By on September 22, 2015


Many in the Volkswagen diesel community are fanatical about their fuel economy and are understandably angry that a fix for the current emissions scandal may see them lose fuel economy in order to lower NOx output. The aftermarket community has provided modifications for the DPF and Adblue systems in the past, meaning there’s good chance they’ll provide parts and tuning to revert any changes Volkswagen may implement on the affected models.

There are a number of paths which Volkswagen may take that range from an ECM patch to new SCR hardware that could be installed.

The non-SCR models may get a software patch that would alter the injection timing and increase the regen cycle. This would cause the NOx emissions to go down but would take fuel economy and power along with it. It could also cause carbon build-up on the pistons and catalyst which could lead to increased maintenance costs for the owners.

The other path for the non-SCR cars is implementation of an SCR system, but that may not be cost effective due to the parts cost and labor required. I speculate that the SCR cars could receive an ECM patch that would increase regen cycles along with increasing the amount of Adblue that would be dosed. This would work out better than any fix for the non-SCR cars but would still result in higher Adblue costs.

Owners may look to the aftermarket to defeat these fixes so that they can keep their power and fuel economy.

The aftermarket community has released modifications for the DPF and Adblue SCR systems long before there was any talk of reduced power and economy coming from a potential fix for the emissions scandal. They looked to gain more power and better fuel economy by modifying or deleting the DPF system. Aftermarket tuners such as Rawtek and Malone Tuning produce kits for DPF models which replaces the DPF and EGR systems with stainless steel exhaust piping and tunes the ECM for better fuel economy and performance. They mark these systems as off-road only as they violate federal emissions laws. Rawtek also produces a kit for the Passat that deletes the Adblue SCR system along with the DPF and EGR and also advertises gains in power and fuel economy.

The tuners responded to the VW stop-gap recall which was released a few months ago, Volkswagen’s attempt to curtail this emissions scandal. The tuners let the owners know that they can revert the recall programming and reflash their previous tune for a minimal cost. The current versions of the ECM hardware and firmware may become an avenue for re-flashing if there is demand from owners after the recall fix as it would allow their vehicles to be reverted back to the programming they had when they purchased the vehicle.

In the end, unless Volkswagen implements some sort of encryption or lock on the fix, owners looking for power or economy will look to the aftermarket and revert back any emissions improvements that are made.

[Image Credit: Tony Hisgett/Flickr/CC BY 2.0]

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52 Comments on “Volkswagen Emissions Fix May Not Last Long Thanks to Aftermarket Tuners...”

  • avatar

    That may the case, but it isn’t the issue.

    The problem is that VW lied to regulators. It’s the same as when Toyota attempted to sneak the issues driving PedalGate past the NHTSA, or how GM stonewalled on ignition failures. We can go back as far as Ford/Firestone to find malfeasance.

    Sure, you can retune your car for better performance and worse emissions; people do it all the time. You simply have to revert to near-factory come your emissions test.

    What VW did was akin to a mechanic who does emissions tests submitting false Pass reports to the DMV, except on a massive scale.

    The recall will be expensive, but the malfeasance suits will hurt much, much more.

    • 0 avatar

      You don’t have to replace any emissions devices if you know your mechanic well enough, I’ve had several vehicles roll through the inspection without cats, not for very long mind you, as I can’t take the smell any way.

      • 0 avatar

        I prefer my local custom exhaust shop which has a sign hanging prominently behind the counter.

        “Don’t Ask Me To Remove Your Catalytic Converter and I Won’t Ask You to Pay a $2,500 Fine.”

        • 0 avatar

          I think on older engines it was really not a bad idea but since I’d say the late 80s the motors are designed to use a cat and removing it doesn’t seem to be as beneficial.

          • 0 avatar

            28 cars later
            I’ve seen modern turbo engines perform very oddly with a high flow cat or straight downpipe. In those cases there is still power to be had it just requires a specific tune to run that part. The new gti is the best possible example of this ironically enough. In other words a stage one tune has to be specific to the backpressure offered by the downpipe.

          • 0 avatar

            I would agree that this is mostly true on N/A engines, however, on an engine that has a turbocharger fitted; cat deletes yield a significant gain.

            Full spool time decreases, lag time also decreases, the entire power curve shifts to the left and benefits from a higher peak. I can’t speak on diesels but I would assume the same holds true.

            Anyway, did I ever tell you how much I hate VW and how happy this controversy makes me?

