Tuning...... A stupid question

[spyderturbo007]

I'm getting confused becuase I've read in several different places that if the computer is seeing less airflow, because of an AFC, then it will advance timing......so is there a line between me seeing airflow so low that it's holding my timing back and lo readings that will advance the timing?

The lower the airflow reported to the ECU, the higher the ECU will advance the timing. The more air you flow, the larger your injectors need to be, and the lower (more negative) the SAFC-II settings need to be. This leads to a vicious cycle of fighting the ECU for timing. This is why piggyback tuning sucks.

Just remember, that the Low settings on the SAFC are not used during WOT operation. So, technically, you could change all of your Low throttle settings to +50% and it wouldn't effect your WOT tune. It would, however, lead to jacked FT's and a CEL.

Sorry for my ignorance but you are losing me with the grams....I'm still learning about how the hz corilates with tuning......is 2.55 grams 2550hz? If not how do I relate grams to hz?

As far as I know, there is not a direct (linear) relationship between Hz and airflow. The SAFC is showing you the signal it receives from the MAS, which is reported to the ECU in the form of a frequency (Hz). If you want to know more about the reason behind that, take a look at how your MAS works.

Anyway, the ECU actually uses airflow mass.....not lbs/min, but g/rev. This means that the ECU is using the mass of air (in grams) per revolution of the motor. To find this number you just need to do some unit analysis and convert from lbs/min. So, with that in mind, the ECU will use it's airflow value in g/rev (along with some other parameters such as IAT, coolant temp, etc) to calculate fuel delivery, timing, etc.

At a value of 2.1g/rev and above, your timing is limited to 17 degrees. Below 2.1g/rev the ECU will calculate timing based on the airflow value so it "should" be higher than 17 degrees at the top end. So even if you are flowing 3.0g/rev, you will only get 17 degrees of timing at the top. Just remember, that the 2.1g/rev needs to be seen by the ECU, which is very difficult to do when running a SAFC. So even though you may be flowing 2.1g/rev, chances are very high that the ECU will never see that much air because of the SAFC correction.

Wow, that was fun.......

OK, I'm done rambling.

 

[madman]

How do I tell how much g/rev I'm flowing?

 

[spyderturbo007]

It's a set of relatively simple equations.

The problem is that I have absolutely no experience with a MAFT, so I have no clue what changes, if any, the MAFT is passing along to the ECU. If you were only using the SAFC-II I could help you out.

Can anyone tell me what changes the MAFT is sending to the ECU so I can calculate his aiflow properly?

 

[madman]

Let's just say it was just the AFC.....what would the equation be?

Then we can go from there.

 

[spyderturbo007]

You need to start with the equation I gave you about 3 weeks ago used to back calculate the actual airflow. You can find that here, post #4:

http://www.dsmtuners.com/forums/showthread.php?t=219971&highlight=airflow+correction

Once you find the actual airflow using the equation above you now need to convert lbs/min to g/rev.

Let's convert lbs to grams first. There are 453.592g in 1lb, so multiply your airflow value by 453.592g.

Now we need to use the exact rpm where the peak airflow occured. Take your number from above and divide it by the rpm value. So you will end up with something like this:

(X lbs/min * 453.592g) / Y = A g/rev

Where,

X = Peak Corrected Airflow

Y = rpm value corresponding to peak airflow

A = Actual airflow in g/rev

 

[madman]

The lower the airflow reported to the ECU, the higher the ECU will advance the timing. .

This is what I mentioned above. In all my logs I'm reporting very low amounts of airflow
so why wasn't my timing higher? Leaner or Richer it never went above 16~17

Anyway, the ECU actually uses airflow mass.....not lbs/min, but g/rev. This means that the ECU is using the mass of air (in grams) per revolution of the motor. To find this number you just need to do some unit analysis and convert from lbs/min. So, with that in mind, the ECU will use it's airflow value in g/rev (along with some other parameters such as IAT, coolant temp, etc) to calculate fuel delivery, timing, etc. .

So if I want to figure g/rev that the ECU is seeing, which affects the timing table, than I should use the lbs/min reported by the pocketlogger right? not figure the actuall airflow before corrections?

In my newest log, I registered 29.23lbs/min at 6676rpms.....that would be 1.98599g/rev right?

At a value of 2.1g/rev and above, your timing is limited to 17 degrees. Below 2.1g/rev the ECU will calculate timing based on the airflow value so it "should" be higher than 17 degrees at the top end. So even if you are flowing 3.0g/rev, you will only get 17 degrees of timing at the top. .

CanadianTSI said that you get the highest timing above 2.55g/rev....so what gives....

