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Hi everyone I'm having an issue with a swap I just put into my 94 integra i put in a jdm B18C got a chipped p28 ecu with hondata s300 v3 chipped everything's good when warm but wont stay on when cold I have to hold the gas till it gets warm for it to stay on any way I can fix that with out have to buy new parts plz any advice
If the winter where you live is really cold and you have the combination of bad idle control valve and bypassed coolant, that problem will likely develope
Ok don't remove anything just yet this is most likely a issue with the tune and sounds like you have no cold start adjustments,
Ok so go into S manager for the Hondata S300 on your laptop, if you don't have one get one and download the latest S Manager software and open it up.
First put the key to on but don't start engine, connect the laptop to the ECU with the USB cord. Once S manager is open click the online tab at the very top and then click download, then click parameters at the top right,
Then click the Fuel Trim tab ,
Then where it says post start fuel adjustment enter a value like 15% to start with.
Once you enter this new value click the Arrow pointing up at the very top of the screen,
Another thing you can try if it still has trouble starting is try increasing the IACV duty a little bit, It might give some slight drivability issues once the engine warms up but if that happens just set it back to normal and the idle will drop to normal. so go to the idle tab,
Where it says IAC Duty Cycle set the bar a little past normal twards the Increase side,
Once again click the Arrow up top to upload the new calibration,
Then try starting the engine, it should start right up on a cold morning!
Last edited by wunfstgsr; Mar 24, 2019 at 05:37 PM.
Also I’ve done this a lot, make sure your coolant temp on the side of the head or the thermostat sensor isn’t swapped with you IACV.
And also check any plug that could be swapped around lookin at your helms manual or google wire colors to make sure they are hooked up in the right spot.
This is exactly what I was looking for thank you very much
Originally Posted by wunfstgsr
Ok don't remove anything just yet this is most likely a issue with the tune and sounds like you have no cold start adjustments,
Ok so go into S manager for the Hondata S300 on your laptop, if you don't have one get one and download the latest S Manager software and open it up.
First put the key to on but don't start engine, connect the laptop to the ECU with the USB cord. Once S manager is open click the online tab at the very top and then click download, then click parameters at the top right,
Then click the Fuel Trim tab ,
Then where it says post start fuel adjustment enter a value like 15% to start with.
Once you enter this new value click the Arrow pointing up at the very top of the screen,
Another thing you can try if it still has trouble starting is try increasing the IACV duty a little bit, It might give some slight drivability issues once the engine warms up but if that happens just set it back to normal and the idle will drop to normal. so go to the idle tab,
Where it says IAC Duty Cycle set the bar a little past normal twards the Increase side,
Once again click the Arrow up top to upload the new calibration,
Then try starting the engine, it should start right up on a cold morning!
Also I’ve done this a lot, make sure your coolant temp on the side of the head or the thermostat sensor isn’t swapped with you IACV.
And also check any plug that could be swapped around lookin at your helms manual or google wire colors to make sure they are hooked up in the right spot.
No its only during engine cold start, once the engine reaches OP temp it no longer relies on the IACV and or fuel trim. So switched plugs are already ruled out. But it is common to get the IAT sensor switched with the IACV or other plugs depending on what harness/engine combo you are using when doing a swap.
Cold start idle problems
