pull 3

[biggreen96]

Pretty graphs Lee, but tables of numbers are much much easier to deal with. Not that I have ANY idea of what is going on or looks good, but something like this is much easier to read:

Code: Select all

SEC	RPM	LOAD	DAM	ADV	IGN	COR	KNC	PSI	WDTY	AFR	MAFV
0.00	2039	0.36	1	45	0	0	0	-8.12	0	19.32	1.98
0.34	2120	0.67	1	44	1.5	0	0	-4.79	0	14.03	2.4
0.66	2194	1.13	1	26	3.5	0	0	0	27.44	12.53	2.68
0.95	2388	1.34	1	22.5	6	0	0	1.74	26.26	13.45	2.88
1.25	2562	1.62	1	18	5.5	0	0	4.21	25.87	12.07	3.12
1.57	2792	1.97	1	14	5	0	0	7.4	25.87	12.42	3.36
1.88	3028	2.16	1	14.5	5	0	0	9.28	28.22	12.42	3.46
2.20	3309	2.18	1	14.5	5	0	0	9.28	30.97	12.53	3.54
2.51	3539	2.20	1	15	5	0	0	9.57	34.1	12.65	3.64
2.83	3826	2.22	1	16.5	5	0	0	10.01	37.24	11.04	3.76
3.16	4124	2.27	1	17	5	0	0	9.72	40.77	11.04	3.84
3.48	4379	2.33	1	16.5	5	0	0	10.01	45.08	11.04	3.96

Then I think the guys that are more "tuning hands on" than I am can chime in.

[skid542]

Thanks, I like my pretty graphs too . Tables may be easier to read in some cases, but the Zeitronix system samples at about 47Hz so I have roughly 47 data points per one second. So the graphs provide a better view of what's going on, particularly when things are fairly dynamic.

I also only have the ability to control fuel so the only things that really matter are AFR, RPM, Pressure, and EGT.


But, maybe you're right and it would prompt a few of the gurus to chime in.

Gurus?

[Legacy777]

Lee,

I agree the graphs are pretty, but are too busy and don't give enough resolution. I really need tables to see what's going on and to be able to isolate each parameter at a given sample time. Any chance you can put the data from each of those runs into a spreadsheet? If you'd like, you can email it to me if you need somewhere to host it.

[Legacy777]

Also, you really need to have boost/vacuum pressure included with each log/pull since it's really the only reference of engine load. Without a reference of some form of engine load, it's very difficult to determine whether AFR's or EGT's are ok or not.

[skid542]

Okay. I'll post up the excel spreadsheet for the pulls. It's a lot to look at it but if that's what works best for those volunteering to help me out - I'll be happy to provide it.


Manifold pressure is shown on the ZT-2 graphs but I didn't put them on the excel graphs because I figured you'd be able to see from the ZT-2 graphs that boost is pretty steady at 10ish psi. But, I did export it to the excel file so it's a column.

Here's the file - https://docs.google.com/viewer?a=v&pid= ... y=CKmPy_4L

It's on Google Docs which I'm not a big fan of so if it doesn't work, I'll email it to you Josh.

The different pulls are separated by several blank spaces. There are more than three pulls on the spreadsheet - the first two sets of data are pulls 1 and 2 and pull 3 is on a separate tab. You're welcome to look at the other data but they're a little shorter.


Many many thanks for the help. Let me know if there's anything else I can do to help make the data easier to digest.

Thank you.

[biggreen96]

Is your throttle position sensor reading reversed?

[skid542]

The Zeitronix WB unit doesn't allow me to 'reverse' the TPS scale so our backwards Subaru TPS sensors get logged backwards.

My EM has the ability to account for this so it looks funny on the Zeitronix log but it doesn't effect anything.

[biggreen96]

Lee, the AFR's looks pretty good to me. They seem to stay very stable and get right back to being where you set them really quick after a shift. They are a tad lower than what the stock ecu is letting happen in my car at those boost levels. (Waste gate boost on a vf39, I'm trying to save $$, lol!)

I can't comment on the EGT's though.

[skid542]

Hmm... okay. I would ideally like them to be at 11.2 anytime I'm above 2psi but in some areas they're a little lean and some areas a little rich.

I know that too rich robs power and can potentially wash down cylinder walls but I don't know at what AFR number is really too rich. I do run a nice oil pressure gauge and it does show if the oil gets thinned out (I've flooded it a couple times on cold starts... sucks...)