So if I'm looking for 19~21* of timing at the top end, I need to keep it under 2.1?

Just remember, that the 2.1g/rev needs to be seen by the ECU

Why??? Now I'm getting confused again.....do I want more than 2.1 or less or does it really matter?

Judging by your Hz count I guarantee that your GM Maf is out of calibration.

Also looking at your o2's your pig rich..

So I changed the MAFT from 650's to 560's. I did this while watching my trims and the hz on the AFC. I read that at idle most people showed around 31hz or so at idle, I was only reading 27hz.

So with the AFC zeroed out and the MAFT at 560's my fuel trim for 1k was good and I was showing 31hz at idle.

I figured this would be a better than what I had.

I have a new log which I will post soon.

 

[madman]

The main difference is that I recalibrated the MAFT.

The outside temp is about 30*lower and I could only get the coolant temp to 195 instead of 205~210 where most of my logs have been.

I've noticed before that I will do a 3rd gear pull, temps in the 190's, and then do one in the 200's, with the same settings and the timing seems to change quite a bit. Normally my timing is worse in the 200's so I have to readjust ......so this log might be good now but worse when it warms up that's why I've been logging temp and trying to keep it above 200 but I just wanted to get a log in with the new MAFT adjustment.

Still 18.5psi.

I know I'm looking pretty lean and I will plan to lean it out and plan to raise the boost once I get the o2 around .96.

AFC -24 -24 -24 -24 -24 -26 -26 -24

3040 20 06.67 0.66
3200 15 08.88 0.90
3448 08 12.57 9.96
3696 05 16.40 0.98
4004 06 17.55 0.98
4536 06 21.34 1.0
4792 07 22.66 1.0
4952 08 23.77 1.0
5180 09 24.54 1.0
5452 09 25.96 1.0
5660 10 26.71 1.0
5888 11 27.98 1.0
6172 11 28.89 1.0
6464 13 28.83 1.0
6608 13 28.87 1.0
6676 14 29.23 1.0

AFC showed 2129hz

 

[spyderturbo007]

This is what I mentioned above. In all my logs I'm reporting very low amounts of airflow
so why wasn't my timing higher? Leaner or Richer it never went above 16~17

Your low timing is most likely related to knock counts, IAT, coolant temp, etc.

So if I want to figure g/rev that the ECU is seeing, which affects the timing table, than I should use the lbs/min reported by the pocketlogger right? not figure the actuall airflow before corrections?

Correct. You have to choose the airflow number, either corrected or not, based on weather you want the actual airflow or the airflow reported to the ECU.

In my newest log, I registered 29.23lbs/min at 6676rpms.....that would be 1.98599g/rev right?

Yes, assuming that the MAFT has no effect on airflow, the ECU would see 1.99 g/rev.

CanadianTSI said that you get the highest timing above 2.55g/rev....so what gives....

I'm not sure. CanadianTSI is a very knowledgable tuner, so I don't know if it was a typo or something else. Above 2.1g/rev you will be on the ECU's highest airflow map. The higher your airflow, the lower the ECU will advance the timing. For years, I have always seen 2.1g/rev is the point at which the ECU caps your timing.

So if I'm looking for 19~21* of timing at the top end, I need to keep it under 2.1?

Yes, but I would much rather push as much air as possible and have the timing capped by the ECU. You will get more power that way and it's a "sure fire" way to spot knock. For example, you have determined that the ECU is "seeing" 2.3 g/rev but your max timing is only 14 degrees. You know that there is something wrong because the ECU should be advancing timing to 17 degrees.

Why??? Now I'm getting confused again.....do I want more than 2.1 or less or does it really matter?

Your goal is to push as much air as possible without knocking. I really only use airflow numbers to determine the max boost to run, as most people don't exceed 2.1 g/rev when using a SAFC.

So I changed the MAFT from 650's to 560's. I did this while watching my trims and the hz on the AFC. I read that at idle most people showed around 31hz or so at idle, I was only reading 27hz.

Once again, I know nothing about the MAFT, so someone else is going to have to jump in on this one.

So with the AFC zeroed out and the MAFT at 560's my fuel trim for 1k was good and I was showing 31hz at idle.

Fuel trims are useless when looking at WOT tuning.

Cheers.

 

[madman]

Yes, but I would much rather push as much air as possible and have the timing capped by the ECU. You will get more power that way and it's a "sure fire" way to spot knock.

But I heard that you get more power with more timing. If you can control knock would it be better to run higher timing, like in the 20* range?

