hello guys
i just want to share with you this it was a good news to me.
i took my car to the dyno for the first time my car has exhaust and cold air intake
the dyno was 286.47@5542 whp and 301.23@4020 lp/tq
but the guy that did the dyno for me he said my car would run rich on rpms and lean on high rpms the air feul ratio was between 10.5-12.0 on low rpms and high would jump to 14.5-15.5 when idling the car was on 16.5-17.5 and some time would reach 18
i was wondering what is the optimum air feul ratio fo z28 i looked i couldnt get exact piont?
last thing the guy said it should between 13.2-13.4

 

Just above or below 13 is a good area, so he is pretty much right on. All engines are different so there is no perfect number for all. You want the air fuel + ignition timing to produce the max area under the curve. Here is a good thread with more info. A search will result in many more.

https://www.camaroz28.com/forums/lt1...o-tune-454536/

 

Where did he put the wide-band O2 sensor? Did he unscrew a stock sensor and put it on that bung? Did he do that with one bank of the engine only, or did he do both banks? I'd be concerned over running 18:1 at idle. The PCM is hard programmed to achieve 14.7:1 in closed loop.

Is it possible he just stuck the sensor in the end of the exhaust pipe? Do you have a cat?

Has your PCM been tuned? The stock programming for power enrichment mode usually targets an A/F ratio of 11.7:1.

Do you have a copy of the A/F ratio vs RPM printout? Can you post it?

 

he actually put the o2 sensor in the back of the exhaust and i dont have cats it is strait pipes to the cat back no o2 sensors on the cari tried to find the o2 sensors before i couldnt i took it to the muffler shop to see what it is. they said no o2 sensors i have a code for ses lights
i dont have that paper but ill try to get from him.
when i start my car on cold start. she doesnt give me any problems, but after first start it starts rich everytime til couple hours when it cools down
i checked that with him it starts at 10.1 air fuel ratio
I have no idea if the pcm was tuned
is there a program i can buy to tune my car?

 

You have absolutely NO O2 sensors at all??? If the pre-cat O2 sensors (the only ones used in OBD-I) are deleted, the PCM can not run in closed loop. Without the feedback, the PCM can't adjust the injector pulse width to correct any errors in the A/F ratio. That would explain why it's not running at 14.7:1 at idle.

When you start the engine cold, the PCM richens the A/F ratio for cold start, just like a choke would do on a carb. So it isn't unusual to have a rich mixture on cold start. The PCM looks at the coolant temp and adjusts the A/F ratio accordingly.

If you are going to run open loop, you have to have a very good tune, and you can't change anything without checking the tune. I run open loop, but the tune is based on dozens of engine dyno and chassis dyno pulls plus track time.

Do you have a code FOR the SES light (DTC 11) or do you have a code AND an SES light? If you have a code, what is it?

You can tune your PCM with Tunercats or LT1_Edit:

TunerCat

CARPUTING.COM

You can also data log the PCM using DataMaster or FreeScan:

TTS Power Systems

FreeScan

You'll need a cable. Andrew at AKM used to sell them, but now I think he has a link on his site to someone who does:

AKM Electronics Home Page

It's going to take a while to learn to tune. You might be better off using a mail order tuner:

PCMforless

madtuner.com - Home

 

[QUOTE=Injuneer;6901664]Do you have a code FOR the SES light (DTC 11) or do you have a code AND an SES light? If you have a code, what is it?

i scanned my car just right no code or anything but the ses light on for the coolant temperature but when i was checking the reading on that machine it showed
no egr reading
Lh o2 sensor was reading to 426
Rh o2 sensor was reading to9xx (i forgot actually)
btw i was using the snap on solus scanner Snap-on Diagnostics: SOLUS PRO Full-function Scan Tool
im confused at this point i dont know what those numbers mean? I dont know if i have an o2s? it is the first time i get confused with my car.
Thanks a lot for help

 

The SES light does not come on for the coolant temperature. It will come on for a faulty coolant temp sensor. If the coolant temp itself goes too high, the "check gauges" light will come on. If the coolant temp sensor is faulty, it could affect A/F ratio. If that is what the SES light is on for, fix the sensor.

The scanner is reading the duty cycle that the PCM is commanding for the EGR vacuum solenoid. If you were checking the PCM at idle, it would be normal for the EGR duty cycle to show as "0", because EGR is not used at idle.

Was the Bank 1 (left/drivers side) O2 sensor holding steady at 426 mV? If so, that may indicate a faulty circuit, which could be a dead sensor, or a non-existent sensor, or the harness not connected to the sensor, or a wiring fault.

In closed loop, the O2 sensor readings should be swinging rapidly back and forth over a range of 0xx - 9xx mV. It appears you are indicating that is what your Bank 2 (right, passenger side) sensor is doing. If that is what the right sensor is doing you definitely have at least one working O2 sensor.

What "exhaust" does your car have? Headers? If so, the O2 sensors would be in the headers collectors. Look there and see if they are there.

If you are running a catback, and the stock exhaust manifolds and Y-pipe, the driver's side sensor is in the base of the exhaust manifold and the passenger side sensor is in the Y-pipe, a few inches below the exhaust manifold. Look there and see what you have.

 

i changed the temp sensor the check engine light is gone now and doesnt give me hard time to start any more here is a video of the scanner reading the o2 sensors
1995 z28 m6 computer readings - YouTube