REALLY Dirty Intakes (was "won't accellerate"

[baumbr]

'98, 3.8L, 140K miles.

Over the weekend I pulled the upper intake manifold to clean the EGR ports. I couldn't even see the ports, although I knew where they should be. Also noted that the lower intake showed the following: Starting from the passenger side, side toward radiator, the first two secondary ports showed rust scale, third port was just dirty, primary ports quite dirty with carbon build up. On the firewall side starting from the passenger side, the first primary port was dirty with heavy wet carbon, the second port heavy with dry carbon, third port dirty. The upper intake manifold primary ports were all caked with carbon/ grease up to 1/8" deep in spots.

I spent several hours cleaning everything until it was factory bright. Before I put it all back together I plan to replace the plugs and wires as the back side is much easier to get to with the upper intake off.

Several questions:
1. With an engine this dirty what else most likely needs cleaned and replaced due to fouling, etc.?
2. Is the rust scale inside the secondary ports indicative of a gasket leak? No indication of the van using excessive water, no water in oil, no oil in water.
3. Is the wet, oily carbon build up near the same ports that have rust also indicative of a bad gasket?
4. Will my efforts improve the drivability i.e. dying after 40 miles?

Thanks folks.

[wiswind]

Well, it sounds like it should help.
Hopefully, you were careful to avoid getting much stuff on down into the lower intake manifold....as it would be drawn into the engine.....and the valves may not seat so well on chucks of crud.

That said.....it may run rough.....maybe even smoke a bit on start - up, as it is almost certain that some cleaner will go in.

If you are using some coolant.....a slight lower intake manifold gasket leak is possible......as mine seemed more black on the passenger side.
The only way to really know if coolant is into the oil, is to send a sample in to a lab for testing.
If you can "see" it, then you have a major problem.

Another test to see of coolant is being drawn into the cylinder(s) is to remove one of the "upstream" oxygen sensors....and see if there is a green stain on it.

From what you say here....if you have a leak.....it is very slight.

Be very carefull putting things back together.....lots of vaccum lines...and branches off some of them....so it is easy to knock one loose, or even forget one.

If the PCV valve feels loose in the rear valve cover, you can get a new gromet for it.
Also, check that pesky 90 degree elbow on the top of the upper intake manifold, where the PCV line connects......they can develop a crack on the inside of the elbow.

I have a "catch can " on my PCV line.....and it gathered very little in the summer.
It did gather a lot in the winter......so cold weather operation seems to be tough for wet stuff in the intake.

The EGR system seems to not clog up except right at the end of the ports.
I had mine all apart......used a bottle brush with cleaner to clean the passages inside the lower intake manifold......and it was not bad at all....did not need to bother with it.
There was just a light black coating.....except right at the end of the ports....where you saw the mess.

Make sure that the IMR plates move without binding....but don't get carried away with moving them too much....as the actuators are prone to develop vaccum leaks....and they are kind of pricy.

If you have the fuel injectors out....you might spray some cleaner (carb cleaner) up inside the "cap" that is over the spray end of the injector.....crud can build up inside that cap.....causing issues with the spray out of the injector.
The injectors seem to be fine otherwise.....
Use a little dab of oil on the "O" ring gaskets on the injector to aid them in going back in.
If you remove them......FIRST....spray cleaner around each injector to remove all the crud that has settled around each one......that is a nasty dirt trap around each one......and it is just waiting to fall right down into the engine.
Of course......follow the steps to release the fuel pressure before messing with the fuel rail......
I did NOT disconnect the fuel line from the fuel rail......I was able to lift it up the slight amount needed to work with the injectors with it connected.

If you remove the fuel rail......One tip that I do.....
After I have the injectors in place, and the fuel rail fully in place......right before I put the upper intake manifold on.......I turn the ignition key ON....but NOT to the start position....you don't want to crank the engine....just turn the fuel pump on......so that the fuel system comes up to pressure.
Then....I look it over carefully to see if there are any leaks.....when I am able to see everything.
Then, I turn the ignition OFF.....(and remove the key).....and install the upper intake manifold....etc....etc.

[baumbr]

Thanks for the guidance WisWind.

While I was in there I replaced all the plugs with Autolite double platinums. The old plugs were sooty and the center electrodes were burned way down. With the upper intake off all the plugs can be reached from the top, although the back side requires some strange yoga positions.

Hooked a vacuum tester to the IMRs and each pulled fully closed at 8 inches Hg without any hint of bleed down, so I think the diaphrams are good. (This was the only P code that came up when the transmission went down.)

Replaced the PCV and the short piece of soft hose that connects it with the hard vacuum line. The original had collapsed and pinched shut. I'll double check the elbows, tees, etc. along the way.

Also cleaned the throttle body with a specially formulated and lubricated cleaner. (I accidently stuck my greasy thumb inside it.) Injectors were cleaned with carb/intake cleaner and stethescope tested after reinstallation. all good.

Next, vacuum and electrical testing of EGR valve, EGR controller, DPFE, TPS and other controls to resolve the drivability problem. Also new plug wires