Hondata

I am running a swapped JDM B16 Engine in my Honda & now i am in process to turbo it i have already build the block with Darton MID Sleeves, 84MM CP pistons, rods , PLX R500(not installed yet) & Garatte GT35 R turbo(not installed yet) etc , I had JDM P30 OBD1 ECU & hence i ordered S300J to fit my ECU.

After rebuild i was running NA during running in period, with stock ECU i.e (without hondata installed), later after run in period i begin with setting up of Hondata,

I got the S300J installed in the ECU exactly as mentioned in the S300J manual.step by step.

After installing the daughter board & connecting it to my laptop & i gave the ignition, the laptop detected the S300 ECU & loaded all the drivers, in the Smanager i can upload download calibration files, do datalogging etc without any problem. but after few weeks i notice a strange but weird problem, whenever first thing in the morning i start the car the CEL light comes on & ECU runs in Limp mode, theres nothing i can do, the smanager cannot datalog anything, i had to switch off & restart again then it works fine, once it starts then there's no problem, the car runs fine & i can upload/download calibration files do datalogging change parameters & upload it etc, this problem doesnt happens everytime but only sometime may be 3-4 times in a week & it happens only during startup, i have recchecked the socketing but could not find anything wrong & i dont have any other S300J nor any other ECU where i can test my already socketed ECU. also one more thing i have noticed while datalogging in higher RPM ranges, is that some time the software freezes i have to close smanager & restart again to get Online, but this happens very rarely.

Hence i am doubting either ECU or Socketing could be a issue, i have checked the wiring for proper grounding & even given a direct ground to ECU Case from block, I have upgraded all the firmware pertaining to S300J from Hondata website & running latest version of Smanager downloaded from Hondata but this frequent but occasional problem of "CEL light coming On during startup" is still present, and now its getting on my nerves. next i want to install my wideband but before that i need to solve this problem.

What should i do?

Are you using resistor or non-resistor type spark plugs?

I am using NGK BKR6EIX-11.

Chip in some suggestion guys.

Limp mode in cold weather = socketing. A dry or cold solder joint will stop making contact when the temperature is low. You can sometimes check this by using a freezing spray on the socket.

In morning the temperature is not that cold here & it doesnt happens every morning,

Morning>Engine Start> Check MIL>Switch Off>Restart again>normal, all this with in 10 secs.

also i forgot to mention it happens in afternoon also or any time during startup (sorry about that) if you drive for 1 or 2 or 4 or more hrs it works absolutely fine once started, but when i halt & switch off and start again with in few minutes, then Check MIL comes on (the engine is still warm).then i have to switch off & start again then it becomes normal, All this things are pointing towards the startup mechanism some thing is going wrong somewhere during startup, i dont think its socketing otherwise it would have given me problem during driving also & i have driven hard doing continues datalogging for hrs, no problem whatsoever.

What is the voltage doing at startup. You may be dropping very low in voltage and that is affecting the ecu.

I also have this start up problem with the s300j. It seems to be more frequent when I updated the latest firmware.

Spunkster wrote:What is the voltage doing at startup. You may be dropping very low in voltage and that is affecting the ecu.

Will check that & tell ya.

The Voltage on startup is normal.
My Battery was relocated to Boot, I put new wires (thicker) & did proper grounding (-)ev Terminal of Battery to the body,chasis & to the engine at different locations. So far the problem has not surfaced.