350z hesitation

[Zociety350]

I’m having a problem with my Z where when I stab the throttle quick it will hesitate, it will go lean and jump back to normal. When cruising I’ll let off the throttle get back in it and have a 2 second delay, it’ll pop then jump back. I’ve tried messing with the accel/wake-up enrichment, cold correction, calibrated MAP, tps, tried all new sensors on car, check base timing etc. Nothing is helping. My tuner thinks it’s not in the tune but I’ve checked everything and I’m stumped. If I turn the load=map to load=off it will rev up no problem with zero hesitation. But run really rich. At this point I don’t know what to do, any help would be great.

[DerekAE86]

1 hour ago, Zociety350 said:

If I turn the load=map to load=off it will rev up no problem with zero hesitation.

This is changing your entire fuel map so much you'd essentially need to re-tune. So just that indicates it is most likely a problem in the tune contrary to what your tuner has said.

Upload your tune file so someone can have a glance through it and maybe they'll be able to see something out of place.

[Adamw]

A copy of your tune and a short PC log of the problem occurring is the place to start.  Also a bit of basic info about the engine - injector size etc.  

[Zociety350]

Sorry for the delay response. As soon as I get home I will get you guys a log and tune file. 

[PopesSimpleSpares]

Any update on this? I think I'm having a similar issue

[Zociety350]

 

 

Sorry for the late response, blew a head gasket so had to get that fixed first. I attached my tune and log. You will notice when driving if I let off the gas completely then stab the throttle it will go all the way lean for a split second and then jump back to normal. I have tried tweaking everything i can find on the software, put all new sensors on the car etc. and nothing really helps. Hopefully someone here will notice something im missing. 

 

It also is a 2003 Nissan 350z, Built low compression engine, 1200cc (Fuel Injector Connection) injectors, Custom turbo kit, fuel system, etc

Log 2023-07-3 12;16;59 pm.llg 7-3-22 12.12.pclr

[Adamw]

You have an issue with your MAP sensor, it is slow to respond to changes in load.  You will notice there are no "near vertical" transitions in the MAP trace - always a gradual ramp between different pressures.  Possibly the hose is crimped/blocked, full of oil, the sensor is faulty, or the measurement point is not suitable.  You can see from the fuel pressure trace that the manifold pressure is changing quickly, just the ECU is not seeing it.  

The example I have annotated in red below is an obvious example, you have snapped the throttle closed at 7000RPM, you should see near instant full manifold vacuum under this condition, yet it is more than 2 seconds later before the MAP shows overrun level vacuum. 

[Zociety350]

3 hours ago, Adamw said:

You have an issue with your MAP sensor, it is slow to respond to changes in load.  You will notice there are no "near vertical" transitions in the MAP trace - always a gradual ramp between different pressures.  Possibly the hose is crimped/blocked, full of oil, the sensor is faulty, or the measurement point is not suitable.  You can see from the fuel pressure trace that the manifold pressure is changing quickly, just the ECU is not seeing it.  

The example I have annotated in red below is an obvious example, you have snapped the throttle closed at 7000RPM, you should see near instant full manifold vacuum under this condition, yet it is more than 2 seconds later before the MAP shows overrun level vacuum. 

You’re a life saver, I have spent countless hours trying to figure this out. It was a vacuum T that had a resistor in it that was meant for my boost guage. Thank you allot for the info. It’s working perfect now.