Glad i saw this post again lol
Or else i would be in deep sh%& in the middle of april when im doing my vortec conversion on my 91 Formula 350 :-)

And it so happens that i will be using a LT4hotcam along with 1.6 roller rockers

Is there anythign i could to as far as proms go to make mine a little better as to breaking in and driveability when the swap is completed ? my formie is my driver and can afford almost no down time on her ...any reccomendations i could do as far as burngin a prom now that would help me out or make my life easier?
thanks later

PS u will be hearing a lot from me within a mth or so :-)

 

Wow, this post is great.
Now I know why my car is running so rich at idle.
I've got a large cam and it's pulling about 15lbs of vacuum at idle.
I need to make my AFPR.

Thanks Tim and everyone else.

 

Back to the top.

 

I still have a lot of questions, I guess they will be answered when I get all the tuning equipment.

I am a very linear minded person so this stuff should make sense to me right? I guess I am really just searching for answers as to where I REALLY need to begin. Burning a chip and JUST doing the flags is of no use to me, my car is running lean and there is no mechanical way to get by this. So I will need a lot of advice on EXACTLY what it is that I need to change i.e. the 2D or 3D tables. When I read these posts about part throttle tuning they really don't "click", but maybe this will change when I get the equipment?? Thinking aloud again I guess, maybe one of you guys will be able to link me to somthing that tells me what parts of the tables I need to change and why... all I do is do searches on this particular forum and still I just don't get it.

 

If you have a Speed Density car then the answer is directly above.

If you've read this post over and over and over again ... and have also given it serious thought and have done everything you can to understand it ... .. . and if by chance you still don't get it then maybe PROM programming isn't for you. If you can't ...

1) Discover your current BLM at a particular RPM and MAP using a scanner.
2) Divide that value by 128 (stoichiometric A/F for 14.7).
3) Multiply that result by the current VE value at the same RPM and MAP where you took the BLM reading.
4) Take that resulting value and put it into the cell with that RPM and MAP.

.... then PROM programming isn't for you. Doesn't get much easier than that.

Tim

 

redirocz-28:

unfortunately nobody can tell you "oh you need to change value A to X, value B to Y, and value C to Z. nobody knows what the proper values to change are for your combination. There is not something in the chip set "wrong" that just needs to be changed so that it's set "right". it's a calibration, just like jets and power valves and pump squirters (carb stuff) and weights, springs, and vacuum advance (dist.).

You need to start with the basics.

(1) have you changed the fuel injectors? are they a different # rating than what the computer originally came with? If so, then you need to change the "injector constant" in the code so that the computer knows what injector size you have.

(2) burn chip and re-test. you should be closer now.

(3) follow traxion's excellent postings and start to get your VE (volumetric efficiency) tables figured out. The VE table is just a table that lets the computer figure out how much air is flowing through the engine. When it knows how much air is flowing, then it knows how much fuel to spray. you will have to apply corrections to this table.

(4) burn chip and re-test.

(5) repeat steps 3-4 as necessary.

As for learning this stuff, if you want to see the programs in action, do this... download tunercat (it comes FREE with a definition file for truck computers). Then download a BIN from such a computer (also FREE). Then use tunercat to look at it. That way you can see the charts we talk about, and practice changing them and such. it's really not that difficult.

 

Tim, it is ridiculous how much sense that just made to me!!! Because of you and Glenn I just ordered everyhting I need to burn proms today. Thanks guys.

BTW, by fine tuning the VE tables (before you even got to the spark advance) did you see a noticeable increase in fuel mileage?

 

fuel mileage won't increase appreciably with changes to the VE tables, as the computer will compensate for an inaccurate VE Table with the O2 sensor and still achieve 14.7:1 AFR during closed loop (such as highway) conditions.

if you want to increase fuel mileage, take a look at enabling highway mode. glenn has some excellent postings on the topic, check the archives.

 

Thanks, I just did a search on highway mode on found tons of info posted by Glenn. I can tell this is gonna be fun and can't wait until my equipment arrives.

 

TRAXION, I would like to introduce you to a friend of mine, VEMASTER. If you are not familiar with what this program does, continue to read.

VEMASTER $8D takes logged info from programs like TTS Datamaster and askes you to input a desired BLM number. Typically, if you would enter 128 then VEMASTER will use that information and change all the VE Tables in the $8D code to try to attain a BLM of 128, thus tuning all of your non-PE FUEL tables for you. It can be found here: http://www.akmcables.com/vemaster.htm

Make sure you get the VEMASTER for the $8D ECM (1227730), there are different versions for different cars.

Unfortunately, this is going to require you to have a laptop computer and ALDL interface cable so you can go drive around for about 20 or so minutes and get some good logs. But, if you can borrow a laptop, you can download the trail DataMaster$8D which lets you record 20 times before you have to buy, and build a cable for less than $10, and you will have the logs you need.

VEMASTER will not be able to get your fuel tables dead-on, but it will get them very close and save you a lot of time in your tuning. BTW, weather conditions will be a factor so try to log your data on an "adverage" day.

 

Ummmm - yea. I know about VEMaster. We met a LONG time ago so there is no need for an introduction. This post was written BEFORE Joe released VEMaster for our cars.

Tim

 

oh, sorry, I sometimes forget to look at the dates and times messages are posted...

 

The only downside with the self tuning stuff if that it just looks for Stoich. If your running some sort of hotrod, then that might not actually be the best AFR for your car. Especially if your looking for economy. Stoich and the original strategy of just AVERAGING 14.7 is for the converter, and has nothing to do with what might be the best AFR for your car.
Incidently, I get my best mileage at 13.8, with just 28d of timing.
Takes time and effort to find the motor's sweet spots.

Again, a WB makes this all so much easier. In what you'll waste in gas trying to figure things out, will easily pay for one.

 

..

 

I am interested in reading but this seems to now be a bad link. Is there a new location?

Happy Holidays,
Mike

 

OK New at chip burning. Just getting started. Anyhow......

Traxion, you mention using a DIACOM scan tool to read the BLM values. Correct me if I'm wrong, but doesn't using the AUTOPROM and TUNERPRORT give you this capability?????

I'm just wondering because I'm trying to decide what to purchase to do this right and also wondering if back in 2001 its possible real time tuning wasn't heard of. Thanks.

 

This post was started in 2001. Tunerpro and autoprom didn't exist then.

 

First off, I want to say thank you for taking the time to create this post. It is very informative. Second, i have a question. Is this method of changing the ve curves the same for a MAF car, or will the ve curves be based off of MAF, rpm, and IAT? For a MAF car, it is relatively easy to calculate the ve knowing these three values.

 

MAF based ECMs don't have VE tables. The air flow is read & reported by the MAF. In the Tuning Guide Book sticky, Chapter 5, '7165 ECM, there are good threads that discuss tuning MAF set ups.

RBob.