Taking 92' Q45 engine apart to fix?!

[s2kysk]

Okay, experts. I started to take my engine apart at least plenum now to get to fuel injectors. I noticed significant amount of oil built up inside of intake runners (wet ones) is this normal? Should I take apart short intake runner attach to head to clean those as well? And is this good time to change timing chain guide? What other parts should I replace while I have engine taken apart? Also, where is good place to order parts (cheap). Thanks.

Young.

[PalmerWMD]

As for parts:

infinitipartsusa.com (=Infiniti of scottsdale parts dept)has always been good to members and gives us real discounts as (tell Joe you aree NICO member)They also started being a site sponsor as of late.:thumbup

The other questions I leave up to the Gurus.

Fred...

PS: It's always a good time to replace guides, some of what you have done will make it a little bit more accessible.

[DAEDALUS]

Yeah, I noticed that...clear oily residue inside the intake. I assume it's just precipitates from the fuel and/or combustion gasses. I would remove the runners too and soak them in a cleaner, but it's recommended that you replace the solid runner gaskets if you do. The timing chain guide job is crucial, like Fred said, but it is pretty much a separate job...not a lot of labor overlap. Replace all hoses under there and check your knock sensors, injectors, and harnesses. If any are bad, now is the time to replace them. Keep the intake ports covered so nothing falls in. Call Scottsdale at 1-888-216-5328.

[don5154]

make sure that the knock sensor wires are supported so they do not touch the engine. My 94 q was wrong from the factroy. The harnas was in cut in two.

[s2kysk]

Here are some pictures of the runners. Is this normal?

Young.

[s2kysk]

Here is back of throttle body.

[DAEDALUS]

Yuck, clean that TB. The plenum looks normal...just needs a good cleaning. There are 2 small ports in the TB right where teh butterfly valve plate closes down. Make sure they're cleaned out too.

[Q45tech]

EGR, PCV, vapors + dirt that made it thru air filter......all mixed together.

Everything should be bright and shiny.

[AZhitman]

GROSS!!! After looking at Quella's sparkly clean TB and plenum that thing looks NAAAAAA-SSSTY!

Get on it - Lots of shop rags and a few cans of TB cleaner....DAE is right on - make sure those 2 tiny holes in the TB (where butterfly closes) are clear - Try blowing air through them as you clean 'em.

[elwesso]

Ok few questions ive been meaning to ask

1. is it easier to take off the TB and clean it2. How hard is it to remove the plenum and replace the hoses with the help of a service manual3. What about cleaning the ports that the arms of the plenum hooks on to?4. Are there any other jobs that should be combined with plenum/tb removal?

Once I get around to doing this, I plan on doing a post up with lots of pictures.

EDIT: I also heard that dennis uses a tool to clean the plenum while it is still on the car. Any info on that? I assume you take off the TB and just reach in and go nuts!

[DAEDALUS]

1. Yes, but you'll need to replace the gasket.2. A REAL PITA the first time, somewhat better the 2nd time.3. Recommended, but more work and more parts.4. Clean out EGR, pipe, and IAC, replace any bad parts/harnesses under plenum. If you have some injectors that are newer/better, move them under the plenum. If your valve covers are leaking, now is a great time to take that on too. It's definitely cheaper and less work to clean the plenum on the car, but not as effective. Good luck with the runners. Plenum removal isn't only to clean the plenum, but also to replace your hoses and to clean the top of the engine. It'll thank you!

[Q451990]

BG makes a throttle body cleaner... get a few cans and start spraying! We used it at T3 on mine and it's sooo much easier than carb cleaner or anything else I've tried.

Heath

[s2kysk]

I saw a great deal on remanufactured injectors, set of eight for $360. I want to pass by experts to see what you guys thought of these. And also, where can you get that BG cleaner stuff?

[DAEDALUS]

I'm skeptical. How do you "remanufacture" injectors? If they're just cleaned out I'm not too impressed. How often do injectors go bad? I've had 1 go out in 4 years, with no record of any others on the service history. Better to stick wth factory IMO.

[s2kysk]

Well, for me I had #4 go out last year and had that replaced and now I have #3 that is totally gone and #7 getting there... I would like to place all to be on safe side. $150 per injector for new... You know what I am getting at.

[elwesso]

heath, how well does the BG cleaner clean out the TB and/or plenum?? That sounds much easier than disassembling the entire thing.

[DAEDALUS]

If you can get some kind of guarantee that the injectors you put in are better than the ones you're taking out, then I am all for it. Only the 4 under the plenum are of real concern when doing a plenum job (to save on future labor)...the others are easily replaced. Maybe do 5 now, and the others as they go bad. With these old cars you have to choose wisely where to put the money...you never know what's going to fail next and whether it'll be worth fixing.

[s2kysk]

Well, I ordered Fuel injectors. Will see how they perform.

[Q45tech]

Injectors in the parts of the US with conventional gasoline [non oxygenated low aromatics] usually last over 200,000 miles! [mine have 247,000 miles in almost 13 years]Those in parts of California and Arizona [many other areas of other states] may fail in 70-100,000 miles.

The gasoline composition changed after the injectors were designed and built and installed in Q....

In 1994 Nissan redesigned injectors to be more toleratant of US Garbage gasolines but they never assummed things would get worse by using [mandating] Ethanol [plus the water it picked up along the pipelines].

[s2kysk]

Q45tech, are remanufacutured injectors withstand our low grade gasoline any better? I talk with the guy and he said they test every injector after rebuild to within 1% spec of OEM and have life time warrenty against defect. I just need to return it and they will send me another to replace it. I couldn't pass up the savings and warrenty.

BTW, I am replacing all eight.

[Q45tech]

You can't cost effectively reman an injector they just clean the old good ones and throw the old bad ones away.

Some how saving $50-$75 per injector doesn't make sense if it cost $500 to change one. Guess I could see the logic in those that are easier to change [1.2,7,& 8]. But a failed injector can lead to hydrolock if it leaks.

The Question is where did the reprocessed injectors come from: California, AZ, NV......MN, ILL etc where they fail or the South where they don't............how did they get them in the first place? From trashed engines most engines are sold by yards complete.

Since they were only used in 300zxtt and the Q say 50,000 cars! Think the Subaru SVX might have used the same injector, not sure!

Maybe they were able to buy REJECTS from oem supplier in Japan?