And I know that too lean is bad under boost but I'm not sure what levels are 'okay'. It's my understanding AFR's really are to prevent overheating the combustion cylinders/heads so I'm trying to watch my EGT's. My EGT's seem a little high - I really don't like them hitting 1300*F but they're doing that at AFR's of 11.0ish towards the end of a pull.


So yeah, I'm still looking for more input, Mr. Josh, Phyrra, Matt, others?

Any many thanks for the help and input Chris!

[skid542]

Bumpity bump.

[Legacy777]

Lee,

I've been way too busy with work. I'll try and take a look at them today or tomorrow and let you know.

[skid542]

Josh, awesome. I really appreciate you taking time to help me out and I totally understand about work and such.

Let me know if there's anything I can do to help you help me .

Many thanks.

[Legacy777]

Lee,

I've looked at the AFR's and really don't see anything that looks bad. If anything, the transient AFR's between shifts are very consistent. Pull 3's AFR's sneaked a little higher after that shift, but I'm not so sure that may have been additional transient affects.

The higher rpms appear to be going a little richer than you may need. You could maybe back things off a touch. Most of my AFR's taper down to around 11 once boost is on.

http://main.experiencetherave.com/subar ... _dyno9.jpg

From the plots it looks like the acceleration enrichment may be a little bit too much, but if it runs ok, you may not want to mess with it.

As for the EGT's....honestly, I'm not sure I'd trust that number. Where is the sensor located? If it's in an area of high turbulance it's going to read higher. Since EGT sensor placement is so critical, the main thing you should keep an eye out on is trends. If you are normally around 1,200 - 1,300, then I'd just keep an eye to make sure you stay around there. See what happens if you lean things out a little bit to around 11 AFR vs. the 10.5.

I've learned that tuning is far from an exact science....and for an engineering mind like myself....it pisses me off You can set things up what you think should work, but if the engine doesn't like it....you need to tune the engine to what it likes, and that is where experience comes in....

Refresh my memory on what you're using for EM again. Sorry....forgot.

[93forestpearl]

I think Josh pretty much nailed most things that I would say.


However, I question your need to be that rich at 2-3 psi. AFR should taper down as torque increases, peaking (or should I say valleying?) at peak torque. You can often pull a little fuel north of peak torque as you near redline. This is because your cylinder pressure is highest at peak torque. This also correlates to an opposite effect with timing. Spark advance is typically at it's lowest point at peak torque, and will climb as rpm's get higher.

[skid542]

Awesome. Thanks for the replies!!

I'm glad to hear other people echo the thoughts on the EGT readings. It's mounted halfway up the up-pipe so I would think it should be in 'cleanish' flow but it's hard to say. I may have found a spot with a small vortici or stagnation. Because I don't have them at the port exit and only have a single probe I'm not trying to tune by them but watch them. The readings are consistent and repeatble though so I will continue to watch them for trends.

I know things are richer than they need to be, for the most part. I'm definately still working on getting them dialed in but I don't have access to an AWD dyno so it's been getting tuned by taking lots of drives and logs and adjusting. There's still a bit to go but I wanted to make sure it was at least safe before I went out and raced it.

I want the AFR's around 11.2 to 11.4 since I'll be running water/meth injection at pressures above 10 psi once I turn up the boost. From what I've read and gathered, the meth will drop the AFR's about .2 (I understand that the WB isn't calibrated for the meth but the .2 seems to be what I should expect to see on the WB from many of the sources who run water/meth).


Josh - I'm glad to hear another engineer who gets pissed off at the lack of concrete variables and settings . This tuning thing definately is not exact, I've made changes and expect one thing and get the opposite. Drives me nuts.

For EM I'm running the MAFT-Pro piggy back. This is the system Dan's friend Derek ran on his Legacy with good results. It is fuel only though and I'm not playing with spark. I've been happy with thus far and the tech support has been phenomonal. I'm only trying to get to 300 ft-lbs at the crank so I didn't feel the need to go standalone.


Dan - That's a good point about peak torque and cylinder pressures. Makes perfect sense but I'd never thought about it. Thanks for enlightening me on it. I also appreciate what you're saying about AFR's at 2-3psi. I'm new to the tuning world and have been being ultra conservative for fear of blowing up my motor so I'll chill out a little if the AFR's get a little leaner here but for right now it seems to transition well from vac to pressure without hesitations or stumbles. I only knew that when there's high loads on the motor AFR's should be around 11.2 so that's what I've been trying to apply across the board assuming it'd be conservative and safe.


Thanks again for the help guys. It is very much appreciated.

