Fuel system to lean???

[MagnoliaMak]

I have a ? for you guys. The diagnostic machine says fuel system to lean. I already replaced the 02 sensor, plugs and wires and fuel filter. My next assumption is either bad injectors or weak fuel pump. My question for you guys is how can i distinguish which one? Those parts are a bit pricey to buy one and that not be the problem. Thanks in advance.

[Bio248]

usually a lean code is because you have a vacuum leak.

[matt5112]

what are 4:2:1 headers?

[MagnoliaMak]

Come to think of it I crunk the car up while I was under the hood and I could hear air blowing. Could that be why?

[matt5112]

Air blowing is more likely the fans.

vacuum leak sounds more like hissing.

[MagnoliaMak]

No it wasn't the fan, it was kind of a hissing sound but wouldn't that be caused by an air leakage?

[matt5112]

likely an air leak if it was hissing.

Was this when the car was warmed up?

If so, i'd break out the carb cleaner and spray around and listen for any change in engine speed.

[MagnoliaMak]

Yea the car was pretty warm when I checked. Where do I spray the carb cleaner?

[BillBoost37]

Your code is P0171

Google will find you the fsm pages on it which will suggest maf or vacuum leak. I've found a few other things including vacuum leak to be the most common. Lemme see if I can find that good post I think I did here.

[BillBoost37]

Heer ya go
I've found P0171 to be a few different things.

Evap backwards: Luckily the W bodies were redesigned and didn't get the same crappy hookups to the evap system as the H bodies. However it's possible the evap hoses at the soleniod were mixed up during work.

Corroded battery cables: If the corrosion is bad enough, it'll mess with the voltages a bit and throw the code.

Vacuum leaks: A very common leak is the EGR tube that leads from the EGR to the LIM. It's nearly impossible to spray with cleaner and get a reaction. Yet if you pull it and look where the piece that holds it to the LIM sits...you'll usually find a crack in it.

[FoSHO99]

Look around the throttle body for cracked hoses or loose hoses, as well as under the s/c snout, there is a T fitting going into the lower intake. If u can hear the hiss u should be able to trace the leak. Unmetered air entering the engine would make it run lean and throw that code.

[01gpgt01]

x2 vac leak

[MagnoliaMak]

Thank all you guys. I've been racking my brain and spending way too much cash for a what seemed like a simple issue. So if I spray carb cleaner in what type of change should I be looking for at idle? I know I probably sound dumb right now lol but this seems so simple it's difficult...

[MagnoliaMak]

Also will a vacuum leak make the car run horrible when you gas it hard?

[matt5112]

http://www.grandprixforums.net/vaccum_leaks.php

Big enough vac leak will kill the car. Thats how bad they are for the engine

[BillBoost37]

A very common leak is the EGR tube that leads from the EGR to the LIM. It's nearly impossible to spray with cleaner and get a reaction. Yet if you pull it and look where the piece that holds it to the LIM sits...you'll usually find a crack in it.

Just saying..

Can't tell you the number of times I've fixed this code by checking the tube.

[matt5112]

I love that tube... Broke a few myself.... and yeah, spray doesnt affect engine speed when its broken.