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Hot restart question.


k4nnon
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Hey all, as th title states i have a hot restart question. Link G4X pnp for evo 9. Im learning the software and getting some stuff dialed in. I just switched back to e85 and im having some warm/hot restart issues. The car will cold start and go through its warm up cycle great, driveability is good. If i shut the car off to get gas, or if i go to lunch and then restart the car, I almost have to floor the gas peddle to get it fired up. when it does start up it almost doesnt stay running until it catches up with itself. Ill have to hold the throttle up to keep it running and when i do the closed loopgoes into idle rpm lock out so it further complicates the hot starts.

Since it seems to start up better if i hold the throttle down i figure the car is starving for air or running super rich due to the e85. what i have done so far is lower all cranking enrichment and post start stuff. this has helped but only about 50% unless i just didnt lower it enough. My question is,,, Does it sound like im doing this right or should i actually be adding additional fuel or time to my cranking or post start tables. If the car starts better when im holding the gas peddle down, i this beacuse the car is starving for air and is too rich or is this because the car is actually lean and my holding the gas peddle down giving the car more air and additional fuel?

 

 

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It would pay to get the wideband working before starting and log a hot start so you arent guessing.  But I would say most likely it is too much fuel.  With ethanol there is a massive difference in how much start enrichment you need between hot and cold.  

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On 6/2/2022 at 5:39 PM, Adamw said:

It would pay to get the wideband working before starting and log a hot start so you arent guessing.  But I would say most likely it is too much fuel.  With ethanol there is a massive difference in how much start enrichment you need between hot and cold.  

Hey Adam, As always thanks for the input. I have the Link CAN Lambda stuff working with the car as well as an alternative wideband that just goes to a gauge. They seem to be working fine but when i crank and start the car there is about a 20s delay before my Lambda1 comes online with the CAN Lambda stuff, its about similar time for the wideband on the gauge, so idk how to accurately check what my AFR is during cranking. By the time the Lambda sensors are online and giving me a reading the car has changed its startup behavior. Iv been playing with some things and it seems to be getting better. I havent tried decreasing the first start enrichment stuff as of yet so that will be next and ill see if the issue seems any better or worse. Thanks again.

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If you are on recent firmware, go to lambda 1 settings and set "Run When Stalled" to ON, it will then start before starting the engine.  Set it back to off after testing as it can shorten sensor life with that enabled.  

rYqY2w1.png

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14 hours ago, Adamw said:

If you are on recent firmware, go to lambda 1 settings and set "Run When Stalled" to ON, it will then start before starting the engine.  Set it back to off after testing as it can shorten sensor life with that enabled.  

rYqY2w1.png

THANKS!! Ill give this a try!

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Finally got around to setting up my old google drive for use so i can now add the link for you guys to view. The first of which will be my current map and two logs, One log is of a cool start up, and the second is a hot start up. The cool start is decent and seems to be fine. The hot start dips the idle and it seems to recover slowly before its stable. Not really sure i need to make adjustments on this one so if anyone has any input its alwys appreciated.

https://drive.google.com/drive/folders/1ctVovrKJeoLEI08LdHJdPDSUOxaj20xI?usp=sharing

 

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You might have to fit the capacitor to the lambda power supply or move the power wire as it is dropping out during cranking (maybe it is powered from an ACC circuit that powers off during cranking?).  It also throws an error 16 during heating which usually means its not happy with the power supply.  

I suspect there is not enough fuel when hot.  As soon as the engine fires you have no post start enrichment and the injector PW drops very low - around 0.44ms. The injectors will be very erratic at that - if they are even opening at all.    

Try the changes in orange below.  Post start may need to be even higher.  The Min Eff PW may make it idle too rich but try it and see.  

plKCFw2.png

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On 6/9/2022 at 4:44 AM, Adamw said:

You might have to fit the capacitor to the lambda power supply or move the power wire as it is dropping out during cranking (maybe it is powered from an ACC circuit that powers off during cranking?).  It also throws an error 16 during heating which usually means its not happy with the power supply.  

I suspect there is not enough fuel when hot.  As soon as the engine fires you have no post start enrichment and the injector PW drops very low - around 0.44ms. The injectors will be very erratic at that - if they are even opening at all.    

Try the changes in orange below.  Post start may need to be even higher.  The Min Eff PW may make it idle too rich but try it and see.  

plKCFw2.png

Hey Adam , just now seeing this reply but all of that makes sense. I believe when i was initially getting the car fired up i had changed my min injector pulse width for some reason but i will change it back to spec and see how it effects the car with those changes. Also you may be correct with the Lambda power wiring, I feel like i have that wired into ACC power as you say. I think its taking power from the cigar lighter, which i checked and it was hot when key on but it may drop out during crannking. Thats on the list to change!  As always thanks for the help...

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