Plenum's To do - please weigh in

[firstq]

I have removed the plenum - finally and am thinking about what to do while I am there.

1. The inside of the plenum really needs cleaning - I am planning to do it

2. The runners that go from the plenum to the exhaust needs cleaning as well - but I am not sure if members advise against taking the runners apart or not (it is the metal pipes that connect each chamber of the plenum to the engine...)

3. After removing injector 4 - I can see some crud around the injector seat (around where the injector bottom seated). Now does this mean I should remove the fuel rail and have it cleaned - or leave it as is. All other injectors are showing good resistance (13.5 to 12.5).

4. Knock Sensors. I would like to test them - can I get to them w/o removing the collant bypass assembly? Any easy way to check them. I heard I can do the resistance check on them as well. Can anyone confirm the best way to verify. The car has 101K on it - a plenum job with all 8 injectors was done some 20K ago, not sure if KS were changed then. So while I am there I would like to check it out - please advise on the process.

5. I will clean the IAC/AAC and EGR. I am hoping the choke/carburator cleaner should work - please let me know if not to be used on these parts.

6. The car history stated "Fuel Hoses Leaking at Fuel Rails" - another place the history states "Customer advised on Fuel Leaks". Now While I am in there I would like to take care of this. How do I verify which hoses are to be replaced? I am hpoing that the metal fuelrail itself is okay - I can blindly replace the rubber hoses that connect the rails and other places (carrying fuel). I will assume that the hoses that connet from the fuel filter to the rail is okay - as this does not require plenum removal and should have been fixed by the previous owner due to a low cost repair.

7. Anything else?

Thanks again for your help. I am taking pictures , I will post them on my site when done.

[DAEDALUS]

2. The runners are not a bad thing to remove and have cleaned, for the same reasons you clean the plenum. Before removal, clean the crud around the base of the runners so dirt doesn't fall in. Before installation, I actually hooked my vacuum cleaner up to some rubber hose to try to suck out the intake ports of anything that might have fallen in. I'm not sure if you should replace the metal gasket or not. 4. Test the knock sensors from their harness connector so you don't have to squeeze your leads into the "valley". This is a better test anyway, as you'll be testing both the sensors and the harness in one shot.6. Most oil/fuel leaks develop into wet or grimy areas. If you're there, why not do all fuel hoses? Factory fuel lines are expensive, but worth it IMO. Consider the labor you've done, then ask yourself if you want to use cheap hose.

[firstq]

DAEDALUS: What are the numbers for the KS resistance test?

The service manual says check for connectivity b/w the terminal and ground. I think I had read somewhere that the range is 550,000 ohm - not sure (Q45Tech post on Yahoo).

Any takers?

The terminal looks like:

-------|1-2-3||-------|4-5-6| -------

The test is b/w what terminals and the expected resistance should be what? Based on the data seems like we need to test the connetivity b/w each terminal and ground , is that correct?

Thanks

[911/Q45]

You'll need to remove the one bypass hose nipple anyway to change the hoses. Then you can visually check the knock sensors for cracks and not just electrically test them.

[firstq]

I removed the KS ocnnectors are the resistance checked out around 550K (pretty close to be accurate). The connector looks ok. Interesting enough, the wire connectors only have one electrode whereas the connector on the sensor itself has two (the connceting harness onto the sensor only exposes one terminal).

911 - are you saying that I must remove the bypass nipple to visually check the sensors --> does that involve actually unbolting the KS as well and perhaps take em out and then visually identify cracks. Is this necessary even if the resistance checks out okay?

Thanks

[DAEDALUS]

zerothread?id=4011

Sounds like you have it all figured out but I'll post anyway. The 550k came from Q45Tech via the thread above (at least for me; I've never been a Yahoo forum member). I just measured a brand new KS and got 555k, which might say more about my cheap multimeter than the KS itself. Yes, there is only one terminal showing, because the sensor is grounded via it's mating surface and the fastener. One of the terminals on the KS is grounded too, indicating some design changes may have been made at the last minute.Let me redraw your diagram and add the clip:

------|1|2||3|4||||5|6|------

Assuming you're facing the open end, terminal 1 is for the right KS and terminal 2 is for the left KS.

I believe Q45Tech mentioned once that the resistance check is a good check, but won't always guarantee a good KS even if the resistance is in spec...maybe he'll be nice enough to validate my memory or my imagination.

[firstq]

DAEDALUS: Thanks for the update.

The KS seems to be okay - I will wait for others to weigh in here as well --> the resistance seems alright.

I was cleaning all the runners tonight and was not able to get to the bolt for the 7th runner. A hose from the valley sits right on top of the bolt and I can not jimmy that guy -had to leave that one as is (tried for an hour and then gave up on it). I can not either disconnect that hose from the other end (in the valley) as well - I think this one has a metal tubing and then rubber on top for further protection (I could be wrong).

I got the fuel rail out and have cut all the fuel hoses to get the rails apart. Got the fuel injection fuel hose from AutoZone (the local Infiniti dealer suggested to get it from them citing they do the same). The trick was to ask for the fuel injection hose and not the regular fuel hose. The SAE specs on it is now R9 - perhaps more than what Dennis once mentioned (R8). So I am not worried there.

