canbaufo

OK, I was wrong about the MAP readings being 12-19 ....I guess I was looking at "MAF" on the Scanmaster thinking it was MAP now that I see the AFGS data from the log. I'm looking at my Datamaster log now and seeing a 1400-RPM/45-MAP combination most of the time while cruising steady (this is where I'm seeing the surge). I have noticed other similar combinations that seem to be pretty steady ....like 50ish MAP at ~1700 and 70ish at ~2000. Idle MAP is 50 at 900 RPM. It uses cells 17 and 18 a LOT and also uses 1,2,6,8,9,10 a decent bit. The short terms are up from LT counts of 118 and 114 to short terms of like 120-130 .....seems like and improvement since it's closer to 128.

Wow, no substitute for real data you can re-review as you please ....the Datamaster's a little awkward at first but the longer I stare at it and play with it the more I get it. This Histogram though ...these cells don't correspond with the cell numbers of the BLM matrix do they? I think these are just load cells from 400 to 6400 RPM ....I notice there is one at 150 MAP that says it's received 4 hits, how can that be if our computers can't see over 100 KPA???? I guess the numbers in the top aren't MAP but just ....ehh, what? .....lean vs rich ....ehhh, ok. ...this is going to take a little while to learn .....arghh. FWIW the histogram shows that I'm staying on the lean side while cruising whether the Right LT vs Airflow is selected or the Short Term ....does that mean I need to add fuel at the rpms where I'm getting hits in the lean cells? Arghh ...I'm getting tired now.

It seems like I'm getting decent resolution since several cells are getting hits....maybe I should add fuel around the 1400/45 intersection?

WS Sick

The ability to log data is one of the best tuning tools ever.

canbaufo

Yeah but trying to make sense out of it and make corresponding changes in another software gives you a headache at first.

BTW, how do you add fuel at low MAP/RPM ???? In the 400-2000 VE table? ...how? I don't know anything about MAF calibration either....is that a place to get more fuel? All I know is someone said adding fuel in the ranges where you see surge sometimes helps ....I just don't know how. Example, in the 400-2000 VE table ....would I increase or decrease the numbers in the cells to get more fuel? (what do those numbers stand for?) I guess they stand for "expected VE at those rpm/load combinations" ....but I don't know whether to calibrate up or down to get more fuel. Probably up.

Going to try 1400, 1700, 2000 and 45, 60, 75 with a min of 28 ......we'll see

canbaufo

2nd revision didn't help. Trying a 3rd revision based on what I'm logging, it's not much different though. I think it's time to bump up timing in the 1000 - 1800 rpm range at 30-50 KPA. My timing is basically stock in that range so I'm guessing I need maybe ~3 degrees more to get some cylinder pressure back in it at those low loads. My guess is the timing will be the fix.

I have noticed that where I see the surge the most is at 1400 RPM and 45 KPA ....when cruising this steady it is staying in cell 17. Cell 17 has BLM's locked at 128 so does that mean it's not really integrating fuel? Also, part of the time it says "closed loop" and part of the time it says "open loop" while at full temperature at this 1400/45 range. So what's the deal, am I basically driving around in open loop when cruising that light and steady? (2-4 % throttle).

Time to bump up timing

kevm14

What's interesting is, even bone stock, these cars exhibit just a tiny little bit of surging in that exact area. A hotter cam just brings it out. I think it's all in the intake manifold.

Anyway, yeah, adding timing should help. Might need a lot more than 3° though.

canbaufo

Now that you mention that I do recall a tiny bit when stock as well. I tried 3* more and it didn't change a thing. If I add any more I will be over 45* at those loads. We're talking really low load here but still, anything over 45* seems like too much.

I have duly noted that the surge only occurs in cells 17 and 18 (especially 17) .....most all other cells are being used fairly frequently and there is no surge in those cells...so it appears the blm boundaries are fine. There doesn't appear to be any learning in cells 17 and 18 (blm's locked at 128) however it shows there is integration. In those two cells sometimes it says closed loop and other times it says open loop with no rhyme or reason well after warm up. Am I basically driving around in open loop in those cells without any learning or integration? If so, perhaps that's how some people are getting rid of surge by adding fuel. I always thought "how can you change part throttle surge by adding fuel if the computer is just going to learn around it and lean it out?" ....maybe not if we're talking about cells 17 and 18.

