Okay Dennis, you ought to get a chuckle out of this.

VENT MODE ON

(Gen-1 Q45) Good Lord!

I did the chain guides myself, but tell the truth guys, NOONE has ever removed and replaced the intake plenum. Right? Right? I'm in the middle of it now. I have 945 of the 4,737 hoses disconnected.

My hat is OFF!!!! to anyone who has actually done it!

Maybe I'll get some perspective tomorrow (GEEZ I HOPE SO), but tonight, DAMN! Looks like I'll be without a car next week. (Glad I've got the '71 Riviera.)

Now that I know what taking the plenum off is like, I WILL buy a better multi-tester tomorrow and check the resistance of all the injectors. I DO NOT want to do this again!

However, I keep reminding myself that having done it once, I know plenty of shortcuts for next time, and that's why I'm STILL looking for a low-miles gen-1 Q45.

The first 45 minutes went like gangbusters. The damned hoses connecting the IAC, the wires to the O2 sensor, and three different hoses under the throttle body were QUITE an impediment.

Grrrrrrr . . .

I know your pain. At least you did the chain guides first--they should have been a nice warm-up. The first job I did on the Q, besides changing the oil and rotating the tires, was a combined plenum and valve cover job. The real downer was not having the parts on hand and having to run to the dealership too many times and pay way too much. If you have all those damn hoses, it'll go a lot faster. Far more frustrating than removing all the hoses, unfortunately, is getting them all aligned and in place concurrently when you put them back. It is really like trying to pick a lock while playing twister. That one hose under the plenum near the firewall (next to IAC) still gives me PTS flashbacks each time I raise the hood.I know Chally has done it twice. I will have to do it a second time as well. I have these brand new knock sensors and harness waiting to go in the car.

You guys are scaring me!!! I just ordered all the hoses and such from joe along with a whole crap load of other stuff. Is it really that bad? Does anyone have any nice instructions or guidence? I cand eal with brakes, shocks and the supesion bushings but theis whole under plenum deal kinda scares me!

I am in the middle of it now (plenum virgin) and it's kinda fun...I am just taking my time working a couple of hours each day and the more I parts I pull the more things I come end of doing. I started to just to the hoses and right valve cover. Since then I have decided to pull the injectors and have them bench cleaned. Doing the left valve cover. All of the fuel hoses and anything that looks like rubber. I am not saying that this is simple but it is a wonderful learning experience and you will learn more about your car than you thought possible. The most important this is to be organized and have a goal. By organized I mean have lots of baggies and put each group of nut, bolts and small parts in separate bags. I need take pictures of each step and make notes. Tke your time and don't force anything. If you start getting pissed, walk away and come back later. I am still in the tear down stage but I know where each hose, bolt and hose was located. And as a general rule I used when removing parts "If you can't get the hose off and your going to replace it, cut it". This make the job easier. I had to cut the 2 small water bypass hoses under the plenum which was easier then trying to force the clamps off and them removing the hose.

wamQ45 wrote:I am in the middle of it now (plenum virgin) and it's kinda fun...

Well, I had a persistant a coolant leak. Each complete heat/cool cycle lost about 1/2 a cup.

It was your plenum-on-its-back picture 4 over in Infiniti General that got me thinking "okay, this weekend." I printed the picture out, and taped it to the hood. I had a much better idea of what to disconnect and what to expect to remove with the plenum. The one picture helped a lot. Thanks.

To help or scare other "plenum virgins," I am planning to take/post some more off-car pix, concentrating on the back of the plenum.

I am beginning to think of this car as training for my next one.

I got the hose "kit" from Joe Tesensky at Scottsdale Infiniti, but going in, I finally had to cut the big 3-way hose for the IAC, which is not part of their kit. Sigh. That was when I was ticked enough to open this thread. It meant no end-of-job last weekend, and with a lag between ordering and receiving, probably not next weekend either. After a long struggle, there just didn't seem to be any other way. Slice. I finally figured my time and frustration was worth whatever the hose cost.

The biggest surprise so far, and something trivially simple you could replace without plenum removal, has been . . . the brake booster hose! The plenum-end had become hard and brittle, cracked almost into the vacuum area. It was about to become a vacuum leak. I think the hard end had been trimmed off once before.

Anyway, more as it develops.

