1997 SE. Manual gearbox. (of course). Stock 3.0. Sorry, I saw a couple of threads for this but not quite my situation. Like 1 of them, following valve cover replacement, she will start but only idles poorly and then dies. Touching the throttle kills the engine toot sweet. I just realized when writing the title that I was assuming the problem happened after the rear gasket replacement as the front one is cake. This is very frustrating, I feel like a greenhorn. I'm actually a licensed aircraft mechanic since '81. Not bragging, just so you'll know how frustrating being beaten by something this "simple". All I did was change the dang gaskets and now she won't run. So here we go. Sorry for the novella, but it's all the info that's fit to know. Oil leak (smoke) at the rear of the engine. 196,000 miles so duh, gasket is leaking. Replaced the front one first. Of course did not try to start it cause why would I? Pulled the harnesses and upper intake collector, removed the vacuum hoses and fuel lines where necessary. Took the collector and cleaned it up, even de-burred the ports cause I'm that way. Replaced some vacuum/fuel hoses that were old 'cause of course they are. New upper collector gasket and EGR gasket. New plugs. 1st, wouldn't start. Now I have to mention that I was working on another project that went bad as well so this job got stretched out over months.(many). Checked connectors and hoses hooked up, made sure EGR gasket was in place, that's what telescopic mirrors are for, and found nothing at 1st. Then started pulling on all connectors to make sure they were engaged and locked in, and found the cam sensor connector not pushed in all the way. I had forgotten that I had even touched that but obviously I did.She started but now the above listed issue exists.I thought I might have hooked up a vacuum hose or something in the wrong place but I took pictures prior to working on it and see no obvious problems. I then employed the shotgun approach, no did not blast it but replaced the following items: both crank sensors, (had already done the cam sensor due to an oil leak), the knock sensor, although I discovered I had already done that one too, (I'm ashamed to say the car has sat for years only being driven around the block due to, you know, life issues), A few miles previous, (years I think), I had replaced the fuel pump. This time did the fuel filter and hoses. Pulled the collector again to see if I could find anything, did not and installed a set of factory re-man injectors which of course I should have done the 1st time (196K miles). I figured maybe she was angry that I short changed her repair a bit. Also replaced the fuel press regulator cause the shotgun still had ammo. I did not separate the throttle body from the collector but did clean it with fuel injector cleaner. Cleaned the other thin wire thingy with thin wire thingy cleaner. Sorry, I'm old and tired, can't presently recall what it's called. Re-used collector gasket cause it's silicone but of course installed a new EGR gasket. Still no joy. I performed a compression ck. 1 cyl a wee bit low but the engine was cold. Nothing that would indicate a major malfunction. I did notice that the plugs, just installed were black and sooty, indicating a rich condition. Sorry, fuel press. reg was replaced after that. Cleaned 'the plugs up and back in with them but not before checking for spark. All plugs fired but I have to say, I was not impressed. My opinion is weak orange sparks on all 6 but spark there was. Then checked fuel press between filter and throttle body, and it's within specs per the factory maint. man. I don't recall the number but I do know it was good. So, before I have this thing towed to an old Nissan mechanic, I should say ANOTHER old Nissan mechanic, as I qualify for that having maintained this thing for 10 years now, and I'm gettin up there, it occurred to me that the shame in that operation would be immense, so I had better head to where I should have gone months ago. To my friendly neighborhood Nissan forum. We're all neighbors after all right? I can't help think it's something dumb like hooking up a vacuum hose wrong as there are 2 "banks" but is there any difference between them? That is my 1st legit question. What could be causing an over rich idle and is that the issue, too much fuel? I stumbled across a reference to a SB that I had found when I was researching this model. Breaks in the wiring harness at the bend in the rear left of the engine compartment in some high mileage cars. Hmmm. There is a kit attached to the SB but it is just some tywraps to secure the harness better. I downloaded a copy of the bulletin and it has procedures to check the different circuits. Before I dive into that, since I refuse to accept that I will have to cut open the harness and spend a bunch of energy wire testing, HELP! I think that's everything. Any input however inane will be appreciated. I will try to accept suggestions. I am a stubborn septuagenarian and sometimes have problems remembering that I don't know everything. There are other improvements I wish to do for Maxine, Have been sitting on a set of Eibach lowering sprigs for nearly the entire time I've owned her thinking maybe that would cure a drifting issue. (missing RH lower control arm bushing) but that's another story. This started during the Pandemic now over a year ago. Man time flies when.... crap, it just flies. Thanks to you all. This is a treasure.

