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BeallJK

Nissan 350z car suddendly dies out during idle

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Hey guys - 

I'm at that point where the car starts up and runs like you'd expect after an engine rebuild and a turbo system swap.  I ran into an issue this past weekend where the car died after about 19minute of just idle'ing in the driveway.    

I had the car started, idle'ing, and just running so I could listen, monitor, watch, etc before I get the car out on the road for basic data logging / mixture map fuel tuning / etc.

shortly after the 19minute mark (19minute 10seconds) the car's idle slowly decreased from ~900rpm to 0rpm over about a 15sec to 20sec time window.    

This is the second time this has happened.  I don't think I'm out of fuel(as I have fuel pressure) and I speculate this has something to do with a coolant temperature comp table - but I'm rather new to Link and my tuning knowledge base is elementary.  

Any insight or comments on my tune are welcome 

I thank you in-advance!

Attached is my current tune 2019-11-17 Revision3 

and my data log is too big (at 7.5mb) but I can email or dropbox if that'd help or if there is a way to shink-down the data log please let me know!  

Data Log #1.jpg

Data Log #2.jpg

Car Pic.jpg

2019-11-17 Revision3.pclr

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I cant see an obvious reason for the stall.  It appears to be fuel related as from about 19:19 it starts to go lean so the CLL reacts and winds in more fuel, it has added about 15% by the end but it is still showing lean.  But as you say the fuel pressure was still showing ok and your inj PW shows the ECU is still commanding fuel so its a bit of a head scratcher and im not really sure of the cause.    

Temps were stable so I think you can rule out temp compensations.

One thing that is not helping is the 300RPM deadband on your idle speed control settings.  This means the throttle doesnt open to try to catch the dropping RPM until falls 300RPM below target, it is probably too far gone by then.  A more typical deadband would be about 50RPM.

How confident are you the Lambda's are reading correct - are you seeing similar numbers on the guage as you do in PC link?  They may also get quite a bit of reversion at idle due to their proximity to the open end and give a false reading causing the CLL to over do things.  If it where me I would probably turn CLL off at idle then give it 10% more and 10% less fuel to see if it makes any difference.

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Thank you Adam - I greatly appreciate your time and response!  I will work in that direction!

I am fairly confident that the AEM UEGO gauges are matching what the Link is seeing.  One 'lost in translation' is the UEGOs are in AFR while the Link is in Lambda but they dont seem far off.  I'll switch the Link over to AFR to confirm.

 

 

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A little update.  This issue has come back where the car will be idle'ing perfectly fine and all of the sudden the car just shuts off.  

I've noticed a few things as I was watching the computer while the issues occurred.  In my most recent occurrence the car would hit ECT of 180, go rich and die out.  

I initially thought it was something to do with my post start but didnt make complete sense as the car was out of Post Start.  Then checked Warm-Up Enrichment.  This was my next logical progression as the car might be looking for a little fuel adjustment?  so I copied my values from the cells where the car was idle'ing fine but no change to the dying at 180degrees ECT.  This didn't make complete sense bc the car was dying rich and copying over cells from the warm-up map would mean it'd be adding fuel.

I was poking around in my fan settings and I that I had them set at 180 degrees (which is relatively low but I run a single 10" fan and I give it a little bit of a head start).  I adjusted the engine fan activation temp up to 190d and the going-rich and dying out followed the 190d temperatures I set the fans to.  What was strange the Link has Fan #1, Fan #2, and Fan #3.  While OEM only has Fan #1 and #2 but the car would die even if Fan #3 was trigger by the ECT rising.

Did a little poking around, unplugged the fan, and the go rich and dying continued. Back in the PCLink Software (embarrassingly, right in front of my face) my Idle Gain Trim was set to 2ms for the engine fan.  The fan activation temp would activate the fan and the Idle Gain would add 2ms of additional fuel, run my mixture rich and it'd kill the engine.  

I set the idle gain trim to zero and the engine idles like you'd expect.  

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