Has anyone changed exhaust and a/c without re-mapping and then did a dyno run? I'm curious as to what the results are concerning fuel mixtures. I'm only interested in actual results on bikes with closed loop systems. One side of the argument is that the bike would run lean, while the other side says that the ecm would still be able to maintain the stock AFR. Actual dyno results would answer the question. Just wondering if either theory has actually been proven.

 

Great question. I hope someone has a factual answer.

I can tell you than a regular automotive ECM will adjust within a pretty wide range. Several years ago I replaced the AC, exhaust, and changed the pulley to overdrive the supercharger on my Ford Lightning. The truck has a wideband meter so I can monitor the A/F ratio and it showed the ECM adjusted to the changes the without any problems and ran the same A/F ratios before and after. Adding an extra 6 PSI of boost is way more significant than swapping out the AC and/or exhaust.

For those interested in the rest of the story, the stock tune left a lot of the potential HP gains from the mods on the table so I eventually added a custom tune to the ECM.

 

It's been my experience that even with a re-map, the bike will not run as it should. I think a fuel management system of some type would help keep the A/F ratios right and the bike will run cooler and with more power.

Also, don't know if I'd want to put a bike on a dyno after intake and exhaust mods without at least a re-map - but that's just me I guess...

 

A guy in the service department told me on my 09 I should not make any changes to my exhaust system "unless" I do the FULL dyno to map everything. He said the stock ECM will only adjust 5% either up or down for the mix which isn't much. Coming from the service tech I know it wasn't a salesman just trying to sell me that service.

I too would be interested to see how far off it would be on a dyno. On my 07 I didn't notice much of a difference on my EGC with having "just" the SuperTrapp SE's on but maybe I was a little lean?. My 07 did feel REALLY hot compared to my new 09 SG

 

soundman:

I can tell you the answer. I bought my '07 RKC used. It had the SE A/C installed with stock exhaust. At the time of purchase I asked the dealer to check to see if the Stage 1 download had been done. It had not been done.

A few weeks later I met the original owner and he told me that he had V&H exhaust and a PCIII on the bike, but put the stock exhaust back on and removed the PCIII before trading it on a '08 Streetglide. He left the SE A/C on because it would not fit on his new '08.

Concerned that my bike might be running too lean, I had it dynoed at an independet shop. My A/F ratio was 15.1-15.6 in closed loop mode. In open loop mode the A/F was in the mid 13's - low 14's. While you can change only the exhaust without modifying the fuel, there is no question that the O2 sensors cannot adjust enough for a higher flow A/C.

I subsequently installed the SE Street Legal slip-ons and had the Stage 1 download done. I have about 4500 miles on my bike and plan to have it dynoed again when I get the 5000 mile service done.

 

I stopped by an Indy today after work that specializes in dyno tuning and talked with the tech/owner there. He explained to me that there is a certain window of the parameters in the ecm that cannot be changed even with the SERT. This window is based upon a set rpm and throttle percentage. This is known as the closed loop operation. Once the rpm's/throttle percentage moves out of this area is when the ecm goes into open loop and the changes (re-map) become effective. The ecm begins to follow the 'map' rather than the 02 sensors for fuel management. The 'window' is the epa test range that the factory has to follow. It seems that this would be your normal cruising rpm's (up to about 2500+-). Outside this window is fair game to change parameters (legal).

IF THIS IS CORRECT...

You could change the exhaust/intake and be fine in the cruising range, as the ecm would have no problem maintaining the AFR. However, if you opened the bike up and ran it hard, the bike would lean out, because the factory map wouldn't be suffeciant for the increase in air flow through the engine during open loop operation.

At least this is what I believe he explained to me. I'm taking my bike in to the dealer next week to have pipes, a/c, cams, and sert installed and then dyno tuned. I'll quiz the tech at the dealer more to see what he says concerning the matter and post my findings.

 

If the factory settings are in the 15.1-15.6 range, then that would mean the ecm/02 sensors were actually working. It looks like your open loop numbers improved the situation. Anyone know what the factory AFR is? I know they are pretty lean, but what's the actual target? Can you post the dyno sheet? I'm curious.

