A bit of tuning help....

[Madcap]

Alright here's what I have going on..... my car is currently setup with:
Injen intake, turbo back exhaust, evo3 o2 housing, mbc, gauge, aftermarket bov, upper intercooler pipes, 16g, 560cc injectors, rewired 255, 3" GM MAF and translator. Im about to get my AFPR. I know people are going to say all cars are different. In the same breath you can also say that all our cars are the same to a point. What am i looking to run for FP and Boost to get what I can out what I have. Also I do have a standard AFR gauge. No wideband but it's something. What should I be looking for on that... idle, mid, WOT?

Thanks Guys

 

[kenamond]

Alright here's what I have going on..... my car is currently setup with:
Greddy intake, turbo back exhaust, evo3 o2 housing, mbc, gauge, aftermarket bov, upper intercooler pipes, 16g, 560cc injectors, rewired 255, 3" GM MAF and translator. Im about to get my AFPR. I know people are going to say all cars are different. In the same breath you can also say that all our cars are the same to a point. What am i looking to run for FP and Boost to get what I can out what I have. Also I do have a standard AFR gauge. No wideband but it's something. What should I be looking for on that... idle, mid, WOT?

Thanks Guys

I like my Fuelab AFPR kit. I also upgraded the fuel lines to 6AN braided SS with shadow series fittings (black and silver...don't like the red/blue anodizing) and Fuelab fuel filter. I know some folks adjust base fuel pressure when tuning, but stock is 43.5psi. The AFR gauge is not going to tell you anything more than a logger, and it'll only tell you if you're rich or lean relative to stoich, which doesn't help much. These cars only run stoich at cruise and idle. But you can see if your AFR at idle and cruise is okay by checking your LTFTs with a logger (should be within +/- 4%). When you're under load, the fuel map is less than 14.7 AFR, so your AFR gauge is only going to say "Rich" when you're under load. It may bail you out if it says "Lean" or "Stoich" under load, but that just means your AFR is *really* lean and by then you may have done damage. If you're going to tune the car yourself, you might want to spend the $250 for a good wideband.

 

[5150DSM]

#1 Before anything, you need to get the AFPR installed. The 255 is for sure over-running your stock FPR, making accurate tuning damn near impossible. In order to tune correctly you need a linear fuel curve which you cannot get with a 255 and an over-run stock FPR. Next, the "blinky-light" AFR gauge is next to useless for anything but a vague idea of what your actual AFR's are.
Your base fuel pressure should be 43.5psi(which you can't set until the AFPR install) and I wouldn't run more than 10psi of boost until you have your fuel under control.

 

[Madcap]

#1 Before anything, you need to get the AFPR installed. The 255 is for sure over-running your stock FPR, making accurate tuning damn near impossible. In order to tune correctly you need a linear fuel curve which you cannot get with a 255 and an over-run stock FPR. Next, the "blinky-light" AFR gauge is next to useless for anything but a vague idea of what your actual AFR's are.
Your base fuel pressure should be 43.5psi(which you can't set until the AFPR install) and I wouldn't run more than 10psi of boost until you have your fuel under control.

I haven't run it since I installed the 16g, injectors and fuel pump. The AFPR is the last of the puzzle for now.

Going back to what kenamond said about the AFR gauge. I never really intended to tune with it. Empty pod needed a gauge. Hind sight now tells me better so now my other "important" gauges.... oil press. and water temp are in the instrument bezel pods. Can you explain alittle more on how the AFR gauge will read correctly at idle and cruise, but not under boost? Shouldn't I be able to compensate some what with the translator?

 

[5150DSM]

I haven't run it since I installed the 16g, injectors and fuel pump. The AFPR is the last of the puzzle for now.

Going back to what kenamond said about the AFR gauge. I never really intended to tune with it. Empty pod needed a gauge. Hind sight now tells me better so now my other "important" gauges.... oil press. and water temp are in the instrument bezel pods. Can you explain alittle more on how the AFR gauge will read correctly at idle and cruise, but not under boost? Shouldn't I be able to compensate some what with the translator?

