G50: Under Plenum Hose replacement (Dial up = unhappy people)

Post by **ceningolmo** » Wed Jan 10, 2007 11:38 am

Just took her for a drive...after some troubleshooting on Wes' part. Thanks again Wes.

First... one must actually connect the injector harness if one expects the engine to start.

Second...one must actually connect the TPS. Or... your Q will not shift out of 2nd gear...and, it will not idle properly.

Third... when connecting the throttle cable, do not tighten it all the way the first time. Leave some slack (yes, just like it says to do in the FSM ) in the cable. When I first started the car it idled fine... but, after hitting the gas pedal it didn't come back all the way. It kept idling at about 2500 until I readjusted cable.

Do not... I repeat... DO NOT... spill coolant all over the front of your effin engine when you decide to bring the coolant level up at the end. Why you ask? Well, the obvious reasons having to do with cleanliness. But, also because it will make your engine smoke like it is on fire when it has run for a moment or two....thus, you will think your car is dieing and you will have a heart attack. I would save you that moment of anxiety.

Finally... pat yourself on the back or have some ice cream or something in celebration of finishing the job!

Thanks for the encouragement everyone. Car #1 is done. Now to start on car #2... this time including valve covers. Wooo hoo.

Post by **texasoil** » Wed Jan 10, 2007 1:11 pm

Having myself doen several 'plenum' jobs, those without TCS are MUCH easier. I found using the 'purple' nitril gloves really saved my hands and wrists from lots of cuts and scratches. Working on the Q engine or under the dash is like trying to stop a cat fight with bare hands.!

Also found compact 3/8" 'butterfly' air ratchet with assortment of extensions, flex drives, u-joint,etc a tremendous time saver. Important to properly orient all the clamps so theycam be reached for tightening--and gotta do them in the right order or "Oh-S--t' I can't get to the stupid clamp to tighten it.. Nowhere else have I ever seen such a quagmire of small bore steel vacuum piping with that many hose ends. Any rational designer doing ANY optimization would have combined most into a couple of manifolds with branch-off connectors. And the number of water lines (on a TCS version) would drive any good plumber crazy!

Post by **ceningolmo** » Wed Jan 10, 2007 3:04 pm

Well, Keith, now that the engine is done... I'll be tossing the recharged accums in tomorrow. Then, I'm done with the Grey Q and I'll park that guy outside for a little bit. Then, the Green Q moves in and gets the recharged accums installed.

I should have your accums coming back to you sometime in the week or so.

Post by **ceningolmo** » Fri Mar 30, 2007 1:43 pm

I'm bumping this for a couple of reasons...

1. I'm just about done with the under plenum job on the green Q and I will be adding some info here soon.

2. This is handy info and I haven't turned it in to an article yet. So, this might give some people who haven't already seen this thread a chance to see it.

Post by **ScottJackson** » Fri Mar 30, 2007 4:54 pm

The hard lessons are the ones that teach the best. A little RTV should be fine, but shouldn't be needed either. Those bolts that hold down the plenum (10mm) are easy to strip if you tighten them too much. The little hoses under the plenum are truly a pain. The first time I did the plenum job it took me probably 8hrs or more. Last time it was about 4 hours... but I work pretty fast (like my record-setting 5 1/2 hr timing chain guide job).

YouTube · Post by **Jesda** » Fri Mar 30, 2007 6:13 pm

Glad I'm not the only person to strip a plenum bolt. I won't be drilling and replacing it, ever.

Post by **maxnix** » Sat Mar 31, 2007 3:14 am

ceningolmo wrote:How do you guys feel about using a little RTV around the edges of the runners to make sure I get a good seal?

With new upper runner gaskets I don't see a need. I decided to go with new lower metal gaskets as they were only $18 each from Joe.

You really do want to do the valve cover gaskets when the plenum is off. The little special retaining washers are not cheap, but necessary if they are like mine at just 60K miles. I have the part numbers for the vacuum and injector hoses i bulk from Joe, which is the only way to buy them cheap.

On the valve cover, plenum, and runners, one must observe the FSM tightening sequence with lubricated bolt and stud threads, new gaskets and washers, in the correct (often two stage) sequence, with a calibrated torque wrench. Thus good even seals are assured for a long life and stripping of aluminum thread receptacles is eliminated.

The wrist torque wrench will never do for even the most experienced technician.