 

Dude, I would be more than willing to read this over to see if I can lend a hand. However, I am not going to read through that wall of text. You need to break this thing out into separate paragraphs or nobody is going to read this.

 

I read it.. Reading is Awsome.

B1 is Firewall Side
B2 is Radiator Side

However, My Shorter Answer will be in Steps..

Make sure you didn't hook the fuel Lines up backwards, This issue has caused many guys unnecessary hours in Diag.
To me this Could be a Maf issue. Get a scan tool, you need to see what the maf is reading at idle. Give its connector a wiggle test to see if anything changes.

Do you hear any hissing at idle.? The next test is to smoke test the intake.. A major vac leak Could be all it is also, but even then, the car will still somewhat run.. Report back.. With the reading's...

 

Air intake leak!

 

This would definitely help.

 

I agree with CMAX comment.

Classic intake air leak.

1. You did not replace the intake manifold gasket when you removed the upper intake manifold gasket the second time. Other members have made the same mistake, and have experienced similar results.

2. The gaskets by the egr door handle tube cam be tricky to install. They tend to rotate from horizontal to vertical when they are installed. That creates an air leak. I hold them in place by poking a toothpick in each hole until I replace them with the bolts.

3. Perhaps the hose which attaches to the front valve cover has become old and won't seal well with the hose clamp. That can also cause an air leak.

You have a quality of workmanship issue.
That's ok. Nothing to be embarrassed about.
I'd have similar issues if I worked on the intake system of an unfamiliar aircraft engine.

The rich deposits on the spark plugs are there because the ecu is adding extra fuel to compensate for the vacuum leak.

Think back to your training about aircraft carb and intake manifolds. Specifically about air leaks.
Same principals. Perhaps you have an old vacuum guage. Tell me what the vacuum reading is, and your altitude.

I'm a bit more youthful than your self. I'm 67.

I have done all the same stuff you just did to your engine. It will run very well once you find the vacuum leak

​

 

Reality Sucks is spot on. You don't have a vacuum leak, you have a MAF failure. Pull it, inspect it, clean/replace it, you know the drill.

 

I doubt its a MAF issue, the car was running before he took it apart for the valve cover replacement. Why spend money on a part that might be still good?

I agree with JVG and think its vacuum/air leak. He reused the old gasket from the plenum, so that makes me believe thats where the issue is at.

 

**He reused the old gasket from the plenum, so that makes me believe thats where the issue is at.**
Why would you reuse an Air intake gasket or any gasket with the exception of the exhaust MLS manifold and cat gaskets which are bullet proof! Sounds like inexperience and lack of following maintenance instructions.

 

My take: I wouldn’t steer into the wrong direction on intake manifold gasket. And this is from experience on a q45 with an (unknown) MAJOR intake gasket leak for years, until I went thru the grueling process of removing the intake manifold twice for other fuel related stuff (its actually not bad on the v8, and I’ve learned to leave the throttle body connected to the plenum. Saves a ton of time).

But yeah, even a major intake manifold leak won’t prevent starting. You’ll get a dancing idle, and bucking when it’s cold... but it’ll likely be subtle when warm.

Question is: is the engine even cranking at all? It could be the starter. I’m on my 3rd one. They sometimes go without warning if you’ve been needing to crank away at it every time you start. I had to rush to fix the long crank on my Q45, because that’s a rack and pinion removal each time. The maxima is much easier, being a transverse engine.

