Is the best way to adjust your mixture from lean to rich or vice versa through the injector # constant ? I have an 88 iroc with 305 tpi and 5 speed, I just put on headers, free flowing exhaust and new injectors. I am running very rich and getting knocks in the engine all the time. It only runs well when I am in 5th gear on the expressway at about 60mph +. I was reading through the posts and have been reading for about 5 hours now but it seems that most people have tougher issues than this one. Just want to know how to lean out the mix so I can drive my car around with no issues and without getting a headache from all the extra gas in the exhaust when I stop at a red light. any help is appreciated. I have tunercat's tuner program and a couple of eeproms to play around with.

i think you need to find out why rich. reducing the BPC should cause less fuel to be injected globally. did you damage the coolant temp sensor?

Not sure about the coolant temp sensor. I did have a leak in my radiator and put some goop radiator compound in there to seal it off, not sure if that would effect the sensor or not? What would be a good way to test the sensor ?

Also, I removed my air system and compensated for that by turning off the EGR Diagnostic in the Switch table.

Some peoples say that you should add / or remove numbers in the maf tables for making it richer/leaner and someone tells you to change the maf scalar (if it needs an bigger change) and someone tells you to change the injector constant..

Wich way is the right way of taking away or adding fuel in specific rpm / load in Closed loop and open loop..

Is the maf tables wrong way to go ?

nobody that could straight this out ?

You really should have a wideband O2 sensor to tune properly, otherwise you really won't know where the AFR is actually at.

As for your question, did you change injector size? If the injectors are larger than the stock ones you just need to change the injector constant. You can then tweak the MAF tables from there if you need to make changes.

example.

If there is bigger injectors than stock then you change the Injector constant to the right size. And if its still not good, then its okay to change the Maf tables... thats the right way to go ?

someone tells me thats that not the way do to it...

Hi.

As I see it.

Inj size should be adjusted to correct flow ( also depends on fuel pressure)

The how to tune the MAF-tables/scalar (for closed loop)
I dont think there is a right way, depends on what works best and what base.bin you start from.

My latest 6E tune ( for a 355 TPI,HSR,head cam) I only touched the MAF-tables, used ARAP as a base.bin. This was tuned with a WB so the there was mV O2-tables changes also to make it happy.

To make it richer and leaner you have to modify the O2 tables.

I'm no tuning expert, but that statement is not entirely true. You can't just turn one dial and richen the mixture, it isnt that simple. You need to know what the car needs and go from there. maybe it needs more acceleration enrichment, maybe it needs more enrichment in PE mode, the list goes on and on. My understanding is that you can modify the upper and lower threshold and average value you want the O2 to read, but that really isn't how you make it richer or leaner necissarily.

First and foremost, you MUST get the injector constant right. Then if you need more or less fuel you can adjust the MAF tables accordingly.

I'm a newbie at tuning, but I've read, researched, and done my homework and I'm still learning tons. My best advice is to spend the time doing the homework and learn some of the tuning basics. Many of the topics discussed on this board are very complex and in-depth. There aren't very many straight answers given around here because frankly there aren't many tuning adjustments that are just black and white. Us explaining how to tune to someone that has no concept of how to tune or what an engine needs, is like teaching algebra to a toddler.

I was ref to closed loop conditions, not under PE, AE or DFCO....

My last tune (2007) I shut of BLM and tuned it after WBO2. Made my engine alot happier. My AFR (WBO2) was varying alot depending of the exhaust temperature. Here is a picture, purple is WBO2, Blue is BLM this is at Idle closed loop, didnt log the EGT but you can see how the AFR goes up and down. This is not a stock engine so I'm not saying this is how it is on all engines.

For everyone who wants to tune their car properly a WBO2 is a must.

As a "wise man" used to preach here, "Give the engine what it wants, not what you think it wants....."

have been away for a couple of days.

I did install 26# injectors. So to tune, I adjusted the injector Constant and I adjusted the display injector flow rate to match as well. But I am still getting a super potent exhaust fume that gives everyone in and around my car a headache. I don't have cats so I know that will add a little bit of unburned fuel but this is really high and the car runs like crap - sounds like a knock in the engine.

what does a wide band 02 sensor do as far as a difference from a regular 02 sensor ? and which tuning program is being used in the uploaded picture ?

Narrowband oxygen sensors are extremely inprecise. They can't tell the computer the exact air/fuel ratio like wideband oxygen sensors. Technically narrowband oxygen sensors produce an exponential voltage signal, whereas wideband oxygen sensors produce a linear current signal. When the air/fuel ratio is perfectly balanced, a narrowband O2 sensor produces a signal of about 0.5 volts (500 millivolts). When the fuel mixture goes rich, even just a little bit, the O2 sensor's voltage output shoots up quickly to its maximum output of close to 0.9 volts. Conversely, when the fuel mixture goes lean, the sensor's output voltage drops to 0.1 volts



A WBO2 is linear so you can exactly what AFR you have.


The program I used is TTS datamaster and is only for scanning.
I use Tunerpro (and sometimes Tunercat) for tuning.

Do you have a scan report? Can you post the *.bin you are using?

/N.

GTA324...

How then does the INT- rich 02 (upper) lean 02(lower) and mean R/L factor into a wide swing of .9(rich) to .1(lean)?

I understand the INT moves but not sure of the triggger of the movement within these boundries in tune. I moved mine 10% richer so as to affect my stoich from 14.7 to a richer CL A/F.

I do however see in my logs that the 02 V is in fact swinging as you state.

RBob does have a writeup in stickies that I will reread.

The ECM uses INT and BLM to keep the "average" voltage from the O2 sensor to whatever its in the code, usually around 570-600mV.

Dont quote me 100% on this, since its been a few years since I read it. But when the ECM sees a few input values from the O2 that is above the desired mV It adjusts the INT one step (short term adjustment) , and if it doenst correct the "problem" it goes another step, then after a the INT has been moved a certain amount of steps (depending on Code) it changes the BLM value (long term adj) 1 step. There is also a "update rate" for the BLM how fast it is allowed to change.

I'm sure someone can tell you more exactly how it works............To keep the ECM happy tune for BLM 128, but then you'll need a WBO2 to tune the O2 tables to get the desired afr for closed loop.

The latest car I tuned have a Idle AFR of 14.0 and 14.7 when driving normal, emission test chip has 14.7 at idle but then it was a little
"jumpy" ....

But for tuning for diffrent AFR a WBO2 is necessary........

Clear as mud?

There is alot of info here, but it can take some time to find it........

/N.

To help the WB temp issue make sure the WB is 24" to 40" away from the exhaust valves. Install it right before the cat. A heated WB lives a short life in the NB bung.

The WBO2's are placed right infront of where the cats used to be, the temperatur I was ref was the narrowband, it was placed in the collector of the SLP headers.

Just to show how the real AFR is varying with temperatur when its in closed loop.