            It is payback for every time I got stuck working on their garbage because no other senior tech would want to.
            Payback for snaking your way out of paying for every and any warranty repair.
            Payback for all of those ignition coils people had to replace on their own dime.
            Payback for every time I had to connect a smoke machine to your crap (often).
            Payback for every failed POS window regulator that left owners & their loved ones exposed to freezing ambient temps.
            Payback for the smell of crayons during summer months.
            Payback for the EA888 tensioner I replaced just last week, they still cannot be bothered to get this bugger right. Seriously?
            Payback for having to remove the entire front fascia because you are a-holes.
            Payback for those stupid blue indiglo gauges, blinding.
            Payback for that annoying and incredibly revolting ignition chime.
            Payback for engines that sludge despite normal care.
            Payback for turbos that quit at 40k miles.
            Payback for carrier bearings that are not serviceable and are made of PlayDoh.
            Payback for my friend who narrowly escaped when his Golf was engulfed by flames in the middle of The Holland Tunnel.
            Payback for manufacturing the weakest control arms in the industry.
            OK Im done for now.

        • 0 avatar

          I would never ask a shop to remove my cats, I know that carries fines and that takes all of 10 minutes with a sawzall, it’s just passing the vehicle is what I’m talking about.

          As long as it’s not new enough to have a O2 sensor after the cat, you can really justify it anyway that suits your fancy, whether realistic or just plain dumb. In my case the old cat (from the 80s) was half way rusted out, so it made sense.

    • 0 avatar

      This is about right.

      When you combine the fine (up to 40K) and the cost to remedy it is far cheaper to buy the car and destroy it.

      there was an interesting memo from DOJ a few weeks ago on going after individual executives instead of getting a corporation to plead guilty. Have to think they knew this was coming.

      So, guilty pleases on lying to government, removing the cars from the market, and a fine based on the amount of pollution created — say $10B.

    • 0 avatar
      bumpy ii

      That assumes that a VW settlement with the EPA, DoJ, etc. doesn’t require installing a difficult-to-circumvent nonflashable ECU.

      • 0 avatar

        What like a Hitachi MMS411A? Not likely to happen.

      • 0 avatar

        Yeah but the ecu is out of sight on the vast majority of these cars and ecu tamper proof seals are widely available to retrofit anyways. I think they are just going to want to see a receipt for the recall associated with the vin of the vehicle. Also, I don’t think the obdII scanners in use are pulling version numbers off of files. How to verify?

    • 0 avatar

      The vast majority of tuned tdi’s are software only and currently pass sniff tests. Are they doing it by piggybacking on vw’s cheat tune or are the aftermarket files managing emissions differently would be a good question. Owners of tuned cars may have flash back to stock for emissions if they change the test or look more closely at engine parameters on the dyno. No matter, almost all of the tuning companies offer either stored multiple maps on the factory ecu (driver switchable) or have handheld obdII uploaders that allow the driver to instantly revert.

      Oh the irony if the end result is a higher proportion of tdi’s carrying high output times.

    • 0 avatar

      For owners of the TDI it is the issue. Most of us are angry at VW but couldn’t give a damn about the emissions.

    • 0 avatar
      Quisnos engine

      I have 2 Volkswagen engines working in my mine the exhaust goes through water scrubbers and I run them at optimum fuel mileage. you cant expect a lot of power because their inner working parts can fail but used at 40 hp rating they accomplish what I need and have over 4000 hrs on each one I use one on a generator the other on jaw crusher/ impact mill, car transport cable into the mine on a 21/2 shaft with belts to each piece of equipment and runs all equipment at one time.
      Many of you may scratch your heads at my post but fixed up right the VW diesel is very fuel efficient as well as being of good power for such a small engine. Thanks VW for your wrecked cars that I can remove and use your very good engines.

  • avatar

    The EPA, CARB and VW will make sure that modifying the emissions fix will be as difficult and expensive as possible. It’s going to cost VW billions to make this go away – do you think they are going to leave themselves open to further fines to satisfy a minuet minority?

    • 0 avatar

      CAD drawings + a few easily available machines + anyone that has a basic knowledge of computers = doesn’t matter what the EPA thinks.

      Local government doesn’t really care, and honestly it has no reason to. Unless your being ridiculously loud and annoying, no small town cop cares if your car smells terrible or if a small cloud of visible exhaust leaves the pipe.

      • 0 avatar

        “CAD drawings + a few easily available machines + anyone that has a basic knowledge of computers = doesn’t matter what the EPA thinks.”

        …until test time comes, at which point it really does matter. A lot.

        Admittedly it’s not yet known what VW will need to do to these cars to make them compliant. If it’s a ECU reflash, then it’s not a big deal; if it’s mechanical changes to the emissions-control system (like, eg, adding a urea-injection system) then it will not come cheap.

        That said, if it is an ECU reflash, the car might run very poorly or have longevity issues as a result. This being a VW it might not be noticeable, but it’s an unknown. It’s also more of a PITA than non-enthusiasts may be willing to deal with.