Your goal is to push as much air as possible without knocking. I really only use airflow numbers to determine the max boost to run, as most people don't exceed 2.1 g/rev when using a SAFC.:

If I'm at 1.99g/rev now at 18.5 psi, I pretty sure that by turning up the boost and if necessary I could even richen up the MAFT to see more air "globaly" to get >2.1g/rev.

But if I can get more timing and power by keeping the ECU <2.1g/rev than I could lean out the MAFT.

.....

I've noticed that by changing the AUX and the BASE settings on the MAFT (the global settings for the fuel injectors) I've gained around 35-40% of airflow seen by the ECU and have only had to make a negative ajustment (lean out) of 6% on the AFC to componsate.

This is compared to Full Throttle, who makes the MAFT, that said if I would richen up the global settings on the MAFT and then lean out the AFC, then they just cancell themselves out, thus seeing the same airflow on the logger and AFC. But I've proven it different, at least on my car.

18.5psi and o2 reading 1.00 (same a/f)
old maft settings 650's seeing 22.20lbs/min at 6600 and 1542hz on AFC / -18 -18....
nw maft settings 560's seeing 29.23lbs/min at 6600 and 2129hz on AFC / -24 -24....

My point is that it seems that I have a lot of control and am able to easily manipulate the airflow with the MAFT. I would think this is a good thing, but then again I'm still learning.

Once again, I know nothing about the MAFT, so someone else is going to have to jump in on this one.

Fuel trims are useless when looking at WOT tuning.

'

This was just to show how I calibrated the MAFT.....incase anyone wanted to know.

 

[spyderturbo007]

The goal of tuning is to make as much power as possible. The higher the timing and airflow, provided there is no knock, the higher your power output will be. There have been many discussions and opinions on which makes more power....timing or airflow. I feel that airflow is going to yeild more power over timing, but I'll stop there.

I don't know that I'm going to be able to help you much more with your actual tune. I can guide you based on my knowledge of the 2g ECU, but I know nothing about the MAFT. I couldn't even tell you which one manipulates the airflow reading first (although I would assume it's the MAFT).

I'm going to shoot a PM over to another guy that has a very extensive tuning background and see what his knowledge of the MAFT is......Maybe he can help (andymoraitis).

 

[madman]

The goal of tuning is to make as much power as possible. The higher the timing and airflow, provided there is no knock, the higher your power output will be. There have been many discussions and opinions on which makes more power....timing or airflow. I feel that airflow is going to yeild more power over timing, but I'll stop there.

I don't know that I'm going to be able to help you much more with your actual tune. I can guide you based on my knowledge of the 2g ECU, but I know nothing about the MAFT. I couldn't even tell you which one manipulates the airflow reading first (although I would assume it's the MAFT).

I'm going to shoot a PM over to another guy that has a very extensive tuning background and see what his knowledge of the MAFT is......Maybe he can help (andymoraitis).

Thank you for all you help and everyone esle too.

I'm going to get it dynoed on the 2nd so we'll see how close I am on the tune.

Here is a couple more logs. I started to lean it out since that last one "looked" rich from the o2. Actually I did four runs but I'm only going to post the 1st (the best) and the 4th (the worse) 2 and 3 just went down hill from 1. The more I leaned it out the slower the turbo spooled, the lower the timing dropped at spool up and the timing was just lower all the way through.

I think I will go back to the settings on #1 and leave it till the 2nd.

This was at 19.5psi.......can't wait for 20+

AFC  -27 -27 -27 -27 -27 -29 -29 -27					
					
Time	Coolant	RPM	Timing	Airflow	O2 1 Bank 1
00:05.0	190	3012	19	7.09	0.08
00:05.6	190	3212	14	9.18	0.94
00:06.1	190	3428	9	11.95	0.98
00:06.7	190	3688	7	15.55	1
00:07.2	190	4004	7	17.14	1
00:07.8	190	4264	7	19.12	1
00:08.3	192	4532	8	20.31	1.02
00:09.4	192	4792	8	22.3	1.02
00:10.0	192	5244	10	23.27	1.02
00:10.6	192	5508	11	24.17	1.02
00:11.4	192	5704	13	25.32	1.02
00:11.9	192	6000	14	25.73	1.02
00:12.5	192	6220	16	26.12	1.02
00:13.1	192	6408	17	26.27	1.02
00:14.4	196	6652	19	26.68	1.02
00:15.0	196	6980	19	26.75	1

AFC   -35 -35 -35 -35 -35 -37 -37 -35					
					
Time	Coolant	RPM	Timing	Airflow	O2 1 Bank 1
00:03.4	192	2964	24	5.4	0.04
00:04.4	192	3072	22	7.28	0.06
00:05.0	192	3440	13	9.71	0.84
00:05.6	192	3712	5	13.19	0.94
00:06.1	192	4032	3	15.08	0.96
00:06.7	192	4360	2	16.89	0.98
00:07.2	196	4624	3	18.23	0.98
00:07.8	196	4948	4	18.87	0.98
00:08.3	196	5224	6	20.07	0.98
00:09.4	196	5500	10	22.16	0.98
00:10.0	196	6036	12	22.68	0.98
00:10.5	196	6324	13	23.27	0.98
00:11.1	196	6552	12	23.68	0.98
00:11.7	199	6796	13	23.97	0.98
00:12.2	199	7004	14	23.77	0.98

I guess this proves you can't go by the NB o2 readings.?.?.?.?.