Have cleaned the fuel rail and injectors with choke cleaner - will be putting the Injectors into rail next. Planning to use vasoline for seating the O rings.

I still have to get the hex nuts for replacing the philips head injector harness screws - will try Ace hardware tomorrow.

The next items to do include: Cleaning Plenum, IAC, EGR, and Throttle Body. I read Dennis mentioning a mini roto rotor for cleaning the EGR - I will have to think about it as to how to make one for the job.

I am getting a little nervous as the time to start to put it back together is coming up and I had removed a lot of stuff to get the things out - now it is the return trip - we will see how it goes.

Thanks again for the help

[Professor_Mike]

The knock sensors can be removed without removing the coolant hoses, they need to be checked for cracks in the plastic. The coolant hoses above the sensors should be replaced as they are prone to failure with high mileage.

[DAEDALUS]

I had trouble with that hose as well. There's nothing special about the way it's hooked up down in the valley that I can recall. It's slid on a metal tube and then clamped with a spring clamp. To remove it, your only choice is to destroy it if it's brittle. To put it on, though, you have the advantage of having soft, pliable hose to work with. I can't recall what I did, exactly, but try getting the hose as close to possible to its final location while still leaving enough room for your tool. After tightening the bolts, squeeze the hose into place. If that doesn't work, then maybe the answer is to put the hose in place first and then use a gearwrench to tighten the bolt.

[firstq]

DAEDALUS: I am inclined to not mess with that hose. But if you think I should, then the only way would be to destroy it (to get it out). If I do not do this, I will have to leave runner #7 as is - it is not too bad - but cleaning would have helped. Let me know what you think.

Professor_Mike: I removed the knock sensors per your suggestion: The RH (you facing the engine)side is cracked in a circle. The LH has one hair line crack on one of the sides (not a big crack - so LH is very less crack as compared to the RH). The plastic casing is otherwise shiny and solid (no scoring otherwise).

So should I replace both the knock sensors (ouch $122*2) --> or jus the one that is cracked more.

New Question:What is the best way to slide the hoses back in - just put a little bit of vasoline and slide the hoses in (or there is a preferred grease - like silicon or something else?).

Thanks

[DAEDALUS]

A dirty runner among 7 clean ones will cause an imbalanced load, though I don't have a clue about to what extent. 1% difference at WOT? 10%?. What I can guarantee is that the labor you spend is worth more than the parts. You don't want to do this job more than once anymore than you would want to pay a shop twice. It's been more than a year since I did my plenum. I no longer ponder the money I spent on parts, but I sure as hell will never forget what a PITA the job is. (You've noticed I have brand new knock sensors and their harness lying around my apartment, waiting for me to muster up the motivation.) The more I work on the Q, the more it is made clear that the only way to do any work is to do it once and to do it right. In my opinion you should replace all rubber, and I strongly recommend that you at least replace the one hose to be able to remove runner #7. I would also replace both knock sensors. For the hoses and o-rings, I wouldn't recommend any petroleum lubes; I think those would eat away at the rubber. Silicone is probably fine, or water-based.

[firstq]

DAEDALUS: Okay, you got me convinced to cut that hose - I am not sure what the cost would be but what the heck who is counting anymore...

For KS - I would think one more day - no hurry. Just so that I understand; as soon as one see the crack on the sensor (hair line or major) --> you guys think it should be replaced, right?

I was cleaning the components all day. The IAC was okay, EGR gave me some grief as the metal pipe coming out of EGR was completely blocked - took 2 bottles of choke flush to get it cleaned.

The real bear was the Plenum - the EGR passage was completely clogged - 100% blocked. I finally broke loose the 10 years of gunk in there. The debry from it is now everywhere inside the plenum. Will use the compressor air to push it out - opening up of the EGR passage inside the plenum would certainly make some difference (only if I can put the whole thing together)

Went to ACE and got some hex injector screws. Got th e di-electric grease as well. Now for hoses, I will use the silicone as you are saying. But for the injector O rings - I think the di-electric grease would be okay- right? Cause the O rings on the plugs had plenty of grease on it when I took them off. Let me know if di-electric grease should be used to hold the two rings on he injector.

I still have to put the fuel rail together - I cleaned the injector with choke cleaner (hopefully it did not destroy it).

New Question:

Can I clean the injectors with concentrated injector cleaner directly off the bottle (like the ones you are supposed to drop in the fuel tank - can be bought for $2 at walmart type). I was thinking about pouring some of the stuff on each injector directly - was not sure if this is recommended...

Thanks

[Professor_Mike]

I wouls recommend replacing both sensors, make sure you clean and tighten the harness connections very well and pack some anticorrosive compound in the connections. The coolant hoses can be removed easily if you remove the aluminum connector on 1 side. Just needs sealer to reinstall.

[Q451990]

I hate to put this out there since I was going to buy a couple for spares and hoped to do a little last minute bidding, but here goes. There's a guy on eBay selling new knock sensors. The part number you want is 22060-90P00. He lists them under several Nissan and Infiniti models, but just check for the part number but I'd really recommend replacing the knock sensors since they're craced AND the harness. I bought mine for $124.85 from Scottsdale in 10/98, just for a reference price. The harness should be about $80.

