I thought I did the right thing picking up a pre DEF 2011, but after a failed EGT sensor sidelined my new (to me) 4th Gen I started doing some reading. Some of the forums say the DEF trucks (2013+) are much better for the engine than the pre DEF trucks. Is this true, if so, what are my options to ensure my pre DEF truck make it to 250-300K miles.

Well, I couldn't help but try it. I disconnected the EGR valve. CEL came up as soon as I started it. Here is what OBDLink showed when I checked the trouble codes. So it would seem that the data out there that 2010-2011 trucks don't set a CEL for an EGR valve disconnected are a myth, or at least for this 2011 it is. I was pretty skeptical about that, now I know.

 

 

 

 

EGR Duty Cycle stayed at zero, which I expected. I had also added a PID for "Relative Throttle A Position"(unfortunately I did not get a screen shot of value). I think that is the Throttle body the regulates the EGR/fresh air ratio. Previously it moved around some and stayed at a relatively low value (20-50% IIRC), but after disconnecting the EGR, it stayed at 90% all of the time. So I think once the EGR is MIA, the throttle valve is commanded to full fresh air, or nearly full fresh air position. EGR Temperature was way lower as one might expect. Normally its around 200*, makes sense considering it should be staying closed. Apparently the MAP sensor I added isn't correct. As shown, that value stayed at zero the whole time. EGT sensors were in the low 600's, previously they would run low 700's, so it seems the EGT's drop a bit. I meant to check intake air temp, but forgot about that, never paid attention, or snapped a screenshot for that.

It ran normal, seemed to be getting a little bit better fuel economy than previous. It did seem to need slightly less throttle to maintain speed, but maybe that was a placebo effect, lol. I plan to keep it unplugged, report back how things go with more miles. I only drove 5 or 6 testing today.

 

 

 

Oh, and it seems the exhaust pressure was a bit higher, at least at idle. Likely since it's no longer going into the intake, and all has to go out the exhaust. Previously, at idle it seemed as though there was a little bit of a vacuum being generated at the exhaust pressure sensor, now there is a pressure. For the record, I didn't get much data on exhaust pressure prior to disconnecting, so it may not be very helpful information.

 

I did my flashing with an excel sheet that addressed specific values and addresses within the computers with simple true/false 1/0 statements. It was outlined in PriusChat which ones to do. I haven't found a full list of what all is possible with it, but I did also disable the outside noise maker that makes a electrical grinding noise to alert pedestrians when in full ev mode. Not exactly needed in the country.

 

On the MAP sensor, I have found that sometimes the little dongles/apps don't always read things 100% correctly. It may be under a different address or the app for some reason can't interpret it. Take it with a grain of salt.

Not surprised on the code, as I mentioned earlier my buddies 2010 set a code too. 

The biggest downside of having the CEL light on: the remote start shuts back down after a few seconds of run time. 

IAT temp is much lower. It wasn't stabilized here, usually runs close to ambient air temps, without EGR. With EGR was usually around 125* IIRC. I still feel that the throttle is more responsive that when it was hooked up. I would like input on what programmers, and who's custom programming (possibly canned program) will be the best route to go. I have an early 2011, so ultimately I would like to upgrade to the 2011.5 and up power level, with a tow tune that is as stock now to protect the converter.

 

I will just add, I was driving the other day, a P094D code popped up for the first time with a NOx insufficiency. The light came on a few days after I finished a 600 mile trip towing 10k. When I get back to Louisiana I think I will pull the egr system off and see how serviceable it is. It went away after a 70 mile round trip up to some mountain property, unloaded. 

@That Guyis it a P094D, or P049D. I don't see a P094D listed. 

1 hour ago, jltait said:

@That Guyis it a P094D, or P049D. I don't see a P094D listed. 

You are right. I can get a bit dyslexic. It is the P049D, EGR exceeded learning limit.

@That GuyLOl, I have the same dyslexic issue, from time to time. I would say that sounds like the EGR valve needs cleaning... Did it get the 67,400 mile EGR service that is recommended?  If not, there is pretty good video on youtube for it. The host name for the video is motorcitymechanic.

I just want to add an update to what I found, that having the EGR unhooked just wasn't worth it for me. I'm Pretty sure it had the truck in De-Rate mode. It was a gutless pig pulling our 5th wheel up hills. I will say that mine also had a P2002, P2BAC codes set, so it's possible it was one of those were causing de-rate, not the EGR codes. I ended up feeling more confident having the EGR plugged in and no codes tripping the CEL. I'll be looking at other options eh, wink, wink. 

Remove the EGR and make a block off gasket without the ports so you do not flow any exhaust gases. Now you can have it hooked up so no code. I did this trick way back in the 80s for gasoline engines and still past smog. It will work also on diesels. 

 

Another example is on a Ford 6.0L diesel ive done freeze plugs in the EGR cooler on one of the fire trucks and all smog is present but plugged so it does not flow. Also on the Ford 6.0L the EGR cooler is known to leak and blow exhaust gases into the coolant. After the freeze plugs in the cooler the problem stopped.