What gas mileage have you gotten with the ARAP chip and highway mode, a couple of days ago I drove to my grandparents - a trip almost 400 US miles, and I got an average of 1 litre gas/10 kilometres. 1 US mile = 1.6 kilometres, but the conversion litre vs. gallon you'll have to lookup somewhere

Is this good or just normal? I tweaked the AFR vs. Load tables in the chip a little bit so that they looket like this:

Load AFR
32 16.0
64 15.8
96 15.8
128 15.4

Which means that at low load it'll run a bit leaner, but it doesn't seem to be a problem.... What results have you other guys got?

------------------
ZaphodB a.k.a Carl Andersson - zaphodb@faxancruisers.org
'89 Camaro IROC-Z 5.7L TPI - Mods under construction :-)
Custom ARAP Chip Under Development/180 t-stat, Edelbrock TES Headers,
SLP Airfoil, K&N Filters, Accel 8mm wires, Relocated MAT, AFPR @ 45 PSI

 

Results will vary by car, but mid 16s AFR seem about the limit. It will take X amount of fuel to generate a given amount of HP, any given car will have a fair amount of rolling resistance, so it's not just a matter of learner is good, there is a practical limit.

 

Play with the AF ratio a bit, but at some point you will notice the throttle getting a little "spongy" and some "surging" occuring. That is when you know you have gone too lean. Also, at some point you will go too lean and you end up increasing your throttle position % more than it was before, and you get no further increases in gas mileage...that is another indicator that you have gone too far.

Another "non prom" thing to look at is your tire pressure. I found an additional couple of MPGs by increasing my tire pressure from my usual 30 psi to 37 psi. It does reduce traction a bit on a standing start, but helps with the highway miles. I check my tire pressure all the time and vary it based on the type of driving I am doing.

 

that's about 23.66 mpg.


James

 

I also have been using the ARAP bin (modified), and highway mode. I have not noticed any improvement in gas milage. I know that this mode works, seen it several times with my scan tool. But I only run in this mode for a few miles at a time, haven't really gone on any trips with it yet. I get about 18-19 mpg now. I think it should do better. But what I have been working on mostly is getting my fuel mixture numbers close to 128, by changing the MAF tables a bit.

I just figured out that it might be better to disable highway mode while tuning for fuel mixture, until you get the BLM/INT values close to 128. Once in highway mode, learn control is off, and you don't get any usefull data on your BLMs. Then once I am happy with that, I will start missing with some other stuff.

------------------
Best ET 14.413 @95.57 without
pulling valve covers or manifolds.
Also with stock 2.77 rear end!!!

 

Mike, that is the best thing to do. You really need to have the mixture right to get the best results with Highway Mode.

However, the ARAP BIN is pretty darn good "out of the box". Pity there is isn't something similar for SD cars...

 

With my latest scan, highway mode disabled, the BLM's ran 122-134, which is a little less than 5% from 128. This was during about a 16 minute road test to work, with "light crusing" all the way. I am just not sure if I can get it any closer, by tweaking the MAF tables. I will most likely do another scan on the way to work friday. I like to get at least 2 sets of scan data, on different days, before I make a change. I want to get these MAF tables finished up soon, so I can work on other fun stuff!!

 

You may want to try locking the BLM min/max to 128/128 to get "finer" adjustments. But if you are in the 122 range, you are probably getting as close as you may get.

 

I actually got 23.5 mpg Highway this past weekend, Drove about 235 miles on 10 gals of gas. Considering I have 3.73 gears, I figure thats NOT bad at all. I didn't get that with my 2.73 & LG4 the car came with, so I am happy...


John

 

That's good mpg, John, even with your gears. I have the lowly 2.77 BW rear end, got to get rid of that!!!

Glenn, I tried locking the BLM to 128. I did some road test scans, and the INT varied up and down quite a bit, like from 108 to 150, and it changed rapidly. I could not find any patterns, in order to make changes to my MAF tables. I like to look for steady state values, IE constant airflow for several seconds, resulting in constant BLMs (orINTs), then I can ratio up or down the number in the table. I just didn't see any useful patterns with the BLM locked to 128. I think the Integrater changes too fast, making short-term adjustments to the mixture. The BLM tends to stay at fixed number longer, esp when the airflow is constant.

Just my 2cents worth!!

 

On my FBod I used to routinely get 25 with a TBI, and the GN at 3,500+ lbs gets 25 and that was pre highway mode.

FWIW, I had the F at 1.0v TPS at 60 MPH, and the GN is 1.0v TPS at 72 MPH.
Both ran the limits on max advance. GN has a AFR of 16.8 but was worked with alot to get there.

 

Mike, that is why like to capture all the data with Diacom and then sort it to get an average reading.

Also, the MAF scalar tables then to work like a set of large steps which can cause you to be lean on one side of the "step boundary" and rich on the other. Also, MAF seems to have a longer transition time but does settle down after a short time at a steday cruise.

I like to check both the "median average" and "mode average". Median means the average of sum of number / by the number in the population. Mode is the most common number occuring in a population of numbers. Consistency between the numbers (median very nearly equals mode) means you got a good sample. Where as, a large variance between the median and mode suggests you need a larger sample size.

I like to use a VERY LARGE sample from Diacom and combine multiple of GDFs from a number of data captures from long drives over varying terrain (hilly and flat). One sample had over 35 GDFs combined for a total sample of almost 250,000 frames. I had to sort and split that over a number of Excel Spreadsheets when I was all finished.

 

Glenn, you must be "data happy", to work with all those numbers!!! I am impressed with you method of analizing the mumbers. I figured out how to pull my numbers from Ease, and get them into a spreadsheet. I usually have about 8-9000 frames of data that I work with. But I mostly just use my Ease scan tool to look at the data. I can look at upto 6 graphs at the same time, and can compare the BLMs with the airflow, zoom in on certain areas, then use a calculator to consider making changes to the MAF tables.

I am starting to understand the limitations of the MAF sensor, and may have gotten all I can from trying to fine tune it. I don't have a lot of time (or extra cash) to just spend on test and tune, so I want to finish up with these tables and work on other things. I been averaging 1 chip a week, but could pick up on that. I plan to get to the track next weekend and see how she runs, so I may push to get some of the chip stuff done sooner!!

Thanks for your tips.