 

[CanadianTSi]

Have you done a boost leak test recently (honestly)...

You might have a small leak that is throwing off your o2's.

But i do agree the first log looks alot better.

 

[madman]

Here are the result of my trip to St. Louis.

My dyno sheets will be posted when I can resize them.

1st log and dyno run at 13.5psi.....he wanted to start low.

Time	Coolant	RPM	Timing	Airflow	TPS	O2 1 Bank 1
00:20.9	199	2884	19	6.21	100.2	0.94
00:21.4	199	3112	20	6.99	100.2	0.9
00:22.0	199	3380	15	9.12	100.2	0.98
00:22.5	199	3688	13	11.13	100.2	0.98
00:23.1	199	4020	11	12.73	100.2	1
00:23.6	199	4340	13	13.75	100.2	1
00:24.7	199	4620	13	16.44	100.2	1.02
00:25.3	199	5076	14	17.13	100.2	1.02
00:25.8	199	5308	15	18.07	100.2	1.02
00:26.4	199	5524	16	18.83	99.8	1.02
00:27.0	203	5736	17	19.55	100.2	1.02
00:27.8	203	5924	18	20.21	100.2	1.02
00:28.4	203	6220	21	21.14	100.2	1.02
00:29.5	203	6408	22	21.55	100.2	1.04
00:30.0	203	6688	22	22.08	100.2	1.04
00:30.6	207	6820	22	22.14	5.89	0.24

Timing looks good but it was super rich as the o2 shows.....158.3HP <10.1AFR....went so low the dyno couldn't even register it.

Time	Coolant	RPM	Timing	Airflow	TPS	O2 1 Bank 1
00:09.7	183	2772	24	5.54	100.2	0.06
00:10.3	183	3136	22	6.45	100.2	0.06
00:10.8	183	3392	18	7.67	100.2	0.06
00:11.4	183	3684	16	9.73	100.2	0.76
00:11.9	183	4020	8	12.39	100.2	0.96
00:12.5	183	4452	5	14.88	100.2	0.98
00:13.1	183	4708	6	15.56	100.2	0.98
00:13.6	183	4952	7	16.04	100.2	0.98
00:14.7	187	5168	10	16.87	100.2	0.98
00:15.2	187	5580	10	17.41	100.2	0.98
00:15.8	187	5788	11	18.12	100.2	1
00:16.4	187	6016	13	18.64	100.2	1
00:16.9	190	6220	13	18.96	99.8	0.98
00:17.5	190	6420	13	19.46	99.8	0.98
00:18.0	190	6620	14	19.37	100.2	0.98
00:18.6	190	6832	12	19.87	100.2	0.98

Run 14 .... Max 216.2WHP 19psi 11.2AFR

*EDIT* AFC is -10 -10 -13 -24 -27 -27 -28 -28

There were no boost leaks.

*EDIT* THERE WERE BOOST LEAKS

 

[madman]

I picked these dyno sheets because it shows the 1st run and run 14 wich was the best (HP wise).

 

[GVR4592]

Are you just using the maft for tuning?

 

[madman]

MAF-t with the AFC

I came in with the MAFT set to 510cc's and the AFC at -27 -27 -27 -27 -27 -29 -29 -27 good timing but very rich.

To lean it out to 11.2 the AFC were in the -40's.

So we put the MAFT back to 650's and now the AFC is -10 -10 -13 -24 -27 -27 -28 -28. This is where Ron left it tuned for 11.2 AFR.

 

[GVR4592]

If it was my car I would temporarily remove the maft, and tune with the afc. The maft is known to be very difficult to tune, and it's not very accurate. I'm not saying to get rid of it completely, but just to eliminate the possibility that it's messing with your airflow numbers.

I'm not quite understanding what you said about the A/F ratio. When he leaned it out from 10:1 to 11.2:1 you were getting less timing advance?

 

[CanadianTSi]

It really does seem that the Maf-t is doing some funky things to your setup. I would get rid of it and go back to the 2g mas, it will make tuning much easier.

