[Stewhoppy]

I have some mods to my Camaro SS A8 as follows:

custom exhaust
deleted secondary CAT's
AFM's are still connected but tied up outside of the exhaust
CAI
deleted the sound tube
oil catch can
throttle control box

Many other mods which are cosmetics (lowered etc), my problem is that it seems to be running very rich. I have disconnected battery overnight to allow reset/relearn by the ECU but still running rich.
Any advice welcome.

Regards,

Stewart

[JeromeS13]

How are you measuring the AFRs?

[Stewhoppy]

Only via the air flow sensor in the intake

[JeromeS13]

Originally Posted by Stewhoppy

Only via the air flow sensor in the intake

How is your MAFS telling you how rich/lean you're car is running? It's only measuring one portion of the equation...

[Stewhoppy]

Nothing else is being measured. It is my observation that is running rich

[JeromeS13]

Originally Posted by Stewhoppy

Nothing else is being measured. It is my observation that is running rich

Your MAFS only reads the amount of air entering the engine. It has no indication of whether the car is running rich or not... If you've modified the car as you've described, the amount of air entering the engine (as measured by the MAFS) should increase...

Specifically, why do you think your car is running rich?

[alan91z28]

Originally Posted by Stewhoppy

I have some mods to my Camaro SS A8 as follows:

custom exhaust
deleted secondary CAT's
AFM's are still connected but tied up outside of the exhaust
CAI
deleted the sound tube
oil catch can
throttle control box

Many other mods which are cosmetics (lowered etc), my problem is that it seems to be running very rich. I have disconnected battery overnight to allow reset/relearn by the ECU but still running rich.
Any advice welcome.

Regards,

Stewart

I don't normally post on these forums as i just read this for interest as I focus on 3rd gen F bodies, but i do a lot of engine swaps, engine tuning, etc

I have not worked with the GEN V LT so my statement is only for your general consideration.

You may indeed be running rich, but to know you really need to see a real number such as the actual fuel trim, a wideband o2 reading, etc... you can use a scanner, hp tuners, aftermarket wideband o2 kit etc

Why could you be running rich? Again I am not making a GEN V specific comment, but you state you have the O2 sensors hooked up outside the exhaust (i am assuming you only mean the post CAT sensors and the front exhaust sensors are there). While commonly believed to only be used for diagnostics, the post cat o2 sensors can and are used by some OEM to aid with the fuel trim control. If used this information is combined with the front sensor to give a more accurate situation as the front sensors see a lot of stress over time. Does GM use this on the GEN V i do not know. However you have the sensors hanging out in open air so you can imagine that the information provided to the ECM by these sensors is lean condition so if used by the ECM to modify what the fronts are seeing only it would want to respond by adding fuel

Again, just a general thought and i have not tuned a GEN V, just speaking from other experience

[Stewhoppy]

Based on my observations only. large amount of sooty material being accumulated in the exhaust and even on the rear of the car. Could also be due to a lot of quite short journeys, although I do try and have areal blast (WOT) every few days.
Never seemed to have the accumulation of sooty material before the CAI was installed.

[Stewhoppy]

Hi,

Thanks for the input, however I have the AFM (active fuel management)tied up out of the exhaust, not the O2 sensors.

Originally Posted by alan91z28

I don't normally post on these forums as i just read this for interest as I focus on 3rd gen F bodies, but i do a lot of engine swaps, engine tuning, etc

I have not worked with the GEN V LT so my statement is only for your general consideration.

You may indeed be running rich, but to know you really need to see a real number such as the actual fuel trim, a wideband o2 reading, etc... you can use a scanner, hp tuners, aftermarket wideband o2 kit etc

Why could you be running rich? Again I am not making a GEN V specific comment, but you state you have the O2 sensors hooked up outside the exhaust (i am assuming you only mean the post CAT sensors and the front exhaust sensors are there). While commonly believed to only be used for diagnostics, the post cat o2 sensors can and are used by some OEM to aid with the fuel trim control. If used this information is combined with the front sensor to give a more accurate situation as the front sensors see a lot of stress over time. Does GM use this on the GEN V i do not know. However you have the sensors hanging out in open air so you can imagine that the information provided to the ECM by these sensors is lean condition so if used by the ECM to modify what the fronts are seeing only it would want to respond by adding fuel

Again, just a general thought and i have not tuned a GEN V, just speaking from other experience

[Wolvie70]

Originally Posted by Stewhoppy

Based on my observations only. large amount of sooty material being accumulated in the exhaust and even on the rear of the car. Could also be due to a lot of quite short journeys, although I do try and have areal blast (WOT) every few days.
Never seemed to have the accumulation of sooty material before the CAI was installed.

Sounds scientific

[grampa_ss]

Everybody's exhaust tips look black after just one day. It's normal (according to all the knowledgeable members on this forum). They say this is common for the LT1 Direct injection engine.

[mdhopt36]

I wouldn't say that was normal.
*****
"back in the day", we used to run at average speed, throw in the clutch and shut engine off and pull a spark plug or two and examine them. Best way I know of to monitor a multitude of things going on in the engine.
A good state of tune usually left a color more grayish near the exhaust exit. Plugs, likewise; with no white around the sharper edges of the plug, no soot, and definitely no "pepperflakes" that signified detonation.
Not sure how you'd do this on today's SS's.

[Stewhoppy]

And your point is exactly what? Nobody said it was scientific, now move along please!

Originally Posted by Wolvie70

Sounds scientific

[mdhopt36]

The car had dual Cats?. My sensor is (?) right after the first one---maybe any change in back pressure could throw the computer off? OK before the mods?