that is how I am starting to tune my PE tables. Am I playing with fire? I know WBO2 is the best way to do this, but it isn't in my budget until I get a job. So far I've gotten my knock counts down from say 10 or so in a 20mph to 100 mph run at WOT down to 2 knock counts. Car definitely feels better, with no bog or hesitation. Definitely a lot of work datalogging, reviewing, writing down what rpm the knock is occuring through the run, then going into TC and trying to add small amounts fuel to compensate.

Just wondering if I'm going to cause more issues than I am aware of.

 

Well, it depends on what you are tuning for. If least number of knock counts is your goal, then i guess you're doing good.

Some people like to tune to make their cars go faster. To do that you usually want to measure performance, change something, then measure again. How it feels, knock counts, etc may or may not be leading you anywhere.

BTW, EVERY time i have ever made tuning changes by feel or a whim i have actually mad ethe car slower. What 'feels' faster, and what 'is' fast are often 2 very different things. Lots of timing and fuel always 'feels' fast. Take that fuel and timing out and the timeslips get better despite 'feeling' slower. Etc.

That's probably one of the reasons there are/were so many slow thirdgens for so long. Everyone just slapped AFPRs on, cranked the FP way up and dialed in another 6' of initial timing. Feels fast. Runs worse than stock. But the TPIS insider book said 50psi is worth 30hp, and it feels like it picked up 30hp, so why is it slow? Must be the TPI.

 

stock timing curve? what is initial advance? i got KC in 30-40 map at 2800-3200. i pulled out 2 deg in that area and they went away.

 

If your getting knock counts, its slowing you down. There is no doubt about it.

Get rid of the knock counts as you are doing, then fine tune the spark advance in the "knock free area" to find what yields the best results.

Many times false knock can lead to us going in circles with timing tables. Key signs of false knock are, unrepeatable knock in an area, irratic knock with no alterations to the chip, no lessening even with gross changes to the timing table.

Just beware that false knock is possible and probably present on more cars here than people suspect.

SOunds like your doing it right with documentations and gradual changes.

 

You have to be conscience of the fact that the knock sensor is only a microphone, and the filtering is just looking for a given noise. You can add enough fuel to change the signature sound of detonation. You always need to read the plugs to make sure you don't fall into the, No Knock Count, so no knock is present, assumption.

 

this is interesting. i ran stock timing curve in my bin. but advanced 10 deg in initial advance. stock was 6 deg initial. dont ask me why i went to 10 deg. i think the head manufacturer suggested the heads can handle more advance. not sure but i did do it. the KC was occurring only under load. moderately hard accelleration. if i drove cautiously no KC. other areas of KC were starter engagement. not sure if it is wise to tune for max TQ in timing tables using KC. not sure if that is a recommended route? i believe the recommended route is on dyno but that is costly? Is that also true for PE? I ran 12/1 on dyno on consecutive runs. So i took tuner cat to 11.5 per the data on TC. not sure if TC showed 12/1 but dropped A/F in PE by 1/2 point as there must be a correlation. not happy with 225 rear wheel HP, 377 TQ. must be more HP trapped inside to be had with tuning.

 

I'm running 6* initial advance. Most of my changes have been only to the PE fuel tables in TC. My part throttle stuff I have been letting VEMaster fine tune, and catching the occassional knock count when I forget to downshift or the like. I must say you can hit some really odd KPA's with a manual tranny.

So with that said, by adding just fuel to quiet the knock counts, then I'm going in the right direction. I want to nail down the fuel curve before messing with spark.

I know that what feels faster doesnt' always translate to actually being faster. I'm going off strictly throttle response at this point when I go into PE. I was getting almost 10* of knock retard at 3100 rpms in PE. That is slowing me down. I have it to the point where I am getting 1.1* of knock retard now. Just need to add fuel at say 2400 and 2800. I'm only making a .2% change to the fuel at a time.

I just hope this shows a difference at the track thursday night

 

But how do you know that you're not just making the car grossly rich adding a bunch of fuel to cover knock? I'll answer for you, YOU DON'T. Maybe you need to take out some timing and lean it out instead.

Like i said, EVERY time i have ever tuned by feel or a whim i have made the car slower next time i went down the track.

