I was wondering if an experienced eye could take a look at the log that I took with TTS Datamaster this morning. I know that my L-terms are running pretty lean and that it needs adjusting. But I want someone to look over it and tell me what else I'm going to need to tune. I picked up around 3k knock counts and i'm getting between 0-2 * of retard .. with the average around .2 .

I'd like to just send ya my .uni file from datamaster so you can see it.

 

I just realized I do have Datamaster.... go ahead and email me the file.


Also, can't you save it as a Diacom file? Or is it Datamaster will read a Diacom file? I forget. If you can, save it as csv that would be better.

cmarcho@hotmail.com





[Modified by Marcho Polo, 4:49 PM 2/1/2002]

 

If you email it to me I will be more than happy to look at it, and will post it and link it up in this thread for others if you would like.

 

Oh, well, since you asked, I put it on my web server for you guys .. both in CSV (excel) as well as Datamaster formats.

here ya go: (3 mb total)

http://www.gulicks.com/vette/curtis383.csv
http://www.gulicks.com/vette/curtis383-2.csv
http://www.gulicks.com/vette/curtis383.uni


[Modified by Glock'94, 10:38 PM 2/1/2002]


[Modified by Glock'94, 10:39 PM 2/1/2002]

 

Your datamaster file looks alike like mine. Looks like you are running lean too! You don't have any WOT runs on the datamaster file though....Did you get any with the others??

 

No, i'm not going WOT until after about 300 miles. I want to be sure everything is seated right. I'm going to check the rockers after 300 miles too to be sure they are still good and tight.

 

You seem to be pretty universally on the lean side - first thing I would do is probably drop the injector constant down by 2-3lb/hr and see where you are then. If you oculd post a copy of whatever your current program is that would help also!

 

No problem ... here ya go :). I have the injectors set to 32# since they are the F*rd SVO 30#'s.
http://www.gulicks.com/vette/383.bin

or the LT1 edit version
http://www.gulicks.com/vette/383.lt1

What is the L-term measuring (as compared to the S-term)? Also, can you explain the knock? Is that knock pinging? I have 11.55:1 compression, and I'm running on 92 octane ... i know I need to go find some 93 or 94 somewhere.

Let me know if there is anything that stands out.


[Modified by Glock'94, 3:41 AM 2/2/2002]

 

Are you still running all your EGR stuff and Air pump?

L-trims are basically your long term fuel trims.

Basically as the S-trims max out the incriment the L-trims. You could think of the s-trims as the ones place and the l-trims as the 10's place in a 2 digit number.

Honestly, ignore the s-trims. They really don't mean much and fluctuate to much to be usefull anyway - just focus on the l-trims. I would try to get them down to 122-124. Since you seem lean all over the easiest way to do this is to just take down the injector constant. Get yourself in the ballpark with that.

I would probably also start out with setting your WOT timing to 33 degrees and advance it up from there. I would get rid of the big dip at 7000 rpm also. Generally i treat from 90-100kpa as WOT - it keeps things consistant at WOT.

I would do one thing at a time though - get the fuel/l-trims sorted out first, then work on the idle until you are happy with it, then start changing the spark tables. I wouldn't mess with WOT too much other than setting it conservative until you can get on dyno with a wideband.

edit: The "knock" can be from quite a few things. I would just make sure and not limit the amount of retard the computer can get take out and worry about the fuel - pinging, etc. can easily be caused by transient lean conditions.




[Modified by ChrisB, 4:04 AM 2/2/2002]

 

Thanks chris!

yes, all my EGR equipment is still on there and working.

The only thing I changed on that program from what it used to be with my 350 was the cyl volume, the injector size, the fan temp, the idle park & drive, and that's it.

The program wasn't stock before, it was done by Speed and Performance in Arkansas. I do have an Ed Wright that goes to a 383 with a comp cams grind and other similar things to my setup. Would you like it to look at?


