So I have a 04 built motor 350z, running on AEM infinity 8. The car has been on a mild boost tune for a year or so and always ran pretty decent. I decided to install some electric cutouts due to my exhaust limiting my top end power. The car drove in the shop great, I welded it all up, never even opened the hood, just simply pulled the test pipes out, cut them and welded in the cutouts and then drove it out.

I noticed right away that the car didn't want to rev past 3k rpm. So I limped the car home and shut it off. The next day the car basically wouldn't start, when it did, it couldn't idle and it wouldn't rev at all. Tons of black smoke out of the exhaust. So yes it was running extremely rich.

(Car runs the exact same with the cutouts open or closed. 02S shouldn't have any effect since its in open loop but I still tried unplugging them and switching them around and such.)

I checked on my logs and saw my IAT was flat at -58 F. Turned out the sensor went bad so I got a brand new AEM exact one. However the car runs the exact same. The injector duty cycle is stuck at 100%, so that is the issue, trying to find out why DT% is pinned at 100. As far as I can tell IAT, MAP, TP, ECT, all seem to be in their proper ranges.

I'm stumped and I'm no tuning expert. Anyone maybe have some base tunes for 350z's? Would love some ideas. Thank you guys, Please help.

 

Sounds like something else got unplugged and didn't get plugged back in. check you TB connections, all your O2 sensor connections, your MAF, etc.

 

UPDATE: Turns out the injectors are not at 100% Duty Cycle, they are ranged from 4-10% roughly. Triple checked everything in terms of sensors and lines. Its all plugged in properly, as well as all reading properly on the infinity. Checked all my vacuum lines and they all seem to be good. Confirmed with AEM that the O2S do completely nothing during open loop operation. Had my tuner send me a new tune modified for my situation, though nothing has changed. I can get the car to start, but it will not idle, and it has so much fuel/black smoke coming out of the exhaust that it fills up my garage in seconds. It doesn't seem to be misfiring, and definitely doesn't have a broken cam/bent valve or anything like that, since there are no metallic or violent sounds. Any ideas guys?

 

What's your coolant sensor readings? That sensor has much impact on warmup open loop fueling period.

Also, are MAP sensors readings correct?

 

Coolant sensor is working good, reading roughly 80 F depending on the day. The map sensor is the tough one. Since the car has 288 degree, 11.5 lift cams, it never had much vacuum at idle. It maintains 10 inches of mercury during idle when it's running correctly. At the moment im only seeing about 2-4
but with it running so rich and not being able to run without some throttle input it's a tough call whether that's an issue or not. All vacuum lines are good, intake it tight, TB is tight. Last year I bought a kinetic intake that ended up having a defective flange that wouldn't seal to the lower jntake, resulting in a huge vacuum leak, but that car still idled, just at a higher rpm.

 

A few thoughts:

Your coolant temp sensor should have nothing to do with the day ... you're probably thinking of the Intake Air Temp sensor ... TCode is referring to the sensor that's in the hard coolant pipe behind the engine ... you could probably fool the AEM by zero'ing out your ECT correction map temporarily to see if this influences your symptoms.

Did you get your injector duty cycle issues figured out?

If you're only generating 2 - 4 in*hg of vac can you modify your fuel map accordingly to have this be your highest (or lowest) vacuum column?

Just FYI, all kinetix intakes are defective!