The first time I took the plenum off it took about a day... now I can remove, clean, and re-assemble in an afternoon. There really is a learning curve involved. I don't remove the hose going to the AAC valve - just unbolt and replace the gasket. Same for the EGR valve. Might save a little time... who knows.

You'll be fine. Just give yourself plenty of time and take a break when you feel like tossing the torque wrench throuh the $1000 windshield

Heath

I know it is too late as you cut the hose, but I did find a way to avoid this. I laid down on top of the plenum on a fender cover and unbolted the valve first. This gave me a bit of flex. I then used a hose loosening tool to pry the upper end off. The tool looks like a dull bent ice pick. You place it between the hose and the tube and work it around 360 degrees. Once you break the seal on the tube it will slide off. With the AAC out of the way, access to the lower end of the Y tube is much easier. When re-installing the hoses, use a thin coat of silicone grease on the rubber. This will help for installation. I was able to remove my plenum the 2nd time in less than 2 hours. If you get all but the 2 coolant hoses and the driver's rocker cover hose loose you can tilt the plenum up on the pass. side and then reach under and disconnect them easier. I used a 12 inch paint stick like a hood prop. The only part of my chain job I am dreading is if I need to pull the oil pan. I don't have the front covers off yet, but I hope the guides are worn but intact. It will frustrate the crap out of me to pull the pan for a sliver of guide!!

firedane

If you are going to the trouble of pulling the plenum you need to clean the IAC valve of carbon/dirt, EGR passages, control unit, and metal tube to exhaust manifold.You may need to make mini rotorooter . Clean/replace PCV valve and metal pipe. Remove and clean both temp sensor as corrosion on inside [coolant side] may affect readings.

Hopefully you don't have Active or TCS cars as that adds hours to the job! Plus another [3rd] temp sensor under plenum.

This is a job you want to do completely as once every 100,000 miles is enough.

landtodd wrote:
The biggest surprise so far, and something trivially simple you could replace without plenum removal, has been . . . the brake booster hose! The plenum-end had become hard and brittle, cracked almost into the vacuum area. It was about to become a vacuum leak. I think the hard end had been trimmed off once before.

I had this same problem and I think that it was the main cause of my problems....

While your in there checkyour valve covers my passenger side was leaking. I guess this is a common problem. I also pulled the fuel rails and will take the injectors to be cleaned today. FYI, to loosen the injectors use WD40. Also, I am replacing the cheezy screws on the injector covers with stainless bolts, I stripped three when trying to remove the fricken things. More pictures to come......

How many more hoses are on a T model? After I get done with my suspension and brake work I plan on pulling the plenum. I hope joe sent me all I need LOL

Ahh. Yes, Yes and Yes.

On initial reading, I thought "I'll be able to add my 2 cents". But I think most of the items have been addressed.

One comment: the 'under plenum hose kit' is a somewhat variable beast- I had Joe send me the print outs for EVERY PIECE OF RUBBER in the engine compartment, then we settled on the order. I've heard it said that they don't always include fuel, primary air, secondard air, and coolant hoses. If you place the order, and plan on it in a weekend, then realize you are missing hoses, the tendancy to 'get the vehicle driveable' may exceed the 'get it done'. I took like 4 weeks. (But then I was also doing guides, chains, valve covers, motor mounts, etc, etc) The bulk was done across Thanksgiving vacation, then finished up at xmas.

I did the heater hoses that go to the firewall too. I also had to cut the '3-legged' hose, or actually just grabbed it with a pliers and crumpled it. Brake booster hose also.

One comment- if you cut hoses it can be a bit of a challnge to figure out where all the new hoses go. When I did it I just figured it would be self obvious. It wasn't that easy. Figured it out no problem, but added an hour or so having to piece all back together.

I'm planning on addressing the injectors in the near future, but I know it will be much faster: new rubber and semi-trained hands.

I agree with wamq45... it is a lot of fun to know the engine so well.

Can you imagine how fast two of us could do one?

Adam

I'm looking forward to getting the plenum nice-n-clean -- if nothing else, for the promised horse power boost!

*** Do you have to part the IAC valve from the plenum to clean it? How 'bout the EGR? ***

I think next time, I'll just buy the gaskets and remove both the IAC and the EGR before removing the plenum. This experience is making me nostalgic for the timing-guide job.