Also your power seems way way low for 19psi.

 

[madman]

It really does seem that the Maf-t is doing some funky things to your setup. I would get rid of it and go back to the 2g mas, it will make tuning much easier.

Also your power seems way way low for 19psi.

I've thought about getting rid of the MAFT but I'm using a tial bov so I have no way to reroute the bov if I go back to the stock maf.

I edited some of the last post, but mainly, Ron, the guy that dynoed the car, thinks there is some type of airflow restriction or possibly the cam sprocket teeth might be off a little.

And yes Ron thought I should be easily at 270whp or more.

I'm not quite understanding what you said about the A/F ratio. When he leaned it out from 10:1 to 11.2:1 you were getting less timing advance?

Yes. That was the problem I had when I was tuning with my logger and Ron had the same issue on the dyno.

Everyone says that my timing should increase since I'm removing airflow from the computer with the MAFT/AFC.....but in my case it is taking timing away. That's why Ron thinks that I'm reaching the peak airflow the motor can run, meaning there is some type of restiction in the intake/head/exhaust.?.?.?

I'm still new to tuning but it seems to make since of why I couldn't get more than 19psi.
No matter how much we turned it up it spiked at 21 (normall for an internall gate) and then leveled out between 18 and 19psi.

You can see in my logs and dyno sheets that when I was richer than 10:1 (check the dyno sheet it wanted to go below 10:1 but the dyno just couldn't ready anything lower so it just flatlined. Ron thought I was esily in the 9's ) and the o2 on the logger showed 1.02 - 1.04 we got 22* of timing up top. At 11.2:1 we only got 14*.

 

[CanadianTSi]

Are you sure you don't have a massive boost leak after the Maf-t?

 

[madman]

Origionaly there was a leak at the injectors and Tb but we got those fixed.

Even if there was some type of leak limiting my boost to 19psi.....shouldn't the motor still make more than 215whp??? It holds 18~19psi all the way to 7000k.

 

[madman]

I'm going to go over the exhuast again and see if I can find a leak.

I'd did the air flow correction and figured I was flowing 34.2 lbs/min.....with that much air I should be able to rule out the motor not flowing enough air shouldn't I?

I'll look into replacing the Maft, which means I need to find another BOV to use temporary and see if it makes a big difference.

If I can get ahold of full throttle I see if they have any sugestions regarding the MAFT being an issue or not.

 

[madman]

Thought I would just post an update.

I've talked to several differnt shops and mechanics and have gotten different possible reasons why my timing is being retared so much.

One that a couple agreed on was gas octane. I'm running 91 -92 depending on the gas station so I add a couple gallons of 100 octane to my tank that had a couple gallons of 92.

Here is the log from the run. This was all the same AFC settings as from the last dyno run.

Time	Coolant	RPM	Timing	Airflow	TPS	O2 1 Bank 1
00:01.7	210	2888	22	5.46	100.2	0.06
00:02.2	210	3040	22	6.25	100.2	0.08
00:02.8	210	3248	20	7.47	100.2	0.1
00:03.8	210	3428	16	8.95	100.2	0.92
00:04.4	210	3960	7	13.17	100.2	0.94
00:05.0	210	4280	7	14.5	100.2	0.94
00:05.5	210	4580	9	15.42	100.2	0.94
00:06.1	210	4852	10	16.17	100.2	0.94
00:06.7	210	5132	10	16.74	100.2	0.96
00:07.2	214	5428	11	17.27	100.2	0.94
00:08.0	214	5680	13	18.07	100.2	0.96
00:09.1	214	6064	15	19.6	100.2	0.96
00:09.7	214	6540	16	19.88	100.2	0.96
00:10.2	214	6736	16	19.85	100.2	0.96
00:10.8	217	6940	17	20.2	6.29	0.26

The shop that did my valve job also had just built a Supra that was having the same issue, bad timing and not making the horsepower that it was suppose to. They added race gas and got a better result like me but still not where it should be. Then the disconnected the knock sensor and presto....problem solved. Faulty/bad knock sensor.

So Within the next week when I get a chance I will try the same and see how it goes.

I still havn't completed a boost leak but I'm sure that my BOV is why I'm not getting more than 19psi. So till then I'll turn the boost down a little as not too overwork the turbo.

 

[madman]

Well I did a leak test and found the coupler on the intercooler outlet and the coupler on the back side of the GM MAF was leaking. I'm still not 100% sure on the Tial BOV, although after I fixed the 2 leaks the system pressurized a lot faster.

Either way I thought I would do a 3rd gear pull and see how it did. Then this happened.....

http://dsmtuners.com/forums/showthread.php?t=227506