Under plenum questions 1990 Q

[mxr662]

Do the intake runners have to be (or should they) be removed to change y-cooling hoses and knock sensors?

Are the plastic washers where the fuel rail bolts on supposed to be soft? Mine aren't.

Should the 8 rubber seals where the fuel rail (injector) goes into the intake runner be replaced.

Andy

[maxnix]

Yes and you should replace the lower gaskets also ($18 each). No, but they should be replaced especially if you don't take the whole rail out. Yes.

Think about doing your VC gaskets while you are there.

[AZhitman]

Andy, looking good!

Hope mama doesn't realize her comforter is being used for a "nobler cause".

[Q451990]

You don't need to remove the intake runners to replace the cooling hoses and knock sensors, but I feel sure it will make it easier. If I remember correctly, those gaskets are pretty pricy, so check on their cost before you go pulling runners out.

As far as the gaskets, I think replacing the plenum gaskets is a must... the rail ones are optional... as hard as they are, I think they're more spacers than gaskets...

Good luck!

Heath

[qsiguy]

I'll be doing the plenum job myself soon, Wes, are all the parts listed on your plenum write up available from Joe? Also, are the gaskets they are talking about on the list?

[burijon]

I recently bought the plenum "kit" from Joe. All it consists of are the 8 rubber seals for the plenum and multiple air hoses. It would seem you could use any hose you wanted to for the air hose after ordering this kit except for the weird bendy ones. I'm calling Joe today to get the Y pipe coolant hoses and various other items missed in this kit.

I tried matching up the parts list with what Wes has in the articles versus the part numbers on my invoice. Only 7 of them matched up and I have many more than that still on the Infiniti invoice sheet!

Great questions mxr662! Post back with any other details as this Friday is D-day for me and the Q!

[qsiguy]

Do you, or anyone else, have a current list of the necessary parts? How about posting what you've got so far. Wes's list seems like it has a lot of parts, are all those necessary? I'm sure you will want to replace everything you can while your in there but there didn't seem to be that many parts shown on the write up.

[burijon]

I have the plenum kit invoice at home. I will scan it and post it. I just ordered another $130 worth of coolant hoses and t-stat today. Rough estimate is that I have spent $310 so far on just hoses. When you consider what we are all doing and saving labor costs that is really cheap to bring the old gal back to life. I bought other things which I will put in a new post once all is done. Sorry for hijacking your thread!

[Q45tech]

Condition of knock sensors and their harness?

We usually warn that a complete total plenum job uses ~~ , $970 in parts [at retail]................smart people might add a new injector harness at the same time as fuel hoses and knock sensors.

[burijon]

I have both knock sensors and KS harness. I did not get the injector harness. I was going to start a new post to avoid hijacking this any further.

[mxr662]

Do you, or anyone else, have a current list of the necessary parts? How about posting what you've got so far.

I ordered the 'Under Plenum Kit', 'Bypass Hose Kit', 2 heater hoses, IAC gasket, EGR gasket, throttle body gasket, 2 knock sensors, knock sensor harness, and a length of Nissan fuel hose. Also some misc clamps and spray cleaners from local auto parts store.

It would seem you could use any hose you wanted to for the air hose after ordering this kit except for the weird bendy ones.

As I removed the plenum several of the hoses seemed almost impossible to unhook. Cutting was the only way to get them off. I want the hoses to be the exact right ones to make assembly easier and have less chance of leaks.

I did not get the injector harness.

Neither did I. Wish I would have, but cash is becoming an issue.

Andy

[elwesso]

Joe has a new kit that is like $800 that includes everything you need. You can always return what you dont use for a 20% restocking fee, but its best to have everything on hand!

The gasket for the heads to runners is a thin metal gasket and in my experience if you're careful with it you probably odnt need to replace it... Take that as you will, but we took the runners off ross's Q and didnt replace the gasket and it runs perfect.

[mxr662]

Plenum is off. Most hoses that were in the kits have been replaced. Removing the drivers side heater hose from the back of the engine was the toughest part so far.

Should the 02 sensors be replaced while I'm doing the plenum or can they be changed easily later?

The two hose kits I ordered do not contain the IAC hoses and I had to cut one to get the plenum off. The one I cut is indicated by the red pen in the picture. The Y hose that connects below the IAC seems soft so I may use it over.

The kit only contained half of the PCV hoses. The missing ones are not installed in the picture.

Somewhere on this site is a blue microfiche scan with all the hoses and part numbers. If anybody has the link to it.....

Tomorrow: Clean Plenum. More cleaning in valley. Drivers side valve cover. Knock sensors and Y-pipe. Make parts list of missing hoses. Decide about O2 sensors. Read plenum posts and FSM.

Andy

[maxnix]

Should the 02 sensors be replaced while I'm doing the plenum or can they be changed easily later?

They can be replaced later, but a nice trick is to loosen the the EGR tube nut on the driver's side exhaust manifold.

[elwesso]

I dont see how replacing the o2 sensors with the plenum off would make life any easier....

[burijon]

Make sure to ohm your injectors if you haven't already. Easier to replace while everything is off.

Good luck!

[mxr662]

I dont see how replacing the o2 sensors with the plenum off would make life any easier....

Because I spied that thing with the wires coming out of it during my mission to remove the heater hoses from the back of the engine. If it is the 02 sensor thought it might be good to do it now.

Make sure to ohm your injectors if you haven't already. Easier to replace while everything is off.

Good luck!

Thanks, the main reason this is being done now is to replace 2 bad injectors.

Andy

[maxnix]

Don't forget VC gaskets, plugs and KS and harness.

[mxr662]

Don't forget VC gaskets, plugs and KS and harness.

Got KS and harness. Will complete drivers side VC this week. Thanks

Andy

[mxr662]

Plenum job is done. No leaks so far. Replaced most hoses under plenum, spark plugs, four fuel injectors, knock sensors and harness. Both valve covers are resealed. Runs very smooth.

Thanks to all past and present members here for your help.

Andy

[Q451990]

Andy,

Congratulations on taming the "damn spider" that lives under your hood!

Heath

[DrewQ45]

One day when I have no choice, I too will battle the spider. Right now everything is nice and petrified. Aside from a few gasoline whiffs in very cold weather, all is quiet under the legs.

[burijon]

Congrats on the smoothness! I am enjoying mine as well!

[goody90q45]

Congratulations on starting the engine and having everything work properly! I know you were very meticulous in the disassembly and reassembly and it paid off. We'll have to get together, plug in our consults and do some 0-60 runs while she's fresh.