 

That would Negate everything you said.. That would then be unnecessary work and Part replacement Just because. A simple Smoke test Would easily identify this. A scan tool with live date is worth its weight. However I can only assume on The OPs ability here.

Re-Read what I said. I did not say buy or replace anything... I Said "Test it" . He wasted more time posting here then actually checking His work..

 

😆

 

He's not coming back anyway. Another dead "help me help me" thread. I'm not buying any his BS story anyway. No 70 something anywhere in the world owns, much less wrenches on, a 4th gen Maxima.

 

Lol but why would anyone go thru the effort to write all that if it wasn’t true? Maybe he’s just been busy trying to figure it out?

 

Crackhead

 

Sorry man. Too many projects. Sometimes too hard headed to accept that **** happens. I appreciate all the responses. My intention is to try to help other folks with their issues through my trials and tribulations. Have been doing most of that on youtube. Other priorities took over and had to wait to clear some of those so I could commit to curing this issue. I think being able to concentrate on a project yields better results. My very long original post was to eliminate all the follow up questions like, "did you replace this or that" etc. I put as much info in there as I could. Failure is not an option at this point. I love this car. Thanks so much.

 

I know this is long overdue but I'm back on this thing as I have caught up on other stuff. I've been doing most of the work on youtube. Still have many vids to go. To answer: #1 I'm confused by this response. The upper intake/collector gasket which I installed a new one of is a fat gasket made of silicone. I could have used the old one, it was still in great shape and pliable.2. Yep, I address this very issue in my vids. 3. I think I used a new hose. I replied to my own post, want to continue the saga. Now looking to find somewhere to send a replacement ECU to get it flashed. Mine apparently was corrupted. I've seen mentioned that jump starting might damage it. I have been boosting mine to start it a bunch. I may have killed it. Thanks. I hope to have this solved soon.

 

Thanks for the reply. It's been a while. Had other priorities pop up. In my novel, I mentioned I had inadvertently not pushed my cam sensor connector to the "click point". That prevented it from starting. But wouldn't run even enough to get a code out of it. Found out my ECU is toast. Now trying to find somewhere to get my replacement flashed to match my VIN. Don't know why it matters, perhaps the anti-theft system. Couldn't care less about that. Just want to get her back on the road. My local dealer needs the ECU installed and is doubtful it will reprogram. I'd like to send it out and get it checked out. Tried a place in Miami but did not get a good feeling, told me mine was corrupted, here have it back.

 

Ouch. Not quite that old but I also own/wrench on a 54 year old boat with a 35 year old outboard, a 26 year old truck, and soon a 33 year old Corvette. I think I replied to another of your comments but I love my Maxi. As I'm sure you know, **** happens. Had other priorities to deal with that pushed her back in the queue. Now, licensed and insured so there's no alternative but to get this solved. Focus is on the ECU now.

 

So here is the final word. The ECU was toast. I had a replacement "successfully" reprogrammed by a local Nissan dealer if you want to call it that. One detail I had forgotten about in my focusing on the ECU, was that the last time I tried running it, I heard a clanking from the right front. Due to my tunnel vision on getting the ECU taken care of, I totally forgot about it. The dealer reminded me by telling me that the timing chain had failed and once started the engine promptly quit. "I'm sorry, it needs a motor" is what the dude told me. That is the end of the line for me and my baby. If I had the time, I would pull the motor and check it out. If toast, I would go get another one and keep on truckin. Alas, I don't have the time, and now I'm having to move as well. So off to Bring A Trailer, or Cars and Bids, or ebay if I have to. Breaks my heart but it is what it is. I have posted several videos of work I have done on my TeamMudshark youtube channel if you want some laughs. Maybe someone will get some useful info from them. Thanks to all who occupy this space and donate their time to help their fellow/fella enthusiasts. You are truly a golden resource.

 

Damn sorry to hear about your woes, shout out to you for actually following up and closing this thread out.

to be honest, im shocked to hear that your timing chain failed because of a valve cover replacement (at least if im understanding correctly) didnt even think that was possible.