Idle and cruise are more or less steady state positions, on fast acceleration and/or WOT the narrowband sensor is simply not fast enough to register the changes in AFR accurately enough for tuning, by the time the norrowband registers a change you have already been running rich, lean or otherwise for several seconds or longer. The translator has little to do with your ability to read AFR's, yes it can adjust the overall AFR but the sensor is not capable of reading it in real-time. If you meant compensation for the lack of AFPR, then no, the MAFT works like any other tuning device in assuming a linear fuel curve; which you cannot have when the FPR is being over-ran.

 

[Madcap]

Idle and cruise are more or less steady state positions, on fast acceleration and/or WOT the narrowband sensor is simply not fast enough to register the changes in AFR accurately enough for tuning, by the time the norrowband registers a change you have already been running rich, lean or otherwise for several seconds or longer. The translator has little to do with your ability to read AFR's, yes it can adjust the overall AFR but the sensor is not capable of reading it in real-time. If you meant compensation for the lack of AFPR, then no, the MAFT works like any other tuning device in assuming a linear fuel curve; which you cannot have when the FPR is being over-ran.

Gotcha on the AFR. Makes perfect sense. Didn't mean using the MAFT to make up for a stock regulator. I mean't making up for the conditions the gauge would be telling me, but seeing as the gauge is on I guess what one could call a "severe delay", that question goes out the window. Ok, I'm able to tune for the 560's with the MAFT easy enough, so in a "general sense" which direction should I be looking to tune during WOT, seeing as the gauge can't keep up? Do you tend to need to tune leaner or richer, and to which degree? I get the basic principles but I'd rather get some experianced "advice"

 

[kenamond]

Gotcha on the AFR. Makes perfect sense. Didn't mean using the MAFT to make up for a stock regulator. I mean't making up for the conditions the gauge would be telling me, but seeing as the gauge is on I guess what one could call a "severe delay", that question goes out the window. Ok, I'm able to tune for the 560's with the MAFT easy enough, so in a "general sense" which direction should I be looking to tune during WOT, seeing as the gauge can't keep up? Do you tend to need to tune leaner or richer, and to which degree? I get the basic principles but I'd rather get some experianced "advice"

Actually, what 5150DSM said is not correct. Narrowband O2 sensors are only good at telling you if you're above or below 14.7 AFR (stoich). They register 0.5v at 14.7 and something higher if you're rich, something lower if you're lean. But you can't accurately use, say, 0.9v to indicate exactly what AFR that is (maybe 11, maybe 10, but you can't be sure). Wideband O2 sensors tell you exactly what your AFR is over a wide range of AFR (hence the name "wideband").

Now, to tie this to idle/cruise vs WOT...

At idle and cruise, the ECU is trying to keep the car at stoich (14.7). It monitors the O2 sensor voltage. It wants it to wiggle above/below 0.5v (which means "stoich"). If it stays above 0.5v (rich), it removes a bit of fuel (pulses the injectors a bit less). If it stays below 0.5v (lean), it adds a bit of fuel (pulses the injectors a bit longer). When the signal is hovering around 0.5v, it's happy. It does this very rapidly. It stores the amount of more/less fuel in short term fuel trims (STFT). These are corrections to the fuel map (internal memory that tells it how much to pulse injectors for a given rpm and airflow). So the MAS tells how much air is flowing, and the CAS/CPS tell it what the rpm are. It looks up how much fuel that requires, then it adds in the STFT value (or subtracts if it's negative). If the ECU detects a special set of conditions indicating that all is well, it will "memorize" the STFT value by storing it in a long term fuel trim (LTFT). This is referred to as "learn mode". So if it "learns" a new STFT, then it stores it in the LTFT then zero's out the STFT. So in reality, the sensors tell it rpm and airflow. These tell it where to look on the fuel map. Then it takes that map value and adds the STFT *and* LTFT.

All of that is constantly being adjusted. The STFT is constantly changing, and if it goes into learn mode, the LTFT changes as well. So the car is auto-tuning itself using the MAS, CAS/CPS, and O2 sensors. If all is well, your STFT is near 0%, your LTFT is within +/-4%, and they don't change much once it's got things figured out. FYI, there are actually three LTFTs: Low, Mid, and High. These relate to low, medium, and high airflow. So if you're in the low airflow range, the LTFT-Lo is being updated. Etc.

All of the above is called "closed loop feedback" or "closed loop mode". There are inputs (from sensors), and the ECU takes a look at them and changes the fuel injection accordingly, which affects what the sensors report, and this feedback is taken into account again by the ECU, etc. in a loop or cycle. The ECU is constantly correcting in closed loop mode.

