Checked that the last time i put gas in, seals nice and tight still and no gas smell coming from it before i open the cap

Question: would a consistently rich reading from the long term fuel trims mean anything?

Bump

Does your Z fire right up (like when new) ?
I read back through the thread & seen 160k on it...with the poor quality gas these day's-you could have an injector or 2 dripping after engine is switched off.
I'd try some old school stuff; after driving & letting cool down somewhat-remove spark-plugs & read them,,,also look down in cylinders with a scope.
Your A/F sensors may be getting tired also.
How's fuel milage,power,oil consumption ?
Get a good tech to ride along w/a graphing scan tool & record it.....something is bound to pop up.
Any extra information is helpful.

Just an update, fired her up this morning from a cold start. Got out and smelled the exhaust from the tailpipes and sure enough i can smell a nice strong fuel odor coming from the tailpipes.

Forgot to mention AF sensors are new and fuel economy seems to be about normal going by what everyone on the forums gets. As far as the startup, i cant remember how fast a good running Z starts up, but it does seem to crank over a couple of times before starting up.

Having no mods; surprised it hasn’t thrown a cel,,,may want to peak at evap canister (R/R behind tire) it could have ruptured or maybe ran over something & damaged it,hose or fittings.

Went out and checked the evap canister, all hoses and connections look visually in good shape with no indications of any fuel leaks. Just the smell of gas coming out of the tailpipes for the first minute after startup.

An educated eye could catch this on a graphing scan tool; I’m learning this newer stuff/ as I come from heavy trucks,Diesel & Old school carburetors etc...it’s really easy for someone who really knows their test equipment & how to use it....not necessarily someone who works at a dealership either.
I’m gonna text & email a couple folks for you & see if I can further steer you in the proper direction.

I have an obd scanner that captures live data and can save it to excel if that would help, just let me know what pid’s you need captured.

How rich are we talking? If it’s constant and high and truly an issue you should have a check engine light by now. You say it’s only from cold start so I would think you may have a slightly leaking injector (if it’s a hard start as well?). This can be checked by doing a residual fuel pressure check and once confirmed you can remove the plugs and check the tops of the pistons for any that are very clean. Other though that comes to mind although I can’t say how it gets effected on Nissan with the vvel but you may clean the throttle bottles and check the air filters. On cold start the ecu opens the throttle more, adds fuel and also retards timing. This is to try and heat the cats quicker so your basically having the air and fuel burn in the exhaust. If you have a restriction on the air inlet (filters/ throttle body) no you have reduced your air to fuel ratio on cold start (you’ll also have a longer warm up time). Again not entirely sure how effected it is with vvel but can be an issue on GM.

Ps scan data won’t show you much if it’s a cold start issue because the AF sensor won’t be accurately reading at that point.

Long term fuel trims are constantly over -10%, they dont get up to the constant -25% that’s needed to trip the computer, but the long terms are definitely showing a rich condition is going on. Throttle bodies and air filters are definitely clean though as air filters are new and throttle bodies were cleaned less than 5,000 miles ago. Another thing to note is that when cruising with emgine rpm at about 2500 the long term fuel trim finally starts to level back out towards the nominal 0%, but as soon as the car is stopped and idling that number goes back up over -10%

Does your baro reading at KOEO match your altitude?

Yes, have tested that and baro reading matches what the weather station says is the current outside baro reading

If you do an ecm reset after warm how quickly and how high (or low I guess) do the short term fuel trim jump? Meaning does it jump to something like -15 and keep pegging there as long term drops.