Supra JZA80 NA-T lean and stalling

[ThatSupraGuy]

Hi all, 

Ive been having an intermittent issue with my car. Once up to temp and at idle it starts to lean out and die. To keep it alive I have to feather the throttle.  I have made a log of it idling and managed to catch it happening. It stalls about 8mins into the log and then about 13mins into log also with me feathering the throttle. If anyone can help that would be appreciated. ECU is supralink pnp. Have also attached tune file aswell.

Thanks.

STALLING.llg SUPRA 2JZGE TURBO.pclr

[Adamw]

I had a quick look and nothing obvious leaps out at me.  

The first stall at around 8mins has especially few clues, with little change in anything immediately prior to the stall. 

But looking at the stall at about 14:40, there is possibly something more obvious going on starting around 13:55.  The lambda starts to go lean and even with the the closed loop winding in the maximum 10% extra fuel trim, the lambda is still showing about 20% leaner than target.  The inj PW reflects the 10% trim, and is similar to areas where the mixture is fine so the "leaness" appears to be some external factor - fuel pressure would probably be the next thing I would monitor or log. 

 

[ThatSupraGuy]

I think I may have figured it out. I think the factory fuel pump controller is causing the issue. I bypassed it using a jumper cable and it didn't stall or play up. Reconnected the controller and about 1.30min into running it started to play up and try to stall. I had a multimeter hooked up to the pump and voltage got down to 12.4v with the fuel pump controller plugged in and with the jumper cable bypassing the controller its at 13.1v.

Fuel pressure is at 2.3bar on the gauge at the regulator.

Only issue now is the pump continues to prime as there is no controller. Is there any way to control the from ecu? Or should I try find another controller?

Thanks

[Adamw]

I dont really know how the fuel pump control works in those.  I see in our supra base map aux 2 is set to FP speed with a low polarity and in your map aux 2 is set to fuel pump relay with a high polarity.

It might be best to just replace it with a standard relay.

[koracing]

Having tuned a few 2jz supras I would strongly recommend installing a fuel pressure sensor.  The OEM regulator and/or wiring seems to cause these to run higher fuel pressure when all cold and lower fuel pressure when warm.  I first ran into this when a car I was tuning would run great on dyno and the 20-30 minutes drives I would take it on when I was tuning, but later the customer would complain that after driving for 30-40 minutes if the car stalled, they could not restart it.  After installing a fuel pressure sensor I found that the differential fuel pressure was 300-400kpa differential when cold, and 200-250kpa differential when warm at idle.  The closed loop fuel trimming was accomplishing the necessary adjustments to keep it running before the pressure sensor was installed to keep it running, and of course when the car stalled, it would reset any fuel trims (G4+).   Since that first car I've seen it a couple more times on several Toyotas with mostly stock fuel system components.  I pretty much insist on any cars I tune at this point to have fuel pressure sensors installed if they are running any stock fuel system components. 

[Samurai Supra]

The factory fuel pump controller is a PWM input speed control unit. Runs 9V on idle & switches to 12V under load conditions.
The general consensus is that it runs fine on a Walbro 255, with a 450 it cannot handle the current & cause stalling.

I ran my car with a stock fuel system & Link with the three stage PWM setting, worked fine. 

I tried a Jag/Ford/Continental style controller but had issues (was a 2nd hand unit, most likely was not working well), so as Adam suggested used a normal relay, working fine.

To the OP, maybe swap the Aux 2 to FP speed & Speed control method to the 3 stage PWM & see if it works. But if you have a high current draw pump, best to use a relay.

[ThatSupraGuy]

Does the NA supras fuel pump controller run the same as TT? When I had the multimeter hooked up to the pump it would always be about .5v under battery voltage until it got up to operating temp and voltage got down to 12.2v, it would start trying to stall and voltage would go lower. After that happened i bypassed the controller and no issues at all. As Adamw said he notice my fuel pump speed is set to high polarity and yet their map is set to low polarity, would this have caused the issue? Car has been running fine for over a year until about 2 weeks ago when it started playing up.

 

[Samurai Supra]

Parts EPC shows the same ECU in the TT and NA. 

My tune had polarity set to high, was working fine. 

What pump do you have?

[ThatSupraGuy]

Walbro 255lph.

[Samurai Supra]

SHouldn't be giving issues with current draw, unless its running out of fuel pressure for your setup.

[ThatSupraGuy]

Turns out it was the idle control valve causing the issues.

Thanks for all the help though everyone.

[ThatSupraGuy]

I lied, its not fixed. Still having the same issue. Have checked fuel pressure when its happening and it stays at about 2.5 bar. Its odd and very intermittent. Drove it to work the other day and about 3 mins in it stalled, started up fine then about 10 mins in to drive started to lean out and try and stall but managed to limp to work. On the way home exact same thing,  about 3 mins into drive it stalled then started fine, then about 10 mins into drive started to lean out and try and stall but cleared up and drove perfect the rest of the way home. 

Anyone have any idea what is going on?

Could it be something to do with closed loop fueling?

It seems very time based.

I'm lost.

Thanks again

[Adamw]

As I said originally it appears to be external to the ecu.  You can see the ecu adding fuel trying to compensate when it starts to happen.

Give us some fresh logs but Im not sure they are going to tell us much.