But when you tromp the throttle and hit boost, the ECU stops doing all of that stuff above. Why? Because if you run a turbocharged engine at 14.7 AFR under boost, you'll knock like crazy, have ridiculous temperatures in the combustion chamber, and burn up a piston or break something in no time. These motors run at around 10 AFR on the stock fuel map, and tuned cars run in the 11+ range. So that narrowband O2 sensor doesn't help the ECU. So the ECU goes into "open loop mode" where it doesn't look at O2v anymore (because it wants to run rich, and the O2 sensor can't tell it how rich it's running). The ECU just goes off of the fuel map on "blind faith" hoping that all is well. The only feeback it has at this point is the knock sensor. If it detects too much knock, it starts to retard the timing on the motor. That ends up decreasing peak temperatures in the fuel-air mix as it's compressed and burning, and that decreases knock.

At idle/cruise, it's safe to run at 14.7 AFR (combustion temps are much lower then).

So...a narrowband O2 sensor is useless to you and the ECU when you're talking about tuning at WOT. Now you can take a look at narrowband O2v and get a decent idea if there's a problem...usually 0.92v or higher is "good enough", but that's not a sure bet and it varies from sensor to sensor, car to car. That's why folks get the wideband O2 sensors when they want to do a good job tuning. They know what AFR they're shooting for and can see if that's what the car is running with.

That was long, but there's a lot going on in these cars' "minds."

Hope that helped more than it confused.

 

[Madcap]

Actually, what 5150DSM said is not correct. Narrowband O2 sensors are only good at telling you if you're above or below 14.7 AFR (stoich). They register 0.5v at 14.7 and something higher if you're rich, something lower if you're lean. But you can't accurately use, say, 0.9v to indicate exactly what AFR that is (maybe 11, maybe 10, but you can't be sure). Wideband O2 sensors tell you exactly what your AFR is over a wide range of AFR (hence the name "wideband").

Now, to tie this to idle/cruise vs WOT...

At idle and cruise, the ECU is trying to keep the car at stoich (14.7). It monitors the O2 sensor voltage. It wants it to wiggle above/below 0.5v (which means "stoich"). If it stays above 0.5v (rich), it removes a bit of fuel (pulses the injectors a bit less). If it stays below 0.5v (lean), it adds a bit of fuel (pulses the injectors a bit longer). When the signal is hovering around 0.5v, it's happy. It does this very rapidly. It stores the amount of more/less fuel in short term fuel trims (STFT). These are corrections to the fuel map (internal memory that tells it how much to pulse injectors for a given rpm and airflow). So the MAS tells how much air is flowing, and the CAS/CPS tell it what the rpm are. It looks up how much fuel that requires, then it adds in the STFT value (or subtracts if it's negative). If the ECU detects a special set of conditions indicating that all is well, it will "memorize" the STFT value by storing it in a long term fuel trim (LTFT). This is referred to as "learn mode". So if it "learns" a new STFT, then it stores it in the LTFT then zero's out the STFT. So in reality, the sensors tell it rpm and airflow. These tell it where to look on the fuel map. Then it takes that map value and adds the STFT *and* LTFT.

All of that is constantly being adjusted. The STFT is constantly changing, and if it goes into learn mode, the LTFT changes as well. So the car is auto-tuning itself using the MAS, CAS/CPS, and O2 sensors. If all is well, your STFT is near 0%, your LTFT is within +/-4%, and they don't change much once it's got things figured out. FYI, there are actually three LTFTs: Low, Mid, and High. These relate to low, medium, and high airflow. So if you're in the low airflow range, the LTFT-Lo is being updated. Etc.

All of the above is called "closed loop feedback" or "closed loop mode". There are inputs (from sensors), and the ECU takes a look at them and changes the fuel injection accordingly, which affects what the sensors report, and this feedback is taken into account again by the ECU, etc. in a loop or cycle. The ECU is constantly correcting in closed loop mode.

