PLENUM REMOVAL 90-93 Q45 STEP BY STEP WITH PICTURES

[goody90q45]

I had the good fortune of having to remove the plenum on the 90Q for the 5th time to replace another injector. I know I could have saved myself a lot of grief by replacing all 8 injectors with new the first time I had the plenum off but I didn't (4 times). There's something special about seeing drops of blood on the shiny plenum that makes me want to replace just one injector at a time. For this bloodletting session I had a day of vacation with nothing else planned so I spent a little extra time to take some pictures and put this thread together.

This thread is not intended to guilt you into replacing every hose or debate whether or not every component in the valley should be replaced while you're there. My sole purpose is to give owners a step-by-step tutorial to remove the throttle body, IAC valve, EGR valve and plenum. If an Q owner needs to make repairs with the plenum off instructions can be found in other threads using the search function.

The tools needed for plenum removal are very basic and about the only special tool might be a 3/8" drive 6mm hex bit for the four throttle body bolts. This isn't rocket science (I work with rocket scientists and most of them couldn't turn a wrench). All removal and reinstallation is righty-tighty, lefty-loosey meaning there's nothing to adjust (i.e. timing) when you're done. The only setting to be careful with is the position of the locking nuts on the throttle cables so as not to affect throttle position by changing the amount of slack in the cables.

The 94-96 Q is very similar to the 90-93 except for the placement of the 2 EGR vacuum solenoids and the routing of the 1/4" vacuum hoses. The main difference is that the TB needs to be unbolted to disconnect the 2 vacuum hoses attached behind it.

Finally- I'd like this thread to be a reference for present and future owners. If I have misnamed any parts or could describe any steps better please comment. Wes/Jesda feel free to pull any or all of this thread to the Tech Help section at Q45.org.

Put on a pair of rubber gloves, have a couple of bandaids at the ready and let's get started.

Tools. There's not a lot of tools needed and for the most part they're basic hand tools. I like using a smaller 1/4" drive ratchet and sockets but a 3/8" drive set would work well too. The plenum is all aluminum so during reassembly too much torque on any of the bolts risks stripping threads. If you choose to not use a torque wrench, especially on the plenum bolts, then go small with the 1/4" drive wrench.

Step 1- Remove Fuel Pump Fuse Remove fuel pump fuse from the passenger compartment fuse box. It is the 15 amp fuse on the right side of the fuse block. After fuse removal, crank the engine for about 10 seconds to relieve the pressure from the fuel rail. Sorry for the rotten picture.

Step 2- Unplug MAF Connector Unplug MAF connector. Hang on tight to the clip. It's spring steel and wants to fly away. I always use a pair of needle nose pliers to remove any of the connector clips. If you have a Jeff Williams front strut tower sway bar now is the time to remove it with a 14mm socket and breaker bar.

Step 3- Remove Air Box Lid And Air Filter Loosen the clamp connecting the MAF to the air inlet tube. Release the 4 clips holding the air box lid. Remove the MAF and lid as one unit and remove the air filter. The air box cavity is a good place to store tools during the plenum removal.

Step 4- Remove Air Inlet Tube With a pair of pliers, pull back the clamps on the 1" hoses on the top and bottom of the air tube. Pull the top hose off and rotate out of the way since it will stay attached to the plenum during removal. Leave the bottom hose attached for now. Pull off the two 1/4" hoses and loosen the clamp at the throttle body (TB) end of the tube. Tilt the tube up and wiggle to remove it and the bottom large hose will come loose at the same time.

Step 5- Remove Throttle Body (TB) I've included this pic to show the 6mm hex bit ($5 at Sears) that I use for TB removal. You can get by with a long allen wrench if that's all you have. If this is the 1st time your TB is being removed you'll know it since the gasket will probably tear to pieces when the TB is pulled away from the plenum. Have a new TB gasket (and IAC valve and EGR valve gaskets) on hand for reassembly.

Step 5a- Disconnect Throttle Cable If you're following this thread for EGR removal only you'll need to disconnect the throttle cable.

