944Fest (aka Dan P)

I'm starting to try to understand the mafterburner, and I'm doing some data logging with my car. This data log was done today with a L Super 65, custom chips, 55LB inj, and a few other doo dads. The fuel press is at 40LB static.
I understand my peak injector voltage should be 4.6V, it seems I've got that right on. It seems mixture does not matter much unless you are WOT, otherwise it is all over the ballpark. If you know what you are looking at, look at this and tell me what you see.

TIA

http://www.944fest.com/480pull2.xls

jy951

Well, I'm using MAFterburner too, but I'm certainly not at GURU status like Ski. For one thing, those 16 and 17s in the 4k-5k RPM range scare me (were you in 5th gear? - hopefully it wasn't under load - like boost - while u had those high AFRs) , the throttle is open (70% or so) and RPMs appeared to be increasing (can't quite remember) .

I usually see AFRs in the 16s and 17s when I'm decelerating (like it appears you were doing at the end of the spreadsheet) . Did u change MAFterburner settings while driving? Or did u compile several runs into one sheet? Because further down, your AFRs are in the 11s and 12s, and the RPM range is similar to the ones that you previously reached 16 and 17s.

Personally, my 951 responds best with AFRs between 11.7 and 12.5 in the 2000-4000+ RPM range. I've designed my fuel curves to give me an AFR spike of 13.1 - 13.3 when I spool up the turbo (LR Super 48), but then it drops back to 11.7 - 12.5 range under city driving. My AFR on transition to boost is between 12.3 and 12.6 (depending on engine load). While on boost, my AFR has ranged from 11.6 to 12.2, depending on how hard I pushed the car during boost transition, plus ambient temperature, etc.

I hope this gives you some benchmark - it appears to work for my 951. So far, no headgasket failure (crosses fingers) and when I'm under boost mucho black smoke comes out the tail-pipe (so, I'm running rich at boost transition and also under boost). This has been my experience with MAFterburner - I still need to turn down my fuel pressure (48 psi) - because I'm rich (11.8 instead of 14.7) under idle.

RKD in OKC

The first thing I noticed looking at your log is that there is a huge delay in your Wideband output after a throttle change. This may be making your tuning off a couple of map positions.

I've found it is easier to tune if you think about the map as three separate ranges. Driving around, first getting into the throttel, and full throttle acceleration. Example: if you are just driving around the MAF rarely goes above 2.6. However, full throttle jumps to above 2.6. Driving around, 2.6 and under, and Full throttle 2.6 and above. The better you have the driving around portion tuned the better the top end normalizes and behaves.

I've been on several tuning drives with Wes from LR in the passenger seat with his laptop. He has me do a lot runs were I get up to the 1.0 on my factory bar gauge but not over. He calls this the tip in voltages. This is how he starts tuning before ever trying a full throttle run. Says if you don't have to bottom end smooth the top end is all over the place. And of course every time we have to change the fuel pressure to get the 4.6 volts, he has to redo all the lower voltage mapping.

You should be setting your fuel pressure by the top end voltage output and AFR not idle. Use the map voltages to set the idle AFR after you have found the correct fuel pressure to get 4.6 volts at the top end of your full throttle runs.

I am by no means an expert and haven't stayed in a Holidy Inn Express, ever. I have had neighbors bitch at me because I was sitting in front of my house adjusting my maps at 7AM on a Saturday. That was when I had the FlowMaster muffler on the 4 inch exhaust and it was pretty loud even at idle. No noise complaints since going to the Magnaflow muffler.

Ski

Dan, it's very hard to get consistent logs when you get off the throttle and then get back on it. I would do the runs/logs start to finish, save that one when you or co rider(laptop person) hit the stop button, THEN get set to do another one. The problem I've encountered to multiple "runs" on one log is the momentary lasp of TPS voltage vs MAFv vs what is happening with the A/F ratio. This all happens in milliseconds but you can see that the log is sampling; taking around 13-14 sample per second.

What are all the mods on the car? One other question, the software version you have, does support your WB sensor and you used the slide bar to set the WB readout on the Mafterburner to match your readout in the car, say at idle?

tedesco

Allthough I am definetly not an expert too I am useing the mafterburner as well. What I ask myself is if it will be possible to ever set up the fuel correctly for this configuration. To me it seems that the MAF is too small. I just look at the first pull. The MAF voltage (V in) reaches 4.6 even you backed off throttle towards higher RPM. I would bet it will run easily into saturation once you keep the foot down and/or only slightly inceras boost. Maybe someone can give further explanations. I would be very interested because I am useing similar equipment.

