First off...1991 Trooper, 2.8L.

Recently I have been replacing air filters as often as once a month. They appear to be getting clogged somehow and it is not from mud or dirt as it usually is. The outside of the filter is fairly clean while the inside of the element is somewhat black. Could this be caused by some sort of backfiring or exhaust getting sucked up into there? The only thing that I can see visibly wrong is the flex pipe from the exhaust manifold to the intake tube is loose. Is this for some kind of heater box for the intake? There is a small exhaust leak on each exhaust manifold near the gaskets. To me that would make sense why the air filter is black but it is only black on the inside. Also, when cold the truck does run a bit poor. I don't know if that is just nature of the beast or if something is wrong with the truck and if that is what is causing air filter clogs. Any and all help will be greatly appreciated.


Thank you,

Kevin

No ideas?

I'm thinkin' that perhaps you're seeing a lot of blowby up into the air cleaner. Maybe a PCV valve needing replacement, or perhaps the motor has a grunch of miles on it?

You'll note that the PCV is in the pssgr's valve cover, and a breather tube in the driver's side valve cover goes directly to the middle of the air cleaner. If you were having tons of blowby it could go to the inside of the filter before being sucked into the TBI.

You also might want to pull the air cleaner lid and see how the injectors are spraying. You should see an even spray pattern, fan-shaped with no "globs" of fuel. Maybe you've got a strange-spraying injector which is polluting your filter.

The poor-running when cold might be tuneup-related. Dist cap, rotor, new wires, and plugs usually work wonders on these motors. I'd recommend AC Delco Rapidfire plugs, std or platinum; the little 60-Deg V6 seems to like these plugs.

The "heater box" on the exhaust manifold is part of a "heat stove" system which provides heated air to the TBI in cold weather. A thermostatically-operated vacuum-bleed valve works to move the flapper valve in the air cleaner snorkel to either admit warmed air from the 'stove' on the manifold, or cold air thru the snorkel. Problems here would mainly affect warm-up driveability in extremely cold weather, probably not the root of your problem.

Or, maybe it's time for a 3.4, yeah, that'll fix that air cleaner problem fer sur!!!! <img src="/forums/images/graemlins/evil.gif" alt="" />

Let us know what you find.......ed