ECU Flashing

[IFlyAZ]

Have a 2002 5.0 engine recently rebuilt with a 5.7 long block. Original manifolds and throttle body, etc. Starts and runs well at most throttle settings. It does however seem very choppy when changing throttle positions. Takes a moment to settle. Can the Control Module be flashed? I have flashed my four stroke Kawasaki motorcycle ECU and the bike runs much smoother. Am I missing something? Thanks.

 

[alldodge]

Welcome
Bold print is not necessary
Some ECM can be reflashed but depends on which one you have. If you have a MEFI then yes it can be done. If something later then that's a maybe. What is you motor serial number?

 

[IFlyAZ]

Original engine 5.0 GXI-A #4012055334. Didnt realize the bold was on...

 

[alldodge]

Your motor uses a MEFI-3 or 4 (probably 3) ECM and if can be reflashed.

To do it, will need something like MEFIBurn
Will need to erase the program and build a new file. Need AFR gauge and install O2 sensors in the exhaust to tune.

Either that or send out to have a approximate tune loaded

 

[IFlyAZ]

Your motor uses a MEFI-3 or 4 (probably 3) ECM and if can be reflashed.

To do it, will need something like MEFIBurn
Will need to erase the program and build a new file. Need AFR gauge and install O2 sensors in the exhaust to tune.

Either that or send out to have a approximate tune loaded

That sounds plausible, any list of known performance shops that can reflash my ECM? Got the bike done for $350. Don't have the background to operate the MEFIBurn software personally. Thanks.

 

[alldodge]

I have not used any of them, but search "reflash marine ECM" and some will come up. Hardin marine and OBD Diagnostics have been in business a long time

 

[dingbat]

That sounds plausible, any list of known performance shops that can reflash my ECM? Got the bike done for $350. Don't have the background to operate the MEFIBurn software personally. Thanks.

Have you tried a hard reset of the ECM back to factory?

 

[IFlyAZ]

Have you tried a hard reset of the ECM back to factory?

Not sure what the steps are to complete this task. Also, my issue is the replacement of the 305 long block with the 350 long block in the rebuild. If resetting to factory, might it not just reset the 305 block params...?

 

[alldodge]

Not sure what the steps are to complete this task. Also, my issue is the replacement of the 305 long block with the 350 long block in the rebuild. If resetting to factory, might it not just reset the 305 block params...?

Have not heard of a hard reset with a MEFI

Also my apologies for reading carefully enough the first time. I thought you rebuilt the 305 with bigger cam and other stuff. Going from 305 to 350 you have another option. You could just buy a 350 MEFI,

Might find a used one in the Offshore Only forum wanted section

 

[QBhoy]

You’ll likely either need to get the appropriate ecu for the 5.7…or maybe not much more effort..would be to go to the only authorised outfit that can mess with the ecu…that would be whipple…be silly not to throw on an accompanying blower too

 

[dingbat]

Have not heard of a hard reset with a MEFI

ECM are adaptive controls. They store programed values in EPROM and working/actual (sensor) readings in ROM.

A “hard reset” in effect replaces the “working” values with the preprogramed values stored in EPROM

MEFI 3 manual

Non-Scan Diagnosis Of Drivability Concerns (No DTC's Set)
If a drivability concern still exists after following the OBD system check and reviewing the Symptoms section, an out of range sensor may be suspected.

Because of the unique design of the MEFI system, the ECM wil replace sensed values with calibrated default values in the case of a sensor or circuit malfunction. By allowing this too occur, limited engine performance is restored until the boat is repaired.

A basic understanding of sensor operation is necessary to be able to diagnose an out of range sensor.

If the sensor is out of range, but still within the operating "window" of the ECM, the problem will go undetected by the ECM and may result in a drivability concern.

Good example of this would be if the coolant sensor was reading incorrectly and indicating to the ECM that coolant temperature was at 50°F, but actual coolant temperature was at 150°F. This would cause the ECM to deliver more fuel than what was actually needed by the engine. This resulted in an overly rich condition, causing rough running. This condition would not have caused a DTC to set, as the ECM interprets this as within the operating "window."

To identity a sensor that is out of range, you may unplug the sensor electrical connector while the engine is running. After about 2 minutes, the DC for that sensor will set, illuminate the MIL, and replace the sensed value with a calibrated default value. If at that point, a noticeable performance increase is observed, the non-scan DTC table for that particular sensor should be followed to correct the problem.

NOTICE: Be sure to clear each DTC after disconnecting and reconnecting each sensor.