1395 miles without refueling

[Musicman]

I do, but I'm still under warranty until next June.

My extended warranty just ran out @ 400k, so I figure what the heck. Even if there is no real benefit, the way ISX EGRs have been failing, I'd run with it disconnected just so I don't have to worry about having to repair or replace it.

I religiously track every drop of fuel I buy, so I'll know pretty quickly if it makes a big difference. I can't wait to see how it does when we hit the road in a week.

[Rev.Vassago]

Please post your results. I'm very curious.

[Musicman]

After a little discussion with my local repair shop, which happens to be a Cummins dealer, I'm rethinking this whole EGR experiment. The service manager at this shop is a no BS kind of guy and would not say something simply because it was contrary to what Cummins wants him to say. While Don (the service manager) agrees that disconnecting the EGR would improve fuel economy and make the engine run cooler, he also answered the question I posed in my first post… it would be bad for the catalyst. He said it might be worth taking a $2000 risk (what a replacement catalyst costs) if fuel went to $4 of $5 a gallon and stayed there, but in his opinion at the current price of fuel, the costs associated with the decreased life of the catalyst would outweigh any cost benefit gained through fuel savings.

[Copperhead]

It has been observed that those with DPF's and such are not candidates for unplugging the EGR. Seems like the results are not good since more of the electronics are talking with each other. Since there is no "catalyst" on a pre '07 engine, it is a non issue. I assume by "catalyst" you meant a DPF. They are not the same thing but oh well. Some are not able to do it for other reasons. We all know that Volvo's will throw a CEL if you just scratch your rear in the wrong way. Seems some with Cummins in Volvo's get CEL and other events when unplugging the EGR. I think there are factors like which software version is in the ECM, which make/model the engine is in, etc that might make for some not being able to put there EGR in "test mode". It's a hit or miss proposition. It just has to be tried to see if it works out.

No experience with DPF's, but on the surface it would seem that a DPF would be better off without EGR. There is less soot generated by eliminating the EGR and therefore it would seem that this would cause fewer regens and cleanings of the DPF. But the engineers have created a nightmare of electronics and interactions going on. I am getting soot levels in my oil that rival those that are running bypass oil filter setups. My last oil sample's soot level was around .2 ppm after 25,000 miles. My oil isn't getting black near as soon as before... almost like when I had a N-14 in the 90's. I can run several thousand miles after an oil change before the oil starts to blacken up.

But from a cost effective standpoint, I am not sure that getting almost 1 mpg better fuel mileage, regardless of fuel price, is not a good thing. And since one has virtually eliminated the EGR and cooler issues on the ISX (especially the pre '07 that had the cooler and EGR on the hot side of the engine), just more rediculous things to not have to replace. I realize that a shop manager has no investment in my truck and therefore, it is not his money heading out the stack. But the shop manager at my dealership has no problem with me doing this to my ISX. He, and the shop foremans, are actually captivated by the results I am getting.

I also understand how some may be a little hesitant in doing this for fear of screwing up. For those, I have no problem if they chose not to. Each one has to live within their own comfort level. I have been known for sticking my neck out and getting whacked with a 2x4. But I still am willing to try some new things. On this issue, it has been a win for me. Probably just dumb luck.

[Copperhead]

Forgot to post how it was recommended to me by a Cummins tech to do the unplug thing...

Let the engine sit long enough to get totally cooled down, preferably overnight. Then turn the key on without starting the engine. Leave the key on for at least 10-15 seconds to make sure the EGR valve stays closed. Then remove the lower 6 o'clock postion plug that pulls out towards the engine block. That is it. Valve remains closed until you happen to plug the EGR back in. There are two plugs going to the EGR, only remove the lower plug. Make sure you tape off the plug and receptacle to keep moisture out.... seems if moisture gets in there, like during a rainstorm, it can throw a mess of fault codes (learned that one on my own).


Results on my ISX in an International 9400i.... before EGR disconnect, mpg average around 6.4 pulling average payload of 38,000 lb. After EGR disconnect, average 7.3 mpg. All pump to pump averages and usually running around 65 mph on the Interstate and doing a lot of two lanes with some good pulls as well. When I can stay out on the interstate and there is a fair amount of easy terrain, the mpgs reach into the high 7's frequently.

[Musicman]

It has been observed that those with DPF's and such are not candidates for unplugging the EGR. Seems like the results are not good since more of the electronics are talking with each other. Since there is no "catalyst" on a pre '07 engine, it is a non issue. I assume by "catalyst" you meant a DPF. They are not the same thing but oh well.

