TORCHD 02 TA

iTrader: (39)

i installed my LTs about 1 month ago. Car runs rich.. what kind of tune should i get with the car? i have no idea what is involved with a tune besides getting the A:F down pat..

any helpful info would be great

thanks

slow

iTrader: (7)

Set the PE table to a reasonable level, and turn off COT, and then see where you're at.

Ryan

brad8266

iTrader: (23)

Disable COT first. The tune VE and then MAF. Set your PE table to command whatever AFR you want. Once the VE and MAF are dialed in good your actual AFR will be damn close to the commanded AFR in the PE table.
How do you know you are rich since the LT install? Did you measure with a wideband?

TORCHD 02 TA

iTrader: (39)

i did turn the COTS off.. i did that back in June.. what is VE and PE?Sorry this is all new to me. most f-bodys run rich with LTs. plus you can smeel it too..

waht else do i need to know?

brad8266

iTrader: (23)

The smell is not a rich smell, it is just that you have no cats. Anyway it wont run rich because the LTFT's in the PCM will automaticly adjust fueling to keep you at 14.7 AFR, so if you think that the fuel smell at idle or cruising means you are rich, you are %100 wrong. remember that the PCM does have learning ability. Go get a wideband sensor and put it in the exhaust when you get the smell and I would be willing to bet it will be saying 14.7, not rich. Everyone goes out and gets longtubes and an off road pipe or duals and claims they are running rich because they can smell it. Well obviously youre gonna smell something, you got rid of the cats. It has nothing to do with longtubes or running rich. It might be rich at WOT but during normal driving it will stay at 14.7. Also keep in mind that the PCM stock commands a very rich mixture at WOT.
I really want to know where everyone comes up with these silly stories about LT's making them run rich all the time and causing "low end loss". These are 2 ideas that I have not seen a bit of proof of. My guess is that it started a long time ago when someone did LT's and an ORY and smelled the no cat fuel smell and decided that it meant he was running rich, then posted it on the internet and it somehow caught on. Same goes for the "low end loss theory"

Anyway the VE table is one of the tables that tells the PCM how much air should be flowing at certain RPM's and manifold pressure. This one of the 2 tables that control fueling. The MAF table primarily controls fueling. You tune both of these tables to dial in fueling. Once you tune these tables so that you can keep your LTFT's around -2, then you are good to go pretty much.
You then adjust the Power Enrichment(PE) table to get to your desired WOT AFR. When you go WOT the PCM goes into PE mode and adds extra fuel, how much depends on what values you set in the PE table. The value is a multiplier of the normal amount of fuel set in the VE and MAF tables. Rememebr that the PCM will normally strive to stay at 14.7, so you multiply from there.
Example: If you want to command 13.0:1 AFR all across the RPM range you can calculate how much extra fuel you will need compared to 14.7. here is the formula I use. Stoich AFR/Desired AFR= PE table value. My PE table is set to give me 13.0 all across the board, so the values in PE are. 14.7/13.0=1.131. Now the PCM will add 1.137 of the normal fuel at WOT.

The key here is to have a well dialed in VE and MAF table because then it is extremely simple to change the PE table to try out different AFR's..

Do a good search around here for this tuning stuff and you will find plenty of information on how the PCM works as well as steps in tuning. The key here is to understand how the PCM works and how the sensors on the engine work with the PCM. Once you know the anatomy of the PCM and sensors, the actual tuning of the PCM will be easy. When I first started I was kinda clueless but once I read enough to understand how the PCM operated, the actual tuning part was simple.

brad8266

iTrader: (23)

That is a very naive statement.

ringram

Very sad, you can have tons of unburnt fuel and still run at 14.7 dude.
Raw fuel in the exhaust doesnt affect Wideband AFR reading.

brad8266

iTrader: (23)

You really think that there is gonna be that much fuel unburnt in there from installing longtubes. If it was that rich it would be popping and doing all kinds of cray ****. Have you ever been in a car that was running at say 9-10 AFR?? If you have then you will know that when it is that rich and there actually is completely unburnt fuel washing everything down it runs like complete ****. It will pop, hesitate, and sputter. I know this because there have been quite a few times where I have had the nirous accidentaly armed with the bottle shut and went WOT so that only the fuel solenoid was flowing with no nitrous. It goes down to like 9-10 AFR on my wideband and sputters and pops.
And if it is that much rich that there is raw unburnt fuel in there then the burnt portion of gas would be way rich also which would be picked up on a wideband.
Use some common sense here. When nice exhaust is installed it INCREASES airflow throught the engine. When airflow increases without a change to the airflow tables in the PCM, you run LEANER because the called for airflow is less then the actual airflow. The PCM has its own learning curve called LTFT's that will compensate for any lean or rich condition by adding or pulling some fuel. It constantly does this to keep AFR at 14.7.
What is sad is that you have no idea what the hell you are talking about here yet you seem to be a competent tuner by reading your website.. Good day to you.