When I bought my bike used this summer, it wasn't running right. Surging and bucking and not much power.

It came with 2 SERT's in the saddlebag, which was interesting. Looked around and decided to call The Dyno Difference here in Dallas. This guy is supposed to be very good and very thorough, one of the reasons I went to him.

First thing he does is check the oil level and suck some out, too high and shows me the air filter, soaked with oil. He cleans it, dries it and asks if I want to tune with or without the cover on it. We chose without.

Next he changes the plugs from the Champions that are in it to the stock HD plugs. Checks the wires, they are good. Drills holes in the Fulsac sport pipes for his wideband O2's, and away we go.

Although he is a TTS dealer, he is able to use one of my SERT's and makes several runs and is done. Tells me he thinks I have a bad O2 sensor, because as soon as he turns them back on, the front one is commanding the bike to go lean. Tells me to run a tank through and report back mileage. He also saves the tune to a USB and tells me to keep it with the SERT.

I report back I'm getting about 31 mpg in town. He tells me to get it out on the road and get back to him. Finally manage to and still getting the same. I change out the front O2 sensor, still getting the same.

The bike runs 100% better than when I got it. Runs fantastic. A slight amount of gurgle and very occasional pop on decel. Heat really wasn't an issue this summer, but some of that could be due to the pipe.

Emailed Ed a couple of times, and he has told me that since I came in, he has seen one other bike have the same issue. Haven't taken it back yet, but wondering if anyone has an idea of why the bike would be commanding a lean condition?

 

Well since you've replaced the o2 sensor, I would talk to Ed and see what he suggests. I would think because the front o2 was causing it to go lean and thought to be bad, that you'd want to have that corrected with the new o2 sensor.

And by the way, that's a very respectable chart. Nice smooth curves in respect to what it looked like before the tune.

 

Thanks for the response. I sent Ed a followup, will see what he says. Here is a copy of the last email I got from him.

Something is messing with the OEM O2 sensors it is either the open exhaust or the pipe does not have them seperated enough. You have talked with FullSac and they said no issues unless wide open mufflers. Correct me if I do not have this quite right, but you have wide open mufflers.
When I was tuning and turned the sensors back on I believe the front sensor(correct me if it was the rear) was not acting right and at the time I said it is either pipe or sensor. What it was doing was going .5 ro 1.0 AFR points lean as compared to the target AFR. This means the ECU is going to add fuel to compensate or to get it back to target. When I tuned it in open loop and checked all this it was not doing this as it was going right to the target.

We are back to the same question, is it the front O2 sensor or is the header/muffler combination?

If it were my bike I would buy a new O2 sensor for the front, install it, and give that a try. This is the least expensive of the options. Buying new header and or muffler gets pricey. I would consider changing both sensors out so that you start with (2) new ones and then see how the MPG goes. If it does not change or improve then we will know it is the header/muffler combination. I have seen this several times where it ended up being one or both OEM O2 sensors.




He had originally suggested removing the cats before a tune, so I ordered the Fulsac sport pipe. The bike already had Rhinehart mufflers on it when I bought it. Pretty sure there isn't an exhaust leak everywhere (he checked and tightened the header bolts).

Really looking for a second opinion on whether Ed is on the right track or not. I did call Fulsac and speak to them and they told me (no surprise) that they haven't had any issues tuning with their sport pipe.

 

I still say check with Ed. He is your tuner and he knows exactly what he did and where. I do know from talking to Steve @ Fullsac that they've had issues in the past with Rinehart 4" mufflers and that Sportpipe, just something about that combination. I as well had issues back in 10 or so when Ed tuned my 09 with Rinehart 4" and Sportpipe. As luck would have it, the Sportpipe broke shortly afterwards at a weld while in the Smokey Mountains and instead of another Sportpipe, I asked Steve to replace with DX and I'd pay the difference (it was roughly 2 weeks old at that time). I changed out the headpipe and took it back to Ed. The issues he was seeing were now gone. Of course if you talk to Fullsac, they'll tell you it's the Rineharts, if you talk to Rinehart they'll tell you it's the Fullsac head pipe. Fullsac has had tremendous success with that Sportpipe and Rinehart has had tremendous success with their mufflers.


On a side note, I've used Ed for years to tune my bikes and never had any issues with him whatsoever, so maybe my opinion is a little biased but nonetheless, he's an excellent tuner and well respected. I drive over 4 hours to get my bikes to him when needed and I'll continue to do so. I'm sure it took you a while to come to the conclusion that Ed was your guy. Have a little faith in what he tells you as I know Ed well enough to say this; if something is wrong with what he did, he has no trouble making it right. Stand up guy.

 

I have no complaints with Ed and just scheduled an appointment with him to go over the tune again.

I was really trying to find out if anybody else has experienced this problem, and thank you for confirming it. Since the arena of dyno tuning is not something I play in, it is always nice to get confirmation from others as to what is going on.

 

I do some work on my HD Triglide with the TTS Tuner and it sounds like a simple troubleshooting tip is in order.
My Trike has the O2 sensors plugged into the bikes wiring right next to each other, connectors side by side. Why not ask Ed to swap the sensors by simply using these connectors. No real physical work and if the issue with the front driving lean goes to the rear cyl the O2 sensor is bad. It is the easiest test with no cost that identifies the front oxy sensor issue.

Wish you luck and please keep us posted,

Ride Safe,
Bob

 

Can't just swap them at the connectors. Why not just knock it out of closed loop and reset the afv's when you flash the map. That should eliminate any feedback from the o2's.

 

I have seen the O2's crossed a couple of times and one O2 will read way off from the other. Easy to check and if you have to swap the sensors will have to be swapped in the pipes as plugs are interchangeable. The Gray goes to the front and Black to back cylinder. It will also usually cause more issues than just leaning one cylinder out.

 

Ed went through the entire bike again, replaced the plugs again, checked the tune and we decided to turn off the O2's and run it in open loop for a tank or two and see what the MPG's do. No charge. Can't beat that customer service.

 

Ed is a good guy.. Give him the opportunity to help you and he will.