        • 0 avatar

          This is one of those wait and see things, it’s very hard to imagine VW being able to retrofit all of these already in place cars with emissions equipment, and have it work within 5% of the current functionality. Whether the loss comes in the form of reliability, fuel economy, urea usage, power, or all of the above, there’s a lot to be seen.

          • 0 avatar

            Yep. From what I’ve read, the non-cheating code ran NOX emissions 40x higher than allowed. If it would have been cheap to bring them into compliance and get 150k miles of relatively trouble-free driving out of the TDI, they’d have done it. The best option for VW at this point is to buy back the vehicles at list price (if the owner agrees not to press civil charges or class action) and do what it can to salvage the Audi and Porsche brands in the States. The question on which the survivability of VW hinges is on their ability to raise cash to pay the forth coming fines, vehicle buy-backs, and class action suits. Would you lend to them at this point? Didn’t think so. This one looks bad.

        • 0 avatar


          They will have to come up with a new ad blue tank if that’s the fix. The one they’ve got doesn’t package with independent rear suspension, and the current mkvii generation is the only one affected by this to come factory with a torsion beam rear. I don’t know how they’ll engineer that quickly, I talked to a Bosch guy once about urea tasks and he emphasized child weather testing and internal baffling to prevent cold weather issues. They are lucky if the part exists anywhere in the near term.

  • avatar

    Great article, Bozi.

  • avatar

    Tuners who defeat emissions control systems could find themselves facing massive fines and/or jail time.

    Do you really want to go there?

  • avatar

    Mey, 98% of owners won’t have a clue on these options and/or will be too scared or too broke to implement.

    Tuners are going to tune – the average slob driving a 3/36 $239 a month sign and drive 0/0/0 lease special is not going to modify their vehicle.

    • 0 avatar

      I think if the power and efficiency are effected enough, a fair amount of owners will find their way to a lawyer’s office a’la the Ford and Hyundai lawsuits over fuel economy. And greenies will likely take to the legal system anyway after being deceived into buying something that’s not actually earth-friendly.

      I agree that few owners will look to undo any ill effect of VW’s upcoming fix, whatever it may be. The vast majority of owners these days take cars as they are, or they do visual modifications to personalize. Certainly mpg-focused owners aren’t doing many mods/tunes.

      • 0 avatar

        “greenies will likely take to the legal system anyway after being deceived into buying something that’s not actually earth-friendly”

        What will they claim as actual damages? A loss of MPG, and maybe diminished resale value, sure, but what price to put on “loss of assumed virtue”?

        Anyway, VW will get all the cases consolidated into a class action, a law firm will get $20 million, and the owners might get a voucher for a free oil change if they’re lucky.

        • 0 avatar

          @jpolicke- they can claim the same false advertisement/ deception that Hyundai and Ford buyers claimed. While they may have gotten the mpg’s promised, they didn’t get the “clean” diesels as promised. Someone will claim emotional distress for having their eco values violated. Don’t underestimate the American legal system. Or overestimate, more accurately. There will be suits filed and probably turn into class action suits, as you point out.

          And I’m not bashing “greenies”, by the way, they just happen to be the group that had a golden egg bestowed upon them. Some of them will take advantage. Lawyers will encourage it. And I only half-disagree because corporations ought to be punished for such blatant disregard of the law.

      • 0 avatar

        Hypermilers definitely do mods and tunes and the VW diesels are popular with hypermilers. So there are likely a higher precentage of VW diesel drivers who would get tunes, but ones designed to restore/increase MPG rather than say someone with a Mustang or Camaro looking for more power out of their tune.

  • avatar

    Whats probably going to happen is the cars will communicate their states at any given time via the internet or something like OnStar and emissions will simply be applied as an annual “green” tax to your local commissar. Such technology is already being put in place as part of the whole police state being built up. You miss a registration? You do not comply with daily emissions? You miss a payment? No go for you as they turn it off remotely. Give it a decade or so.


  • avatar

    Big flail without sufficient test results.
    Diesel engines emissions test include the hardware/software for error codes, visual inspection of emissions devices, and a visual engine acceleration snap test for smoke lasting more than 5 seconds.
    Not a word on smoke emissions without the test device plugged in to the ECM.
    A bogus gotcha by the EPA?

  • avatar

    Perhaps VW will get a bit more invasive with the big brother use of specified/actual module coding and software levels. If a car visits the dealership and is connected via OBD port to the shop computer the computer can be told to check software revisions and coding then re-write the module at will to bring things back in to conformity. This is how a an OBD port ECM flash tune is dumped by the dealership in a jiffy. Fortunately the newer modules use a faster data bus speed so rewriting doesn’t take forever.

