I am gettin' sick and tired of two time runs very near each other and then first round running way faster/slower. I cannot seem to make a bracket car out of Redtird. I have resorted to using an ET predictor to try and match computer against computer, still no luck!

The car generally leaves HARD (1.48-1.54) so that doesn't seem to be the problem.

Is my computer jumping from OPEN loop on one run to CLOSED loop on another run? Something is affecting consistancy and I gotta fix it. This car should run DEAD NUTS ON, every freakin run!

ANY ideas appreciated!!

HInk

 

I hate saying this to you, of all people, but back to basics... Perhaps a track rental for a day with a few people with some different experiences?

Perhaps something real simple like checking all connections. Electricity does funny things to ET. Maybe the PCM itself is starting to go, but changing parts is an expensive and slow way to correct problems. When a PCM starts to go sometimes it can be very inconsistent, other times it just craps out.

Have there been ANY changes. You know what I mean: The small stuff that you changed last month that you don't think about because it isn't supposed to matter.

Can you feel it when it slows down? SOmething as simple as a burned plug wire (which I found a couple of weeks ago), can cause a couple of consistent runs in time trials and then bang, all of a sudden it speeds up by a tenth or better.

Back to basics.

 

i run open loop only. closed loop is horrible for bracket racing

 

Hey Kevin, Are you sure it isn't you? I have the same problem. I can't seem to do the same thing from one run to the next. BUT if you think it's the car, try logging all yur runs with Datamaster and look at them. BTW the Z is running great with the TCI unit. NO shift problems at all. Well worth the money. New best a couple of weeks ago. 12.79 at 105. Lost big time though, redlit and broke out!!! Maybe we can hook up at Martin sometime before season's over?
Skip

 

I have obd2 but how much difference in a bracket car could it make?I generally run 12.7`s in the summer heat and on any particular bracket sunday say my dial is 12.71 I will run within 2 one hundreds all day long.
I think something is wrong(worth a look) cause I know you are a good bracket racer and its not driver error.
imo check with a scan first

 

What engine temp are you running at? I found that when I tried to run my car at 160-170 it was inconsistant. Running it at ~180 made it a tad slower (a few hundreths), but also made it consistant within 2 or 3 hundreths. The car was deadly - provided I could cut a good light

Oil temp also plays a roll. If your engine is stone cold and then you get the coolant temp up to, say 170, the heat has not "soaked" into the parts yet. So the oil viscosity will be a little different than if the engine was at "normal" operating temp.

An Oti spark will definately cause inconsistancy if it isn't 100%, as will the coil.

Just some thoughts. Hope you get it worked out.

 

I believe changing to OPEN loop and removing some variables of the CLOSED loop is the way to go. I think I have to take as much OBD1 computer programing out as possible. I realize the computer is constantly making adjustments for running perfection, but that is killer to a bracket car.

If I can get the computer to be consistant, I have a hand held ET Predictor that I can input all weather conditions and it will take those, based on my BASE run of the day and predict an ET for current weather conditions.

By the way Skip... A bracket racer has to do EVERTHING within his power for HIMSELF to be consistant. You always try do do EVERTHING the same. About the only thing you may do different is look for the groove at the starting line and place car into it.

Glad your tranny is working out and MAYBE I can go to Martin SOMETIME this year!!

 

Are you letting it run 3+ minutes before the runs you make? I remember someone saying that to ya at the national event coughjeffcough. I really don't know much about the LT1 computer so I'll stay outta here!

 

if all other conditions are met, the computer will go into closed loop 3 minutes and 26 seconds after starting the engine, but regardless of what you do, a closed loop setup will never perform as consistently as an open loop setup

 

3min and 26 seconds gets you into CLOSED loop. Now my question is: Is that 3+ minutes of constantly running? Or: Does the computer reset when you shut car off, i.e. moving in the staging lanes?
By the way I remember you from one of the M events, you run a Pontiac, right? And I asked you why you called yourself "Chevyguy".?

By the way Denny... That is EXACTLY what I tried in the first race and ran like .4X off of my predicted dial-in and got WHUPPED GOOD!!. I mean I got spanked like a ball-baby, red headed step child! I don't EVER in my 20+ year career of drag-a-racing, remember getting caught like that, that soon! I looked like a red-headed newbie drag racer that had just been beaten before staging the car.

Thanks Chevyguy... your input is GOOD! Keep it coming.

HInk

 

Your car is not running in the correct fuel cell at idle!
Your block learn is adding over 11~13 % fuel...
...your LEAN.
Did you adjust that fuel pressure up 5~7psi as I recomended???

You can cover up the problem and force open loop but your tune is not close enough yet.

My recomendation of allowing the the car time to go closed loop was something you could control and at least the car should repete the number time after time.... it won't be fast and I hope you didn't think it would be.
Being lean at idle in closed loop forces a overly rich condition for the run, hence the 4tenths off. Then if you manage to run while the car is in open loop its not quite as rich....
...the generals code masters work.
Guys I scaned his car with datamaster hes doing a no-no
trim cell 16 vrs 18 thing.
Kevin has no way to tune himself so I feel that since he has a adjustable fuel pressure requlator he could raise fuel pressure iin small amounts untill he sees his blocklean/ trim go the other way and pull fuel out at idle and get the car running in the corect Idle Cell.
Just a band aid for now, to bad my laptop wouldn't link to your ecm Kevin. Maybe next time we try having the battery on a charger or cables...
...me thinks the ol voltage was dipping low during the read and thats why it wouldn't get past 70ish percent complete.

Jeff


Oh, yes you have to keep the car running once in closed loop, if you key off your back in open loop again till you pass all oof the code master keys to closed loop again.

 

Jeff,
what are your thoughts on having the BLM's locked @ WOT?
Kevin

 

Kevin (Kgresock)...
...wot blocker will stop his problem cold but you have to remember his fuel map (maf table) is alittle lean at idle and his timing is also a little cold for na power. I like to make the tune run the car in the 124~126 block learn area at idle then wot blocker is not needed. Some people feel wot blocker is a work around others are cool with it...
...I guess it's what ever works for each instance, but I like too achive the correct fuel cell at idle. That is what I like to see.

Jeff

Hink could you trailer Redbird to my house one weekend soon?
I will fix it for you buddy!

 

Jeff,
agreed...best case is 128 +- in idle cell.
The fact that it is not points to several potential problems..
FP, exhaust/vacuum leak etc. Might possibly be cause by cam reversion. If the case is mechanical ( cam) how would you tune
to achieve desired BL's ?
If you(and HInk) wouldn't mind I would like to be present during the tune
to further pick your brain.
Kevin

 

And I'll be there. Whatever is good for you!

I originally posted back this morning thanking you guyz and apologizing for my tuning idiocy (danm computer problems here at home)! I'm just a driver guyz!

Thanks BUNCHES and I trust HR can get me outta this one and winnin' again!

HInk