Bolt on tweaks

[TD95Z]

Hey guys,

I'm looking for some input on tuning tweaks to get a little more out of my current setup. 94 A4, LTs and 2OTL, CAI, 160 stat, 2400 (12") stall, rear LCAs, still on 2.73 gears. Full weight other than the AC, spare, and back seat. I was able to pull a best of 13.31 last year at a DA right around 2000, with a 1.8 60'. The tune is still 100% stock, so I am leaving some on the table.

I don't have time to obtain a mail order tune in time for my next track outing, but have Tunercat and Datamaster available. I'd really like to dip into the 12's even with the 2.73s still in place. Can anyone provide some areas to focus on in the tune to at least get me a little closer to optimal? During a search, I did find a post from one of the bolt on guys here that suggested upping the shift points to 6000 improved times for a couple people. I've also seem to recall that the fueling is set on the rich side stock and might be worse with the LTs.

If anyone has some tips, please share. While i have no experience with tuning, I'd like to learn. The car is not a DD, so I can afford the potential downtime if I make some mistakes along the way.

Thanks in advance.

[blkchevyz]

read this first, its old but still has good info and can get you pointed in the right direction.
http://www.lt1pcmtuning.com/tips/
lower the temp the fans come on, if you dont have a shift kit already you can mess with line pressure, shift point.

make sure you are not getting any knock first, if you are then clear that up if you are not you might try adding a degree of timing or two. just keep an eye on knock retard
regarding getting the afr dialed in you really need a wideband o2.

[TD95Z]

Forgot to add that I have a Performabuilt trans, so I don't want to mess with the line pressure. Also, I have read Solomon's tips and will utilize that info along the way. Thanks for the reminder to check for KR. With LTs and a stock KM, definitely a possiblity. I will try to get some WOT logs ahead of the track outing so I can provide data for review.

[DMBlack]

****Insert I am NOT a tuner disclaimer here****


The stock LT1 tune is pretty rich at WOT. I have luck pulling fuel (lowering the numbers sometimes even negative) above 2500 rpm in the PE %Change to Fuel/Air Ratio vs RPM at WOT table. I have always done this with a wideband and tried to get a constant 12.5-13.0 during a run. I have not done this with using the factory narrow band sensor so I don't what to look for if trying to do it that way. If you want to tune yourself, buy a wideband as it will be one of the best tuning investment you can buy.

Every car is a little different. When my car was bolt-on only it ran best at 12.8-13.0 afr.

Keep an eye on knock retard. If you don't have any you are good. If you do, you have to find out if it is real detonation or "false knock". Either way, find the cause and fix it. If you are getting knock counts and the PCM is pulling timing it will really kill your times.

[TD95Z]

I finally got around to messing with Tunercat and Scan 9495. Did the basic stuff like turn off AIR and EGR and lower the fan on temps. The car now stays right around 180. I did a few short WOT bursts and got no knock retard in 1st gear, but did have a spot around 4k in second that pulled 4 degrees. Unfortunately I couldn't get any good full runs on the street, so I will have to continue this at the track.

Based on the advice in here and elsewhere, I did create a tune with 2 degrees added across the main spark tables, along with one that has the shift points bumped. I figure I will try each individually and see what happens. If each has a positive response, I can merge them into one. I'll look into a wideband before trying to pull fuel.

One followup question: In the TCC forced lockup at WOT table, the value is set to 100 mph. I trap 102 in 3rd gear. Would it make sense to bump this up to where it isn't locking up right before the end of the run? Being on 2.73s, I don't see any value in locking it any earlier since it will dump RPM towards the top end of the track and is rough on the TCC.

[Mystery Bird]

Yes, I would move that table up to a point where the converter doesn't lock in third.