The whole point of a DIY is to do it better than a flat rate mechanic can by taking the time to do the little things like cleaning everything to as new condition and very careful reassembly, not to butcher your car. There is no savings there for poor performance or soon repeated labor becuase of careless reassembly.
Modified by maxnix at 6:25 AM 3/31/2007

Post by **bullittandy** » Sat Mar 31, 2007 4:23 am

maxnix wrote:
The whole point of a DIY is to do it better than a flat rate mechanic can by taking the time to do the little things like cleaning everything to as new condition and very careful reassembly, not to butcher your car. There is no savings there for poor performance or soon repeated labor becuase of careless reassembly.

Modified by maxnix at 6:25 AM 3/31/2007

Really? The point of working on your car is NOT to "butcher" it or to mistakenly reassemble it incorrectly? Thanks for the tip.

I've been there ceningolmo, all you have to do to redeem yourself is to do a couple more plenum jobs so that each gets easier. First time I pulled the intake/exhaust manifold off an old Chevy 250 I-6 it took me over two hours, the last tim, 20 minutes.

YouTube · Post by **Jesda** » Sat Mar 31, 2007 10:00 am

I thought the point of DIY was to have enough money left to feed your kids...

Post by **ponzy** » Mon Apr 02, 2007 11:09 pm

brian, i think it's better to change the upper runner gaskets since its rubber ($4 each) than replacing the lower runners gasket (metal)?

i still have some fluctuating issues with the Q. Idles at 450-750 but once in accelaration no vibration, runs fine. MIL is on all the time.....i was supposed to buy a software for my usb-consult but i think theres some compatability issues with 94-94 TCS. i am still awaiting for some good news on that thread.

Post by **maxnix** » Wed Feb 04, 2009 10:32 am

ponzy wrote:brian, i think it's better to change the upper runner gaskets since its rubber ($4 each) than replacing the lower runners gasket (metal)?

Better to do both!

Post by **Denver90Q** » Wed Feb 04, 2009 1:23 pm

No reason to replace lower runner gaskets unless you mess with them which I would not recommend as the bolts are easily stripped.

Post by **maxnix** » Wed Feb 04, 2009 7:54 pm

Denver90Q wrote:No reason to replace lower runner gaskets unless you mess with them which I would not recommend as the bolts are easily stripped.

To clean them or the engine V well or to access the KS and harness, you just about have to remove them. Gaskets themselves are no big deal.

Although, I must say I am shocked Ross would go to all the trouble he did and not clean his. Don't understand it.

And stripping those M8 bolts would take some real bozoness. Torque is 12-15 ft. lbs.
Modified by maxnix at 2:24 PM 2/7/2009

Post by **MR. Q** » Thu Feb 26, 2009 3:15 pm

Under Plenum hose kit (ordered from Joe) - replace all relevant hosesBy Pass hose kit (ordered from Joe) - replace all relevant hoses

Why isn't the Under Plenum hose kit all the hoses you need? What's the By Pass hose kit for?

Post by **maxnix** » Fri Feb 27, 2009 9:17 am

By pass hose is for the secondary air system and intake and the under plenum.

I purchased vacuum hose and fuel hose in bulk form Joe. I replaced about 5 by pass hoses (the two that connect to the secondary air manifold and the plenum, and the one from the stop valve to the rop rear of the plenum.

The former were pricey, but have metal inserts in them ($45 each). Also replaced the hose from the air distributor behind the radiator fill casting to the plenum.

Pull even good looking coolant hoses as you will often find corrosion and hose decomposition on the inside on the block end connectors.

You will spend have your time cleaning if you do it right. If you replace VC gaskets, be aware thet the grit on the topside of the gasket will want to fall into your engine when you remove VC and gasket.

My engine V looked like the Alberta tar sands.

I like the Nissan recommended RTV, and don't forget all gaskets, KS and KS harness.

Post by **Denver90Q** » Fri Feb 27, 2009 1:44 pm

Manix, I have bypass kit and already did the radiator hoses. I plan to pull the plenum soon. What hoses do you think I still need to get? I like the bulk hose idea as they would also work on my 1990 and I assume cheaper?

The engine on my 1995 is super clean both outside and inside. The car itself has about 80k miles but I think the engine was replaced by Infiniti at 10k miles. That was when the car was less than two years old and I understand they were still doing long block swaps .

One of the injectors #4 has "failed open"and I need to change it. The car still runs ok even though it tests at infinity but you can tell the power is way down and there is a check engine light. I was going to leave the hoses alone, unless I broke one but might as well replace them if they really do need it? Thanks.