Thanks

 

soundman: The Factory target A/F is 14.7. That is what is mandated by the EPA.

Here is a post I wrote several months ago. It may not be 100% accurate, as several others have pointed out, but it is essentially correct:

The 2006 Dyna Series and all of the 2007, 2008 and now 2009 Harleys are fuel injected and have oxygen sensors in the exhaust pipes to control and limit emission in compliance with EPA regulations. The maximum legal air fuel ratio is 14.7:1. This is very lean and as a result, these bikes tend to run hotter than earlier bikes.

For these 96" twin cam motors, the factory ECM operates in 2 modes - closed loop and open loop. In closed loop the O2 sensors tell the ECM how rich or lean the exhaust gases are and the ECM adjusts the fuel flow to each cylinder to maintain the A/F at 14.7:1. Closed loop only works in the range where the throttle is open from 0% to about 40-50%. This is where most of us ride normally. Above about 40-50% throttle, such as at high cruising speeds or fast acceleration, the ECM operates in open loop mode and the O2 sensors have no effect. The ECM then gets signals from other sensors in the engine and it does a decent job adjusting the A/F to a much richer range than 14.7:1.

On these bikes adding an air cleaner and mufflers that flow better than stock causes the bike to run leaner than 14.7:1, resulting in a hotter running engine. The ECM and the O2 Sensors can no longer adjust the closed loop A/F ratio back to 14.7. On my bike the A/F was 15.1 after adding these two items. You need to do something else to correct the lean running. With the Harley SE Street Legal slip-ons and the SE A/C, the Harley Stage 1 download adjusts the timing, raises the rev limiter from, I believe, 5500 RPM to 6200 RPM and somehow (but no one knows for certain how it does this) brings the Air/Fuel ratio back to the legal limit of 14.7:1. From my personal experience, this setup definitely provides some performance benefit. However, it does not provide any cooling benefit over a stock bike.

Unless you are planning to go beyond a new exhaust and air cleaner with your bike, you really only need to concern yourself with richening the closed loop mode.

There are many ways to get your bike to run richer (ie: cooler) and there are as many different opinions as to how to best accomplish this as there are Harley riders.

Your choices depend on how deep your pockets are. You can have your dealer install a SERT* and set up your bike on a dyno, You can add the Nightrider O2IED's or XIED's, a PC III, a TFI or a V&H Fuel Pak or other similar devices made by other companies. Some of these may require dyno tuning to set them up properly. Another choice might be a ThunderMax or other similar device that is self programming.

Some of these are add-ons to the factory ECM and others replace the factory ECM. Some of these use the factory O2 sensors and others require you to disable, remove or replace the factory O2 sensors.

 

Mr Clean,

Thanks for the actual numbers. Your post reflects basically what a dyno guy told me the other day (see my summary above). However, he said that the closed loop area could not be modified on a 'street legal' device such as the sert. He said that the open loop area is where most of the re-mapping work is done during a dyno tune. Also, just to make sure we are understanding AFR, 14.1 is a richer mixture than 16.1. Correct?

I'll be having my bike worked on next week with stage 1 plus cams. They are going to dyno tune it and I'm getting the before and after results. I'll be there when they do the tuning, so I'm going to comfirm these ideas with them. I'm still doing my homework on this subject as I like to know exactly what's what, not just what somebody thinks. I like to see the proof. Thanks again for actual numbers.

 

Well to help you on this question Jamie at fuelmoto changed just the slipons on his own 09 harley. they have the dyno sheet posted on their web site. it showed a +5 hp and +7 torque just by adding the slip ons. I called him to talk about this and if the new slip ons would turn blue without a mod to the EFI. He told me as long as I left the stock air cleaner that the slipons would not turn blue. He also said the new power commander is 4-6 weeks out and will be called Power Commander V for the new 09s. With this info I ordered the slipons and will post to you all when I get them installed.