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Offline Tittle Diesel Performance

Thinking about a programmer??? Read this!
« on: June 08, 2019, 07:10:37 PM »
Ok so you’ve just installed that awesome exhaust (or cut the muffler off) now your worried your gonna damage the engine because the manufacture said so.... well wait a second... for those who don’t know programmers aren’t required for O2 sensor equipped vehicles. As long as the O2 has about 8-18” worth of exhaust tubing behind it (between sensor and atmosphere) then your alright! Make sure the flex joint BEFORE the sensor absolutely does not leak!!!! Any extra fresh air flow into the exhaust across the sensor will offset the reading and dump fuel into the engine trying to offset for this. Worse the leak, more fuel gets thrown BUT to a point, there is a range it’s allowed to read in before setting a code then running in an open loop/ O2 Off state which is a pre set map to run in loosing self correction.

Now one thing to consider if your dead set on programming, most systems bypass the O2, keep in mind this looses all self correction factoring, altitude, barometric pressures, density altitude changes etc etc that aren’t picked up by MAP and IAT sensors are lost. Granted MAP and IAT are really all you need technically...but for efficacy and there for power, fuel consumption, and reliability O2 correction is the way to go. Engines now adays (I’ve verified with CFMOTO) to be tested to 100% duty cycles meaning with all functions working properly the engine can endure max power output for 100% of a time frame. In fact CFMOTO tests each engine on a stand before they go in the vehicle but the design engine was tested to 100% cycling. Does that mean 110* in the desert running at full load with zero movement/airflow that it won’t over heat??? NO!! But what’s great is as parts become heat soaked and the burn changes or detonation occurs the O2 will see changes in the exhaust and offset for it!

New engines due to EPA restrictions run lean with very low ignition timing to burn hot and clean, if your exhaust glows under long high loads then don’t be surprised, doesn’t mean there is an issue just high egt’s to meet epa standards. Oh and most headers are thin wall pipe which are gonna glow anyways...

So take into account when shopping that will the $300-700 upgrades for 2hp at the tire really benefit? The exhaust was made to flow enough to make its rated power, so a free flow likely won’t make enough difference to feel honestly. If you want sound then go for it, I get it a cool twin lumpy idle is cool or a thumping single but don’t expect the world. Backpressure isn’t required for an engine to run, don’t listing to idiots say “well you’ll burn the valve” no... you won’t as long as you have a long enough header length to keep cold air from going back up the exhaust, that burns be valve.

So think hard before companies take your money and your not happy...
-19 Zforce 500 50” wide, 2” front 3” rear wheel spacers, EX flares, dialed in stock suspension
-19 Cforce 800XC 50” wide, 60” Denali plow, Kolpin basket, Polaris lock and ride kolpin grips, *working with dyno jet for power commander 5 adaption*...pushes the 1 ton trucks in and out the shop, 6500-9000 lbs up inclines without breaking a sweat!

I’m Brad, Diesel (and gas) Mastertech for 12 years with background in performance engineering and development, Tittle Diesel Performance Owner and Head Tech


Offline ctdls

Re: Thinking about a programmer??? Read this!
« Reply #1 on: June 09, 2019, 07:03:00 AM »
Lots of information here, I need to see if I'm understanding correctly.

You are describing a closed loop system using a wide band 02 sensor rather than a narrow band. Being there is a small catalytic converter I've always assumed narrow band to maintain stoich, then switching to open loop for high load conditions. In OL they would use mapped fueling based on IAT & MAP.

Or is it a closed loop narrow band system using stoich for WOT? I've thought these motors are lean WOT & that would explain it.

It is impressive how fuel efficient & clean these motors run, I'm not so sure long term reliability durability isn't paying the price.
ZF 800 LX Trail, stock for now.......not for long.