Cat delete tune

[robvas]

Did you log timing on those runs by any chance?

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[engineermike]

Did you log timing on those runs by any chance?

Yes, but keep in mind I have the xdi gdi pump and a humidimod so I can get away with more timing/boost than most on true 93.

 

[robvas]

Yes, but keep in mind I have the xdi gdi pump and a humidimod so I can get away with more timing/boost than most on true 93.

was the timing the same on the catted run as the cattless run?

 

[engineermike]

was the timing the same on the catted run as the cattless run?

Good question…on the catted pulls I mentioned it commanded richer lambda which feed-forward commands about a degree more timing in this case. However, the actual lambda didn’t change so the catted pulls ended up sensing a little knock and it pulled some timing from a couple of cylinders. The net change might have favored the catted case by half a degree in aggregate.

I had actually forgotten until now that we made two pulls in each case. Upon seeing the power increase from adding cats, we immediately made another pull with no cooldown to see if it was a fluke and it repeated.

 

[WildHorse]

Your adding restriction which is probably adding a little more boost. I call that detrimental gains.

 

[engineermike]

Your adding restriction which is probably adding a little more boost. I call that detrimental gains.

Nah. If you add a restriction and it adds boost, then power change is net loss. I’m not the first to find that charge blowthrough can reduce power. It can even happen NA.

 

[WildHorse]

It can even happen NA.

Right. Maybe with open exhaust on a 1.6L Suzuki engine.
Even then you'll prolly lose average, with only gains on PEAK,
as I mentioned earlier. Maybe yer missing something in yer
tune, as factory calibration never shows a loss with CAT deletes.

 

[engineermike]

Right. Maybe with open exhaust on a 1.6L Suzuki engine,

14 psi in the intake port, 5 psi in the exhaust port, 4 valves all open at the same time….i don’t think it’s hard to imagine blowthrough happening.

I will say it’s harder to get blowthrough on an na setup than boosted.

as I mentioned earlier. Maybe yer missing something in yer
tune, as factory calibration never shows a loss with CAT deletes.

If your FAOSC is still enabled and your blowthrough logic is still disabled and/or not calibrated, then I would say you are missing something in your tune. The FAOSC alone can throw off the accuracy of your air/fuel by 10% even if you install “anti-foulers”.

 

[WildHorse]

If your FAOSC is still enabled and your blowthrough logic is still disabled and/or not calibrated, then I would say you are missing something in your tune. The FAOSC alone can throw off the accuracy of your air/fuel by 10% even if you install “anti-foulers”.

Don't have anti-fowlers, AF within 2% (tuned). Even 10% is easily compensated by the as-built logic. But as the OP noted, he's NA. He'll never see 10% without a tune. And facts are facts: Increase in MPG, increase in HP without the restriction on stock logic. You'll only get 402/403 with zero other codes. And the logic doesn't do anything differently when those codes are present. IE: party time.

 

[engineermike]

Don't have anti-fowlers, AF within 2% (tuned). Even 10% is easily compensated by the as-built logic.

Then you don’t understand. Due to FAOSC and blowthrough, your wideband readings are inaccurate. You might think you’re at 2% but it’s because you’re looking at erroneous data. 10% fuel trim IS the compensation by the “as built” logic and it’s wrong because it’s using bad data; widebands are wrong. I have direct experience with this both ways.

For FAOSC the way it works is the rear o2 sensors are used to apply a correction to the front/widebands. This is done because narrow bands are actually more accurate in measuring lambda but only near stoichiometry. The problem is that the catalyst changes the gas chemistry before it gets to the rears. The logic knows this so there is an offset table that is applied to the signal. When you remove the cats, the offset is no longer accurate, which means the widebands are corrected to an erroneous value. Anti-foulers and fuel trims can’t fix it because the logic believes the wideband data is correct after it applies the correction but it is not.

And facts are facts: Increase in MPG, increase in HP without the restriction on stock logic.

I wouldn’t call either of those “facts” irrefutable.

 

[DB83]

Maybe here's the correct place for me to ge help as you guys seem to have a lot of knowledge on the subject.

The car has been running the ford PP2 kit and ford performance cat back exhaust on it for the last couple of years, with no issues. Cars been running great.

After behaving like an idiot, and revving the car out in a car meet, I had a cat failure on my stock system, so I decided to go long tubes with kooks 300cpsi cats. Not the green cats. I fitted a ported GT350 intake manifold at the same time.

System has been on the car now for a couple of thousand miles, and i've reset the CEL a few times to see if it stays off, but every time i reset it, the CEL is back within 20 miles. The CEL is for both banks, so i've ruled out a rear O2 failure.

Is it just that the Kooks cats aren't able to bring the readings into spec? Could the GT350 manifold be contributing? Other than trying anti-foulers is there something i can adjust? Would the Ford PP3 map help maybe?

 

[K4fxd]

It's the cats. They do not "clean up" the exhaust as well as the originals so the ecu thinks the cats are bad.

Anti-foulers should help

 

[DB83]

With the FAOSC still enabled though, will this slowly through off the AF ratio?
I'm using HP Tuners if that means i can adjust anything in there.

 

[K4fxd]

I haven't tested this so it is speculation.

I would think the error will be the same in this case with or without the foulers.

 

[DB83]

That's what worries me. It seems it would be safer to turn FAOSC off.

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