Something new coming down the pipeline???

lmorris · November 2, 2015

I have heard about NOX adsorbers but was under the impression they were far too expensive for automotive use any time soon...or are they...

JoeR · November 3, 2015

Dodge has used NOx absorbers on their 6.7L engines. VW and International too.

Joe

Keith Browning · November 4, 2015

What is the definition of the PIDs?

JoeR · November 4, 2015

NOX-ADS-REGEN is the PID that shows the NOx Adsorber is being regenned. That happens at temps around 1600F. (I'm not sure if that's the textbook temp, but that's what I've observed on the Dodge Cummins. NOx adsorbers regen in around 15 seconds.

NOX-ADS-DESULF shows when it is desulfating the NOX Adsorber. The NOX Adsorber doesn't grab SOx emissions on purpose. It's not a regulated emission. Unfortunately SOx will stick to the NOx Adsorber and keep it from grabbing NOx. SOx can be regenned, but it is at a slightly higher temp, but just as quickly.

I'm surprised to see these pids on a 6.7 Ford, if that's what it is connected to. I didn't think they used one. If they are using one, it would only be to grab NOx on a cold start. Once it's running DEF is the reducer.

While we're on the subject, can anyone tell me how Ford exhausts put the SCR system before the DPF? They are the only ones doing it that I know of, and as far as I knew soot would pollute the SCR and keep it from working.

Joe

amailloux · November 4, 2015

GM puts the SCR before the DPF also.

Matt Saunoras · November 4, 2015

If I recall correctly weren't the early 11-12 cab and chassis vehicles the only ones with the DPF and SCR reversed?

JoeR · November 4, 2015

If I recall correctly weren't the early 11-12 cab and chassis vehicles the only ones with the DPF and SCR reversed?

It was my understanding that the cab and chassis has the DPF first. Only pickups have the SCR first.

Joe

JoeR · November 4, 2015

GM puts the SCR before the DPF also.

You are correct (but you already knew that!) :grin:

I thought Ford was the only one. It's a great idea as long as it works....which it obviously does.

Joe

lmorris · November 4, 2015

I'm surprised to see these pids on a 6.7 Ford, if that's what it is connected to. I didn't think they used one. If they are using one, it would only be to grab NOx on a cold start. Once it's running DEF is the reducer.

Joe

It was hooked up to a 2016 F350. Ford does not use them yet....I tried to find those pids in datalogger and they are not there. I have seen other vehicles with pidsin freeze frame data that are not used. Hotline says they are sometimes left behind from testing and development.

Matt Saunoras · November 5, 2015

Attached is the 2011-2012 6.7L Chassis Cab (Narrow Frame) EGT sensor locations and diagnostics "service tips"

The pickup uses the SCR before the DPF, apparently all model years are like that. That definitely counts for me learning something today.

2011_2012_67L_EGT.pdf

Brad Clayton · November 5, 2015

Some theories I have heard over the years: The SCR was put in front of the DPF on pickups so the extra thermal event could help keep the DPF hot. And the DPF was put in front of the SCR on the cab and chassis so it would be placed under the cab and thus factory controlled for heat shielding as there would be no control over what a body builder installed on the chassis.

JoeR · November 5, 2015

Some theories I have heard over the years: The SCR was put in front of the DPF on pickups so the extra thermal event could help keep the DPF hot. And the DPF was put in front of the SCR on the cab and chassis so it would be placed under the cab and thus factory controlled for heat shielding as there would be no control over what a body builder installed on the chassis.

That makes sense, in both cases. Thanks!

Joe

amailloux · November 5, 2015

So I thought he scr was placed before the dpf, but after the catalyst to get it up to temp as fast as possible. When watching the scr data, the ecm commands post injection and the cat lights, then egts 1 and 2 come up pretty rapidly. It takes a quite a while under light load to get egt 3 and up to the 450 plus degrees needed to reduce nox. In stop and go, the dpf can run cooler and only he scr must be kept up to temp reducing fuel consumption and allowing a lower idle.