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XiED impact on Catalytic Converters
It came to our attention that there were some unsubstantiated comments on some of the Forums that XiED's could cause catalytic converters to 'melt down' and result in a destroyed engine. These are completely fabricated stories that can easily be dismissed because issues as serious as this would have been reported in large numbers on the various Forums. The truth is just the opposite. Riders continue to report positive results when using the XiED and ViED's.
In our usual manner, we decided to present more substantial information how the XiED and ViED's interact with catalytic converters.
The information presented is factual and from reliable sources. We have listed the engineering references that can be verified and Harley-Davidson sources. While we are not going to present a detailed 'white paper' on this matter, there should be enough information presented for someone to start to understand what happens in a converter on a H-D motorcycle.
The first thing to establish is that 'Three Way Catalytic Converters' like those in the Harley-Davidson work most effeciently when the lambda value of the exhaust entering the converter is 1.0000 or AFR of 14.7:1. Mixture control must be followed up in a lambda closed loop control circuit. A review of the AFR tables in any canned Stage 1 SERT/SEST fuel map shows that for most riding conditions, later model HD bikes operated in closed loop mode at 14.6:1 AFR, meeting the criteria as defined for proper converter operation in Stage 1 configuration. These AFR maps should just verify that the OEM closed loop operation is consistent with proper converter operation. A copy of a typical HD AFR map is available for viewing on the TuneYourHarley.com site.
In order to understand how a catalytic converter reacts to a change in fuel mixture, next have to establish when a real change occurs. Many Riders/Shops/Dealers might think there is an impact to how the converter works when upgrades like exhaust and air cleaner changes are made. It was just established with a review of Stage 1 fuel maps that the AFR tables remained at 14.6:1, essentially Lambda 1.0000 (actually 0.9932). Even changes to engine size from 96CID to 103CID or 110CID by themselves are not going to change the Lambda 1.0 operational requirement at the converter.
Lets make the assumption that a Rider made Stage 1 upgrades, but did not remap the ECM. It is very common for a Rider to install exhaust upgrades and/or air cleaner upgrades to their bikes. Normal Delphi closed loop ECM operation dictates it will monitor the O2 sensor in the exhaust to restore the fuel mixture to the OEM 14.6:1 AFR. The exhaust mixture is back to the Lambda 1.0 required for effecient and normal operation of the catalytic converter.
Lets do a quick review:
- Catalytic Conveters work best when the exhaust entering them is at a 14.7 AFR (Lambda 1.00).
- HD bikes stock, with exhaust,air cleaner upgrades, with or without Stage 1 are going to run at 14.6 AFR, effectively Lambda 1 (Lambda 0.9932).
So far, the average scenario set up shows the engine and the catalytic converter will operate normally with Stage 1 upgrades. But lets see what happens as the closed loop fuel mixture starts getting getting a little richer.
Now is where you need to understand how a converter works and what fits within normal limits. We simplified some simulation methodologies as laid out in a 2004 ASME paper on catalytic converter modeling . Essentially the conveter allows the 'oxidation of HC and CO'  through the use of noble metals like platinum, palladium and rhodium. The oxygen required for the oxidation process is either present in the exhaust gas as exhaust-gas oxygen (resulting from incomplete combustion) or it is taken from the NOx which is reduced at the same time . We also speculate that in the case of Harley-Davidson engines, that the reversion impact in the exhaust system is also a source of oxygen.
Here is a critical statement in the normal operation of catalytic conveters as provided by Bosch Automotive Parts:
"the oxygen storage capacity of three-way converters plays a crucial role. The lambda accuracy in the dynamic range is typically 5%, i.e. fluctuations of lambda 1.0 in this scale are inevitable. However, these deviations are no problems because the converter stores excess oxygen in the lean phases for use in the following rich phases."
Any technichian who has logged raw data feeds directly from the H-D O2 sensor knows that the Delphi ECM is very conventional in its cycling between rich and lean in closed loop operation. There is no reason to believe that H-D is not operating within the basic parameters laid out in the Bosch Automotive Handbook.
Lambda calculation can be used to determine the percentage change in fuel added to the engine to create the new target AFR. It can be easily shown that FL-XiED-10, FL-ViED-10, X14iED, O2iED with AFR's under 14.0 are under this 5% change level by by looking at the lambda and % richer calculations. The XiED, FL-XiED-09, ViED at 5.5% richer for 13.8 AFR are slightly over the 'easily handled' range for a converter.
