Reviving a tired 2011 FX50S "build thread"

95maxrider

Member
Hi everyone, my name is Nick and I recently picked up a second FX, this time an FX50S from 2011. My wife is still driving her 2007 FX35, which has its own build thread.

DSC07469.jpg

I had been interested in a second gen FX for a while, specifically the 5.0 version, on account of how awesome the engine is, but the stiffer chassis and better suspension were also intriguing. But since nothing is wrong with the FX35, it was hard to justify replacing it with anything newer. That is until this FX50S came up for sale in my town!

It was first listed for sale back in the summer for around $10,000 with 117,000 miles. The seller was up front about it having an intermittent no-start problem, even after having the BCM replaced due to water damage on account of those crummy sunroof drain pieces on the firewall. There was a tear in the driver's seat, and the dashboard was cracking. I went and test drove it, mostly out of curiosity. I noticed a clunk from the rear, indicating the diff bushing was bad. I liked how direct the steering felt, but didn't like the transmission tuning or the feel of the gas pedal. I didn't make an offer, since there was just too much wrong with it.

But about two months later, I got another alert; the price had dropped to $6,500! But I'm saving up to renovate my garage, and didn't make a move on it. Then a month later I got another alert, price drop to $4,500! I couldn't resist any longer, so I reached back out to the seller and he was kind enough to bring it by my house so I could put it up on the lift. I was pleasantly surprised by how much of the suspension on the second gen is aluminum, rather than the steel of the first gen cars. There was some surface rust on things, but nothing too scary.

In my excitement, I forgot to scan the car for codes. My agreed to meet a few days later at the bank to complete the sale, but on that day I remembered about scanning for codes, and the seller said he could do it. Well, apparently there was a pending code for P0011, "A" Camshaft position - timing over-advanced or system performance (bank 1).

To make a long story short(er), the seller let me work on the car for a month to try and figure out what was wrong with it, since he wanted it out of his hair. Unfortunately I was tied up working on my step dad's Subaru the whole time, and only was able to swap the cam sensor from the intake to the exhaust, to see if the code would follow it. So far, the code hasn't come back. I also noticed that the interior lights didn't work and the front camera didn't work. I eventually offered $4,000 and he accepted, so I now properly own the car! Time to get busy!

DSC02887.jpg
 
During the month or so that I had the car before I actually bought it, I finally experienced the no-start problem one night. It had been fine for about 2 weeks before that. I drove it to the store to get some stuff, came home and parked it. Five minutes later I came out to move it and it wouldn't start! The seller mentioned he thought the steering column lock module might be going back, so my mind immediately went there. But after playing around with it, it seemed like the steering column was locking and unlocking normally. I then started wondering if the BCM had gotten damaged by water again, or if there was something wrong with the alarm system. After checking every single fuse in the vehicle (yes, even the ones behind the damn battery) everything checked out. So I finally tested the battery, and what do you know? The battery was very low. It probably should have been the first thing I checked, but since I had just driven the car it didn't really seem to be an obvious culprit. After charging the battery up, the car started fine.

While I was doing all that testing, I removed the fuse for the steering column lock, so it can't work anymore and I don't need to consider it as a variable anymore. But there does seem to be a parasitic drain on the battery, and I don't think the battery is in good health, even though it tests fine.

Before I forget, here are some pics of the interior:

DSC02878.jpg

DSC02879.jpg

DSC02880.jpg

DSC02889.jpg

Anyways, once I bought it, I wanted to start fixing things. I started by getting a used front camera, and that worked, so that problem is resolved. I then pulled off the billet grille the previous owner installed:

DSC02816.jpg

The car had a light on the dash for "IBA Off", or intelligent brake assist off. I dug through the owners manual, and sure enough the sensor for the system is in the lower grille opening, being blocked by the billet grille. It also seemed as if the previous owner had unbolted the sensor from one of its brackets to make room for the billet grille, so it was hanging down and being obstructed by the bumper. Access was tough, but I was finally able to get it bolted back up properly.

DSC02818.jpg

And wouldn't you know it? That solved the light on the dash! Moving right along.

I found the shift lock cover when I went to the junkyard, so I installed that:

DSC02824.jpg

Installed all new wiper blades:

DSC02830.jpg

Installed a new cabin air filter:

DSC02828.jpg

But then I had to do some real work. I needed to figure out why the interior lights weren't working. The previous owner said it might be the illumination control module, but when he replaced it a while ago it didn't solve the problem. I decided to get a used one and try it out, but when I disconnected the one in the car I knew I was in trouble.

DSC02825.jpg

Yeah, water was still getting into the car and had ruined the ICM. I tried out the used ICM I bought, but it didn't work. The electrical connector looked about the same as the module, so I figured I would need to splice in a new harness without water damage. It took a while to do it all, but after splicing in a new harness along with a new/used module, the interior lights were finally working!!

DSC02888.jpg

It felt good to make quick progress like this. While I wait for parts to arrive from Amayama, I moved on to other things. I pulled the wheels off and gave them a good detailing and polishing. I also did a quick cleaning of the brake calipers:

DSC02843.jpg

DSC02845.jpg

DSC02844.jpg

DSC02846.jpg

Also polished up the muffler tips:

DSC02833.jpg

DSC02838.jpg
 
Next up was more exhaust work. I determined that the exhaust leak I heard was coming from one of the flex sections in the y-pipe. I briefly considered ordering a whole new pipe from Amayama for $500, but then thought better and decided to just replace the flex sections. I like the top of the line Vibrant "turbo" flex sections since construction is very robust and they're fully stainless steel. Turns out that I needed a 2" x 4" long flex section, so I bought two and got to work.

