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Diesel Tech Questions: Emissions Deleting and Checking Codes

Top Tech

Bruce W. Smith
Oct 31, 2016
Photographers: Bruce W. Smith
Emissions Deleting: The Cons
I’m looking for information! I’m a new diesel owner, and I’m wondering what are the pros and cons of doing an EGR, DPF, and factory muffler delete, along with uploading a custom tune.
-via email
Photo 2/4   |   “They’re power-robbers and prone to causing plenty of maintenance issues as they get older…” These are just a couple of the problems diesel owners cite as reasons for deleting diesel particulate filters and the pollution-control components on today’s pickups. While the griping is understandable, it’s important to keep in mind that the much bigger downside of removing DPFs and smog hardware is that it’s illegal and voids warranties. Remember, removal is done at your own risk.
This is a question diesel-performance shops around the country get asked a dozen times a day. We’re only addressing the cons (because in the grand scheme of things, from an economic and legal standpoint, they honestly outweigh the pros—by a lot). Here’s our take:
The negatives that are associated with deleting and/or ECM calibrating around diesel engine’s emissions controls are many. We’ll talk about legal issues, but first let’s discuss warranty. Increasing an engine’s power and torque also raises the amount of stress that’s placed on the drivetrain. Typically, the weakest link in this area fails, and when such breakage occurs (and it will), repairs are in order. Who pays for it? You.
Any tampering with, modifying, or removing of the OEM pollution, cooling, and noise-control components automatically voids a manufacturer’s powertrain warranty according to spokespeople at Ford, Ram Truck, Nissan, and GM (the typical powertrain warranty covers the cost of parts and labor to repair/replace the transmission, axles, differentials, transfer case, and so forth, for 5 years or 100,000 miles).
Emissions-skirting “deletes” and “tunes” also void the Federal Vehicle Emission Warranty, which covers everything related to a diesel-powered pickup’s EGR system, usually for 5 years or 50,000 miles. This includes fuel pumps, EGR coolers, ECMs, engine sensors, turbochargers, manifolds, and charge-air coolers—just to name a few parts.
Another “warranty” to consider is that of the ECM tuner and calibration you use. Electronics are known to fail, and aftermarket tuning hardware and software are no exception. Programmers and tuners come and go. So, a calibration you install this year may not have technical support next year, or a few years down the road, which means you’ll be buying another one. Tunes and programmers aren’t cheap.
There’s also the legal side to consider. Honestly, this really is the bigger enchilada when it comes to the cons associated with disabling a diesel pickup’s emissions gear. Regardless of where you live or the age of the vehicle, if it is equipped with pollution controls, it’s against federal law to remove, modify, or tamper with those components. Yes, we understand that as the owner, you can do whatever you want to your truck. However, if the rig is driven on the public roads, the federal Clean Air Act (CAA) still makes it illegal to mess with anything related to pollution control.
To that end, the CAA gives the Environmental Protection Agency and its assigned outlets the right to prosecute anyone for removing, tampering with, or modifying pollution-related parts on any vehicle, as well as the right to prosecute the owner of said vehicle.
To what extent the prosecution goes seems very vague from the response we got when we asked the EPA about the specifics on the enforcement and fines, which, according to Title II of the CAA, can be up to $3,750 per device removed and $37,500 per vehicle modified.
“Every case EPA handles is unique, and the agency considers a range of factors when deciding whether or how to assess a penalty for an alleged violation, like the seriousness of the alleged violation, the alleged violator's good faith efforts to comply [with] the law, and an alleged violator's ability to pay,” an EPA spokesperson says.
Getting busted for driving a modded diesel pickup or actually deleting smog hardware also depends on where you live. The EPA pretty much leaves the “enforcement” of CAA regulations to local and state authorities. While some states, such as Oregon and Mississippi are lax on these matters, others (California and Pennsylvania, for example) are stringent. “Many states have mandatory vehicle inspection and maintenance programs that can spot these violations,” our EPA contact says. “Some states have also empowered their police departments to write citations for vehicles that have evidence of tampering or produce excessive smoke.”
Rolling coal and a loud exhaust are easy ways to attract attention that could result in a fine and having to replace parts that were removed—and if you ever looked at the price of replacement EGR and DPF pieces, you know they can cost several-thousand dollars.
Which brings us to the last con to consider: Resale and licensing. There are many states that require pre-sale smog inspections. If your truck has deletes, or any part of the pollution control systems tampered with, this may make it very difficult to trade-in, re-sell, or license (register).
While deciding to delete your truck’s emissions equipment is a personal choice, we strongly urge you weigh the gains in performance (although we didn’t address those power and torque increases here, they are the typical result of “deleting” and tuning around smog equipment) against the potential monetary losses and legal issues that come with that type of modifying.
We’re in close touch with aftermarket performance companies that are concerned about this rock-and-hard-place situation and are developing upgrade parts such as turbocharger systems, cold-air-intake kits, ECM calibrations, and other pieces that can enhance the horsepower and torque of emissions-equipped diesels, without compromising their compliance with EPA and California Air Resources Board regulations.

