Contour Enthusiasts Group Archives Forums Modifications Duratec Maintenance UIM/LIM cleaning and Plug changing soon...

Alright, Our Mystique has almost 67,000 miles and we picked up some Autolite APP764 plugs and a plug gapper(lost the one we had ) Anyways, the plugs are gapped and ready to go in.

We also ordered the Felpro upper intake gasket from Advance Auto. Anyone have any tips for the UIM cleaning?? Any tips on what to use to clean the UIM??

Hopefully this will all be done next saturday... Maybe we'll see better gas milage and performance.

Main site - mods - how to.

I would strongly recommed cleaning the intake manifold chemically without taking the mainfold off the engine. It is much easier and there is less chance of having someting else go wrong while you have it apart.

Do it before you change the plugs. Change the oil afterwards.

Get a bottle of liquid pourable injector cleaner. The last time I did mine, I used Berryman's B12, but I have used BG, Red Line, and Techron. The cleaner is fed through the vacuum taps on the top of the intake manifold just behind the throttle body. To remove the vacuum line, hold the retaining collar with a small screwdriver while gently prying on the fitting to pull it out of the intake manifold. Remove one line at a time for cleaning.

Find some vacuum line just the right size to slip into the hole. You need about two or three feet. Slip one end into the vacuum hole and the other end into an open container of injector cleaner. Find a pair of Vice Grip pliers and pinch the hose shut. Start the engine and very gently twist the screw open on the Vice Grip to permit some liquid to flow. This part is tricky since it is really hard to meter the flow and if you get too much the engine will stall. It may help to hold the throttle open a little while feeding the cleaner through. When the bottle is about half gone, switch to the other vacuum port.

Next, clean the throttle body. You can use a little of the same cleaner you ran through the vacuum port if you want, but I usually use a spray aerosol throttle body cleaner. With the engine off, remove the intake hose from the throttle body. Spray the throttle plate and bore with cleaner. Open the throttle plate to make sure you get the whole bore as well as the plate covered. Using a small reasonably soft brush, gently scrub the throttle plate and throttle body. I like to use an old toothbrush. Use a soft cloth or dampened paper towel for the final wipe down if needed. When you start the engine, it will run rough for a moment while it cleans out the cleaner (and junk) from the cleaning. You may need to hold the throttle slightly open to get it started. Once the engine has settled down (usually within a minute or two), shut it down. Make sure the air filter is in good shape and clean or replace if needed. It is my practice to also add an injector cleaner to the fuel tank after doing this to help clean the injectors. If the fuel filter has net been changed in the last 30,000 miles (some people say 15,000 miles, your choice) this is a good time to change it too.

This does not need to have an oil change or spark plug change after doing this, but if you are going to do such services, it is better to do them after so that you don't take a chance in fouling new plugs and you can dump the junk out of the crankcase.

This service will have effectively cleaned your throttle body, the intake manifolds, the valves, and the combustion chambers. The need to actually remove the intake for physical cleaning is greatly reduced.

I do this fairly often, about every 10,000 miles. It ALWAYS makes a very pronounced difference in how the engine runs. I have not had my upper intake off, but I would be willing to bet that if it were take off shortly after such a cleaning that there would be minimal build up on the secondary plates. Every car would benefit from this kind of service at least every 30,000 miles.

By the way, you don't need to remove the upper intake to change the rear spark plugs. There is a how to in the FAQ section. It helps to move the coil pack, but some have reported that they don't need to. To remove the coil pack, a 1/4" drive 7mm flex socket is most useful. Make sure that you don't forget to replace the ground strap and the radio noise supressor when finished. There are four bolts holding the coil pack. You really don't need to reinstall the rear two if the two front ones are properly tightened.

Hmmm... I'll have to think about doing that instead, although I already ordered the gaskets...


I'm curious to see if there really is that much crud in the intake...


How do you mean it makes a difference?? Runs smooter, better gas milage, quicker??

Smoother and better throttle response over the entire range. Most noticable to most at light throttle acceleration but to an enthusiast it would be noticable throughout the entire range.

If you want to see how well it works, try cleaning it chemically and drive it to see the difference then pull the upper intake off and have a look.

Try cleaning the throttle body first so that you can see just how dirty the rest of the intake manifold is before you do the chemical cleaning.

If I were to do it again, I would have done the chemical cleaning instead of taking of the UIM/LIM.

For my 95 there wasn't much crud, not enough to make me go HOLY CRAP. ...and I didn't notice much improvement.

The biggest improvement by far was the EGR passages behind the throttle bottle, those were plugged completely. There was a huge difference in acceleration after cleaning those out...and gas mileage improved.

If you're going to clean the secondary plates, you NEED to remove the LIM.

If I had to remove and clean the UIM/LIM intake again, I would take them to a garage and have them do a chemical dip. Because there is only so much a tooth brush and a Saturday/Sunday can do.

Save yourself the time and do the method described earlier in this thread. Plus cleaning out the EGR passages (behind the TB) then the new plugs, and the oil change.

If you're not happy after all that, then satisfy your curiousity by taking apart the UIM/LIM and cleaning both. Because is whole weekend in itself.

I meant to say Throttle BODY not Throttle Bottle.

Also - in addition to my post, if you do take off the uim to clean it, you will see that you can't do much by soak it.

The only advantage of taking off the LIM is to clean the crud off the plates...other than that, the openings in the UIM/LIM are quite large for the volume of air required and the build up on the walls of the UIM/LIM won't even come close to restricting air flow.

There are tests you can do to see if your secondary plates are binding! With the '95 which have vacuum actuated secondaries, you can disconnect the vacuum line and manually actuate the secondary plates and physically feel if they are binding. Mine were able to move freely and didn't behave like they were binding... not sure how to test the ones that are cable actuated. But I'm sure there is some literature out there for that.

Just some more food for thought....

So in summary - I don't see any reason why to take off the UIM/LIM unless there is a problem. If you're thinking of doing it just because, I wouldn't.... do the vacuum cleaning method first.

I'm pretty sure the secondaries are opening, but it seems like it should have more power than it does.


If you do the berrymans, do you just run the engine at idle or do you rev the engine??

Is berrymans reall that potent?? Will it really make its way into the oil, or is that just a precaution??


Thanks for your help everyone.

It will not hurt to gently rev the engine. I would not go over about 2000 RPM. You may need to open the throttle a little while adding the chemical to keep the engine running.

Yes, Berryman's is very potent when used in this manner. Yes, some will was past the rings and make it into the oil. It doesn't really hurt the oil, but if you are changing the oil anyway, change it after doing the cleaning.

If you already have the gaskets, you might as well pull it. I have a 98, and when I did the cleaning a few months ago, it was crud city. And I really did notice a difference after the cleaning; little more pep in the step. Yeah, the air passages are big enough not to be too affected by the buildup, but what amazed me was how clogged the egr passage and pcv tube were--that can't be good.

Plus, it's a pretty good learning experience to get in there and see what's going on.

Just take your time. Give yourself a Saturday *and* a Sunday. Take everything off the first day and scrub up those parts really good with a brass-bristle brush and several bottles of cleaner (Valvoline TB cleaner works *really* good). When you're all refreshed the next day, take your time and put everything back together carefully. Torque all the bolts on the UIM to spec, and you're all set.