Remove throttle cable by rotating the spring assembly upward. Rotate the cable until it aligns with the slot in the semi-circular channel and pull it out.

Step 5b- Unplug TB Electrical Connectors Unplug the 2 Throttle Position Sensor (TPS) connectors on the left side of the TB and the solenoid below the TB. Push the connector cluster out of the way below the valve cover.

Step 5c- Unplug Vacuum Hose on Right Side of TB Pull off the vacuum hose from the solenoid on the right side below the TB. Leave the other end (under the TB) connected.

Step 5d- Unplug Vacuum Hose on Left Side of TB Pull off the vacuum hose from the solenoid on the left side adjacent to the TB. Leave the other end (under the TB) connected.

Step 5e- Remove 4ea TB Bolts Remove the 4 bolts using a 6mm hex bit and a ratchet wrench or a 6mm allen wrench. In the pic the 2 top bolts are visible and the other 2 bolts are directly below. With all 4 bolts removed you will be able to pull the TB straight out about an inch to be able to disconnect the last 2 hoses.

Step 5f- Remove Coolant Hose on Right Side of TB With the TB pulled about an inch away from the plenum pull back the clamp on the hose on the right side and disconnect the hose. Disconnect the right side hose first since it is the shortest and restricts movement of the TB.

Step 5g- Remove Coolant Hose on Left Side of TB With the right side hose removed you'll now be able to get to the left side hose and clamp. Disconnect this last hose to remove the TB.

Step 5h- TB Removed A pic with the TB removed. The hoses on either side of the TB pointing to the right are the coolant hoses disconnected in the previous 2 steps.

Step 6a- Remove EGR Valve Vacuum Tubing EGR valve removal is independent of the plenum removal. If you're following this thread only for the EGR valve removal, start here.

Pull off the "Y" shaped vacuum tubing as one piece.

Step 6b- Remove Throttle Cable and Bracket If you're following this thread for EGR valve removal only, complete Step 5a first (Disconnect Throttle Cable from Throttle Body).

Loosen the 14mm nut holding the throttle cable to bracket taking care to only rotate one of the nuts so as not to change the setting (which will change the throttle position). Remove the two 10mm bolts securing the throttle cable bracket.

Step 6c- Remove EGR Solenoid Solenoid and bracket above the EGR valve are attached to the plenum with two 10mm bolts. Remove these bolts and pull the soleniod/bracket assembly straight up to disconnect from the tubing below it.

Step 6d- Loosen EGR Exhaust Inlet Tube I use a 10" crescent wrench since I don't have a 29mm box wrench. Either works fine. Be careful when first breaking the nut loose not to break the delicate nipple off the solenoid valve below it (bottom of pic). It's a flared fitting and the loosened nut will pull completely back to expose the flare.

Step 6e- Unbolt EGR Valve and Remove Remove the two 12mm bolts holding the EGR valve to the plenum. With the bolts removed the EGR valve will pull straight up and out.

Step 6f- Pic With EGR Valve Removed Pic shows the 3 inlets that need to be cleaned/cleared in order to ensure proper EGR function- Exhaust tube (on right), temperature probe port and inlet port (on plenum). Somehow I deleted the picture of the temperature sensor being removed with a 14mm box wrench.

Step 7a- IAC Valve Removal IAC valve removal is independent of the plenum removal. It is located at the rear of the plenum close to the firewall. Start here if the IAC valve is being removed, cleaned and reinstalled.

The first step is to remove the 10mm bolt holding the throttle cable bracket to the plenum. The IAC valve is directly below. The cable cluster should lay out of the way along the windshield wipers.

Step 7b- Remove Bolts Securing IAC to Plenum Using a small (1/4" drive) ratchet wrench with a 10mm socket, remove the 4 bolts securing the IAC to the plenum. The top 2 bolts are shown in the pic and the other 2 bolts are directly below. The IAC can now be pushed back towards the firewall and left connected for plenum removal. If the IAC needs to be removed for cleaning, back off the hose clamp with a pair of pliers on the 1" inlet hose on the bottom of the IAC, remove the connector clip (needle nose pliers) and unplug the connector. It's the yellow connector on the right side of the pic but yours may be a different color. With the clamp removed the IAC will now pull straight up and off the bottom inlet hose.