Thanks, firedane, for the suggestion about the tool for losening hoses. I've never knowingly run across one of them, but I'll be on the look out. Where did you find yours?

And Adam, yup, I think the car is going to sit up for a couple of weeks, because I flatly refuse to pay triple Joe's prices locally. (That's with shipping included.) Good opportunity to order some odds-n-ends, like the miniature radio buttons, BG products, flex fan, power steering high-pressure hose, strangely engineered ground cable. I anticipate laughter when I find out what the "three legged" hose will cost!

And yes, Joe's kits are a nice start, but you're right -- they are kinda variable. I bought my rear sway-bar kit from him, and it lacked a few obvious pieces ($6 bolts). In addition, I have some lingering doubts about using shock busings instead of sway bar busings (minor differences), although he assured me this was okay . . . the shock bushings are 2/3 cheaper. I hope there's no real reason for that.

Hey! To be fair, I need to point out that when I mentioned the bolts missing from the kit's invoice, Joe overnighted them to me gratis. People make mistakes, and Joe took care of it just like I hoped I would be treated. Joe and his crew are great to work with. Particularly because of my insane local dealer prices, they offer me a heck of a deal! I have and will continue to buy everything I can from him.

As a matter of fact, only one part, a sunroof switch, has gone on my car in a year that didn't come from him, and that part was a gift.

"the shock bushings are 2/3 cheaper. I hope there's no real reason for that."

The rear 20 mm sway bar pushes on the end link with 160+ pounds per inch of deflection without washers to distribute the force it will smash right thru the average rubber bushing.So the durometer of the bushing is significant in the first 2" of body roll as the bushings get compressed. The sway bar may do nothing then work a lttle till the bushing is fully compreessd, then finally act as designed.

A simple 20 mm bar may [with solid urethane] provide 3 times as much resistance in the first 1" of roll [1/4" of bar movement]compared to a rubber bushing......38lbs vs 0-12 lbs ........even a quarter of a turn on the compression nut is meaningful.

Setting up bars to handle the varying load and yet not feel excessively stiff over unibumps [one wheel bumps] is difficult!

"The Shore hardness is measured with an apparatus known as a Durometer and consequently is also known as 'Durometer hardness'. The hardness value is determined by the penetration of the Durometer indenter foot into the sample. Because of the resilience of rubbers and plastics, the indentation reading my change over time - so the indentation time is sometimes reported along with the hardness number"http://www.matweb.com/reference/shore-h ... meter.html

The Active 20 mm bar and factory hardware is a great place to start as you can always make it softer by backing off the bushing nuts or harder in intial impact by using metal washers to build up the compressibility of the bushing [as the rod is threaded so the nut will not overcompress the bushings which will ultimately make them split!

The front 29 or 28 mm bar has only 2 end link bushings with significant play [again the thread limits] to avoid impact harshness in the typical 1" bump.The bar is as strong as the springs [limit of the normal ratio 50/50] but isolated by the bushing so it never moves the full 1" in a 4" wheel movement.

The TOTAL roll front stiffness [springs plus friction plus bar plus bushings] is not linear [166+166=332 #per inch].......it might be 200, 240, 290, 310 say 1040 not 1328 with new bushings adjusted just right maybe only 800 # with worn bushings and an 1/8" slop.......an extra 1.5" of body roll.

Modern strut designs use a softer bar connected directly to the strut so there are no bushings to create variability and changes with age/wear.....the Q is maintenance intensive to maintain as new performance!!!!!!!!!!!!!!!!!

The tire sidewall stiffnesss is a critical part and the bushings [slope of engagement curve] are tailored to a specific tire sidewall compression curve as is the camber gain angle in the suspension........usually the company sends the requirements to the tire manufacturer and they build a tire to fit then 2-3 brands are tested and the winner gets the contract.......obviously in Fords case the low cost was more important than specs but then again they may have met them new but not after a year [of stress] who knows.

Okay, the plenum is off. Got pix if anyone wants some.

I would love some pix

I don't have anywhere to put them, so I can send them in e-mail. Send an e-mail address to: [email protected]

Quote »Also, I am replacing the cheezy screws on the injector covers with stainless bolts, I stripped three when trying to remove the fricken things. More pictures to come...... [/quote]That's a common problem. Back when I replaced mine TJ sent hex head screws for replacements. Said his techs. were always cussing the OEM screws...

