Carl's Z

Ok, here it goes; Ever since I did the AFM rebuild, I think I'm running rich, maybe. The smell reminds me of an engine burning "varnished" gas. It's pretty strong while taking off or at a light. I'm having a running problem right now that I think will be cured by a new set of wires this weekend, but I was wondering if the smell was something that anyone has dealt with before!?


Thanks for all advice in advance...

Carl

PS: I don't believe at this point that I have an exhaust leak...

NismoPick

Exhaust leak wouldn't be the problem, since exhaust is AFTER the combustion chamber (unless it's a manifold leak before the O2 sensor).

Easiest way to tell how your engine is running: pull & look @ the sparkplug tips.

In my opinion, anyone that plans on tuning the engine by changing the fuel ratio, needs an air/fuel gauge.

Carl's Z

Well, I wasn't planning on changing anything, and theoretically, nothing HAS been changed. It's just been smelling funny, and thought someone might have some insight on it...

jfairladyz

Is the smell from the exhaust? Or is it coming from under the hood?

NismoPick

Edit... that's a for Carl, not JfairladyZ

duowing

My car is doing a similar thing. It's not coming from the back, it just has more of a gassy smell sometimes around the front of the car.

RodMoyes

Leaky injector and/or leaky cold start valve...

Rod.

duowing

How hard is it to replace injectors or cold start valve? And how do I test them to find out if they're bad?

NismoPick

easy.... easy.... and use a multi-meter.

duowing

I think i still need to get a damn Haynes Guide.

RodMoyes

Cold start valve leaks are notoriously common. You can usually watch it leak if you stand over it while someone is cranking the car over (when cold). The injector leaks are also quite common and either or would explain your symptom. Injectors require a liitle more work to replace (Cold start valve is cake). To do the injectors, you pretty much need to remove the fuel rail... not for the gunshy but not too bad.

Rod.

duowing

Can you just remove the fuel rail, or does a whole bunch of stuff have to be removed to get to the fuel rail? I think you had to remove a whole bunch of stuff before you could get to the fuel rail on the 300ZX's. Other than the smell of fuel, would there be other symptoms related to leaky injectors or not really? I mean like loss of power or anything?

RodMoyes

Symptoms? Yes... all of the above. Loss of power, rough idle etc...

Rod.

duowing

Hmm...see sometimes I smell fuel, but the car seems to have a smooth idle, and doesn't seem to have a loss of power, etc.

RodMoyes

The smaller/larger the leak is, the more/less it will affect performance. All I know is that those are the two most common problems that would result in smelling raw fuel. Maybe you've got something else going on. But, being that the car is 20+ years old... and not knowing when or if they've ever been replaced... how good do you think those little rubber seals still are?

Rod.

duowing

Anyway, just so I have a heads up, what needs to be removed to get to the fuel rail?

RodMoyes

It's pretty self explanatory... just follow the rail and you can see where all it's attached. It's not hard, but it is time consuming. To do it right, you need to remove the P/S pump bracket and a few other things that seem unrelated... just take your time and you'll be OK. Be very carefull with all those little vaccum lines and fittings... old age=brittle.

Rod.

duowing

Ahh, see with the 300ZX you had to remove the whole intake cover,t hen the intake collector, and I think a few other things before you could get to the fule rail. Still not a huge dealm but you'd be messing with gaskets that would then need to be replaced and just somewhat of a pain.

RodMoyes

Yes, The Z31 is a rat-bassturd to work on... the Z32 is a double rat-bassturd to work on. The S130 is much more "User Friendly"

Rod.

jfairladyz

Owning a Z32 is reason enough to never want to open a hood again. NIGHTMARE. I dreaded everytime the caller ID had my buddies name on it with the Z32 cause I just knew he needed help with something on it. He spent more time under that car then he did driving it. It was a heavily modded beast putting out in excess of 400+ WHP (as verified at Stillen open house). And he payed the price for having all that done to the car. It was constantly in need of attention. He envied me cause my engine bay was so simple and uncluttered even though his car would mop it up without breaking a sweat, though it usually broke something else All in all though it was a blast to drive when it was on the road. Poor bastard had it stolen from right in front of his house too.

duowing

I'm glad to hear about working on the 280ZX. I know getting the heads off the 300zx was a gigantic project. You had to remove the intake cover, intake collector, fuel rail, exhaust manifold, intake manifold, numerous vaccum lines, unhook multiple connectors all over the car, remove the A/C, Power Steering, and Alternator. You had to remove their respective brackets, remove the fan clutch, the timing belt covers, cam pulleys, and possibly a few other things. My god that was an annoying project. I'm gonna have to take my car out for a spin a little more. Haven't had time to drive it a whole lot lately, maybe it is just an injector, but I don't think you smell that gas smell all the time. Oh and jfairladyz, even though you said the Z32 would beat your S130 with no sweat, it seems like upgraded to the extent that Z32 was, it should have at least put up a decent battle.

duowing

Man $50-$70 for 1 fuel Injector!? $137 for a cold start valve?!

Is there any chance that a bad O2 sensor can cause it to inject more fuel where you'd smell it?

Carl's Z

Mommy, Duowing hijacked my thread...j/k

My smell seems to be coming from the exhaust...

RodMoyes

Well I wasn't talking about your smell!

J/K

If you smell fuel coming out of the exhaust, it could be lot's of things. Bad o2 Sensor, Misfiring cylinder... even... A leaky fuel injector!!! Yes, a leaky fuel injector can dump more fuel into the cylinder than it can burn, hence... gas smell from the exhaust. Voila!!!

Rod.

RodMoyes

I forgot to mention, that any of those things can fry your Catalytic converter in no time... Fix it!!!!!

Rod.