This extra fuel is used to increase exhaust gas temperature in both the DOC and DPF to more than 1,000 degrees F in order to burn off the soot in the DPF. During active regeneration (commonly required on trucks that idle a lot or aren’t worked hard), the ECM calls for fuel to be injected on the engine’s exhaust stroke. Passive regeneration occurs when the engine is producing sufficient heat to keep particulate matter low, such as in heavy towing or hauling situations. There are two forms of regeneration: active and passive.
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To keep the DPF from becoming chock full of particulate matter, a process called regeneration takes place, which effectively incinerates most of the soot buildup within the DPF. Some growing pains existed in GM’s first go-round of equipping the Duramax with a DPF, as many of the units used in LMM applications (’07.5-’10 Silverado and Sierra HDs) were prone to cracking and leaking. Designed to trap harmful pollutants that aren’t completely burned off in the combustion process, the DPF eventually accumulates enough soot to be periodically burned off through a process called regeneration (more on that below). In order to lower particulate matter emissions by 90 percent, the LMM came equipped with a diesel particulate filter (DPF) located down stream from the diesel oxidation catalyst (DOC).
![dpf delete lmm duramax dpf delete lmm duramax](https://lh5.googleusercontent.com/-AV_77X_K0OQ/VCF2MYFuAWI/AAAAAAAAItc/5n2fJYz2Bfo/s800/20140919_171600.jpg)
Fun fact: Every completed 6.6L Duramax undergoes an 8-minute hot-test on an engine dyno to verify its performance and build quality before it’s allowed to leave the Moraine, Ohio production plant. In April of 2007, engine number 1,000,000 was put on display at DMAX Ltd. It was during the LMM’s tenure that GM produced is 1 millionth Duramax. OHV, four-valves per cylinder, single camīosch high-pressure common-rail, direct injectionĮxhaust gas recirculation (EGR), diesel oxidation catalyst (DOC), diesel particulate filter (DPF)Ĭast-aluminum with six 14mm diameter head bolts per cylinder (with sharing)Īn Early-Production LMM Becomes Duramax Number One Million
![dpf delete lmm duramax dpf delete lmm duramax](https://cdn.drivingline.com/media/2310254/003-duramax-lmm-exhaust-aftertreatment-diesel-emissions-data.jpg)
1) It received cast-aluminum heads superior to any other Duramax produced, 2) it was equipped with revised injectors which provided both added power and more complete combustion and 3) it came bolted to the all-new GMT900 platform and was wrapped in a fresh body style.ĭon’t forget to tune in for Part 5, where we spotlight the LML-the Duramax that brought more robust internals, a higher pressure injection system and additional emissions equipment to the table. But outside of those shortcomings, the LMM came with several upsides.
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In the aftermarket, cracked pistons remain common thanks to the LMM’s use of the same pistons employed in the LBZ.
![dpf delete lmm duramax dpf delete lmm duramax](https://www.flopro.com/img/products/dsl/gmcdpf1112.png)
The LMM is no different, with its labyrinthine-like exhaust after treatment also contributing to poor fuel economy, diluted engine oil and reduced long-term engine longevity. Its bore of 4.06 in and stroke of 3.9 in also created a displacement of 405 ci.Īs is the case with most modern diesel engines, emissions-control devices account for the majority of premature failures. The LMM Duramax brought 365hp and 660 lb-ft of torque to the table along with its emissions equipment, including exhaust gas recirculation, a diesel oxidation catalyst and a diesel particulate filter.
![dpf delete lmm duramax dpf delete lmm duramax](https://dalessuperstore.com/files/f143358805.png)
Despite the added complexities of the new emissions control system, GM was still able to increase power output and remain a step ahead of Ford and Dodge. Basically an LBZ saddled with an intricate exhaust after treatment system, the LMM remained architecturally similar to the Duramax mills that preceded it.
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For GM, an updated version of the 6.6L Duramax, RPO code LMM, was all that was in store, whereas Ford and Dodge unveiled completely new power plants (the 6.4L Power Stroke and the 6.7L Cummins, respectively). That year, Ford, Dodge and GM all released engines designed to meet the new particulate matter (PM) and nitrogen oxide (NOx) limits mandated by the Environmental Protection Agency. Increased emission regulations began to alter the diesel landscape significantly in 2007.