Tiico Owners Page



 The Tiico ECU

-Current Third Generation ECU's part# RSU 906 258D/E

---These were designed using the A2 Fuel Rail Kit, with 037 906 031AK injectors and correct pressure regulator, along with the 2.1L Cat and 1.9L rear muffler, and current 4-wire 02 sensor.  We also made sure they were using the correct map senor that had parameters to operate below 15 degrees Fahrenheit and verified personally that they actually used all the correct components we sent them when they did their calibration.

---The result is a closed loop, fully calibrated ECU.  They do not throw erroneous 02 codes, or any others that are not warranted.

---The ECU's self-learn at altitude and wipe the pants off of the earlier systems in regards to being more emissions friendly.

---Ignition timing is to be set @ 6 BTDC using proper Basic setting procedure

---They are to be run on a minimum of 91octane. 




-First Generation RSU 906 258 , and 258 A

---This system was designed to run water boxer Injectors (0 280 150 206)

---It is capable of clearing DTC’s, but most will return within a day or two.  Although the system obviously recognizes the O2 sensor signal.

Due to incorrect parameters in the file formatting they will continue to throw fault codes showing incorrect 02 sensor signal, or no O2 sensor signal, and adaptation limits either exceeded, or not met.

---This system is not capable of learning on its own over time and cannot automatically adjust its fuel mapping parameters at altitudes above sea level.  

---Symptoms include rough idle.  Cold start issues.  Erroneous codes.  Eventual hard fault**

---If you have one of these systems and it stores the fault code or DTC:  **"Oxygen sensor control limit exceeded ", and cannot be cleared due to a hard fault, the ECU basically fried, or technically locked out from the oxygen sensor portion of the file formatting.   

---Replacements for the “258 A” ECU’s are not available new.




-Second Generation ECU's part# RSU 906 258 B or C:

---They are a primitive "closed loop" system using a 4-wire O2 sensor with the data wire going to pin #38

---They were designed using the water boxer injector and a mild performance cam of 268 instead of a 264.  The mild cam was not that big of a deal except at idle until the engines broke in.

---These ECU's learn on their own, and do not need to be adjusted at altitude

---Ignition timing on these is to be set @ 6 degrees BTDC using the proper basic setting procedure.

---In summary if you have ECU # RSU 906 258 B/C make sure you are using water boxer injectors…your system will run much better.  

And make sure the timing is set @ 6 BTDC.  If you have this system and have already upgraded to the A2 fuel rail set-up…you'll need to update your ECU as well.

---Replacements for the “258 B/C” ECU’s are not available new.





**REPLACE THAT OLD & BRITTLE WIRING!  NEW Wiring Harnesses are Available, already set up with the 4-wire O2 Sensor**