But when you tromp the throttle and hit boost, the ECU stops doing all of that stuff above. Why? Because if you run a turbocharged engine at 14.7 AFR under boost, you'll knock like crazy, have ridiculous temperatures in the combustion chamber, and burn up a piston or break something in no time. These motors run at around 10 AFR on the stock fuel map, and tuned cars run in the 11+ range. So that narrowband O2 sensor doesn't help the ECU. So the ECU goes into "open loop mode" where it doesn't look at O2v anymore (because it wants to run rich, and the O2 sensor can't tell it how rich it's running). The ECU just goes off of the fuel map on "blind faith" hoping that all is well. The only feeback it has at this point is the knock sensor. If it detects too much knock, it starts to retard the timing on the motor. That ends up decreasing peak temperatures in the fuel-air mix as it's compressed and burning, and that decreases knock.

At idle/cruise, it's safe to run at 14.7 AFR (combustion temps are much lower then).

So...a narrowband O2 sensor is useless to you and the ECU when you're talking about tuning at WOT. Now you can take a look at narrowband O2v and get a decent idea if there's a problem...usually 0.92v or higher is "good enough", but that's not a sure bet and it varies from sensor to sensor, car to car. That's why folks get the wideband O2 sensors when they want to do a good job tuning. They know what AFR they're shooting for and can see if that's what the car is running with.

That was long, but there's a lot going on in these cars' "minds."

Hope that helped more than it confused.

No, I actually understand. Better then the cookie cutter answers you find. All you hear is "get a wideband" with no explaination why it's so different. And I'm sure thats due to having to type 2500 words to do it. When unexplained in that way it gives the impression that "ok I don't have a wideband, but I have something that's close and good enough" The problem is that they need to stop using AFR for both devices. It confuses people.

 

[Madcap]

In that case what can/should I safely run for the time being?(boost,FP) Keep all but injector size translator settings at 0?

 

[kenamond]

In that case what can/should I safely run for the time being?(boost,FP) Keep all but injector size translator settings at 0?

Once you go up in injector size, you have to do something more to handle it. The ECU is under the impression that if it opens the injectors for a particular duration and if it has 43.5psi fuel pressure difference between the rail and intake ports (i.e. across the injector), that it'll deliver a specific amount of fuel. When you put 560s in there, the ECU doesn't know it and will pulse the injectors like they were 450s. So too much fuel goes in, you run pig rich, and get angry. SAFC lies to the ECU about airflow. You adjust how big of a lie it's telling. The ECU sees the altered airflow signal (thinks less airflow is coming in) and pulses the injectors a bit less. You twiddle the knobs and look at wideband or knock or EGT or read plugs, and figure out when you have it "good enough". But that airflow signal is also used by the ECU to control the timing curve. So when you decrease airflow, you get the AFR right, but the timing starts advancing which can lead to increased knock.

ECMlink and AEM-EMS let you directly modify the fuel maps without messing up the airflow signal. They also let you adjust the timing map. So you "cut to the chase" with those instead of trying to fool the ECU into doing what you want.

 

[5150DSM]

What Kenamond is saying is exacty right and far more detailed than I could have easily explained it. My reference to speed was in regards to the gauge and not the ECU, which I probably should have clarified. By the time a "blinky light" gauge shows an extreme lean or extreme rich condition, which is extrapolated by voltage, the condition has already existed for several seconds and therefore is not relevant to "real time" tuning.
Just clarifying my answer, it was not my intention to be vague or to supply bad information.

 

[Madcap]

thanks guy. im about to start tuning with a wideband. I've read up on AFR and boost levels and want to make sure I've understood what I've read. Again, here are the mods:


Injen intake
turbo back exhaust
evo3 o2 housing
mbc and gauge
aftermarket bov
upper intercooler pipes
EVO3 16g
560cc injectors
rewired 255
3" GM MAF and translator
AFPR @42psi
(still have SMIC)

from what I've read my AFR at idle and cruise should be around 14.7:1
WOT should ideally be at 11:1

one more remaining question is boost level. I see a lot of people running 20psi. How do I go about finding the correct boost for my setup? What kind of HP should I expect with what you've experianced and seen with similar setups?

 

[skatershawn]

is that bence racing im seeing?

well id say youll be good at 18psi but you can turn that setup to around 24psi and be safe!


just make sure you tune it right and you should be fine!!

 

[Madcap]

Ok, the wideband is in and a FMIC is on its way. Why is my car stalling when I have the RPM signal wire hooked up? In this case its pin 4 of the power transistor. I have the idle dialed in perfect. Anyone have any tips as to the MID and WOT tuning?