Another_User

Ok, I figured out that my car ran better in open loop than in closed loop (although pig rich). No surging or bucking (after I reset the LTFTs too). Then I re-enabled LTFTs and closed loop in the same drive. Plenty of surging and bucking to go around. So I just made a run with "Idle Proportional" fueling disabled. No bucking or surging. There was a bit of a throttle transition surge, but I am pretty sure that is because I have been messing with my Idle Airflow table. It looks like this may fix it (ready for another drive tomorrow!). Can somebody else try this out and see how it works for them?

WS6snake-eater

Hell I'll give it a shot

2000TransAm24

iTrader: (2)

When I went to open loop it helped my surging/bucking on deceleration but the surging I get when my torque converter locks is still there. Probably the fact that I have mine lock up at a low speed and in third gear as well as fourth doesn't help.

Another_User

Yeah, it sucks that there are so many variables. I am running an SD tune, plus I have DFCO disabled, both of thos can affect the outcome too. I just hope when I take another drive tomorrow, that all is still well!

Another_User

Any results?

P.S. I found that low rpm is really sensitive to trim variations on the VE table if your LTFTs are turned off.

Edit: I just took a drive. The thing was definitely running lean before turning off proportional idle. Now my VE table is falling into place better. At least all my research provided something useful finally.

luv2spd

iTrader: (1)

Another User- when you're done could you send me your file so i could look at your ve table. thanks

Another_User

I'll do one better, I'll post it on the share board with all the rest of them. I may just post my latest revision up tonight. It's pretty much done now anyways.

Slowhawk

iTrader: (12)

I'm surprised you guy's are having bucking problems with such small cams

What I've done and seen alot of is "over tuning" which means you make so many changes thaty it just doesn't get better.Sometimes I would just go back to a stock program and start over.

Are you guy's tuning starting from the idle?Meaning getting the idle squared away before any other changes? The reason I go there is because it can most definitly affect minor throttle input which causes bucking.A hanging idle will buck a car,expecially an A4 car. Some of the bigger Cam cars I do seem to like more timing in the lower rpm ranges,Some like less.
Just a few idea's for you guy's

Another_User

The hotcam is not an easy cam to tune. I have gone back, many times, and started from scratch. I have no trouble tuning idle. After my drive today, it is definitely a lean issue due to proportional idle being enabled. My being so stuborn finally paid off, because I have been fighting it for awhile. In fact, the tune I used today was made from a stock copy that I updated from scratch last night, just to make sure there was no leftover "crap" from messing with the same file over and over.

HumpinSS

iTrader: (1)

So what exactly does the idle porportional tables do. I dont have bucking that would drive me crazy and i have a bigger cam 230/232 110 +4

Another_User

Proportional Idle leans out your fuel mixture (you can tell by comparing the normal and idle tables) at idle, which it considers to be anything 5% TPS and below (I should have tried it earlier, but it seemed to simple). I was reading my Holley carb book and they were talking about how idle has no load and it is normal to run a car at idle with a minimal amount of fuel. So I pulled up both the tables and compared them, and sure enough that is what proportional idle does. So I disabled it and the bucking and surging stopped. Apparently low-TPS fueling is picky though, because when I disabled LTFTs I would occasionally get a buck or a surge as the STFTs moved. That's something I noticed, STFTs like to kind of "coast" sometimes and will leave lean or rich spots. LTFTs are jumpier because they are "learned" and will push your fueling right to where it needs to be.

AFPewter

Has anyone else tried this? I'll give it a shot once my HP Tuners unit gets here (hopefully this week). I'll try anything. I have to be over 75 MPH before I can use 6th gear because of the surging I get with the TSP 231/237 cam.

Another_User

I can use 6th comfortably 60+ now. But it still doesn't go too far out of whack lower than that.

luv2spd

iTrader: (1)

So can you idle in first like through a parking lot without any bucking now?

wait4me

iTrader: (10)

isnt the bucking you guys are talking about because your running airflow table or park position airflow tables are too high? that always fixes it for me???

luv2spd

iTrader: (1)

I thought too much running airflow would just cause a cruise control effect, not bucking. I don't doubt whay you say though b/c you def. know more than I do!

wait4me

iTrader: (10)

we are all here to learn i think the bucking is because the computer is trying to get the rpms up to what it is requesting and it just cant because of the gear it is in is keeping it from doing what it wants, a car with a stall converter will just rev to what it is, but us m6 guys dont have the slipping like they do..

luv2spd

iTrader: (1)

What about the bucking at lower rpm (<1300) and light throttle. I get that sometimes although its a lot better now than it used to be. Add or subtract timing? I've actually found that the bucking idling around in first got better when I added timing, but I'm not sure about the bucking at light throttle and rpm.

fbodysetc

iTrader: (5)

This may be a stupid question but weres the share board Thanks Nathan

luv2spd

iTrader: (1)

Horist's Site There ya go!