My 2003 Pete 387 with a C15 motor had a catalytic muffler. It was located in-line with the exhaust between the passenger side fuel tank and the drive shaft. It was told that it was unusual for a 2003 to have the catalytic muffler, since they weren’t phased in and mandated until the ACERT 2004 engines, but I had one anyway on my 2003 for some reason. I know Cummins and Caterpillar vary in their designs, but I would assume that if an ’04 C15 has a catalytic muffler that an ’06 ISX would have one as well. I also know that the service manager at my local Cummins dealer seems to think my truck has some sort of catalyst as well. I didn’t get a chance to talk to the mechanic who normally works on my truck though and the service manager could have thought we have a newer truck (most people think its brand new when they see it). I have to admit that I’m new to Cummins and have only owned Cats in the past, but I think I’m capable of distinguishing a catalyst from a diesel particulate filter.

I will investigate further though and if there is no catalyst or catalytic muffler on the truck then I may go ahead with this little experiment. Even if the truck does have some sort of catalyst and its life is shortened, it still may be worth unplugging the EGR. If doing so were to increase our mpg from the current 6.75 to 7.5, it would mean an extra $7,700 a year in fuel savings (at $2.60 a gallon).

[Copperhead]

Yes.... I have heard some Cats have catalysts. But we are talking about Cummins. No such critter on any Cummins setup. Just the DPF's in '07 and above. Catalyst was not dependent on the truck manufacturer, just the engine manufacturer. All emissions requirements are tied to the engine not the truck. Pre '07 Cat Accerts didn't have an EGR even though all the other brands did. This is also why you can order brand new glider kits from FL (Corando and Columbia) and Pete (386)and put, say, a '98 engine in it if you desire. Perfectly legal (except in CA in 2014). That being said, a catalyst reduces CO levels like they do in cars. EGR reduces NOx and in the process, generates more soot because of the reduced combustion temps. If a EGR engine will not hurt a catalyst, then disabling it should make it last longer (less soot to clog it up). Cat used a catalyst on a lot of Accert engines because they were not using EGR and it made the EPA a happy camper. These issues are why Cat is going out of the truck engine business. They can't get around not using an EGR anymore and the other emissions stuff like they could with the Accert. 2010 requirements just flat made it impractical to continue investing R&D into making truck engines. Cummins and Detroit never used a catalyst as they were both using EGR unlike Cat Accert. They just went to the DPF for '07.

Didn't mean to imply you didn't have the knowledge to distinguish between a catalyst and a DPF. Some others have been known to confuse the two. Since the discussion was about the Cummins, I made the mistake that you might have confused the two. My fault.

[Musicman]

Yes.... I have heard some Cats have catalysts. But we are talking about Cummins. No such critter on any Cummins setup. Just the DPF's in '07 and above. Catalyst was not dependent on the truck manufacturer, just the engine manufacturer. All emissions requirements are tied to the engine not the truck.

Didn't mean to imply you didn't have the knowledge to distinguish between a catalyst and a DPF.

I talked to my local Cummins dealer's service manager again today when I went down to pay my bill and he is adamant that my truck has a catalytic muffler. It's been a long time since I've been under my truck and I really don't recall seeing one (at least not one that looks like the catalytic muffler on my '03 C15).

I didn’t take your comment about confusing a DPF with an EGR to be a personal affront – after all, you don’t know anything about me. I didn’t realize however that there was wide spread difficulty in distinguishing between the two, as they are so dissimilar in form and function.

On another note, I reevaluated unplugging the EGR, which I thought I’d already done, but after reading your description of which plug to disconnect, I think I may have unplugged the wrong thing. As I’ve mentioned before, I’m kinda lost when it comes to Cummins engines. Caterpillar always provides a comprehensive manual, but Cummins apparently doesn’t do this, as I’ve been told there is no such thing as an ISX manual. Anyway, I thought I knew where the EGR is located and what exactly to unplug, but I may have wrong. After unplugging what I thought was the EGR, the truck seems to run fine, but now the check engine light is on, so I may have to give up until I can be sure just what the heck I’m unplugging.

[solo379]

It's real easy to find out, just tell them your vin number, and ask them to look for the price on muffler. My ring at around $2500 each (i have 2)

[Copperhead]

On another note, I reevaluated unplugging the EGR, which I thought I’d already done, but after reading your description of which plug to disconnect, I think I may have unplugged the wrong thing. As I’ve mentioned before, I’m kinda lost when it comes to Cummins engines. Caterpillar always provides a comprehensive manual, but Cummins apparently doesn’t do this, as I’ve been told there is no such thing as an ISX manual. Anyway, I thought I knew where the EGR is located and what exactly to unplug, but I may have wrong. After unplugging what I thought was the EGR, the truck seems to run fine, but now the check engine light is on, so I may have to give up until I can be sure just what the heck I’m unplugging.

Including a pic of the EGR on the Cummins (2003-2006) it is on the hot side just in front of the turbo. The pic shows tape over the correct plug to remove. The receptacle that it came out of is just above the plug in the picture. Tape both the receptacle and the plug to keep out moisture.

