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Discussion Starter · #1 ·
Greetings.

A friend of mine


Greetings.

A friend of mine is looking at an early 80s injected 400. So far everything looks OK, but we're trying to figure out whether or not the emissions are OK.

Here's the numbers:

Left side at idle
HC(ppm) 321
CO% 2.69
O2% 1.86
CO2% 11.9
A/F Ratio 14.5

Right side at idle
HC(ppm) 181
CO% 0.43
O2% 3.24
CO2% 12.5
A/F Ratio 16.8

The reports shows "close to the same at 2000 RPM"

What does this show about the engine? Why might the left side and right be so different at the HC and CO%. Most importantly, does anyone know if it will pass Texas emissions in the Metroplex?

Gracias
 
G

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Discussion Starter · #2 ·
Hi Tillman, welcome.

2.69%


Hi Tillman, welcome.

2.69% CO is way too high - should be 1%-1.2% pre-cat, which very well could drop the HC's to around 180-200 where they should be and

0.43% CO is way low - should be identical on both sides (1.0%-1.2% pre-cat if equipped)providing these numbers are Pre-Cat.

After the cats the numbers should be substanialy lower...maybe the 0.43% number listed.

It would greatly speed up the tweeking process to balance both banks with Vacum Gauges and set idle mixtures pre-cat to spec. As long as HC's don't spike settings as low as 0.80% CO are acceptable.

*note: if so equipped disconnect O2 sensors while performing adjustments.

Regards, JRV
 
G

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Discussion Starter · #3 ·
Thanks

Your comment about p


Thanks

Your comment about precats made me look at the sheet again, and there's a note that states "air injection ports in exhaust pipes -- just below headers"

I'm guessing that this means the numbers are not tailpipe numbers but instead, as you mentioned, pre-cat.

Does it feel like it just needs a tune-up to get the numbers straightened out?

Sorry about having to be a proxy, but my friend's behind a content filter that doesn't allow chat sites.
 
G

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Discussion Starter · #4 ·
Hi Tillman,

the numbers don


Hi Tillman,

the numbers don't look real bad, pretty close actually. However, both sides definately need to read very close to the same for the engine to run right and produce the lowest emmisions readings.

From the numbers you posted it looks like it needs tweeking more than an actual tune-up imo.

I'm not so sure that air injection reference has any value or relivance to our discussion here. You will need to look under the car to see if Cats have been added and if they have you will need to find a way to take exhaust gas readings upstream of the Cats. If no Cats are present then you can sample at the tailpipes..

HTH's

Regards, JRV
 
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Discussion Starter · #5 ·
It does help, but I think I&#3

It does help, but I think I'm a bit confused. When I had the 328 smog tested, the sensor went into the tailpipe of the car. Isn't that correct procedure on the 12 also? If so, wouldn't we be concerned about post-cat levels (if the car is so equipped)?
 
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Discussion Starter · #6 ·
Hi again,

For "Inspecti


Hi again,

For "Inspection Stickers" the test is post Cat...how much is this car polluting in a general sense and does it pass a set of base numbers.

For "testing, tuning, adjusting" all measurements of exhaust gas need to be pre-Cat. There is no way to know how efficient the Cats are working, so when tuning an engine all dilutive pieces must be by passed to get to the real numbers the engine is producing. All the WSM specs are pre-cat numbers, not post cat, and without knowing % of cat efficiency there is no way to know what the engine is actually producing.

Yes I know people try to cheat...but they are only fooling themselves and cheating their own engine solely taking post cat numbers or adjusting using post cat numbers.

Truthfuly, by spending the extra time tweeking the engine correctly it will stay in tune, last longer and run better for longer periods than if set cutting corners.

HTH's

Regards, JRV
 
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