Heath

[firstq]

The KS are on the way from Scottsdale. The harness seems to be intact.

New question:

Unfortunately, the fuel leaked all night into the open cylinders (2 of them #4 & #6). I have removed the fule where I could get into. But I am fearful of this thing hydrolocking when I crank the engine.

I need to crank the engine before putting it all together. Can i crank the engine by hand (just 1 0r 2 full cycles). Is it even possible.

Otherwise I was told to remove the spark plug from the cylinder #4 & #7 when cranking the engine to get the excess fuel out (if any still there) - otherwise risk the hydrolocking.

Please advise.

Thanks

[Q451990]

That's no good... did you not disconnect the fuel hoses from the rails? I'd wait for Dennis to comment on this - my guess is that your fuel will eventually leak down past the rings before you get everything put back together. You might not get compression for a while on these cylinders, so expect some hard starting. I would disconnect the fuel pump fuse and turn the engine over several times after re-assembly to get some oil back up on the rings...

Heath

[firstq]

Lesson learned Heath - the fuel hoses were disconnected - but after few days of keeping the cap off the fuel tank - I put it back on thinking of no harm. That created enough pressure on its on and the fuel started to drop from the fuel hoses lying ontop of the intake valve openings.

I will keep the fuel fuse out while cranking when all done to lube the cylinders - as you have suggested.

Can I pour some oil in the intake ports directly for lube before putting it all back together?

Thanks

[Q451990]

It'll probably smoke some at first, but that should be OK - it's actually part of what you'd do in a compression test, so it shouldn't hurt anything. I'd put it in through the spark plug holes, not the intake port - you have a more direct path to the cylinders that way.

You can go ahead and reconnect the fuel lines, just leave the gas cap off - pressure builds in the tank from heating up in the sun or ambient temperature changes... When you start the car just disconnect the injector fuse (and fuel pump fuse) and you won't get any more gas going to the cylinders. I'd turn it over a few times and then put the fuses back and start her up. An oil change will definately be in order since any gas that made it down to the oil pan will have diluted your gas.

I learned this the same way when replacing injectors... had a valley full of gas and antifreeze for a while...

I'm not sure where you're located, but theres a tool place here in town called Harbour Freight that sells an inexpensive hand pump with two hoses for $9.99. It's actually on sale for about $5 right now. It would also work well for getting fuel out, p/s fluid changes, etc...

Heath

[firstq]

Heath - I am in North Phoenix and a frequent buyer from Harbor Freight (Bethany Homes & 35th Ave). Can not beat the prices almost all of the times (unless of course you can find something useful at the dollar store).

[firstq]

Guys - any best practice for putting the fuel hoses on the fuel rail (while I am doing the plenum job). The older fuel hoses were leaking and I am replacing all of them.

Can I use any type of material to slide the hose back onto the rail?

I have heard various things: Lithium grease, silicone, etc - what should be safe here?

Also, are there any better alternatives than the original factory hose clamps that may provide better control/locks. The factory ones have philips type screws and I am not convinced that can be tightened enough. But again do not want to riun the hose by over tightening as well.

The plenum is going back today - if all goes right, I may be cranking the engine today...wish me luck guys, I have never done this much of work on the Q before...

Thanks

[911/Q45]

I just did this and had luck putting the front and rear hoses connecting the fuel rails on first then attaching the other two hoses to the hard fuel lines from and to the fuel tank on the bench, then feeding the hard line through the maze and attaching to the nipples in the valley. Use the factory clamps, keep them 3mm from the end of the hose, keep the phillips crews oriented so you can tighen them conveniently and cut the new hose to length from the old ones you removed. Good luck!

[firstq]

After a long ordeal - I managed ro crank the engine today. And the whole neighborhood filled with white smoke...

Very rough idle and white smoke - hmnnn....what did I do wrong? This is not what I expected after 10 days worth of work. Just the sheer idea of removing the plenum to identify the problem gave me shivers down to my spine.

The coolant started showing in the engine valley - after inspection found out few clamps were not on the hoses - bummer. One happened to be in the engine valley. Finally was able to twist and turn my hand around ang got it on nicely.

Next thing - screwed up the thread on the two adjacent plenum tighteners. The threads in the runner got messed up. So had a run to Home Depot to find a way to salvage with a work around nut and bolt. (this could have been the deal breaker)

What else - dropped my 10mm socket inside the valley while tightening the plenum and could not find it for long. While doing the test drive heard a sound as if some hit the car with a piece of stone - I guess that was the socket finally dropping out of the car.

After a series of ill luck days (dripping fuel into intake, etc) - today was my lucky day - made few mistakes while putting the plenum and was able to fix them w/o having to take it off.

The car runs awesome - a lot of crisp acceleration and response.

Guys - thanks for all the help you folks provided - I am yet another proof of the value this groups provides - w/o you guys I would not have been able to run my car again.

Thank a lot.

[DAEDALUS]

GOOD JOB!