Post by **IvoryQ** » Sun Oct 10, 2010 4:00 pm

OK. Thanks to all these postings and the illustrated procedures, I have started my plenum project to replace my failed #3 injector on my 1994 Q45 @ 189K miles.

I managed to get the plenum off today with damage to 3 hoses that I need to get replaced for sure but I guess I will go for all of them based on advise. Well, one of those three hoses was the one under the IAC valve. It was in great shape but being so stubborn, it required cutting through. I feel bad about it but oh well!

My primary purpose in plenum removal is to replace all injectors. #2 failed last month and the dealer did it as it was the easiest. 3 weeks later, the #3 failed! Well, I wanted to tackle the plenum removal myself given the amount of labor and $$ involved. While in there, I will also change the KS. However, I want to understand if I need to change the following:

1- PCV valve: It is out there and does not appear to be hard even with plenum in place. Can I do it later?
2- O2 sensors: I saw them in a few threads and on this one. Is there no way to replace them with the plenum on? I know some sensors were replaced in the past but not sure if it involved all of them or only ones accessible. Can the O2 sensors be replaced later if needed?
3- Does the under plenum hose kit that I hear about include the IAC hose at the back of the engine? The one with 3 ends.
4- And I see Joe's name a lot on parts but not sure how to reach him despite reading the past threads for the last few weeks? Is he in Scottsdale?

Thanks for the help

Post by **Q451990** » Sun Oct 10, 2010 8:17 pm

There's no advantage to replacing the PCV valve with the plenum off... like you said, it's right in front. Of course, it's cheap and you'll already have the trim off, so you might as well do it at the same time. O2 sensors are no different plenum on or plenum off, but the knock sensors are a must while the plenum is off. If they have cracked cases I would go ahead and replace them and their subharness - even if they're ohm testing ok. Joe is the parts manager at Infiniti of Scottsdale, a/k/a www.everythinginfiniti.com a/k/a www.infinitipartsusa.com

You can deal with anyone there, but they have had some service issues lately, so if you can get Joe and tell him you're from NICO you'll probably have a better chance of getting your order right the first time.

Good luck!

Heath

Post by **IvoryQ** » Sun Oct 10, 2010 9:08 pm

Thanks for the tips. How about the spark plugs? Is there an advantage to doing them while the plenum is off?

Thanks.

Gokhan

Post by **Infinitiguy19** » Tue Oct 12, 2010 4:56 am

There is no need to pull the plenum off to do the spark plugs. The best thing to do when replacing the spark plugs is to also replace the Valve Cover gasket (1990-1993 is RTV and 1994-1996 has a pre-made rubber gasket). If you are unsure when the valve covers were resealed and you can't find out through the receipts or Infiniti service history that you have then replace them. But you should know that its not a easy job to replace the valve cover gaskets.

Post by **Q451990** » Tue Oct 12, 2010 9:31 am

The only advantage to doing them at the same time is that you'll already have the throttle body off, which you'll want to do to to make room for the valve covers. I would probably try to do them at the same time if you have the $$$ for the parts. It's just easier when you already have your tools out, your back already hurts, and your hands are already dirty...

Heath

Post by **imstu** » Wed Aug 31, 2011 4:08 pm

I'm a bit confused. I called Ken at Infiniti parts and he said there is no under plenum or bypass hose kits, Nissan doesn't make them. Just individual formed hoses so no bulk hose either. I'm ordering the round rubber plenum seals (8 ea), 2 knock sensor harnesses, a TB gasket, an IAC gasket, and an EGR gasket. I live in Arizona so the heat takes it's toll on rubber. Should I be ordering anything else?
When I tried to ohm the knock sensors with neg lead on batt and pos on KS I get "open". Between the two KS pins, I get 1100 ohms. When I tried to ohm the injectors, (+ on batt neg, neg wire to pins) I get "open" on 1,7,4,3,5,2 and fluctuating ohms on 6 & 8. I have a new set of purple top injectors to put in. I'm reeeally dreading this job having never done it before. I also can't view the pics in this thread for some strange reason. I'm sure they would be very helpful. Any suggestions would be greatly appreciated.
BTW, this is a stock 94 Q45.
Thank you!
Stuart

Post by **goody90q45** » Wed Aug 31, 2011 5:10 pm

I'm a bit partial to this thread for plenum removal:

post4015619.html?hilit=plenum#p4015619

Try turning the ignition to the ON position without starting the engine and try the ohm tests again. Better yet, remove the center ornamental cover and ohm test #1 and #2 FI directly on the injector- probes of the voltmeter to the pins of the FI.

