I already searched for previous threads on this topic but all of them pertain to cammed cars. I'm still on a stock cam, stock motor but my Freescan logs are showing BLM splits of 5 to 9 only in cell 17. The right bank consistently shows a lean trend, but it gets worse in cell 17. From what I've read, cell 17 is the deceleration cell when TPS is at 0%. I did raise DFCO enable RPM to 2000 and bumped the DFCO spark retard to 28* (for more aggressive engine braking) before I started leaning out the MAF tables. On a stock tune by BLMs were around 119 on average, and now they're almost 128. It's only the split in cell 17 that has me baffled. Is that even something to worry about since it's closed throttle decel?

Can somebody tell me how to put my logfiles up here?

 

I guess there are not a lot of responses on this because BLM numbers with TPS=0% are not effecting performance or running conditions. Usually when tuning you're only interested in throttle conditions when accelerating or cruising. To tell the truth I never looked at then until I read this post. After looking I noticed mine are jumping around during cell 17 when DFCO is not enabled and my injector pulse width's are a not equal, but I never though about why, could e O2's are not exactly identical. In blm cell 17 you are in a situation where engine rpm is decreasing, vacuum is very high and PCM is trying to obtain and hold specific RPM based on speedometer reading "Throttle Follower IAC Offset Vs MPH" table and the engine variables are changing dramatically. I would guess the imbalance is due to the intake manifold characteristics in this condition. But that's my guess, worst case you could have a leaking injector, you would have to look a the Injector left and right BPW's and see if the PCM is feeding the imbalance in fueling or if it's coming from somewhere else like imbalance in air flow , injector flow or just how IAC ports react to high vacuum.

 

It may be your IAC reacting slow. IACs will cause blm issues, as this is the reason people modify IAC holes within throttle body. Just a guess.
In regards to your DFCO for compression breaking, what do your DFCO tables look like.
My LT1 table is 4-1200 rpm its .8% tps, and 1600 is 1.2% and 2000-3600 rpm its 1.6%, if this makes sense?

 

RACEON, I found after adding my cam I was rarely. if ever, entering DFCO because of the stock MAP setting of 23 kpa for DFCO enable (constant tables). With my cam I never hit a MAP below 23 under normal driving conditions. The MAP, RPM and TPS variables are alterable to fit my driving preferences. Plus Solomon (LT1pcm tuning) did some modifications with his tune we installed last year. Also on your A4 the DFCO Enable delay (constant tables) is 0 seconds stock while on 88's M6 the stock delay is 1 second guess that's to prevent oscillating in and out of DFCO with the stiffer drive train effecting MAP fluctuations.

88irocz28, this forum does not allow attachments, you need to put the log up on a file share site and post the link here, its a PITA. You can e-mail me a copy of the.uni and I'll take a look at it.

 

Thanks bobdec. I just looked at an older file and I never got below 35kpa, and mine is still stuck at factory 23/30 Kpa settings.
my cam is 230/236 in a 396, vacuum is somewhat low.

 

Yea, what I did was log normal street driving and then look at my MAP when letting off the throttle at various speeds and rpm, then tweaked the MAP settings up and tested it. To much DFCO may give you a surge effect if it cuts in at the wrong times. I ended up enabling DFCO at 38kpa and disabling at 40kpa. My cam is 214/228 112 lsa not as radical as yours. Not that it effects this but have you taken a look at your 'BLM Cell MAP Boundaries' table. After installing a cam you may have to tweak the low boundary otherwise you never get into BLM cells 0-3 and end up running on 12 instead of 16 cells. Stock setting is 32kpa, again something you won't hit under normal driving with a cam'ed car. My settings are 38, 54, 74 they seem to work and give me more cells during driving, the stock settings are 32, 50, 80.

 

Thanks bobdec.
I will play with the cell boundaries. Do you tune for others or yourself?

 

I only do my own personal tuning. About 1 1/2 years ago I purchased a mail order tune that honestly did nothing for me so I decided to learn myself. Even with lots of reading and testing I found getting my timing tables correct for my cam &1.6 RR power curve was driving me crazy. Key part of tuning is to know what you don't know. So I tried a mail order (self load) tune from Solomon at LT1pcmtuning about 6 months ago, his timing tables, and special tweaks to the transmissions tables made a noticeable difference. I emailed him a log after the first install and he altered some other parameters to fix a rich at low end condition. So ended up using professionals for the hard stuff and mess with the parts that I "think" I understand myself.

 

Thanks again. His prices are very reasonable especially if you have all the gear to flash ro burn and to read data.