With all the recent talk on SD (Mafless) tuning lately I have tried to come up with a step by step list of how to go about tuning for Speed Density. I would like for the experts to read over what I have come up with and please give input so that I can correct anything that is incorrect. Please keep in mind that I am posting the following list as a question, not as a how to. I am sure that some of the info may be incorrect and therefore would like as much input as possible. Thanks for taking the time to look it over and please let me know what you guys think. I believe together, we can come up with a pretty good "how to" for others to follow. This is a start:

Step by Step for SD tuning:

1: Unplug MAF (Replace with strait bellows if you do not have intentions of ever using a MAF again ie. always speed density.)
2: Disable the SES lights for MAF codes P0101, P0102, P0103 (No check engine light.) Do not completely disable the codes or the PCM will not fall into SD mode. Only turn off the SES light, DO NOT DISABLE THE CODES THEMSELVES!
3: Change all points to 1.13 in the Open Loop F/A vs ECT vs MAP table (commands AFR of 13.0)
4: Change all points in the Closed Loop Enable Coolant Temp vs IAT table to 250* (Disables closed loop)
5: Copy High Octane table to the Low Octane Table (computer reverts to low octane table when MAF is unplugged, this assure optimal timing)
6: Change all points in the Power Enrich Fuel Multiplier vs RPM table to 1.0 (disables PE mode)
7: Use your wideband and HPT histogram to verify AFR of 13.0
8: Make adjustments to the VE table accordingly to dial in a 13.0 AFR (a lot of driving or dyno time)
a. you will need to add to VE to correct for a lean condition.
b. you can subtract from the VE values to correct for a rich condition.
9: Hand smooth VE as described by Magnus (a smooth VE results in crisper throttle response)
10: Change all points in Open Loop F/A vs ECT vs MAP table back to stock (re-enable stoich commanded AFR)
11: Change all points in the Closed Loop Enable Coolant Temp vs IAT table back to stock (re-enables closed loop operation and fuel trim leaning)
12: Change all points in the Power Enrich Fuel Mulitiplier vs RPM table back to stock (re-enables PE mode)
13: Use wideband and PE table to dial in desired WOT AFR. (optimum HP at WOT)


14: From here you can now plug you MAF back in (you might not want to since it will be running so good) and you can begin to modify your MAF table to get your trims back in line with what you were seeing while in SD...(More on this later.)
Please discuss

 

I just ordered the HP Tuner and am very interested in "How to SD Tune". This is exactly what I am looking for. A step by step from the people who know...

 

SD tuning isn't for A4 vehicles though, right?

 

I for one believe that the whole A4 thing is false. I have personally driven my car around with the MAF unplugged for a few days, and had no ill side effects. Please view this post: http://www.hptuners.com/forum/YaBB.p...num=1095941398

Apparantly others feel the same way!

 

Sweet, I'm really behind on my V8 Tuning reading on HPT forums. Thanks for pointing that one out.

 

Nice checklist

I am considering going to full SD mode at some point as the O2 issues and MAF issues are driving me nuts.

If you wanted to stay in speed density how would you setup part throttle tuning etc. Say to maintain ~14.8:1 at cruise and then have tip in and WOT in the 12.9-13.0 range?

I'd like to see a full checklist for SD mode only. (No O2's, No MAF, scaling for larger injectors accounted for)

Aside from a slight hit in gas mileage I think you could get a car VERY drivable with a proper SD tune. PLUS the MAF wont be a restriction in the intake tract.

 

you still run closed loop for SD tuning at part throttle. SD is not open loop. it just helps to disable closed loop to stop your fuel trims messing with the fueling while trying to get the VE table right, then enable it again.

 

ahh I see!

 

The SD/A4 thing is not entirely false,if you pull the maf keep in mind some early cars WILL command high line pressure to the tranny ALL THE TIME, which must be fixed or you will smoke the tranny this can be overcome with LS1edit or as the HP tuners thread says for HP users they will fix it for you if you send them your bin file, because the current version cant access everything.

 

TTT updated. Changed some incorrect info. I have been following this method, and have been able to achieve LTFT's of -2 - 0.

 

Yes the 13.1 is to ensure a safe AFR to work with, so that you won't have to deal with a lean condition.

