JM wrote:
> Comboverfish wrote:
>>> Forgot to mention, no codes set, and I cleaned the EGR and ports when I
>>> got the car (had the problem then also). Also, if I pull the vacuum
>>> line to the EGR valve, effectively disabling it, there's no change. It
>>> does feel like that kind of a problem though
>> If I had it I would look at fuel trim with a scantool, under many
>> different driving conditions. If fuel trim was too far off I would
>> suspect dirty MAF sensor elements first. I suppose that you have
>> checked the integrity of the large intake hose (splits, cracks, fit)?
> Yes, I've been over that hose and the various ones that branch off of it
> a few times, and everything seems in order. I don't have a tool that
> will let me see the trim values but I'll keep that in mind in case I do
> take it somewhere for another look.

I was out today and noticed there is a distinct hissing sound when I rev
the engine coming from somewhere around the EGR valve or possibly the
intake manifold. I know this particular year Altima was known for the
intake manifold gasket breaking down and leaking, but this sounds like
it's closer to the firewall than that.

I went over all the vacuum lines I could see and they all look good, so
I'm a little puzzled where this sound is coming from. I have tried
shooting throttle body cleaner where the manifold bolts to the head,
with no change in idle, and I also sprayed around the various metal bits
of vacuum line, but this had no effect.

I'm half hoping I'm on to something though...