And as always, I'm more than open to further comments or schoolings.

[93forestpearl]

Awesome. Thanks for the replies!!

I'm glad to hear other people echo the thoughts on the EGT readings. It's mounted halfway up the up-pipe so I would think it should be in 'cleanish' flow but it's hard to say. I may have found a spot with a small vortici or stagnation. Because I don't have them at the port exit and only have a single probe I'm not trying to tune by them but watch them. The readings are consistent and repeatble though so I will continue to watch them for trends.

It's all relative. Mine was in the collector right before the uppipe and I would creep up to 1700 degrees at times. 1400 on the freeway. Others that have them right next to the port are often under 1500. Keep in mind rich AFR's will keep the EGT's down. Since you can't touch your timing, I won't get into that.

I know things are richer than they need to be, for the most part. I'm definately still working on getting them dialed in but I don't have access to an AWD dyno so it's been getting tuned by taking lots of drives and logs and adjusting. There's still a bit to go but I wanted to make sure it was at least safe before I went out and raced it.

Don't get discouraged. It is very time consuming when starting from scratch.

Josh - I'm glad to hear another engineer who gets pissed off at the lack of concrete variables and settings . This tuning thing definately is not exact, I've made changes and expect one thing and get the opposite. Drives me nuts.

I love answering my customers' questions with "sort of." LOL. Nothing is concrete in my line of work, unless you work in the quality department. I hate X-bar charts anyways.

Dan - That's a good point about peak torque and cylinder pressures. Makes perfect sense but I'd never thought about it. Thanks for enlightening me on it. I also appreciate what you're saying about AFR's at 2-3psi. I'm new to the tuning world and have been being ultra conservative for fear of blowing up my motor so I'll chill out a little if the AFR's get a little leaner here but for right now it seems to transition well from vac to pressure without hesitations or stumbles. I only knew that when there's high loads on the motor AFR's should be around 11.2 so that's what I've been trying to apply across the board assuming it'd be conservative and safe.

You have to work pretty hard to make the car stumble from being over rich. Under high load I was getting over rich missfires in the low 10.x:1 range. The freshness of my plugs also played a factor. It is hard to make the car run poorly from being too rich, but you build up carbon and at the extremes, was cylinder walls and end up with lots of fuel in your oil. That and you are hurting your torque production with over fueling.

Just something to keep in mind. If you had a way to monitor knock, that would probably make you more comfortable pulling fuel.

[Legacy777]

You have to work pretty hard to make the car stumble from being over rich.

Been there......the values in the acceleration enrichment got reversed so it was dumping shit ton of fuel in at high rpms and stumbling/bucking badly. This came from one of the tuners like this. Something they just overlooked. Everything else ran fine. It wasn't until I sat down and looked at print outs of the configuration before & after did I catch it.

[skid542]

Dan, many thanks again for the advice. It's also good to know what you were seeing on your EGT's. I was afraid mine were too high which didn't make any sense to me since I knew I was rich.

With regards to too much fuel - I agree that I am too rich and it's hurting power, or more specifically torque. A good knock detection system would make life easier for sure and let me rest a bit more comfortably. I can watch my scan tool for a flicker of knock indication but I'm not entirely sure I trust it at that level.

And washing down my cylinders is a big concern. I'm running a nice digital sending unit oil pressure gauge and if I see my pressures are down 5ish psi from when I put brand new oil in and have everything warm - I am changing my oil. I've flooded it out a couple times too and had to change the oil after thinning it out. Over the years I'd heard you and a few others mention this problem and watch a couple guys spin bearings because of it. But right now oil is cheaper than a new motor and much quicker to change .


The acceleration enrichment is tricky for my setup as I have a TPS enrichment and a boost enrichment (gives more fuel on rising manifold pressure). I was getting bad misses during quick shifts and ultimately ended up cutting the values in half. I kept backing off until it smoothed out and then it started to miss again so I added just a hair back into it. I can no longer out-shift the system and can't make it buck.


All that said, I'm anxious to start getting it further refined. The MAFT-Pro system will log (at least 4hr that I've found) and you can replay the logs back. During the replay it will feed back the effective VE (it has a closed loop function under boost) and it lets me slowly get the primary VE table dialed in. I'm making progress but am sure I'll have more questions before it's all said and done.


The big thing though is the car is a daily driver and an auto-x machine so it's got to be very good at part throttle and rapid throttle transitions which so far it seems to be doing okay at. We'll see in a couple weeks when I race it and log the race.



Again, many many thanks for the help guys!