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Hesitation/Misfire when cold, seems to disappear at operating temperature.


JackB

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Hi all,

Have an sr20det with a linkG4x. Currently running into a driveability issue when the engine is cold.

Upon any throttle input when cold, the engine hesitates massively for a second or two and then appears to be fine, even at that same throttle posistion.

This does not happen as the engine warms up to operating temperature.

Upon taking a log, it appears the fuel pressure drops to 0 as this is happening, then returns to normal. Again only when cold.

RPM and MAP cut limits arent met when this is happening either. Could there be some other reason for the fuel pressure loss?

Thanks in advance if you can offer any advice. Attached is a log file of a relatively long drive, showing the issue when cold and absence of the issue when warm.

Thanks,

Jack

PC Datalog - 2023-05-17 5;12;04 pm.llgx

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Can you attach a copy of the tune, the fuel pressure looks more like a set up issue, it looks like it is just dropping to zero because anvolt 4 has an incorrect error high value, it looks like about 1.75V.  The lambda doesnt go lean when the fuel press shows zero so I dont think the fuel press is actually low.  

I suspect your hesitation issue may be accel enrichment related.  I will confirm after seeing the tune but it looks like there are possibly two issues - 1. Your accel enrichment deadband is set to low so you have accel fuel constantly dumping extra fuel in when its not needed, fixing this may make it run a bit leaner.  2. I have a feeling you dont have enough accel sens and possibly not enough cold correction on the accel fuel, there is barely any when warm and not much more when cold.  

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Hi Adam,

I am very glad you mentioned the acceleration enrichment issue. This is something that I have been playing around with, yet to yield a good result though. The values for that log file are just the standard sr20 settings that I was testing. The previous settings I had attempted to tune are located in the tune file attached and yielded the same problems described.

Also thank you, the an error high value for anvolt 4 was set at 1.75V!

Thank you very much

 

13toedit.pclx

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No problem, attached is the new log. My laptop did seem to have a connection issue midway through where some data for ect between 30-60 degrees was lost. I will take another log when the engine cools down. 

Thank you.

 

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