We also explored the possibility of an additional source of oxygen for a motorcycle converter that would not be present for an automotive converter. The OEM HD mufflers are much more free flowing, allowing fresh air to flow back into the exhaust to the converter. This is even more possible with the addition of aftermarket mufflers. There is the impact of reversion on H-D exhaust systems due to simple mechanical actions in the engine. These effects can be simulated by sophisticated computer programs and studied for their relative effect on engines. A detailed port flow analysis of a Twin Cam 96 engine showed peak reverse exhaust flows that could excede 160 feet per second for over 40 crank angle degrees.
These factors should easily raise the 5% oxygen storage factor to cover the 5.5% AFR of the standard XiED's.
So the facts surrounding the use of XiED and ViED in bikes with HD bikes with catalytic converters seem to come down to this:
- The average HD with exhaust/air cleaner upgrades and with or w/o the HD ECM Stage 1 download is running at a 14.6:1 AFR or Lambda 1.
HD 103 Stage 1, HD 103 Stage 2, HD 110 and HD CVO 110 engines are the same. 883, 1200XL and 1200XR engines are the same.
- A typical three way catalytic converter has a 5% tolerance designed into it. This tolerance is not a 'failure' tolerance in the sense that dramatic things happen, only that the effeciency of the converter to oxidize the polutants is reduced.
- The XiED/ViED's only alter the AFR from 4.1% to 5.5% over OEM 14.6:1, depending upon the model bike. This also assumes a 'steady state' on fuel enrichment, which does not occur in closed loop. The ECM will cycle, so the maximum value is achieved a very small percentage of the time. In any case, only some of XiED/ViED are only marginally at the 5% tolerance level.
- Converter limits would never seem to be exceeded by the 14.0 AFR FL-XiED-10 or FL-ViED-10 for the 2010>later Touring bikes.
- Converter limits would never seem to be exceeded by the 14.0 AFR X14iED, 14.2 AFR O2iED, 14.3 AFR Dyn OiED for 2007> bikes.
- Converter limits being exceeded seems very unlikely by the 13.8 AFR XiED, ViED, FL-XiED for 2007> bikes.
- Considering that normal open loop AFR's are already set at 13.8-12.5, the HD converter and ECM already have a mechanism in place to 'regen' and handle richer fuel mixtures.
- There are substantial numbers of Riders using XiED/ViED for 2010 and later bikes with converters. There are also Riders of earlier California bikes with converters that wer using XiED/ViED's. If there were problems with the converters, you would expect many reports of issues on the Forums. These do not exist.
- The XiED/ViED's are not capable of richening the fuel mixture on an engine as much as other popular piggyback controllers or software management. But there never seems to be any unfounded remarks pointed at these upgrades for their potential impact on catalytic converters. Not that I believe in conspiracies, but this could make you start.
- There is strong circumstantial evidence supported by computer simulation, that additional oxygen would be available to the converter through reversion in the exhaust system. This could raise the 5% tolerance level normally attributed to automotive converters signficantly. Definatley more than enough to maintain the efficiency to handle the small increase in fuel ratio by the standard XiED's.
Based on research and feedback available from Riders on Forums actually using the XiED products, any reasonable person would have to conclude that XiED's do not causing any problem with catalytic converters.
There is no evidence that Nightrider XiED product create problems with converters when used in a responsible manner.
 BOSCH, 2007, "Automotive Handbook", Catalytic Converter, pp 681-682, comments are paraphrased.
 Ponikakis,GN, Konstatas, GS, Stamatelos, AM, "Three-Way Catalytic Converter Modeling as a Modern Engineering Design Tool"
[3,4] BOSCH, 2007, "Automotive Handbook", Catalytic Converter, pp 681
 BOSCH, 2007, "Automotive Handbook", Catalytic Converter, pp 681
 Parts listed that alter fuel mixtures or replace OEM pollution control devices are for Race Only Purposes. Check with local regulations and laws to ensure compliance. In California, Race Only products must not be used on any vehicle that is registered or licensed for use on public roads.
 Engine Analyzer Pro V3.9, Performance Trends Inc.
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