Ran into some starting/running issues on my bike with T-max installed…need some help diagnosing;

Bike won’t start or stay running with Thundermax installed. I can take it off and put the factory ECM back in with the piggyback Dynojet Power Commander and it starts up and runs great.

Been through all the settings on the Thundermax, re-installed the correct map, re-initialized the system before trying to start, verified all the sensors and relays are good as well as the O2 sensors.

What gives with the Thundermax!?!

 

So is it safe to assume the bike is an 07 bagger and the unit is new? Send a run to Tmax, it's in the documentation on how to do it..

Do you have the O2 sensor wires crossed?

 

yes having O2 sensors reversed will cause the ECM to not adjust properly. Also with my 07 sportster i had to set the target AFR rather rich until the computer could build a map. Double check your o2 sensor wire installation and go from there. After that send a run to T Max. They are pretty good on helping.

 

Yep 07 Bagger…new to me T-max, was never installed on the original bike it was programmed for. I re-registered it and loaded the appropriate map as per their instructions.

I’ll double check the O2 wires but 99.9% sure they’re correct.

Can’t get it to start and/or run long enough to document a run…between the long cranks and backfires (both through the intake and the exhaust) it sounds like it’s being starved for fuel. But swap in the stock ECM and a Power Commander and it runs like a champ.

 

Send the info to Tmax. They'll help if they can.. Even if you are not the original purchaser. One thing possibility would be a weak crank sensor. The HD unit is sensitive enough to pick up the signal but the Tmax is not..

 

Heres also a list of what I’ve replaced in my quest to get this to work;

Crank sensor
TPS sensor
IAC valve/sensor
Battery
Stator and rotor
Starter relay(s)
Cleaned injectors
Fuel filter
Fuel pump
New fuel lines in tank
Fuel Regulator
Fuel regulator housing (Trask)
Fuel check valve and line to injectors

Have a new head temp sensor coming as well

 

Update…after swapping back and forth btw the Thundermax and the Power Commander I came to the conclusion that it was something in the map that was programmed into the Thundermax that was preventing the bike from starting and running.

After re-installing a bit “simpler” map for my setup and re-initializing everything the bike started up great and runs very strong. Guessing my hunch was right so hopefully fingers crossed it continues to run great.