An example of tuning on a whim would be adding fuel to cover timing. I'm a big fan of aggressive timing tables. Which also led me to be a big fan of adding a bunch of fuel to cover knock (in the beginning). Which lasted exactly until i took my car to the track after a winter/spring off and me tweaking on it. Boy was i surprised when i was pulling 10% or more from my PE fueling as well as 6' from my timing tables...to the tune of picking up almost half a second and 2.5mph. The car felt slower, and was not tuned how i thought or wanted it to be. But timeslips do not lie.

BTW, when i first got my car it had a big knock problem in the region you're talking about. Right in the low 3k range around peak torque. The band aid solution was to run less timing there. The right fix ended up being a set of flow matched injectors. I knew i was only knocking in 2 holes by looking at plugs. My theory was those injectors were lazy, leaving me especially lean right at peak VE. Considering just an injector swap left me with a normal looking timing table again i think my theory proved out.

 

Hey Ed, been awhile since I've seen you post. Been awhile since I saw you at Cedar Point.

Anyways, you're right, time slips don't lie. I went to the track with 4 chips burned, with different changes made to the PE table. My first run was the exact same as my previous best of 13.5 but with a lower mph due to a 1.9 60'. Swapped chips, did'nt get a time slip. Datalogged the run, picked up 8 knock counts between 4k and 5k. Swapped chips, ran a 13.4 @ 103 mph. Laptop shut off, so I don't have a clue what happened. Swapped chips again, datamaster wouldn't start the logging, I didn't get a time slip. This is basically how my night went, so I left pretty pissed off and about beat the guy in head at the timeslip booth with my breaker bar.

So basically I wasn't able to see if the changes I was making were doing any good.

Injectors were cleaned and flow tested by Cruizin Performance before I installed them. They are 24 lb LT1 injectors.

Spark curve is a stock curve for a L98 or Lb9 (i forget which)

I love not having a clue

 

GTechs can pay for themselves rather quick when you have nights like that.

There's a new similiar devise out now that supposed to be better.

If your into being creative, you can build one using a Radio Shack stopwatch. I spent like $35 doing that almost 8 years ago and the dumb thing still works. Oh just use the VSS, then ignore say the first 3 tire revolutions. It's good enough to tell ya if your going the right way in the tune.

 

Didn't realize that was you. Didn't know you were from FL, what the hell were you doing all the way up that way?

But anyhow, i know you're meaning well with your tuning. But i seriously can't stress enough that unless you are measuring performance, you just cannot tune for max performance.

But since you have datamaster going, there is another option even beyond what grumpy suggested. You can aways find yourself a flat piece of highway and do 1 gear blasts, use 3rd or 4th. and just measure 40-70 times, 60-90, etc. Whatever speeds make sense for the length of road you have to work with. Just be religious about your starting pointand get WOT a couple seconds before the speed you're actually measuring from to rule out transient effects.

 

I agree I need to measure performance in some way to see if the changes I make are working. There is no arguement there. I am still furious that out of 8 runs, I got two time slips that were mine.

Anyways, I started playing around with this out of sheer boredom. I just moved to FL from NY and havne't found a job or started college yet. That is why I was at the Ohio gathering. It wasn't all that far for me at the time.

Now I had talked to PK a few times, and he was saying I should add fuel to see what would happen. He basically has the same motor as I do, I'm just running a smaller cam due to the TPI. He keeps adding fuel, and it just keeps running faster. I burned 5 chips, each adding .2% across the whole PE table. Not the best idea, and I would kill for a WBO2 with all this free time on my hands

Thanks for the feedback guys. I might try the track again next week.... maybe by then they'll pull their collective heads out of their ***

 

Oh, alright. I kinda wanted to go to college in FL at one point. Got pressured and tricked out of it by family though.

Give the mph timing method a try if you have nothing better to do. As long as you use the same stretch of road and average a few runs it should be pretty good.

 

You wouldn't want to shed a little more light on that device would ya?

David

 

You obviously haven't spent much time on DIY-EFI.org, he describes the trigger circuitry, etc over there somewhere.

And while a noble venture in the good old days, a good scan tool can accomplish the same thing with maybe just a hair less resolution. What you lose in reolsution you make up for in being able to time more than just 0-distance measurements, such as 60-90 times, etc.

 

Ok, I've used the quarter mile stuff in Moates' software before. And no, I havent' been over to DIY-EFI.org in a while.

Thanks,

David