Step 8- Remove Center Engine Ornament Cover The 3 major components are now removed from the plenum. Time to move on to the easy stuff.

The engine center ornament cover is held in place with 2 bolts and a nut, all are 10mm.

Step 9- Disconnect Throttle Cables From PS End Of Plenum Disconnect the 3 throttle cable ends by rotating the spring loaded holder. Remove the cable from the bracket by loosening only one of the 14mm bolts on each cable. I labeled each cable to take some of the guesswork out of reassembly. Only the cables need to be removed, the brackets can stay attached to the plenum. Reminder- Be careful not to change the position of the 14mm nuts.

Step 10- Remove Brake Booster Hose From Plenum Pull back the clamp at the plenum end of the hose and pull the hose off. The other end can remain connected to the brake booster.

Step 11- Remove Bracket From DS Rear of Plenum One bolt holds the bracket to the plenum. A 10mm ratcheting combination wrench works best. The plenum won't lift more than an inch if this bracket is not unbolted.

Step 12- Remove O2 Sensor Connector Bracket This bracket is on the PS of the plenum adjacent to the transmission fluid dip stick. It's sharp and will cut you. Remove one 10mm bolt and it's out of your way.

Step 13- Disconnect Coolant Hose At EGR Inlet Pull back the clamp with a pair of needle nose pliers and disconnect the hose.

Step 14- Disconnect Exhaust Gas Hose- DS Valve Cover On the large 1" hose from the valve cover to the manifold under the plenum, pull back the clamp with pliers and pull off the hose. Leave the other end of this hose connected.

Step 15- Disconnect Exhaust Gas Hose on PS Valve Cover This hose sends exhaust gas from the PS valve cover to the manifold under the plenum. Pull back the clamp with pliers and disconnect only the valve cover end of the hose. The fuel injector harness is seen in this pic unplugged in front of the hose. Before I started this job I ohm tested the injectors to make sure I knew which one needed replacing (no surprises).

Step 16- Remove Plenum Bolts Plenum bolts are 10mm, 2 per runner. Many of the rear bolts after being loosened should be pull out with a pair of needle nose pliers. You've probably already dropped a couple of smaller bolts into the great valley under the plenum. No need to risk losing one of these dealer-only bolts.

Step 17- Disconnect Exhaust Reciculation Hose Below TB With the 16 plenum bolts removed you should be able to lift the plenum to get access to this hose. Disconnect only the TB end.

Step 18- Disconnect PCV Valve Hose The PCV valve is located at the PS of the engine center ornamental cover which was previously removed. Back off the hose clamp from the valve end (closest to the radiator) and try and remove the hose. My hose was stiff and I had to raise the plenum a couple of inches to pull it loose.

Step 19- Disconnect Gas Cannister Vent This hose is located next to the solenoid in front of the TB.

Step 20- Disconnect IAC Exhaust Gas Inlet This is the toughest part of the plenum removal- And as bad as disconnecting it is, reconnecting this hose is worse. This is the last connection and can be seen by lifting the front of the plenum a few inches and looking to the center rear. Move the plenum around until you can get enough space to back off the clamp with a pair of pliers. Free this hose and the plenum will lift off.
Modified by goody94q45 at 6:00 PM 2/14/2009

[96Qowner]

Wow, Mike!

You're one of the most valuable posters on this forum. What can I say. All of us, and all of those to come, thank you for this wonderful writeup.

And by the way- Old Farts Rule!

[Infinitiguy19]

Mike this is the best write up I have see I mean you make this look like what it is (really easy).

"most people just need to get over the fear of breaking stuff because once you break it you will have to learn how to fix it"

Wes Stinson, in some post

Wes if your still here you need to add this to q45.org and make this a sticky.

[boonseyQ45a]

omg..... this is a good write up, i admired that you have taken good pictures illustrating each and every steps carefully......

i have an 94 q45a do they have the same tps sensor (step 5c)??? i have a vaccum hose right at the same area that i cannot find where it belongs to.....

