G4X 4AGZE goes into fuel cut?

[NSFKNX]

Hey everyone,

I have a 4agze that after it worms up goes off and on into fuel cut and surges like someone's turning a light switch on and off. It bounces between 1800-2000rpm and is running rich. I've played around with the idle base position, injector time, idle speed (open and closed loop) and no dice. They do all make changes to how it runs but still goes into fuel cut.

Any idea's on where i should look?

Thanks

[Vaughan]

Attach a PC Log of it happening and a copy of your tune please. It does sound like it is getting too much air to idle though but seeing what the idle position and statuses are doing is important for diagnosing the exact issue.

[NSFKNX]

here is a copy of the general log.

PC Datalog - 2024-02-18 6;58;33 pm.llgx

[Vaughan]

I would say start by reducing your idle position, that log shows it at 78% the entire time.

If lowering the idle position right down doesn't bring the engine speed down enough then you have an air leak that you will need to find and sort

I also suspect that there is something wrong with your Lambda input on An Volt 9 as 0.5 Lambda would normally stall the engine and you have closed loop Lambda using this value which looks incorrect. Probably turn off CLL while trying to solve this issue too.

[NSFKNX]

40 minutes ago, Vaughan said:

I would say start by reducing your idle position, that log shows it at 78% the entire time.

If lowering the idle position right down doesn't bring the engine speed down enough then you have an air leak that you will need to find and sort

I also suspect that there is something wrong with your Lambda input on An Volt 9 as 0.5 Lambda would normally stall the engine and you have closed loop Lambda using this value which looks incorrect. Probably turn off CLL while trying to solve this issue too.

Do you mean An Volt8? There's nothing on An Volt 9. When i go into Fuel Main and look at Open Loop Lambda Correction it shows "ON" and when i go to Idle speed control it says Open Loop

[Vaughan]

8 minutes ago, NSFKNX said:

Do you mean An Volt8? There's nothing on An Volt 9

Sorry yes An Volt 8.

9 minutes ago, NSFKNX said:

When i go into Fuel Main and look at Open Loop Lambda Correction it shows "ON"

Open Loop Lambda correction is adjusting Pulsewidth based on target Lambda and should be on, Closed Loop Lambda adjusts pulsewidth based on feedback from the actual Lambda value trying to correct it to the target Lambda and should be off at the moment. Fuel -> Closed Loop Lambda -> Closed Loop Lambda -> lambda Mode.

11 minutes ago, NSFKNX said:

when i go to Idle speed control it says Open Loop

Idle Loop Control in open loop is fine, just means the output is based entirely on the tables and settings and doesn't look at actual engine speed and then apply a trim on top of the values to correct engine speed to target. Note you never actually enter idle speed proper as you are always in RPM Lockout because you have too much air getting into the engine so closed loop vs open loop idle speed control wouldn't matter in that log. You need to go to Idle Speed Control -> Idle Base Position Table and reduce the values in it and see if that brings the engine speed down to an appropriate level.

[NSFKNX]

8 minutes ago, Vaughan said:

Open Loop Lambda correction is adjusting Pulsewidth based on target Lambda and should be on, Closed Loop Lambda adjusts pulsewidth based on feedback from the actual Lambda value trying to correct it to the target Lambda and should be off at the moment. Fuel -> Closed Loop Lambda -> Closed Loop Lambda -> lambda Mode.

 

I cant see that?

[Vaughan]

These are settings so they are found in the ECU Settings tab on the left had side of the PCLink window. Your screenshot shows the runtime view which contains a bunch of the runtime values and statuses which are feedback as to what various functions are doing.

[NSFKNX]

found it

[NSFKNX]

PC Datalog - 2024-02-18 8;48;43 pm.llgx

Here's the last on of the night. I think there might be a vacuum leak somewhere  lol

[Vaughan]

yeah if it's still doing the same thing with the idle position massively reduced that sounds like an air leak. maybe disconnect any itnake piping from the throttle body so you don't have the super charger contributing to any surging and then start checking things like throttle stop, brake booster vacuum line etc

[NSFKNX]

Thank you guys so much. The supercharger works on a clutch and hasn't clicked on. I will start with disconnecting everything one at a time. Thanks again.

