Strong gas smell when starting

Originally Posted by Jhill

Well I'll have to disconnect my mafs to make sure the z doesn't do something different than what I'm used to but from what I'm hearing is it's running really well at cruise load but issues at idle (where engine are most sensitive). I've seen engines with moderate leak down (valve train issues) do this but it's usually accompanied by a rougher idle and an intermittent misfire but at 158k on an engine not known to have valvetrain issues I doubt it, vacuum leaks can cause this but I would suspect your fuel trim would be going + not -, mafs acting up (typically accompanied with a dead spot in the powerband) but I'll admit none of the car lines I've worked for had dual intakes but I assume it averages

both. I will say I have had one injector have a poor spray pattern sort of have the same symptoms you describe but again a rough idle and misfire that would smooth out and run fine at cruise with more airflow/turbulence to atomize the fuel (not sure what fuel trims would be doing as it was pre obd) but this is highly unlikely i think. Slightly leaking injector but usually accompanied with a stumbling start.



Do you have a scope with amp clamp? If so scope the amperage for the injectors power wire (before it splits into parallel) and see if all the injector amperage are relitively equal.

Originally Posted by Z_ealot

Unfortunately a scope is one tool i dont have in my arsenal, I’ll see if i can put together a graph of what exactly it’s doing at cruise speeds as i do have another data file that i recorded over an 80 mile trip after resetting the ecu that i havent processed yet. Appreciate the help in trying to track down this issue, it has been a pain in my side for the last few months trying different things to find out what’s causing it with what little knowledge i have and every mechanic I’ve tooken it to has said there’s nothing wrong with it that they can see


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Originally Posted by Jhill

Yea the graph isn’t helping me much, it’s hard without being there to get a feel and then have the graph re affirm my suspicions side from that it only shows what’s happening and not really a “why”. The part that stands out to me as odd is it not running well with the mafs disconnected. As I said I’ll have to test it on my own to reconfirm but I have never had a car not run “well” with mafs disconnected (like you’d be hard pressed to even know the maf was disconnected aside from the MIL). To me that feels as if there is something way beyond spec causing an issue. Typically as I said from what I’ve seen is the manufacturer has a pretty damn good idea of how the engine should run just from countless hours of bench testing and they build a pretty good map around that (like an alpha n tune) then the other sensors really fine tune it in but without mafs it runs off the data they’ve gathered that they can be fairly certain will allow the engine to run “well”. Hopefully that makes sense.