dimented24x7

iTrader: (2)

Might be more apropriate for the PROM board but i know alot of other tbi'ers are lazy like me and relying on snakeoil proms, base timing, and FP do their tuning...

Well, over the last few days ive done around 30-40 bins for my car. One of the first things I found out is that with the base timing set to around 25+ degrees BTDC I was probably getting a peak of over 50 degrees of advance at WOT with the stock timing table. Needless to say, the engine wasnt making much power above 3500 rpms. Not too much knock but the timing was jsut way too early. Had decent torque with all the timing at extra fuel but not much power. The fueling was atrocious. It ran so rich it would practically damn near burn my eyes out.

I decided to use a tpi timing curve from one of the 90+ SD cars as a template to make a new table along with setting the base time from way the hell of the timing tab to around 2 degrees BTDC. Obviously since the tpis build good cylinder pressures at WOT and at mid-rpm operation theyre timing is a bit different then what i needed. I took a touch out of the timing at mid rpms and map and added some timing to the areas the engine is normally in during part throttle operation. I also added LOTS of timing to the higher map/rpm values to get the engine to not bog real bad. I also leaned out the VE tables ALOT to get the BLMs above 108 and up to around 126 or so. And, of coarse, i also did the usual adjustments of movign the idle up from the stock setting, turning off the non-existant egr, etc... Overall, though the timing curve was, and still is, the biggest undertaking since that was where the tuning was the worst off.

I got some real impressive results from this. The engine has lots more torque and the throttle response is much better. It also pulls to around 4500 RPM without much trouble at all. Before in first gear the car would kinda pull and maybe kinda break the tires loose around 2500 rpm. Now i cant even hit the gas in first without the car becoming an unguided missle. Regardless of the rpms, the rear end will completly go sideways (assuming the posi decides to work) and ill go rocketing all over the road. Hopefully it wont be that bad when its warmer out (better traction with hot rubber). When it does hook, it pulls real good. The car also accelerates much better when i go to merge on the highway. Still needs alot more work but its a good start. Wont really know what it has untill i rebuild the trans. Only have first gear at WOT, all the others slip.

On a low note, though, my fuel economy went down a bit. Even though its running at or near stoich, it went down around 3 mpg and another few when the TCC burned up and started slipping. After turning off the lockup, it went down to around 18 mpg overall vs the 25+ that it used to get. I guess i cant have more power, better VE efficiency, and still use less gas.

For all of you tbi'ers who havent bought the prom buring eqiupment yet, what the hell are you waiting for? Doing up the bins and burning the chips is cake, especially if your using EEPROMS/Flash. The stock programming sucks... Buy the equipment already... The only hard part is knowing what to put into/change in the bin to get the desired result.

Slade1

You got a list of everything you need to do a TBI chip?

I may go this route this year to try to help out my EGR's lack of aid for keeping the NOX down. I also want to break the 200 HP barrier with stock heads, intake, cam and with 178 RWHP on the stock manifolds a little tuning may just be what I need with headers to bring it over the top.

dimented24x7

iTrader: (2)

I have:

Pocket Programmer 2 (xtronics.com)

2 28C64 EEPROM chips and a home made adapter to use them in place of the crappy 2732 eproms. Craig Moates offers the prefabbed adapters at moates.net so you can replace the stock eprom with a much easier to use Flashrom. Youll need to unsolder the stock Robenson Nugent socket though, which can be a real PITA. If you just want to slum it you can jsut buy the 2732's and use them but i found they where unreliable and you need to get a UV eraser to erase the older eproms.

winaldl or some other data logging software and a cheapie laptop to datalog.

Tunercats tuning software and $4D definition file. I Like TC alot but you can use freebie software as well. Pretty much the same end results with each but the feel and interface is different depenging on what software your using. (tunercat.com)

Stuff I dont have and things youll want...

Wideband 02. I dont have one yet so i really cant optimize my timing since i dont want to risk jsut guessing on the right PE AFR by using the stock o2 alone.

Gtech or similar device so you can see if the changes you make really make the car faster. Since your engine is realativly close to stock youll have a hard time telling what changes really work just by feel since the tuning is realativly close already. Might feel faster but be slower in reality.

Theres a whole list of other things you can do but the stuff above was a good start for me.

Pablo

iTrader: (1)

right on, its a great thing isnt it? There is sooooo much more tunability with FI.

Once you get to a certain point with a carburetor making improvements beyond that start to get pretty intricate and end up affecting things you wanted left alone. They are also pretty inconsistent. With my car idling with the tbi my afr was moving maybe .1 up or down, actually it was hardly moving at all it was a rock. There was nearly no lope either. The carb on the other hand is up or down .3 or so constantly moving and there is a definite lope

I also wish i could tune the pump shot on a carb like tbi. I can just mash the gas from any rpm and the car will just go with TBI, with the carb you have to be carefull of your rpm and load or you are toying with a lean out and subsequent bog (this is probably where people get most of their notions of where certain combos make power since some give better signal to the carb)

RBob

iTrader: (1)

RBob.

Chuck!

Im totally lost on the timing tables. I know mine are way off and Im losing a lot of power as Im basically running the stock ones, but Im not quite sure as to how to go about changing or even where to start.

ShiftyCapone

iTrader: (7)

C'mon chuck you are a computer geek. You'll get it. If there is one thing that I learned in school is that trial and error is fail safe.

Dewey316

LOL, but it can be a rather expensive error when you are dealing with an engine.

dimented24x7

iTrader: (2)

Ive seen others say you can tune by seeing where there is and isnt any engine knock and use that to see where it needs more or less timing. Doesnt work for me since i have low compression smog heads with a low temp T-stat but you could probably use that method. I tried it and i kept overshooting and giving it too much timing and it would start to bog down before it began to knock. I lucked out, though. I have the muffler dumping out underneath my car so the tone of the exaust note goes along way to telling me if i have too much or too little timing in certain spots. I wish there was a more exact way that i could get access to but at least it kinda gets the curve close.

Ronny

iTrader: (1)

Pablo, how can you read the air fuel ratio at idle? i assume it is open loop at idle? are you running a wide band O2 ? i am missing something. i dont think my winaldl reads ratios. i am getting a pulsating idle when engine fully warm. if i blip throttle it seems to help. rock solid at start up. no vac leaks. is this considered to be a lean condition at idle? would adding fuel at idle smoothen it out. keep in mind when engine cold idle is real nice. that is when off choke but yet cool coolant, like warming in driveway awaiting temps to come up..

kevm14

I don't think you were getting 50d. Are you using TunerCat? If so, you are probably adding the main spark bias to the final calculated SA value, which is incorrect. TC allegedly corrects the main spark table with that spark bias value, so you should ignore it. 30d sounds more reasonable...

Dewey316

IIRC, my stock bin had a max total spark value of 38* there is a constant in the constants list that limits the total amount of spark.

kevm14

Right, and I think about 46d is all you're going to get out of a physical distributor.

Something's messed up in the $62 definition file for my ECM, though. My max advance at 4800rpm at 100kPa and PE mode calculates out to like 21.78d and TC agrees with my calcs....but I am damn sure my swirl port head TBI 350 needs way more than 22d at high rpm.

dimented24x7

iTrader: (2)

The thing is i had physically set the base timing to probably over 25 degrees BTDC. Couldnt tell because it was so far off the timing tab. So the max timing would be the the base time plus whatever was called for by the ecm.Needless to say it didnt run well at WOT. I have it set to 2 deg BTDC now.