UIM & LIM Removal And Cleaning

The Ford Mondeo hit our roads in 1993, and has consistently been a sales success. Now on its 4th incarnation, it remains a drivers favourite.
For more information, visit the Ford Mondeo forum on TalkFord.com, the definitive resource site covering all Fords from the present day to the 1970's.

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Overview Guide
Ford Model:	Mondeo
Petrol/Diesel:	???
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Duratec V6 UIM & LIM Removal And Cleaning

If there is anyone attempting this procedure, it would be appreciated if photo's could be taken to accompany this guide, and posted on the TalkFord forums as it would be of benefit to the TalkFord community.

Parts Required

• Haynes Manual (for a further guide, tightening sequences & torque settings

• Socket Set

• Spanner Set

• Tooth brush or a non-abrasive brush

• Metal polish & cloth

• EGR Valve Gasket (Part No. 6326205)

• Throttle body to UIM gasket (Part No. 7318043)

• 1 x UIM gasket pack (Comes with 2 per pack as needed) (Part No. 3523225)

• 1 x LIM gasket pack (Comes with 2 per pack as needed) (Part No. 3902545)

• 2 x Cans of Carb Cleaner (May need 3 cans depending on how much cleaning is required)

Abbreviations

UIM= Upper Intake Manifold

LIM= Lower Intake Manifold

MAF= Mass Airflow Sensor

TB= Throttle Body

EGR= Exhaust Gas Recirculation Valve

IAT= Inlet Air Temperature Sensor

TPS= Throttle Position Sensor

ECU= Electronic Control Unit (Brain)

IMRC= Inlet Manifold Runner Control

Definitions

UIM: The UIM is the cluster of 6 cast pipes that feed the inlet ports with air. The UIM is connected to the airbox via the MAF, Bellows and Throttle Body.

LIM: The LIM is the secondary inlet port block, similar to cars fitted with secondary carbs or twin chokes ( e.g.; twin 40's). It consists of 12 ports (2 to each cylinder), one port is always open and airflow is controlled by the Throttle Body. The closed or "butterfly" operated port is the Secondary Port.

The Secondary port is controlled by the IMRC and is regulated by either the driver "flooring" the car, this is known as Wide Open Throttle (WOT), or by the engine reaching a preset RPM, approximately 3800rpm. These Secondary ports are either open or closed, they are not variable.

MAF: The MAF is a sensor located in the MAF housing, this measures the flow of air into the Throttle body and tells the ECU how much fuel the engine needs to match the volume of air entering the engine.

Hints

Organise your work place. There are a few bits to come off before you can get to the ports that require cleaning, so be careful with all parts. Remember where you removed them from! A good tip: Once you've removed a component, place the nuts or bolts onto the mating threads, this stops you ending up with "spares" at re-assembly.

Fuel System De-pressurisation

At this point you need to decide if you are going to de-pressurise your fuel system now or during dismantling, as there are 2 methods.

Method 1 - Fuel Pump Fuse Removal

This is considered to be the easiest method to De-pressurise the fuel system, and can be done before removing the LIM.

Locate and remove the fuel pump fuse. (Fuse number 14, located in the engine compartment next to battery)

Start the car up and let it run for the 5 – 10 seconds that its does, and wait for it to run down. This process will de-pressurise the fuel system.

Switch off the ignition, and replace the fuel pump fuse. (DO NOT switch the ignition back on)

Remember that if this is the method that you choose to use then it needs to be done now before other parts are dismantled, as obviously you need to be able to start the car to de-pressurise the fuel system.

Method 2 - Disconnecting the fuel feed and return lines

This is a trickier method than method 1, and can be done during the removal of the LIM, so carry on with the rest of the guide until you reach the LIM removal section which will refer you back to these instructions.

There is a bleed valve located to the right hand side of the engine on the fuel line. It looks like a tyre valve, but slightly larger. Place a container underneath the valve to collect any spillage, and a cloth or rag over the end of the valve, to prevent you from getting fuel on you and to absorb any excess fuel. Slowly de-press the inner part of the valve (as if you were letting a tyre down) this will release the pressure in the fuel system. I found that there was not a lot of fuel expelled during this procedure.

Disconnect the fuel feed & return lines: Remove the securing clips from around each pipe, this will leave you with the pipe join to release. To disconnect the metal pipe from the flexible pipe you will need to make up a small tool to assist you in releasing the two pipes from each other.

This is really easy, get a piece of plastic pipe (or something with a circumference similar to the solid metal pipe) approx. 10 - 15mm diameter, cut it to about 2cm in length then cut one side of the ring to allow you to put it onto the metal side of the pipework. You may find that you need to trim the pipe to reduce its diameter to make it a good fit around the pipe.

Push the piece of pipe into the open end of the pipework join; this will lift a securing spring inside the metal lipped join over the internal lip that is holding it in place. Once released pull the solid pipe and flexible pipe apart.

The above sounds complicated, but it is really self explanatory once you see how the pipework is being held together. You might have a small amount of fuel leak from the join, so be ready for this.

General Sundries Removal

Disconnect the battery; you don't want to take any chances!