If you want to take the 13.1 afr route then yes the wideband is neccessary, however many have seen success leaving the vehicle in closed loop and using the trims. However depending on how big your cam is, and how your exhaust is setup, (headers, and such) your trims may not be completely accurate at lower RPMs. I found this to be the case when tuning my setup. Because I have headers, and the 02's have been moved further back in the exhaust track, they tend to get false lean readings, and the computer will then adjust the trims to dump more fuel. So I was just chasing my own tail. WBo2 is deffinatley the way to go. Also keep in mind that if you are trying to tune in closed loop you will eventually be forced into Open Loop or PE, when you enter the higher RPMs depending on where you have your threshold set, and this too will begin to scew your results. Best bet is to use a WBo2 in Open Loop, and get everything dialed in from there.

Yes on some vehicles the IAT is in the MAF. There is a schematic of the pinout on HPTuners forum. I think I have seen it posted here as well. It shows and describes how to keep the IAT in tack and just cancel out the MAF. I'll see if I can find the thread and post the link.

Yes step 8 is the acutal process of seat time/driving, correcting, driving some more and checking.

 

This is also a great method for those who still have a pretty much stock setup. Like I mentioned earlier once you throw in a big cam and headers into the situation, your trims at lower rpms <1200 really become unreliable. This is where the WBo2 comes into play. However it is a great method to start off with. I used this method before I was able to borrow my buddies WBo2, and I did get things nailed down pretty close. It's just with the WB method I was able to get dead nuts on across the entire table.

 

Ck above your post I just answered your qeustions but for some weird reason it posted them above your post. I wonder if the server clock is off again

 

freakin weird

 

Few questions:

The 13:1 number - do you choose that mixture to ensure that you're running too rich, rather than flirting with being too lean?

Is a wideband necessary? Sounds like it is... although it seems like progress can be made without one. Rather than running a wideband, can you tune via fuel trims if you don't disable closed loop?

The IAT sensor. I hear mines in my MAF. What do I do about that when unplugging the MAF?

Step 8 - that's where you drive/dyno, log, and correct... correct?

 

I use a different method than the ones outlined by WS6snake-eater.

Here's my method:

1) unplug the MAF (and for us 5 wire MAF guys -- IAT included -- that means cutting the yellow wire in the MAF plug -- the MAF sender wire)
2) Reset your LTFTs and log, trying to hit every cell in the LTFT histogram in the scanner (if you are going to plug in your MAF again you can ignore those cells over 4000 rpm as they are purely driven by the MAF anyway, according to the HPT gurus -- I personally did them all anyway as I wasn't planning on using the MAF anymore)
3) calculate the change to each VE cell using this formula:

LTFT value + STFT value = change to the VE value

You will run into cases where the LTFT is negative and the STFT is positive -- doesn't matter, just add whatever signed values you see and add the result (again whatever sign) to the VE in that cell. This gets you pretty close. You may need to repeat 2 and 3 two or three times.
4) Fine tuning: disable your LTFT learning (by setting the LTFT learn enable min temperature to 284 or the same as the max setting -- You can also turn it off in HPT VCM scanner, but mine kept coming back on every 15 minutes or so...), reset your LTFTs and relog, but this time ignore the LTFT histo (since its turned off) and focud on the STFT histogram
5) calculate the VE adjustments by adding whatever STFT value you see in any cell to the VE table value. You may need to repeat 4 and 5 two or three times.
6) re-enable your LTFT learn, plug in your MAF,
7) scale the MAF to get your trims back to where they were with the MAF unplugged -- you're done

 

After resetting trims, do you need to let them relearn or do you immediately start your logging? Do you need to give them 20 mins or so of warm up time as well? I thought I remembered a few guys on the HPT forums saying to do these things.

 

You have to let them relearn. The advantage of using the STFTs for fine tuning is that they learn in microseconds.

 

If you are running the latest version of HPTuners you can turn off your LTRIMS and use your STRIMS to tune the ve table.

This eliminates the seat time involved with LTRIMS and give you more of a real time picutre of what the car is doing

 

I just tried this. I've got 13.0 basically from 800RPM <-> 5200RPM. Swapped the other tables to their previous values, re-enabled the DTC's and plugged in the MAF. LTFT's immediately jumped to 24 and the STFT's were showing 2 at idle (6 max). What happened?