I remember reading somewhere that if evap purge was less than x% (can't remember how much) then the car would use cells 17 and 18, otherwise it would not.

I'm still trying to determine why my car has never, ever, even when stock, used cell 18 for WOT and everyone says it should. The fact that my car has shown evap activity at WOT in the past, would be the only reason that I could find for it to NOT use cell 18.

But by looking at my BLM map, the car SHOULD be in cell 15 when it's in cell 15, so I can't say that anything is actually WRONG with my car. Just trying to figure out why mine is so different than most everyone else's.

 

I see that we have the same set of Craftsman tools.

 

Maybe I need to look into that, the way mine acts if I could just get it to stay out of those two cells I would never have surge. It may be the specific load/map combo that's causing the surge though, rather than the learning in those cells.

RedCamaroZ28, interesting and intelligent approach doing the tuning without the MAF first. Sounds pretty time consuming though. Also, I didn't even notice that you can lower the max blm down from 160 ....that will obviously help in my case. Wait a minute, I think you meant the other way around ...below 128 means it's trying to compensate for extra fuel, so I'd want to raise the minumum up from 108 wouldn't I ? ...maybe I'm misunderstanding. I have already made a new program with a bump of 3-5 in the 13-26 GPS range of the MAF table .....I will install and run in a couple days and see if it helps. So in a nutshell what eliminated your surge? (if you can put that in a nutshell)

 

canbaufo: My mistake, your right. It is the limit below 128 which you will want to change. If you are using Tunercat this option is in "ECM constant table" and is "Minimum BLM". It is VERY time consuming, but hopefully once I get all this out of the way I will never have to mess with it again. Well, at least on my car anyways. Also, to elimate the surging first I got all my BLM's as close to 128 as possible. Then I began adding 1 degree of timing in the main spark table until I saw KR, then once I saw KR I subtracted 1-2 degrees. One of my problems is I am getting false KR from my rockers (I have a LT4 KM, too), so I have to listen very closely for any detonation. Once I got the spark tables the best I could and most of the surge eliminated, I then set my minimum blm to 115 and added fuel via VE tables (still in SD) to get rid of almost all surge.

Tomorrow I'm hoping to plug the MAF back in and getting my first experience with reworking the tables. My plan is to find the formula of the MAF table curve, adjust the whole thing by X constant to get everything close, then fine tune. Then, hopefully this weekend I can get a hold of a WB O2 and tune for WOT.

Ryan

 

Well, I added fuel in the MAF table at the AFGS where I see the surge. I know it worked because the LTerm Counts are locked at 108. It doesn't like it though ....and I only added a little! The surge is actually worse!

Here's what I don't understand: Why is it using cells 17 and 18 at RPM/MAP combinations that are within the boundaries of my BLM matrix in areas where it should be using cells 00, 01, 04, and 05? For example, I have Datamaster stopped right now and it says 34 MAP at 1425 RPM ...that should be cell 00 but it says 17 ..??? Now I've stopped it on cell 18 and it says 72 MAP at 1275 RPM ....this should be cell 12 according to my blm boundaries! ....I don't get it!

I guess I'm going to go back to the spark table, I only added like 3 degrees last time. I guess I'll bump spark up to like 50 at the low loads where I'm seeing the surge and see if that does anything, then go back and make finer adjustments if it helped.

By the way, I don't see anyway to turn off evap purge .....I geuss you all just mean whether or not it's still phsically installed. I have headers so I doubt it ....maybe it's not plugged off or something.

 

My car only runs in 16;idle, 18; at other than idle TPS and 17: hard deceleration. If yours goes into 17 while not decelerating, I'd guess that you must be pulling some serious vacuum or your sensors think that you are.
All my emission stuff is off, including CCP, EGR. MY scanmaster just reports zeros in them.

 

It pulls about 17 inches of vac at really low loads. Cell 17 is used when cruising steady at a very light load (just barely decelerating) and under hard deceleration as you said. Cell 18 is used at steady cruise when I'm just barely accelerating. Cells 5, 6 and 9 are used a lot during steady cruise but I don't have any significant surge in those. Surge is only present in 17 and 18. Buddy of mine in here who fixed my cam problem (and other) said it acts like a lean condition to him ........which makes sense considering it uses 17 a lot and it probably doesn't add much fuel in 17 since it's supposed to be the deceleration cell. Thing of it is ....I've already added a little fuel in the MAF table to the extent of locking the blm's at 108 when it's in 17 and 18 ...and it was no help.

I have now added as much as 8 to 11 degrees of timing above stock in the areas where I see surge .....STILL no help at all. I guess it's time to look into the evap purge setup ....I don't really know because mechanics and friends have done most of the work on it. I have noticed that Datamaster reports 00 for CCP and EVAP when in 17 and 18 ...but it reports some activity in those fields when other cells are used. Seems like if EVAP/CCP was my problem it would show values in those fields when in those cells. ???? ....I dunno.

My LTerm counts are ~118 ....so integration is pretty close. Now I'm thinking maybe I should actually remove some fuel in the MAF table to get the BLM's closer to 128 (it acted worse when I added fuel). Jeez ...this isn't easy to get rid of, maybe it just can't be eliminated? My cam is 220/226/112+6 @ .544 lift with 1.6RR's, heads flow 265/195 peak with 185cc chambers, LT headers. I feel like there's a way around it ....since the real surge is ONLY in cells 17 and 18, but maybe not.

 

Hard deceleration? Wouldn't you want to mess with closed-throttle spark advance for that?

 

No problem with hard deceleration. When I see the surge it is using the lower rpm open throttle timing table. I only see the surge at very light load (2-4% throttle) in cells 17 and 18.