Remove the plastic cover at the front of the engine using a socket or ring key, replace the bolts back into the mating threads for safe keeping.

Remove the MAF, Bellows and induction filter (if fitted). All wires and pipes should be positionally noted and tucked away to allow further access.

On the throttle body, turn the plastic throttle cam to allow the throttle cable wire to be removed from it's housing, by removing the location clip from around the cable locator. Slide the location nipple from its position to release the cable.

On the right had side of the Throttle Body, you'll see 4 bolts holding it onto the UIM, there are also 3 more holding the throttle linkage onto the UIM and throttle body. Remove all these fixings and remember where they come from! The throttle cable bracket can now be removed.

The throttle body can then be removed from the UIM, remember there is a gasket on there, this will need replacing. The throttle body can be polished whilst you’re at it. The mating faces of the TB and UIM should also be cleaned, and all remaining parts of the old gasket completely removed, to ensure a good seal on re-fitting.

Remove the 2 bolts from the EGR valve, the front one is easy enough but you may experience difficulty with the rear one. Try some penetrating oil (WD40?) beforehand, this should help. Pull the EGR slightly to the right, it will not detach fully due to the metal pipe on the base. A little movement is required only for access. Remember there is a gasket on there, this will need replacing.

The mating faces of the EGR valve and UIM should also be cleaned, and all remaining parts of the old gasket completely removed, to ensure a good seal on re-fitting.

At the rear of the engine there is a little black connection block with a series of small vacuum pipes attached to it. This block needs to be removed from the UIM by removing the 2 small bolts at the rear of the block. Be careful, they are easily dropped! Remove the connecting multi-plug.

UIM Removal

Fully slacken all the 6 bolts, (using the un-tightening sequence in the Haynes manual holding the UIM in position, do not attempt to remove them until the UIM is off the engine, it is easier to leave them on at this stage.

Remove/prize the vacuum pipes from the UIM, using a wide flat bladed screwdriver, and move out of your way (careful with them as the end of the pipes will be brittle). Gently "rock" the UIM until the seal is broken, lifting up and moving to the left, remove the UIM from it's seating. Store in a safe place.

Remove the two plastic/rubber gaskets from the LIM and discard, these will need replacing.

The "Secondary throttles" should now be in view!

LIM Removal

De-pressurise the fuel system as described above.

Disconnect the wiring for the coolant temperature sensor, which is located above the starter motor.

Disconnect wiring from the injectors using a small screwdriver to push the middle of the spring clip in, to release the injector plug.

Disconnect the IMRC cable from the secondary spring mechanism, by disconnecting the cable locating lug.

Unscrew the LIM securing bolts in the un-tightening sequence described in the Haynes manual.

Remove the LIM and keep the securing bolts safe. Remove and discard the two manifold gaskets.

Cleaning

You'll need a couple of cans of Carb Cleaner for this, maybe 3 depending on the mileage since last cleaned. I use Wynnes Carb Cleaner, available from Halfords at about £4.50 per can. Be careful, if it gets in your eyes, it burns like hell and never smoke or light a naked flame near the fumes or container, it's highly flammable!

The first thing to do is lay the UIM on the floor and soak all ports and inside with a full can of cleaner, leave this to soak whilst doing the Lowers.

Lay the LIM on the floor. Spray the cleaner directly into all 12 LIM ports, specifically into the closed ports, these are the dirtiest. Allow the cleaner to do it's work for a few minutes (Put the kettle on).

Using a small, soft toothbrush, start by cleaning the primary ports (open), use a little more cleaner from time to time to keep the brush wet. You'll soon see the alloy coming back to it's original grey colour.

On the right hand side of the LIM, you'll see the linkage for operating the secondary butterfly ports, open and close them whilst spraying the cleaner in the ports.

Wedge something into the secondary linkage to open the ports and free your hands.

Using the toothbrush and cleaner, do the same to the Secondaries as you did to the primaries, remember do the butterfly valves too. These should come up "brass" when properly cleaned.

Give all the ports a final spray and using a soft cloth, wipe all the ports clean and also surrounding areas. Don't forget to give both manifolds a good clean too, especially the mating gasket faces.

Back to the UIM, Using the toothbrush, remove any build up around any ports. There will be excessive carbon on the throttle body port and the small ports surrounding it, you may have to carefully scrape these deposits with a small blade screwdriver. Give the insides another good spray with cleaner.

Using your garden hose, give all ports on the UIM a good "blast" out, this removes all the cleaner, oil and carbon residue loosened by the carb cleaner.

Allow the UIM & LIM to dry or assist with some rags.

Reassembly

Re-assembly is the opposite of removal, just remember; most parts that you have been handling are made from alloy, do not over tighten the bolts or you'll strip the threads!

It is recommended that all gaskets are replaced during this removal exercise, as a matter of course.

Re-Connect the battery.

There will be some smoke (well a lot actually) on engine start up. It will also sound rough and miss-fire for a while. Do not rev the engine until it's hot.

Enjoy your extra power!

Disclaimer

The Author will not be held responsible for any damage to any component during the above procedure, nor will he/she be held responsible for any resulting damage or malfunction of any component which has been mentioned in the above literature. This "how-to" is to be used as a guide only.