Rough Idle & Gas/Exhaust Smell

[kmoore74]

I have an '01 Isuzu Rodeo Sport 2.2L 4-cyl. that I bought brand new in '01. It's been a really reliable vehicle. I have 161K miles on it. But, it's recently began idling rough and I can smell some gas/exhaust mixed fumes when sitting still. It only does this once the car has reached normal operating temp.

I just recently replaced the fuel pressure regulator, fuel filter, spark plugs, wires, and the valve cover gasket. I have also ran Seafoam into the throttle body and gas tank. What else could it be? Possibly the EGR valve? I attempted to replace it a cpuple weeks ago, with no luck, because of where it's located - behind the engine and under the firewall, I couldn't get to one of the bolts. Anything ideas?

Thanks,
KM

[StevenZ]

Does the smell appear to be raw gas or exhaust gas?
If raw gas, you should be able to check for leaks - vehicle running at idle. I would inspect areas around the recently serviced components, e.g. fuel regular, etc.
If exhaust gas, I'd inspect your exhaust system. I had an exhaust flex coupling fail that leaked exhaust gas and was noisy. Had a local shop weld one in and back to normal.

[kmoore74]

StevenZ,

Thank you for your response. It appears that I do have an exhaust leak where what it appears to be, like a flexible coupling, just under the driver side seat. I do believe that is the cause of the exhaust/fuel odor I've been smelling.

But, even though I have replaced the EGR valve since my initial post, it stills seems to idle a little rough when stopped, after it reaches normal operating temperature. It's not as bad as it was, but it's still doing it.

So, after replacing the EGR valve, the fuel filter, the fuel pressure regulator, and plugs and wires, I'm at a loss as to why it's still idling rough.

Any thoughts on that?

[StevenZ]

Have you replaced the exhaust flex coupling? If not, you may want to do so and see if it also resolves your rough idle issue. I had simiar symptoms and they cleared when the flex coupling was replaced.

[amigo-2k]

The rough idle could be due to a bad intake manifold gasket ... super common ... I've had mine replaced 3x in the past 14yrs ...

[amigo-2k]

The rough idle could be due to a bad intake manifold gasket ... super common ... I've had mine replaced 3x in the past 14yrs ...

[kmoore74]

StevenZ/amigo-2k,

I have had my exhaust completely replaced my exhaust (excluding the catalytic converter) and have replaced my EGR valve, and cleaned the throttle body, along with all the other crap in my first post. The damn thing is STILL idling rough and I can STILL smell exhaust fumes when sitting at a stop. But, this damn car isn't giving any kind of warning/check engine light. So, I have to assume, maybe incorrectly, that if I take it somewhere to have them do a diagnostic, they won't get any codes, since the check engine light isn't on. Am I wrong?

I may look into the intake manifold gasket. I'm now thinking that maybe my catalytic converter is going out and it's not allowing the exhaust fumes to flow through it as their supposed to. But, who the flip knows...

Anyway, if either of you, or anyone else has any suggestions through experience, please feel free to chime in.

Thanks,
Kenny