AFR and slight tuning adjustment causing drastic changes?

[thegriffinator]

Just installed a thundermax on my '01 magnetti marelli ultra classic.

Guess I'm just trying to understand how the tuning items I tweaked could've had such a negative impact.

I installed the basemap for 88TC MM EFI, and it sounded good, but the AFR was rich (set between 12.75 and 13.1)

I took it up to about 13.7 idle and 14.1 cruise, about 13.7 WOT. Just a minute of idling and the motor was smoking and the heat shields were like touching a burner on the stove, so I shut the bike off. I thought 13.7-14.1 AFR was very reasonable and well bellow stoich (14.7)?

Next go around, I adjusted the timing by 1-2 degrees in the idle/low RPM area following wannabmayor's videos on timing adjustments, and richened the AFR to about 13.5 at idle, 13.8 at cruise.

The bike wouldn't even start after making these changes. It cranked over for about 3 seconds and then had the loudest pop I've ever heard come out of the exhaust.


I reinstalled the base map at the 12.75-13.1 AFR and left it be. Sounds good again.

Is this normal? Do most bikes have to run this rich or have no freedom in adjusting timing? Didn't think 1 or 2 degrees would take me from running well to not running at all

[rigidthumper]

Have you given it any riding time to measure/adjust (what they call "auto-tune")?
How old is the fuel filter? That can greatly affect fuel flow. While there, verify fuel pressure.
Are you running the original injectors?

[thegriffinator]

Have you given it any riding time to measure/adjust (what they call "auto-tune")?
How old is the fuel filter? That can greatly affect fuel flow. While there, verify fuel pressure.
Are you running the original injectors?

I am running the original injectors. A fuel filter change definitely couldn't hurt. I haven't ridden it at all, I assumed I should tweak the AFR first before riding

[rigidthumper]

It's supposed to be a suitable base map, and adjust to actual measurements by the O2 sensors during operation. You can then incorporate the measured changes into the map, and it should learn while you continue to ride. Try mid 14s in the highway range, upper 13s in the idle, and 12.8 WOT/hi load areas.

[thegriffinator]

I'll try that and replace the fuel filter, will update how it goes.

Thank you.

[thegriffinator]

Update: Have not replaced fuel filter yet, but more related issues have arisen. It isn't from the changes in tuning. I had gone on two great rides with this thundermax setup (basemap). I wrote the learned items from the autotune to the bike after the second ride, as I saw some slight changes throughout certain RPMs.

I get on the bike this weekend to go ride, fire it up, runs great. Idle up to about 1500 to go down the driveway, come to a stop, and it dies. Try to start it up, it cranks for about 3-4 seconds (same as before) and then one pop.

After a little experimenting, I just need to let it rest for a few more seconds before I start it back up, but anytime I let off the throttle the bike dies. I reinstalled the basemap with no learned fuel measures and still having the same issue. Anytime I rev the bike at all it drops RPM quickly and dies. This happens within 1-2 seconds of letting off the throttle.

Will look into further adjustments by the throttle body, and different tuning adjustments I can make in relation to decel. This is most certainly a decel problem, just have to figure out what is causing it.

[Tacocaster]

O2 sensors are supposed to be Wideband's (like Bosch) for T-Max but you say you have the originals installed? Originals are Narrowband, as I recall.

[Ohio HD]

He has a 2001 bike, so it has no O2 sensors from the factory. I would imagine he installed wide bands.

[hrdtail78]

I assume you have the complete conversion from tmax?  Have you followed the direction and done the initializing procedure.  This is how the ECM (Tmax) knows IAC position and if not set correctly.  Can bring problems that you explain.