  • avatar

    This whole thing has made me have even more respect for VW. For over forty years we’ve been sitting helpless while regulators put more and more restrictions on how cars can be designed. I actually have to applaud someone who took the time and effort to basically tell regulators to piss off.

    The only fix I’d like to see done here is repealing just about every fuel economy and emissions law on the books.

    • 0 avatar

      ” I actually have to applaud someone who took the time and effort to basically tell regulators to piss off.”

      Oh, yes, because faking the results for the purposes of passing the test and then lying repeatedly is something John Galt would do.

      This isn’t little-guy heroism or VW-as-David standing up against Big Bad Government, this is a business practicing what amounts to fraud. What’s next, printing fake nutrition labels and putting plaster of Paris in your milk? How about fake expiry dates on meat? Faking toxicity tests on shampoo?

      Oh, yeah, very heroic. Very “stand up to the man”

      • 0 avatar

        “This isn’t little-guy heroism or VW-as-David standing up against Big Bad Government, this is a business practicing what amounts to fraud.”


        VW is GM, except without the humility. Oh, and with a German accent.

        The sooner VAG gets schooled by buyers and governments, the sooner they can fix their problems. Once they do that, I can become a fanboy again!

    • 0 avatar
      SCE to AUX

      You must be under 40 years old, or a Fox News disciple.

      As a Pittsburgh resident, I vividly remember lung-choking pollution, red/brown sunsets, and the local results of acid rain.

      Mfrs have NO incentive to provide cleaner cars, so protection of the public is best regulated by the government – not the market.

      I’m a card-carrying member of the Vast Right Wing Conspiracy, but it saddens me that so many Republicans are drinking nonsensical Kool-Aid.

      • 0 avatar

        Really? Where did they move the meetings too?

      • 0 avatar

        I’m not against pollution control on cars, and honestly I don’t care one way or the other in this situation, I vehemently dislike the EPA, but VW did give itself an unfair advantage over the other makes that were playing by the rules. So I really couldn’t care less, it’s all entertaining to me. However, with that said, I would have to say we’re well past the point of diminishing returns if a car requires special equipment to inject urea into the engine.

        And again, I’ve driven without cats and been behind cars without, but I enjoy feeling the same when I arrive as I did when I left. Similarly, an open top 6.5 diesel H1 gets a bit tough in stop and go if any system is functioning incorrectly.
        2006 duramax seems peak diesel to me, no extra equipment, but you don’t smell it either.

  • avatar

    I was reminded of the early days of California smog controls. Some guys had to run “nox boxes” I don’t remember exactly what they did except made your car run terrible. Put it on, pass the test and take it off.

  • avatar

    After what my local APR tuner did to my GTI’s ECU on a botched installation (and then proceed to lie/obfuscate) if I had a TDI, I’d take the performance/mileage hit before taking it anywhere near my local tuner.

  • avatar
    SCE to AUX

    I’m wondering how long it will take for the EPA to monitor DMV/DOT vehicle transactions, tracking VINs, and requiring a certificate of road emissions compliance document to accompany the title when buying or selling a TDI?

    This would effectively stomp out the tuners and scofflaws.

  • avatar

    I wonder who the next car company will be doing the same thing to pass the EPA testing. How many states have inspection rules? New York state only plugs into the computer and if no codes appear you are good to go. Even if the air bag light is on you are good to go. Note to EAF you have a problem. Have you ever owned a Subaru?

  • avatar

    If VW and EPA attempt to address VW’s violation by applying a software patch to the guilty cars, it won’t go well. Owners will sue VW for the hits to performance, MPG, reliability, and resale value. Owners will curse EPA for party-pooping, and possibly override the patch in the aftermarket anyway.

    So it would be in the interest of both VW and EPA, strangely enough, to leave the guilty cars alone. Instead:
    1. Figure out how much additional NOx the cars will produce over their expected lifetimes.
    2. Figure out how much money it would take to reduce that much NOx from other sources. You could use incentives: cash to utilities to convert coal-fired power plants to gas, cash to consumers to buy battery electric vehicles (BEVs) in states with clean energy grids. You could use direct action: install solar panels atop government buildings. You could use mandates: require VW to sell X amount of BEVs, and leave it up to them to figure out how. In designing the plan, include administrative costs, and focus on geographical areas where NOx reductions will help the most due to smog levels or acid rain or whatnot.
    3. Calculate substantial punitive damages.
    4. Add the figures from #2 and #3. That’s your fine. Suspend part of the punitive damages so long as compliance with the agreement is maintained.
    4. Implement #2.

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