Joe at infinitpartsusa.com was putting together an under-plenum hose kit and had it listed on their website. If you can't find it there do a nico search (hose kit?) and you'll find at least a few threads with the list. IMHO, if you have a 2nd vehicle and can wait a week or two for parts to arrive, I'd take the plenum off first and see what really needed to be replaced, rather than replace every hose for over $1000. Most all of the hoses are pre-bent (stealership only) and only the small vacuum hoses can be cut to size from a longer length of hose.

Post by **imstu** » Thu Sep 01, 2011 9:56 pm

Thank you for the info Mike. I have been trying not to take the car out of service because my girlfriend is going to school full time and working full time too and she uses it to get to both places. It's running so bad and wasting so much fuel I'm not going to have a choice. I'm out of town for work for a week and as soon as I get back I will take it apart. Another challenge is I have to do it late at night because I'm not supposed to work on cars at my apartment complex. If I had a place to work on it, (garage) this would all be much simpler. Oh well, the job would have been impossible if it wasn't for all the info I am getting on this site! I've been looking at the stupid blinking AIRBAG light for a couple years not knowing how easy it was to reset til I found the solution here. Thanks again for the help!
Stuart

Post by **DRFTBLD** » Tue Oct 25, 2011 12:50 pm

Is it just me or did all the pics go missing! :/

Post by **Q451990** » Wed Oct 26, 2011 11:14 am

Sadly the pics are gone... they were on a photo server that no longer exists.

Heath

Post by **JeffTepper** » Fri Mar 14, 2014 10:41 am

Ross's (Ceningolmo) picture links in this thread are dead. It does not appear that he has posted here since 2007. Does anyone know where I might find active links to those pics?

Thanks in advance for any assistance.

Regards, Jeff

(I do have MikeG's post with pics from his 9-18-08 post)

Post by **dnudelman** » Fri Mar 14, 2014 11:04 pm

http://q45.org/plenum.html

Post by **maxnix** » Sun Mar 23, 2014 10:01 am

JeffTepper wrote:Ross's (Ceningolmo) picture links in this thread are dead. It does not appear that he has posted here since 2007. Does anyone know where I might find active links to those pics?

Thanks in advance for any assistance.

Regards, Jeff

(I do have MikeG's post with pics from his 9-18-08 post)

Email me and I can send you quite a few.

G50: Under Plenum Hose replacement (Dial up = unhappy people)

Re: Under Plenum Hose replacement (ceningolmo)

Re: (texasoil)

Re: (ceningolmo)

Re: Under Plenum Hose replacement (ceningolmo)

Re: Under Plenum Hose replacement (maxnix)

Re: Under Plenum Hose replacement (maxnix)

Re: Under Plenum Hose replacement (ponzy)

Re: Under Plenum Hose replacement (maxnix)

Re: Under Plenum Hose replacement (Denver90Q)

Re: Under Plenum Hose replacement (ceningolmo)

Re: Under Plenum Hose replacement (MR. Q)

Re: Under Plenum Hose replacement (maxnix)

Re: G50: Under Plenum Hose replacement (Dial up = unhappy pe

Re: G50: Under Plenum Hose replacement (Dial up = unhappy pe

Re: G50: Under Plenum Hose replacement (Dial up = unhappy pe

Re: G50: Under Plenum Hose replacement (Dial up = unhappy pe

Re: G50: Under Plenum Hose replacement (Dial up = unhappy pe

Re: G50: Under Plenum Hose replacement (Dial up = unhappy pe

Re: G50: Under Plenum Hose replacement (Dial up = unhappy pe

Re: G50: Under Plenum Hose replacement (Dial up = unhappy pe

Re: G50: Under Plenum Hose replacement (Dial up = unhappy pe

Re: G50: Under Plenum Hose replacement (Dial up = unhappy pe

Re: G50: Under Plenum Hose replacement (Dial up = unhappy pe

Re: G50: Under Plenum Hose replacement (Dial up = unhappy pe

Re: G50: Under Plenum Hose replacement (Dial up = unhappy pe

Nissan Forums

Infiniti Forums

Datsun Forums

Technical Forums

Classifieds / Marketplace

Nissan Motorsports

General Forums