RKD in OKC

As long as the MAF output does not exceed 5 volts it is OK. If it exceeds 5 volts you need a bigger MAF. Mine is an Autothority and has enough range to flow over 400 rwhp without reaching 5 volts.

944Fest (aka Dan P)

Here is another one to peek at: http://www.944fest.com/480pull3.xls

These are some solid pulls, in #3 there is a point where I am full throttle for over 8 seconds. (I'm gussing that was 4th gear) The lower gears just don't allow WOT for more than 5 seconds.

The highest V out I'm seeing on #3 is 4.56, isn't that about right? The mixture with my foot to the floor is 'often' mid to low 11's. What is a good WOT target? How about idle? Right now my idle is in the 11's.

Yes, my mafterburner has the recent software update to match my WB, I have the AEM/bosch setup.

Both of these runs were almost from a stop all the way up to the top of 4th.

I really appreciate the input, folks. Thanks..

Ski

idle - 14.5 to 14.9, as it will probably dither a bit...do you have the factory O2 sensor hooked up or not?

WOT, fully on boost, I like 11.9 - 12.3, a little safety factor there. I, like Richard, at the start of boost, have mine around 12.7-13.0 but it immediately drops to 11.4 - 11.5 as the boost kicks in, then my curve starts leaning out and the A/F runs toward 11.9 - 12.3 all the way to 6300, which is usually my shift point when playing hard with the street car.

Are you familiar with Conditional Formatting in Excel? If you are then do not read any further but here goes.
1. Select your column and highlight the whole thing
2. Select Format, then select Conditional Formatting
You will see that you have boxes for the CELL value. One thing I find helpful is coloring the A/F column
3. You will see Cell Value, next box, drop down the menu and choose Equal to or less than, make that number 12.5, choose Font, choose the color GREEN
4. then click ADD for the second condtion
5. same as 3, but make it equal to or Greater than 12.6, and make that font RED

This will point you toward your lean cells, which may or may not have voltage issue but it sure makes reading the spreadsheet a breeze, I'll see if I can load it up here.

944Fest (aka Dan P)

Bret, thanks for all of the info. I really like the colored bits you did, thanks for the excel pointers. I will work on those. The part where you ask about throttle position, I'm guessing I'm gradually coming off the throttle there as it gradually comes down from 60's to the 30's, then stable in the high 30's and low 40's. So far in my analisis I've only been focusing on the WOT stuff to make sure my mixture is safe when the power is max. Most of my runs during WOT the mixture is in the low 11's, it seems that sample you found, 1.5 seconds at WOT is very lean. That is not good, but from what I see it is some what of an isolated case. It looks like it is right after a shift, as the RPM's drop 2000, and then 1 second later the mixture starts to enrichen.

The factory 02 sensor is gone, I have the Lindsey 4" exhaust and the O2 bung is not until after the turbo. IIRC, the factory O2 sensor is in the crossover pipe and ahead of the turbo, which makes me think I'm inviting a delay, maybe just a split second but delay none the less, in recieving the data. My understanding is this was done to clean up the crosspipe flow.

I will definately get that idle leaned out, it smokes more than I'd like down there.

You pointed out a couple of possible problem areas, are there any areas where you would say "That looks good right there, make no changes to that"?

kasturbo

Dan, did you just plug that factory o2 hole?

944Fest (aka Dan P)

Yes. Lindsey supplied me with a bung in the new exhaust, near the turbo downpipe. It had a plug screwed in it. I was instructed to use the plug to cork the factory hole and put my new wideband sensor in the downpipe.

kasturbo

So your car will always run in open loop then? Have you seen any issues with this?

944Fest (aka Dan P)

I don't know what that means. I'm guessing that is what happens when DME is not getting any O2 signal anymore. It would be a piece of cake to put it back in if anything thinks that would help out.

Look at my data logs. Do you see any issues I might attribute to that? I really don't know what to look for in that department.

kasturbo

The DME uses the o2 sensor for input when under normal driving and uses closed loop maps. When at WOT it switches to open loop and uses those maps. By removing the o2 sensor, you force the car to run in open loop mode. It your chips and tunning are good then it won't matter. This would have no affects on your logs as you are running at WOT.

I'm sure someone with more experience can add to this.

Ski

The car will run in open loop but just lean it out with the fuel cells, 3rd and 4th cell, as this is where you will probably be showing idle - not a big deal. Don't forget to use the built in calculator, where you put in A/F number, then what you want it to be, hit calculate and the amount to lean/richen will pop up in a percent mode.