[koracing]

Having just tuned one of these engines in an AW11, it was very tricky to get the idle control to work right.  It's like there's almost no resolution below about 35% duty, and was very tricky to get the right balance of timing control, idle control range (closed loop), base positions, throttle stop screw settting, and the idle air bleed setting.  Stock ecu seemed to have little to no issue controlling idle, so I suspect there may be a frequency response issue versus newer toyotas as I was using the "normal" 3SGTE base map frequency numbers.  

Also the vacuum diagrams and all the VSVs on that motor are pretty tricky to get just right if you're not familiar with them (which I certainly was not, but did just mess with it last week).  

I would start by backing off the throttle stop set screw until you are certain the throttle is all the way closed, and then make it just crack the throttle off of the bottom most position maybe 1 turn of the set screw (2.5mm hex key/allen head with a 8mm jam nut).  Close the idle air bleed (slotted screw under the black cover/grommet on the right side of the throttle body facing up) all the way in and then back it out one turn.  Make sure your idle speed base position is set to 35%.  Adjust up the idle air bleed screw (back it out) until it idles near your target idle speed.  If you run out of idle air bleed (i.e. you back it all the way out or more than about 4-5 turns out), close it down to 1 turn out again, and adjust the throttle stop screw to open the throttle 1 to 2 more turns and repeat.  Once you get it idling close to target, turning on idle ignition control can help it get the last little bit to target.

[NSFKNX]

Awesome,

Thanks Kris

[koracing]

You should also be able to determine a vacuum leak by covering the throttle body inlet completely with your hand while idling and it should kill the motor.  If not there is definitely a significant vacuum leak.

[NSFKNX]

Hey guys, I've got all the vacuum leaks sorted out and I'm good there. I wired injector 3 & 4 up and set it up for sequential fuel injection. When it gets up to operating temp my "Idle position (%) = 60 (at idle)" "Ignition Idle Status & Idle Status = Hold - Throttle open" and. I continue to get a message at the top stating "Fuel Calculation clamping at its minimum value". I've played around with Idle Speed Control in Open and Closed Loop, The higher the number 65 the lower my idle goes and the lower 35 the number goes the higher the idle goes. When I play around with the Fuel Table 1%, I highlight a bunch of cells down low and when I lower the number to 29.4 my A/F's raise to 14.7ish, when I put it to 50 the idle goes up and my A/F's drop to 8ish and my idle goes up. In my head when i play with both of those tables they should do the opposite. If i go higher I get an RPM lockout on Ignition Idle Status & Idle Status. 30 on a VE table seems so low or am I on the right path to where i could go out and start road tuning it?

The things I'm trying to figure out is why won't my idle go down to 900 rpm and what does Fuel calculation clamping at its minimum value mean?

PC Datalog - 2024-04-28 6;19;58 pm.llgx

[Vaughan]

The hold, throttle open will be because your TPS value is at 2.2% at that point in time, have you calibrated your TPS recently? Once TPS is below the lockout and idle becomes active then it can do closed loop things if you have that turned on. In terms of the engine speed being too high at that point that means that you need less dashpot or less base position most likely.

[Adamw]

41 minutes ago, NSFKNX said:

what does Fuel calculation clamping at its minimum value mean?

This means the calculated injector PW based on your operating conditions is less than what you have set as the minimum effective PW.  So the ecu is clamping at the minimum instead of giving the calculated value.  This is just information so the tuner knows he wont be able to make it any leaner.  Most likely your minimum effective PW setting is wrong, typically around 0.1-0.3ms for most injectors.    

[NSFKNX]

38 minutes ago, Vaughan said:

The hold, throttle open will be because your TPS value is at 2.2% at that point in time, have you calibrated your TPS recently? Once TPS is below the lockout and idle becomes active then it can do closed loop things if you have that turned on. In terms of the engine speed being too high at that point that means that you need less dashpot or less base position most likely.

Yeah I had just recalibrated it, I will do that again.

I will play around some more.

 

Thank you

10 minutes ago, Adamw said:

This means the calculated injector PW based on your operating conditions is less than what you have set as the minimum effective PW.  So the ecu is clamping at the minimum instead of giving the calculated value.  This is just information so the tuner knows he wont be able to make it any leaner.  Most likely your minimum effective PW setting is wrong, typically around 0.1-0.3ms for most injectors.    

Ok so it is what i think it is. I have mine set to .4ms. I've found factory is supposed to be 2.5ms. I didn't know how it would affect it. 

Thank you