Also the bracket that holds up the vacuum lines, coolant lines, etc, underneath the plenum, i unbolted the bracket and install on the engine before i reinstalled the plenum, this can be done for easier future r/r correct if wrong, but for the tps questions mike your help any others will be appreciated

thanks,mitchell

[goody90q45]

i have an 94 q45a do they have the same tps sensor (step 5c)??? i have a vaccum hose right at the same area that i cannot find where it belongs to.....

Is it this one by chance? This is what I found on my 94Q. By disconnecting and plugging this hose the EGR valve doesn't open (but the ECU still advances the timing). The engine runs much better with all vacuum lines routed properly.



If it is this hose this thread will help. Good luck.

zerothread?id=176267

[maxnix]

Together with Ross's even more extensive photos, almost all one needs the FSM for is the torque values.

Ross' is an earlier Q45a.

[mtzgr777]

That's an awesome write up! Now how do you put it back together? You guys have me at the edge of my seat in regards to taking apart the plenum!

[goody90q45]

Putting the plenum back on is the reverse of installation. A couple of things will be different:* The rear hose on the plenum will be difficult to reattach. You just have to lube up the mating hose and nipple and work with it until you mate them up and they slide together. Expect to draw blood.* You'll want to have new gaskets- EGR, Throttle Body and AAC valve. After 15 years they'll be brittle or stuck on the plenum face. The 8 intake gaskets are also nice to replace but not always necessary. I've never used the new set I bought and have had the plenum off 3 Q's with no issues. Your local weather will have a lot to do with how well these have held up.* Use a torque wrench to tighten every bolt that goes into the plenum, especially the 16 bolts that attach the plenum to the lower runners. Torque values are all on one drawing in the FSM.

Stay organized, label hoses and take notes as you pull the plenum off. It may be a couple of days to a couple of weeks before you put it all back together after completing your under-plenum repairs. Each one of those repairs (KS replacement, hose replacement, injector removal, etc.) has many threads talking about how-to and a lot of good info is available using the search function. Good luck.

Don't go in there to replace KS until you verify that they're really dead by ohm testing them at the connector.

[mtzgr777]

Thanks for that info. I did OHM test the KS, the results are on my other thread:

zer...59217

[Infinitiguy19]

Does "Step 20- Disconnect IAC Exhaust Gas Inlet" need to be done to get at number 3 fuel injector? What steps can be skipped over to get at it? I am looking to get the replacement of number 3 injector done under 9 hours. I have never replaced a injector in a Q before or reinstalled a plenum. I have removed it off a junk Q many years ago. I am no rookie but I am no "plenum pro" either.

Happy Thanksgiving NICO!

[mattd1979]

When I remove the plenum, I just leave that part attached and remove the lower portion of the y-hose from the lower metal pipe. I also leave the AAC valve attached to the plenum.

Matt

[goody90q45]

Does "Step 20- Disconnect IAC Exhaust Gas Inlet" need to be done to get at number 3 fuel injector? What steps can be skipped over to get at it?......

The IAC valve doesn't have to be removed to lift the plenum but it's only 4 easy-to-reach bolts and a clamp so remove it for no other reason than to clean it. You can remove the TB and EGR to clean them but the lower intake exhaust on the back side is much tougher to disconnect and even harder to reconnect. Leave it attached and once the 16 plenum bolts are out you'll be able to tip the plenum up, prop it with a 2 x 4, and have plenty of space to get to the #3 FI. Get new gaskets for the TB, EGR and IAC. The 8 plenum gaskets are expensive and will probably be OK without replacement but it's your call.

[Rakesh_mp]

Thanks for a great write-up! I've never worked on a car before, but with a lot of research, a bit of common sense, and these perfectly written instructions, I was able to change out all of my injectors and clean all the necessary parts. My '93 Q45 (114k miles) is running beautifully again. Thank you!

[Brew Q]

Hopefully you installed a '94-96 fuel rail and their updated injectors? Otherwise you may be doing this again in a year...the ethanol destroys our 90-93 Q injectors.