Hey guys,

I've been havin a hell of a time getting my car smogged. You can check out my post here: https://www.thirdgen.org/forums/west...emissions.html

Anyways,

I got the tb, plenum and egr valve pulled off. I ordered a new oem egr valve (negative backpressure) so I'm good there. I cleaned up the throttle body pretty well. I took all the old gasket off the upper runner area on the runners and the plenum. BUT, inside the plenum is all black with carbon build up. I'm thinking that might produce a negative result with emissions. Is this correct? I've sprayed Deep Creep Sea foam into it but doesn't seem to do much good.

Should I try and take it someplace to get a deep clean / soaked? Or should I just throw some brake cleaner on it and do the best I can?

 

Brake cleaner, Varsol, Castrol Engine cleaner etc...

All will clean that up nicely. I left my plenum in a varsol tank for a week. It turned white

 

Between the crud that comes in through the EGR system (which dumps right behind the throttle blades in the plenum) and decades of small particle crap getting past the air filter, they do get rather cruddy looking inside.

 

No, the buildup on the plenum should not be the cause of you failing. I don't know what kind of gas you are running, but put a high quality gas in there, 87octane, it will burn cleaner. Then after the test dump some octane boost in it.

 

Best way to go without worrying about pitting or
discoloring the aluminum, I would reccomend a bead/sand
blaster if you have access to one.. You get every nook &
cranny and the aluminum is restored to what it once was..
just remember to remove the IAC, TPS, and the like before
you stick the sucker in the blast chamber.

If you dont have access to a bead/sand blaster
then I would follow the suggestions of the other
guys have made.

A dirty plenum wouldnt contribute to failing
emissions unless it was in seriously bad shape.

Timing, type of fuel, and/or catalyct converter(s)
are usually the main contributors to a failed emissions
test. I always get a 1/2 tank of 91+ octane fuel, and
a bottle of alcohol, and make sure you are running
the car at operating temperature of 205-degrees or
more.. My best results are right at 220-degrees for
emissions testing only !!

Good luck with emissions

 

I just shot some gumout in mine, let er soak for 10-15 minutes and took it down to the car wash.

 

Muratic Acid and a garden hose. Buy it at ACE Hardware and use latex or rubber gloves. Spray into plenum with a spray bottle and repeat until you see the Al of the plenum. I think it goes without saying to use eye protection also.

I used this on my accessory bracets, sprayed a good metal etching primer on it, and used high temp Al paint-looked better than new. Good luck.