Couple Newbi questions

[gpr]

I just got efi live and haven't had much time to mess with it. I mainly have used it to change basic parameters ect... with very little engine tuning. I haven't tuned any new efi cars before, so i have a few questions.

1. When WOT doesn't the system go to close loop? If so shouldn't there be a preset a/f ratio it uses, and the o2 sensor adjusts it to that ratio?

2. What tables do you modify to change the a/f ratio? It seems like there is a ton of different tables you could use, not sure which is the best one for WOT and part throttle during normal driving conditions (engine warm etc...)

3. Do newer vehicles come with wide band o2 sensors? If so are you guys logging the a/f off these sensors? or do i need to instal one and hook it up to the v2?

4. Can i save tunes on the v2 scanner and use it to plug into the vehicle and install a new tune? i copied .tun files over in the EFI Live explorer, but when i plug it into the vehicle it doesn't show up as having any files save. I switched it over to use the units internal memory, but it still doesn't work.

I know i need to read more documentation but these are a few of my first quesitons i have to help me get started, so if you could point me in the right direction i would appreciate it.

Also here is another thought of mine after i have read how everyone suggest to change timing on the dyno. One time me and my brother essentially made what we called a "mobile dyno" We used a sensor to pickup the wheel speed of a bike. We then would chart the rpm versus speed versus time. Essenitally this allowed us chart accelleration over time. this way we could put it in one gear and start at about the same rpm and punch it, then go make jetting changes and do it all over again. Now it didn't give us hp estimates (even though we could of somewhat calculated them based on weight, gear ratio, and approximate wind resistance). But what we could see was if we were accellerating faster to tell if the changes made a good or bad impact. Long story short, couldn't you do this by loggin the vehicle speed sensor in your logs so you could tell if your vehicle increased rpm quicker in the same gear after you made timing changes????

thanks!

[mr.prick]

1. When WOT doesn't the system go to close loop? If so shouldn't there be a preset a/f ratio it uses, and the o2 sensor adjusts it to that ratio?
Open Loop, there are tables for WOT AFR (PE), NBO2's are for Closed Loop (stoich)


2. What tables do you modify to change the a/f ratio? It seems like there is a ton of different tables you could use, not sure which is the best one for WOT and part throttle during normal driving conditions (engine warm etc...)
Specifically? it depends on the OS/vehicle,
look in the Fuel folder there will be sub folders (Open Loop, Power Enrichment, Trim, ect.)


3. Do newer vehicles come with wide band o2 sensors? If so are you guys logging the a/f off these sensors? or do i need to instal one and hook it up to the v2?
No GM vehicle that I have heard of yet. :nixweiss:


4. Can i save tunes on the v2 scanner and use it to plug into the vehicle and install a new tune? i copied .tun files over in the EFI Live explorer, but when i plug it into the vehicle it doesn't show up as having any files save. I switched it over to use the units internal memory, but it still doesn't work.
BBF is not available yet.

[gpr]

thanks for the help, as i was looking at a few things in a few other threads I think i figured it out. The pcm essentially uses a closed looped system while cruising around to keep the engine close to a 14.7 a/f ratio with the narrow band sensors. Then once you get on it, and everything passes PE parameters it goes into the PE mode, which is then open looped, correct?

Once it is open looped then it uses tables b3605 and b3618 for the target a/f correct? If this is correct how does the pcm know how much fuel to inject to get to that a/f ratio on those tables???? my guess is use the MAF sensor to see how much air is entering the engine, and the rpm, then based on the Main VE table it calculates that amount of fuel needed. Am i anywhere close on that guess? If so once you change engine components how do you know what your VE's are going to be???

I am currently messing with a 02 pickup with the 5.3l engine and i was reading the other thread to help me out. One last thing. What is the Long Term Fuel Trim, and what does it do exactly?

Oh and I think GM has incorporated wide band sensors in some vehicles. One of my wide band kits needed a new sensor and instead of buying a new one from the manufacture for double the cost I went to the parts store and they said the part number was showing it was used on some Cadillac models.

Thanks again for all the help.

[ScarabEpic22]

thanks for the help, as i was looking at a few things in a few other threads I think i figured it out. The pcm essentially uses a closed looped system while cruising around to keep the engine close to a 14.7 a/f ratio with the narrow band sensors. Then once you get on it, and everything passes PE parameters it goes into the PE mode, which is then open looped, correct?

Exactly, NBO2s monitor fuel trims and provide the PCM with feedback to try and command as close to a 14.7 AFR. Once you go WOT, and the TPS, RPM, and delay conditions are met, the PCM enters PE mode and relies solely on the VE table and modifier tables for fuel (injector tables, intake temps, etc are all factored in). Called Open Loop operation because the PCM ignores the feedback from the NBO2 sensors.

Once it is open looped then it uses tables b3605 and b3618 for the target a/f correct? If this is correct how does the pcm know how much fuel to inject to get to that a/f ratio on those tables???? my guess is use the MAF sensor to see how much air is entering the engine, and the rpm, then based on the Main VE table it calculates that amount of fuel needed. Am i anywhere close on that guess? If so once you change engine components how do you know what your VE's are going to be???

I am currently messing with a 02 pickup with the 5.3l engine and i was reading the other thread to help me out. One last thing. What is the Long Term Fuel Trim, and what does it do exactly?

Oh and I think GM has incorporated wide band sensors in some vehicles. One of my wide band kits needed a new sensor and instead of buying a new one from the manufacture for double the cost I went to the parts store and they said the part number was showing it was used on some Cadillac models.

Thanks again for all the help.

Get a WBO2 from a reputable source (Innovate, AEM, PLX, etc) and install that to obtain proper fueling readings. Cant just plug any WBO2 into your truck that wasnt designed for it and make it work, it has to be an aftermarket kit with the converter box that Innovate and aftermarket manuf's make. Leave the NBO2s alone and install the WBO2 pre-cat.

[gpr]

I already have an lc-1 from innovate.

Okay i think i finally understand what is all going on now and will try to start and tune it in. The only other thing I'm wondering is have many people tried lowered the throttle position so that PE mode starts earlier? i was thinking of trying around 75% throttle.

From your tuning experience, if you don't mod the engine, but just have simple mods (intake and exhaust) do you need to mess with the VE table? i would think that the characteristics of the engine and where it makes power wouldn't change until you change cams, heads, pistons etc.. where it will then shift the power curve around and need the VE table changed, so until then i should be fine changing the B3618 table.

Oh and what have you guys found as the "ideal" a/f ratio for these engines? on our bikes they make max horse power around 13.1 and max torque around 12.7, but it seems as if cars typically like it richer and get peak power around 12.7ish, and i would assume peak torque is even richer, correct?