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Stalling when comming a stop.


lostsoul
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I have the problem that the engine stalls when coming to a stop, if sitting at idle I can "blip" the throttle and it comes back to idle fine ... only drops under target by 100 - 150 rpm then settles on target no problem. Can you point me in the right direction as to what to look at?

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Hi Lostsoul,

unfortunately you haven't given us much to work with, 

like what vehicle/engine is it,is it DBW, does it have an idle control system,what ecu are you using etc etc.

A copy of your PCL file would also help.

Does the stall happen all of the time,only when engine is cold, only when hot, only with air/con on etc etc.

So many variables to consider.

Regards

Dave.

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Details:

Vehicle = Z32 300zx Twin Turbo with modified VG30DETT engine ... things that may matter are, Heavily ported heads, solid lifter CAMs and larger Throttle Bodies.

No DBW and has an Idle Control System ( not factory ) http://www.nzefi.com/product/2-wire-remote-mount-idle-speed-control-solenoid-kit/

Happens both hot and cold ... there is no air/con etc. The only load on the engine would be the power steering and the factory viscus fan. 

Attached is the .pclr and log   ..... stalling event is at 2:40

Thanks for looking

 

Road Tuning.pclr

Log 2017-02-28 12;51;34 pm.llg

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What injectors are you using? The dead time table is a little different. It looks like you entered PSI numbers instead of KPA

How did you set your base fuel pressure? as i read the logs as 39.7psi

Your knock Target table is set to 0 and active. Its pulling timing out

 

Yeah Dave :)

Edited by Ducie54
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From my understanding your fuel pressure log shows that pressure drops with boost. Also at idle your fuel pressure is 33.1 plus MGP of -6.7 gives base pressure of 39.8

It looks like your using a NZEFI PWM controller your DC are to low causing the pressure drop. I would set it to 100% until you have things sorted

Fuel_pressure_drop_with_boost.thumb.png.

Fuel_pressure_idle.thumb.png.914d7d66d7d

Is there any reason why you using a 3D dead time table? This is the data from there website 

ID1000_info.thumb.png.43add1730a47280f80

Edited by Ducie54
added more
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Reason for 3D table is there is different deadtimes for different differential fuel pressure. The rest of his 3D table can be found on ID`s website..

Looks like the reason for dropping fuelpressure can be found in the fuelpump speed table. Looks to be at 45% DC at the lowest part of the pressure. This would also explain the very high VE numbers it the map.

For some reason Differential Fuel pressure has flatlined at 302 kpa so it doesnt seem like the fuel pressure correction is working like it should. (Where the ECU automaticly corrects for changes in the differential fuel presure).

As for the original question.. If your idle target is 980 try to adjust the throttleblades so that it will idle at say 750-800 rpm with idle control turned OFF. That way it will always have enough air to idle at al least that rpm and let the ISC valve do the rest to reach your target. Other than that i havent gone very thourough through the logfile yet to see if anything else sticks out.

 

EDIT: Fuel system type is set to MAP referenced! Set it to FP sensor and the correction should work. And prepare for a retune my friend ;)

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