Quick Engine/Exhaust Question

[Milenko2121]

I started my car up today after fixing a leaking vacuum hose and when I started the car(cold), it ran perfect, no misses and it purred exactly like it should, but after it started warming up, it started getting off beat again.

Could this be my valves? I'm adjusting them tomorrow because they're off by about 0.05 to 0.15 across all 12 of them.

My assumption was that when the valves heated up the clearance got worse so that's what's causing the exhaust to be offbeat.

Or could it be a vacuum problem? but wouldn't a vacuum problem stay the same no matter hot or cold?

what other ideas could it be?

[madkaw]

Getting your valve clearance correct is a MUST, but hard to say if that is the problem . Is this car stock?

[Milenko2121]

Getting your valve clearance correct is a MUST, but hard to say if that is the problem . Is this car stock?

yes, it's stock.

and yeah, i'm getting the valve clearance done tomorrow. bought the feeler gauges today and the torque wrench.

what my assumption about it is, is that since my valve clearance is off, it's causing left over gases from the exhaust to stay in, and after every few detonations, it causes a misfire which I believe is what makes it become offbeat. Just an idea though...

I'll find out tomorrow for sure though after I get the clearance corrected.

and yes, I'm stock

[Milenko2121]

Ok, adjusted my valves, and now my engine doesn't pop through the intake anymore, and the exhaust sound is a lot more consistent.

Right now I need to find the air boot from the airbox to AFM and then from the AFM to the Throttle body because mine are ripped and leaking.

Anyone know a cheap place to get these? with or without the fitting on top of the hose.

[FastWoman]

Ah! Your problem is the ripped boots -- at least the one from the AFM to the throttle body. It's letting unmetered air enter the intake, so less fuel is delivered. When you start your engine, the fuel/air mixture is richened. When the engine warms up, the mix leans out to normal. Rather, it would be normal if you didn't have a leaky boot. In your case, the mix probably starts somewhat normal and becomes lean.

Try Courtesy Nissan for the boots. I think they're still available. You can also find them on Ebay.