rough idle and running rich

[tahoedriver]

Hey all, hope someone could shed some light on my situation. My grandma has a 1999 3.9L V6 with 230,800 miles on it. The engine idles rough and there's a strong smell of gas from the van as it idles which leads me to think its running rich. When accelerating and normal driving, the idle goes away and the engine runs smoothly. Fuel pump has been changed, so I don't think it has to do with press. or the pump. When I pulled the plugs, it had a strong scent of gas but looked like normal wear and tear from a good spark (not charred or black). Tune-up (engine/tranny fluids, sparks and wires, cap and rotor, fuel and air filter)was done 3 months ago and everything looked normal. I was thinking distributor needs to be replaced as there seems to be a lot of play when I rotated it back and forth. Timing chain also came to mind. Shops are kinda out of the question as she's very strapped for cash and I unfortunately can't devote alot of time as I got school to deal with. Any thoughts or ideas will help.

[tempfixit]

Originally Posted by tahoedriver

Hey all, hope someone could shed some light on my situation. My grandma has a 1999 3.9L V6 with 230,800 miles on it. The engine idles rough and there's a strong smell of gas from the van as it idles which leads me to think its running rich. When accelerating and normal driving, the idle goes away and the engine runs smoothly. Fuel pump has been changed, so I don't think it has to do with press. or the pump. When I pulled the plugs, it had a strong scent of gas but looked like normal wear and tear from a good spark (not charred or black). Tune-up (engine/tranny fluids, sparks and wires, cap and rotor, fuel and air filter)was done 3 months ago and everything looked normal. I was thinking distributor needs to be replaced as there seems to be a lot of play when I rotated it back and forth. Timing chain also came to mind. Shops are kinda out of the question as she's very strapped for cash and I unfortunately can't devote alot of time as I got school to deal with. Any thoughts or ideas will help.

Have you checked the fuel pressure regulator to see if any gas is present in the vacuum line??? IF so the regulator is faulty.

Do you have a scanner that can read fuel trims???

Is check engine light on, if so any codes or get codes read and post.

Have you checked for a vacuum leak??

[alloro]

The fuel pressure regulator, just like the fuel filter is built into the fuel pump assembly. So since the FPA was just changed, the problem lies with something else.

If the problem is the distributor you will get a CEL on the dash for the misfires. This leaves you with either the MAP or O2 sensors being out of specifications, or one or more fuel injectors are worn and leaking. If there is a strong smell of fuel after the van has been sitting for a bit I would put the injectors first on the list. However, if the smell is more so when the engine is running, then it's one of the sensors I mentioned.

[tahoedriver]

Thanks for the reply's, I should've mentioned that the engine light never came on. Not sure about whether it ever came on before the fuel pump was switched, I will check on that though. Also, both the rough idle and the van running rich were issues before the fuel pump was switched out (replaced 2 weeks ago) The smell of fuel is noticable from outside when the van is idling. No smell inside. Not sure what you mean by "If there is a strong smell of fuel after the van has been sitting for a bit..."?? It's been driven on a regular basis (every other day) with no smell until the van starts up and idles. After being driven, there's no smell from what I can tell.
My question, if there's no engine light and no code how will I know which o2 sensor to replace? I don't think any of them have ever been replaced. Also, what is the MAP sensor and what does it do?
P/S Sorry for the rambling, I'm more or less the car guy for my grams and I'm trying to be specific...maybe too specific haha.

[alloro]

Originally Posted by tahoedriver

Not sure what you mean by "If there is a strong smell of fuel after the van has been sitting for a bit..."??

what is the MAP sensor and what does it do?

By sitting for a bit I meant drive somewhere, visit for a couple of hours, then go back out to the van.

The MAP (Manifold Absolute Pressure) sensor measures vacuum at the intake manifold. It's function is to report the vacuum reading to the ECM so that the air/fuel mixture can be adjusted to compensate for higher or lower atmospheric pressures. If it reports an incorrect vacuum reading to the ECM, then the engine will run rich or lean, depending on which way the MAP is off.

[tahoedriver]

Well, I've been busy with classes and such but here's a little update. My pops took the van in to have its codes read as the engine let was on and it pulled 4 codes (p0300,p0303, p0304, and p0305). From previous replys I was intially leaning towards the MAP sensor but after reading the codes I'm reconsidering the distributor being the problem. Would a faulty distributor cause rough idle? if so wouldn't it run rough even during city driving? Also, would it account for it running rich?

[hundahunta]

i would also make sure the plenum is not leaking