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Secondary Air Injection (AIR Pump)
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Author:  cribbj [ Fri Nov 27, 2015 8:51 am ]
Post subject:  Secondary Air Injection (AIR Pump)
Late model Ferrari's have a secondary AIR injection system which works for 20-30 seconds on the first cold start of the day, then not again until the next day (if the ambient air temps are cold enough.), or if the car/engine sits outside in freezing weather and the engine becomes stone cold again.

I know the purpose of the system, and I can appreciate the rationale behind using it for the older ceramic substrate TWC's to prolong their lives, however I'm wondering if newer, more modern catalysts with metallic substrates really require the system, as many cars/exhaust systems don't use it?

I'd like to remove the system, as it's a bulky, ugly mess in the engine bay, however it's one of those OEM installed pollution control systems that, if removed, would probably cause the car to fail a visual out in Cali. But that's not as huge a concern for me, as much as the possible annoyance of its absence setting a CEL.

Apparently other sensors on the engine look for the AIR pump to be working, and if it's not, one or several sensors in conjunction will set the CEL; the MAF by sensing a slight increase in air flow/air pressure, the downstream Lambda seeing a shortterm bump in its reading, etc. So all these would have to be worked around.

So, any thoughts on:

1. Whether modern catalysts need this system?

2. If #1 is no, then how to remove it without setting CEL's?

Again, I plan to keep the OEM Motronics ECU's in the car in order to pass annual inspections (which are simply OBDII scans), however the engine will actually be running on an aftermarket ECU(s).
Author:  mk e [ Fri Nov 27, 2015 10:10 am ]
Post subject:  Re: Secondary Air Injection (AIR Pump)
cribbj wrote:

Again, I plan to keep the OEM Motronics ECU's in the car in order to pass annual inspections (which are simply OBDII scans), however the engine will actually be running on an aftermarket ECU(s).


I really don't know the answer to #1 but assume that since most cars don't have an air pump anymore its not actually required.

But the real answer is we we need to figure out how to generate the OBDII signal, you know...so you can check engine status with off the shelf scan tools of connect to the various other dash tools and such.

The other option is to feed the OEM ECU from a true engine simulator...but that seems harder than setting up OBDII. Not sure.
Author:  apalrd [ Fri Nov 27, 2015 1:27 pm ]
Post subject:  Re: Secondary Air Injection (AIR Pump)
The air pump is used to speed light-off.

Engines with air pumps will run rich during warm-up, the air pump will provide additional air which will allow the rest of the fuel in the exhaust to burn. This decreases hydrocarbon emissions from running rich, and heats up the catalyst so it lights off faster. It's only needed when the engine is cold and must run rich.

However, the whole air pump system (air pump, secondary air MAF sensor, and one or more injection valves and control solenoids) is very expensive. It was removed as a cost savings. Modern cars attempt to run stoich straight off the start flare, even before the O2 sensor heats up. This reduces the CO emissions during warmup, but it takes longer to light off the catalyst. They will instead run retarded during light-off to increase EGT and warm the catalyst - running retarded also decreases in-cylinder temperatures and NOx formation. HC will be high as a some of the fuel won't evaporate when the engine is cold, this is significantly worse with alcohol fuels.

A lot of hybrids and other low volume, already expensive and low-emissions packages (including some PZEV california packages) still have air pumps to improve startup emissions, especially for hybrids where the engine might not run for very long and the emissions of intermittent running without fully warming up can be really bad.

tl;dr it was removed for being expensive and they try to get by without it.

The diagnostics will depend on what sensors it has. If it has a total air MAF (including both engine and secondary air), it will look for a change in MAF as a result of switching the pump and valve on and off. If it doesn't, it might have a secondary air MAF sensor for diagnostics and control, or a pressure sensor for diagnostics only.
Author:  TheDarkSideOfWill [ Tue Dec 29, 2015 9:10 pm ]
Post subject:  Re: Secondary Air Injection (AIR Pump)
The stock ECU looks at the aggregation of those inputs and lights the CEL when the conditions match those required for the particular DTC. In computers that are hacked by the aftermarket, it's typical to simply turn off undesirable DTC's.

I'm sure that Motronic has been hacked in other applications. Does anyone do this type of tuning for Motronic Ferraris?
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