[Modified by Glock'94, 4:12 AM 2/2/2002]

 

Here's a copy of mine too (if anyone is interested). I am loading up a program today to hopefully get the LTerms down some, they are in the 138-143 range in this file:
http://www5.ewebcity.com/timbarnes/D...Tim383run4.uni

 

Hey Glock... I tried 30# injectors on my 383, recal'd for the same O2 sensor #s and lost 2/10ths in the 1/4 compared to the stock 19 # injectors. The only explanation that makes sense is that the fuel is atomized much better using my stock injectors (19#) at 55 lbs of fuel pressure vs the 30# at 40 lbs of FP. The injector pulse width at idle was < 1.8ms (getting too low for consistency). My personal experience (along with many others) is that 30# injectors are to big for a 383 making 350 to 450HP (crank). I use 30# injectors on my 420CID and it makes 450 dyno'd hp at the wheels (about 540HP at the crank using the 20% loss #).

I looked at your #s and I'm puzzled as to why you appear to be lean. With your injectors already being large for your engine, you should be on the rich side with the injector PWs I'm seeing in your file. What's your fuel pressure?

 

Your faster qtr mile times were probably due to running lean with the 19# injectors. HP will go up as WOT gets lean beyond 13:1 but the combustion temps go up and you risk motor melt down. 2/10s (20+ HP) is a pretty good size gain from fuel atomization. Its probably something else. Were runs done back to back on the same day in the afternoon. Climate changes will affect power also.

GM put 28# units in the LT4 motor and it makes about 360 at the crank. You maybe able to get away with smaller injectors (30# is too small for safe 540hp) but you will have no margin for injector flow reduction due to clogging etc. overheating the injectors also.

 

I'm at stock fuel pressure. I don't have an adjustable fuel pressure regulator. Also, if you look at that .uni file before I changed the injectors, you'll see that my BLM's were right around 128 or so.

I need to check my fuel pressure. Last time I checked it, FP was at 43psi or so (before the rebuild). I guess i should check it though.

As soon as I figure out how to let my computer be programmed, then I'm going to change the injector constant to 29.5 as said above.

 

Oh, and does anyone know how lean 140 is compared to 128 ... like is it bad for me to be driving around with it lean like that until I can get the computer reprogrammed again? I mean, I can calculate a percent of 9.375% lean, but how bad is that? ((140-128) /128)


[Modified by Glock'94, 3:37 PM 2/3/2002]


[Modified by Glock'94, 3:37 PM 2/3/2002]

 

Hey Curtis,
Mine was even leaner than that and I was drag racing it at the strip :eek: :eek: and it ran a 12.61! I've put just over 4,000 miles on mine running it that way - hopefully I haven't done any damage. I put in a new tune today and my LTerms are now at 120-124 and it looks like ALL of my knock is gone too! I have one Datamaster run where my Lterms were at 159 - I know that can't be good! Looks like I am on my way to running in the 11's now on some DR's!

 

Wow...nice run with so little fuel haha. So what did you change to get your Lterms down? Just lower the injector constant?

 

Here's were it gets a little tricky. The calculations your computer was making were not commanding enough fuel (by about 9 percent or whatever) - but since you were in closed loop the O2's compensated by increasing the fuel - so in that sense you didn't run lean at all, you just forced the O2's to compensate.

But the problem with that is that there is lag time in the O2's - both from simple gas transport to the amount of cycles it takes the computer to correct you all the way. While you are in one cell at steady load you should be fine, but it's easy for you to go lean in transient acceleration - e.g. as you are going through the rpm band/cells, etc. You were probably no-where near lean enough to hurt anything, but I wouldn't be suprised if the knock sensor kicked in, or you were just down on power, etc.

 

Thanks Chris (you've been very helpful!). That makes perfect sense. No, I haven't been doing any hard accelerating. Just normal crusing. When driving around with Datamaster recording I picked up about 3000 counts of knock. Those are probably due to running lean as well as using 91 octane with my 11.5:1 compression. I filled up with 91 and added octane booster last night, and I'm going to see what effect that has on the knock.


[Modified by Glock'94, 4:26 PM 2/3/2002]

 

here's a new log after changing the injector constant to 29.5.
http://www.gulicks.com/vette/programming/2-4-02.zip

and here is another one i did tonight:
http://www.gulicks.com/vette/programming/2-6-02.zip




[Modified by Glock'94, 10:26 PM 2/6/2002]