Cracking the Codes
I just returned from a month-long tour of the Rockies, towing a 37-foot, fifth-wheel trailer with my ’09 Dodge Ram 3500. The truck’s 6.7L Cummins engine has 67,000 miles on it. After driving into town without the trailer, the Check Engine light came on, and the following diagnostic trouble codes displayed in the information window: P0401, Exhaust gas recirculation low. Insufficient detected; P0420, Catalyst system efficiency below threshold (Bank 1). Can the first code be attributed to a stuck EGR valve? I don't understand the second code. It's funny, but after I tow my trailer for a while these problems tend to show up.
Parker French
-via the Internet
A clogged EGR valve is the most likely cause for this type of situation. The valve is clogged with caked-up soot, which is preventing the proper flow of exhaust gases. This is common on trucks that see long periods of light, non-towing, stop-and-go driving that’s interspersed with occasional periods pulling heavy trailers.
Light-duty driving can cause carbon (soot) to accumulate in the EGR cooler. Once the cooler gets really hot under the heavy load, soot is burned and forced downstream to the EGR valve. But, in some instances, there’s so much soot that it restricts the passageway that it must flow through to be evacuated.
Our friends at Mobile Diesel Service in Oakland, Oregon, just had a customer’s Ram with a similar issue. “We scanned it and found an insufficient flow fault code P0401,” recalls Shawn Smalley. “That’s normally an indicator of a bad or clogged EGR valve.”
Indeed, the technician found the emissions sensors and EGR valve clogged up with soot. He cleaned everything and installed a good used EGR valve to help save the owner a few bucks. On a hunch, the tech also removed the front of the EGR cooler as a precautionary measure—and found it completely plugged. The cooler was removed and replaced with a Bostech 699 cooler assembly. Problem solved.
If you can remove the EGR valve from your truck’s engine, soak it for a couple of hours in a good cleaning solution such as fresh diesel fuel or Purple Power (see page 154 of our October ’16 issue for details on this and other EGR-cooler-cleaning solutions). Then take a small, stiff brush and clean out all the passages in the valve around the spool. If you want to try and save a little money and have the time, try cleaning the EGR cooler by filling it with the same cleaner, letting it soak for a few hours (shaking it up a few times during the soak process), then flushing it out with water until it runs clear. A cooler that’s heavily sooted may take a couple of flushings. Cleaning it could extend the cooler’s longevity. This is also a good time to use a specialized electronics spray cleaner on the MAP sensor.

Flat Spot
Do custom tunes and stock programing all seem to de-fuel before shifting gears? I just traded in a ’10 GMC Sierra 1500 for an ’06 GMC Sierra 2500HD, and it’s my first diesel truck. What I notice is when I lay into the throttle and hold it, she pulls like a train and then kind of coasts, shifts, and repeats that right up through the gears. I’ve got a tune installed, but my gasser did the same. Is this flat spot under power something that’s added to the shifting strategy to protect the transmission?
-via the Internet
Photo 3/4   |   That “flat spot” you feel when your truck’s transmission shifts while the hammer is down is caused by the ECM helping to protect the clutch packs in the gearbox. Without the slight reduction of power at the shift points, the chances of a transmission suffering significant damage are pretty high.
Yes, and you should be thankful it’s there. That delay is one of the things that allows manufacturers to provide 5-year/50,000-mile powertrain warranties, because it helps prevent potential drivetrain issues caused by aftermarket performance tunes.
The “flat spot” you feel and hear is built into factory ECM algorithms (and many aftermarket performance tunes) to protect the transmission, more specifically its clutches and related components. The slight drop in rpm and easing into the next higher gear helps lessen the tremendous torque load that’s placed on the clutches under heavy throttle.
Softening the shifts also helps protect the U-joints and other drivetrain components, especially when you add in another 100 to 150 hp from a tune. Conversely, some of the hotter race-only tunes inside multi-level programmers are designed to provide the hardest, fastest shifts possible. But keep in mind, such modes will also shorten the life expectancy of stock transmissions.

Winter Treads
I just got transferred from sunny Southern California to Wisconsin and am looking for input on what the best tires are for the Snow Belt? My ’14 Ford F-250 has the stock Firestone Transforce HTs. They work fine around here, but I am a bit skeptical about how they’ll do up North.
-via the Internet
Photo 4/4   |   Safety and overall driving performance can be greatly increased during the dead of winter by using dedicated snow tires, which are designed to bite and hold snow in their tread blocks while remaining flexible in sub-freezing temperatures.
The HT is a decent all-season highway tire. However, based on our winter-driving experiences, all-season tires are pretty much worthless when the pavement turns white. Your best bet from a safety and performance standpoint under those driving conditions is to use dedicated snow tires mounted on steel rims if you plan on driving a lot on packed or plowed roads.
There are a number of winter-specific light-duty truck tires from which to choose, as well as all-terrain/all-weather rubber such as Nitto Tire’s EXO Grappler Heavy-Duty AWT. Check out Tire Rack for prices.
An investment in a set of good winter tires on cheap wheels will more than pay for themselves if they help you avoid even one fender bender. Swap back to your stock street treads come spring.

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