[Rev.Vassago]

That's the one I thought it was. Thanks for the pic. I'm almost tempted to try it, even though I'm still under warranty till next June.

[Musicman]

Including a pic of the EGR on the Cummins (2003-2006) it is on the hot side just in front of the turbo. The pic shows tape over the correct plug to remove. The receptacle that it came out of is just above the plug in the picture. Tape both the receptacle and the plug to keep out moisture.

That is indeed the very plug I unplugged. Others on here say they haven't had the check engine (orange check mark) come on, but that is exactly what happed after I unplugged the EGR. The truck was cold (hadn't been started in two days) and I had the key in the on position for quite a while before unplugging. I only thing I can't remember at the moment is if I turned the key back off prior to unplugging or not; but after shutting down and restarting a few times, I still have the check engine issue. The truck is still sitting by my shop with the EGR unplugged. Maybe I'll plug it back in, run the truck a while to warm it up and see if the light goes out, let it cool overnight and then try doing this again. If it's going to cause the light to come on, I don't know if this is worth playing with. When I had something really go wrong, I'd never know it.

Thanks, by the way, for the pic you included. I was pretty certain I had the EGR, but as I’ve said 100 times before, I’m a former CAT devotee and therefore a bit of an idiot when it comes to Cummins. At least I know for sure I’m unplugging the correct thing now.

[Musicman]

Well, I tried plugging the EGR back in and then disconnecting it again, but I still have the check engine light illuminating. As before the truck started and idled fine so I decided to use the old electrical tape on the check engine light trick and go pick up a load in Mattoon, IL (about 150 miles from my house).

The truck ran fine going up, but then again I was empty so there wasn’t much demand being placed on the engine. After picking up, I came back to the house because the load has about three extra days on it and can deliver anytime in Montebello, CA. On the way back (grossing abt. 76k pounds) the engine purred right along. The boost gauge was only putting out 2 – 3 lbs in the flats (normally I’d expect at least 5 – 8 lbs with such a heavy load) and the pyrometer indicated slightly lower exhaust temps than I’d expect as well. On the couple of small hills I encountered on my drive, power seemed to be unaffected in either in a beneficial or detrimental way.

Conclusion: We’ll try running with the EGR disconnected out to SoCal and see what kind of effect it has on fuel over the next 2k miles. After that, I’ll reassess whether we’ll continue with our little experiment.

[dieselmanic]

ahmm, I don't know if i would go into CA with a disconnected smog control device. Just saying.

[Musicman]

ahmm, I don't know if i would go into CA with a disconnected smog control device. Just saying.

What they don't know wont hurt me.

[Copperhead]

All you have to say is if they check it is that "the darn plug keeps coming out of the EGR and I am not a certified Cummins tech, so I'll have to get it in a shop as soon as I can". Or you can tell them that Cummins has put it in "test mode" and doing a running analysis on the engine. Better yet, don't say a thing and I'll bet they wouldn't even know it. Those guys are not firing on all thrusters anyway, and I would bet that a lot of them couldn't find the EGR on the engine if you asked them where it was. You give CARB too much credit.

[Musicman]

Well, 7k miles driving with my EGR disconnected has yielded the following:

-- there is an improvement in fuel economy, though the biggest increase (perhaps as much as 20%) seems to be with loads under 30k lbs or so. With heavier loads the mpg increase has been about 5 - 10%.

-- the truck runs much cooler

-- boost and pyrometer readings are lower

-- engine noise seems to be reduced

-- my "check engine" light has remained on from day one, but other than that the trucks runs as good as ever

[solo379]

1859 miles. Fill up 234 gallons.....

[Musicman]

1859 miles. Fill up 234 gallons.....

14526 Miles 2095.058 Gallons = 6.93345959873188 MPG

We have been running heavier freight than normal recently, so I think the numbers are a little less than they would be if we have been running what we normally do. We had three loads totaling over 5k miles that had us grossing 79k + and running into some pretty nasty winds on I-40 and I-10. Our average loads are more in the neighborhood of 20k – 30k lbs, so looking at the data from those loads, our average mpg goes up to about 7.5, which makes me ecstatic. Over the 225k miles we’ve had this truck, we’ve averaged 6.72 mpg, so even 7 mpg is a welcome increase. I’ll be interested to see our oil analysis when it comes back after our next PM.

[Scottt]

I was cruising down the boring highway 54 in kansas with 4 trucks and we got to talking about fuel mileage and I asked if anyone had heard of unplugging the EGR on a Cummins.

A driver that hadn't been talking chimed in laughing and said his shop recommended it but he said they went a little further. He said his shop brazed his EGR shut so he didn't have to unplug it.

Is that possible??