Heath

Todd, I need to test all of my injectors, so I need to remove the dreaded plenum. I have a 92 Q45. Can you send me the pictures and any more information on the procedure. I am also a plenum virgin!

Thanks, Mark

Hi Mark,

You have to send me your e-mail address. Your preferences prevent me e-mailing you from NICO.

-Todd

Sorry it took so long. The hose tools I have are from Snap-On and an import company called ATD. They look like an ice pick with a bent end. One is at 90 and the other a U. End of the pick is rounded to reduce chance of a hole punch. Slide between hose and tube, work around the tube to unstick the hose. Then hose can usually be pulled off without damage to the tube. Hose is usually ok also.

Firedane

Hi I am a 1st grader on Plenum but have to face it!My 90Q has 3 bad injectors, 2, 6, 8 I replaced 2 & 8 but still runs very rough. have to work on #6I tried to open the Plenum while I was working on 2 & 8, but after I disconnected the hoses I can only lift passenger side on the plenum for 1/2 inch.it's very hard for me since so many hoses under it. Has any of you guys done it before can provide a step by step? I'd appreciate your inputthanks/Phil

First of all I prefer the term "Plenum Virgin". I did mine and it just takes organization. I put all of the hardware from each part in zip-lok bags. If you have not done them I would do the valve cover seals while your in there. An depending on milage look into the 02 sensors. Oh! and I assume that you want to replace all of the hoses under the plenum (don't forget the hose to the brake booster). My only other comment would to replace all of the screws on the injectors with stainless socketed cap nuts. Enjoy!

You guys have a lot of guts, because I won't do it, deferring to someone who has done a few hundred! Then I pay them Extra to go super slow and methodical.

Sure I hover over like a mother hen, which distracts them, but double, triple checking is good because during their normal work they rush [pressure to get it done and on to the next car].

I'd be tickled to have someone else do it, but paying for that 8 hours of labor just ain't currently in the cards!

Important note: The driver's side oxy sensor is lashed to the bracket mounted on the plenum in back. Don't do what I did and break the wires thru ignorance. (Oh well, it was time for new oxy sensors anyway.)

landtodd wrote:I'd be tickled to have someone else do it, but paying for that 8 hours of labor just ain't currently in the cards!

Important note: The driver's side oxy sensor is lashed to the bracket mounted on the plenum in back. Don't do what I did and break the wires thru ignorance. (Oh well, it was time for new oxy sensors anyway.)

:Werd

Can anybody give me an estimate on what a independent should charge me to remove plenum, change hoses, clean everything that should be cleaned, and put it all back?

Also, should we have a FAQ for plenum removal and what should be done while you have the plenum off?

The reason I say that is, although I'm new, it seems that you guys that know your stuff get asked these questions quite often and it seems like it would be easier for you to just have separate FAQs for most of the major maintenance/fixes.

Depends on how many of the underhood hoses you want to replace. Everything would cost you $1,000 [parts alone] just for hoses. But many: heater, brake vacuum, rad, some fuel, evaporative control, etc can be changed without the plenum work.

Generally the average hose parts are around $260.........with 7 hours labor............$750 total at $70/hr.

Because the $490 labor is high* compared to parts cost unless you decide to replace the knock sensors and harness [another $400].

*Generally our average jobs are 57% parts and 43% labor on a Q.Now if you purchase the parts from Scottsdale you save 25-30% from list . Independents will have to buy all hoses from the dealer and they will charge you list. Net you could save 15% on the bill by buying all your parts but most shops set their labor rate to include a 30% markup margin on parts..........so don't be offended if they want more labor when you supply parts.The dealer gets roughly 75%-100% markup margin on parts.

T3 charges $70/book hour supplying parts and $90/ book hour with customer supplied parts. Obviously we make less this way but it at least we don't have to worry about warranting the parts and replacement labor. If the part fails you get to pay again if the part itself failed.

The trick is to weigh the look, feel, and sense of each hose and determine which will fail in the next 4 years and change them while things are open.

It's been 3.5 years [185k] since my plenum was off [for the second time] now at 254k I want to wait at least another year......roughly about every 90k in the South.