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ECU reset?

ruinator

NAXJA Forum User
Location
New Mexico
Last week I upgraded to 19# injectors. I drained/reset the ECU. My jeep runs great, great upgrade. My problem now is the check engine light. In researching threads I have read it may take "50-100 cycles" to relearn or reset. I reset the OBD II and with a minute it came back on (error 43, misfire) It runs pretty dam well, maybe a stutter/misfire at low RPM exceleration. I assume this is just the computer relearning? How long should the 50-100 cycles take? Should I redrain the ECU? Any help appreciated!
 
CEL means you have a problem.... How are you reseting the ECU? With a scan tool or by pisconnecting the battery? A Reset should turn off the CEL, and clear codes. If you are getting CEL after reset then you have a code the is kicking on start-up, or you are not really getting a RESET.
 
I am wondering if I am not getting a "complete" reset. I d/c the battery touch the ground to the positive for 30 seconds with the ignition on. good enough?
 
I am wondering if I am not getting a "complete" reset. I d/c the battery touch the ground to the positive for 30 seconds with the ignition on. good enough?

That'll do it, thus, like stated above the problem is a legit fault as it threw the code after the clear of the ecu.
I will assume you have tried several resets and the cel keeps lighting up. Can you give some info on what exactly was done, injector condition, etc.?
 
i bought used ford injectors. Soaked them in cleaner. blew them out with cleaner while activating them with a 9v battery .5 sec at a time. Replaced all orings. All appeared in good condition.

Maybe I am off track but, the Jeep runs GREAT. I only done 2 resets. One with the battery, 1 with OBD scanner
 
The CEL came about 5 min. after erasing w OBD scanner. Is just resetting a few times an option? Myoriginal concern was how long for the ECM to relearn the system. I think the injectors are fine since it runs so dam well
 
edit- here we go- found the same basic post on a number of forums

Info from a JEEP Technician -

This very simple procedure will Erase the “Adaptive Memory” stored inside the PCM and allow a new “Adaptive Memory” to be developed.

After performing this procedure the PCM will re-learn and store into Adaptive Memory your engines performance characteristics.

Please perform these steps exactly as they are written, in the order they are written. This will cause the adaptive memory in the PCM to be erased and cause the PCM to go into Fast Learn Mode adaptive mode.

Disconnect the POSITIVE battery Terminal and touch it to ground ( not the battery negative terminal ) for 30 seconds. The engine block or the A/C compressor pump will work as a ground. (This is to discharge the PCM capacitors, which maintain the Adaptive Memory.

Reconnect the Battery Cable
Turn Ignition Switch to the “On” position but DO NOT start the engine
Turn Headlight “On”
Turn Headlights “Off”
Turn Ignition Key “Off”


The PCM Adaptive memory has now been flashed, or erased from the PCM.

When you start the engine it will be running off a set of pre-programmed tables that come with the PCM from the factory.

When you get the engine up to operating temperature the PCM will start to collect data for the “Adaptive Memory”.

The PCM will collect data for Adaptive Memory for the first 50 Warm-up Cycles.
 
Last edited:
Computer reset isn't going to fix
a stutter/misfire at low RPM exceleration.

The pcm will pick up on that misfire and flag it as such. Causes? Could be lots of things.. dirt down the injector boss that caused a valve to hang- sticky/ clogged injectors- poorly seated injector connectors- etc etc.
 
Tried it on my 99. My P0455 code /cel got fixed today(passed smoke test and replaced a hose) but the yellow emissions warning on the obdII scanner will not go away. I tried to erase the code on the scanner and that worked ( cel went away). But I tried to reset the ECU and the yellow warning is still on the scanner. Any suggestions?
 
I followed the instructions listed on this thread. But I will disconnect the pos terminal over night and try again in the am. I will admit I did it in a hurry about 11pm and may have messed up....it's a gift!
 
was the part # 0280155703 ?
I'm trying to upgrade my 94 wondering if that is the correct injector for my xj

This thread is 10yrs old with the last visit from 16Guns was in 2012. The injector in question would be a stock size injector for a '94.
 
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