BTW, how do you add fuel at the low loads? I don't understand the MAF frequency table and the VE tables are suppossedly not looked in or used much at all .....

LWillmann

The VE tables are used on the OBDI cars I believe, but not on the OBDII cars.

The MAF frequency table is where the PCM get's the air part of the combustion formula. The MAF sensor itself returns a frequency to the PCM. The PCM looks that frequency up in the table and gets the proper air-flow data for that frequency, it then uses that data to calculate the needed fuel.

So, increasing the air-flow value will tell the PCM there's more air, therefore it will add more fuel. Decreasing it will cause the PCM to think there's less air and it will add less fuel.

This will work to a point, since if you're falsely changing values, the PCM can get around it if it's still within the PCM's ability to adjust (within the BLM boundries 108-160). It will also affect ALL driving situations, all fuel cells, etc. So it's a global change.

MAF table adjustments like that seem to be better suited if your car is adding or pulling fuel consistently and you want to get the BLMs to 128, you can recurve the MAF table to bring the values in line.

One thing to remember, when messing with the MAF table, make the changes smooth. You don't want any jagged or sudden changes from the base curve. It can really screw with drivability.

arnie

You sure of that, or at least, have it turned around?

canbaufo

Yes, but can the PCM make adjustments in cells 17 and 18 ???? Again, the reason I ask is long terms and short terms are locked at 128 in those cells. My short terms and long terms (other cells of course) are slightly under 128, just how I like it ....this means fuel is slightly on the rich side and the PCM is constantly trying to take just a little bit out to get to the ideal 128. My feeling is that I can add fuel in the VE table and/or MAF table only in the ranges where I see the surge (cells 17 and 18) and the learning won't be able to overcome it ...hopefully it will be a fix. Going to start with the VE table. Going to make a big BIG change just to see if it likes it, if it does I will go back and make changes in smaller increments for the final tune.

LWillmann

I can't say about cells 17 and 18, My car is almost never in either of those cells. The only time I've seen the car in them is during OL before the car has warmed up and entered CL.

JPSartre12

My car uses ONLY 16,17 and 18 and, according to my Scanmaster, is adjusting BLM and INT values in cells 16 and 18,after warming up, for sure. Don't see it in Cell 17 enough to remember if it adjusts or not.

LWillmann

Do you still have evap purge setup on your car?

JPSartre12

No CCP or any other emmission stuff in the car.

canbaufo

Hmmm, if there's learning in those cells (17 and 18) then this is going to be very hard to beat. I bumped the VE tables in those ranges significantly and it didn't change a thing. I guess the only thing left to try is physically bumping the fuel pressure and/or bumping the MAF values up....at this point I've tried about everything else it seems. The GPS where I see the surge is 13-26 ....VERY specifically so. Should I only increase that to say .... 16-29 ....or do I need to feather the change in the blocks below 13 and above 26? Also, what is a reasonable adjustment? I'd have no idea if I should go with an increase of say .... 3 ..... or more like 6 or even more.

I guess I could add a ton of fuel just in the range where I see the surge, perhaps to the point of locking the BLM's at 160 .....then have regular fuel in the other areas so the learning and driveability won't be so adversely affected. Make any sense? If I only add a little fuel the learning's just going to thwart it anyway.

LWillmann .....not sure on the evap purge, a friend of mine did the initial tune and I've just been playing with it. Somewhere in "chassis" or "fuel" I'm guessing...I'll check it out later. What effect does that have?

redcamaroz28

canbaufo: If you want to make your car run rich by maxing out your blms, why don't you lower your max of 160 to 140-145. If you do this everything else must be 0 to negative XX trims so that you don't run rich when you don't want it to. I've also tuned my car speed density to that I actually do see a difference when I make changes to the VE tables. Doing this I know the VE is correct for the motor, so I then went and did all my modifying to my spark tables. Now that I have eliminated almost all cam surge, I plan in the next few days on plugging the MAF back in and adjusting it to get my blms's back in line. My thinking in using this method is I get the right fueling for each specific rpm vs map cell, then I adjust the MAF airflow to match the fueling of the VE tables.

Ryan