The mesh/braiding on the OEM ones was failing so I ripped it all off.

DSC02831.jpg

Cut off the old ones:

DSC02866.jpg

DSC02867.jpg

And welded in the new ones.

DSC02868.jpg

I'm far from a pro, but this should work.

DSC02871.jpg

The new flex sections flex a lot better than the original ones too, so I'm pretty happy, especially for only $80.

While I had the whole exhaust off, I cleaned up all the flanges in the hopes everything would seal up nice and tight.

DSC02872.jpg

When I tried to remove the nuts that hold the muffler to the cat-back, all four studs snapped. I then had to cut through each of the studs and then blast them out with my air hammer.

DSC02876.jpg

Thankfully those were the only studs that broke, although I had to split the remaining nuts in half with my air hammer rather than removing them with a socket as they were so far gone. But the threads on the remaining studs were still in good shape, so I chased them and got new zinc coated hardware for everything.

While I had the muffler off, I also decided to tackle the rear diff bushing. One again, I considered buying a whole new rear subframe from Amayama since it's only $400, but shipping probably would have been expensive, and that bushing would probably fail in 5 years, so why bother? I bought a tube of 3M Window Weld 08609 and decided I would try to repair it myself. I cut off some rubber at the top and bottom of the bushing to expose the empty cavities on both sides of the bushings. I then used my air gun to blow the cavities clean (a whole lot of strange dust blew out), and then sprayed the insides down with brake cleaner so the urethane had clean surfaces to adhere to. Once it was dry, I filled it all up with the urethane until it started coming out the front of the bushing, and I was sure it was full.

DSC02877.jpg

The car is still on the lift, but I'm excited to drive it, I have a good feeling about that bushing.

Oh, I also did an oil change using Motul 5w-40, and replaced a gallon of the transmission fluid. I'll do another few drain and fills of the trans after I drive it around for a while and make sure it isn't behaving weird after getting some new fluid in.
 
Long time, no updates! It took a long time for all the parts to arrive from Japan and the UAE from Amayama, but they're finally here and I've started working on the big project! The car has had an intermittent no-start problem for a while now, as well as a parasitic drain. Searching here indicates that the starter may be responsible for both problems. But since the starter is buried under the intake manifold, deep in the V, I figured it would be a perfect time to do lots of things "while I'm in there". Mission creep kept expanding my to-do list, until the job included:

-Reman starter
-Reman alternator (came with the vehicle)
-OEM water pump, thermostat, coolant hoses, radiator cap
-OEM intake manifold and throttle body gaskets
-NGK Iridium spark plugs
-OEM valve cover gaskets and PCV valves
-New belts, tensioners, and idler pulley
-New OEM fusible link and ignition button
-Probably more things I'm forgetting

So yeah. Let's dig in. It's hard to capture in pics just how dirty this engine bay was. I've cleaning everything up as I go.

DSC02956.jpg

New fusible link

DSC02966.jpg

Lots of parts, mostly OEM

DSC02978.jpg

The thermostat was grungy

DSC02981.jpg

As was the water pump, but it otherwise seemed like it was good shape.

DSC02986.jpg

Reman alternator

DSC02992.jpg

The "service position" when working on the starter. This was very unpleasant!

DSC03007.jpg

Reman starter

DSC03009.jpg

DSC03012.jpg

This FX50 has about 118k on it, and the factory idler/tensioner pullies were completely shot. One had a bearing so bad that the pulley could wobble. I had a feeling they were all done because I could just hear the bearing noise when the car was idling. I can't wait to hear how quiet and smooth this is going to be with all new pullies! I also found a rodent nest under the intake manifold, but it doesn't look like it did any damage to any wires down there thankfully. I guess that's what happens when cars aren't driven often enough!

I've spent a lot of time cleaning up gasket surfaces, like for the intake manifold, thermostat housing, and water pump. Hopefully everything will seal up real good when I put it back together, because they were pretty nasty before. When I removed the fuel rails, one of the injectors got stuck in the intake manifold and ripped off its pintle cap, breaking it in the process. Thankfully I was able to retrieve it from on top of the intake valves before it went into the engine! I think I located a replacement pintle cap, but it wasn't easy. Apparently these injectors were only used in this one application!!

I still have a ways to go, but I figured I should post this up now. I still haven't driven the FX further than my cul-de-sac since I did the work on the rear diff bushing. I heard it clunk the very first time I put it in reverse, but I haven't heard it clunk since. But I want to drive the car around for a while before I can definitively say whether my diff fix worked or not.

I also did a full 2 stage paint correction on the car, and the paint looks really nice now. I also filled in and clear coated something like 100 paint chips. I then had to level them all out with various grades of sand paper, and then polish out all the micro scratches. This process really sucked, but the results are pretty good (but not perfect).

Lots more to come!
 
Hey man congrats on the pick up! Great price and I’m glad you’re saving her and bring her back. I have a 2014 QX70S 5.0 with 135k miles and had the no start issue. Changing that starter should clear up your parasitic drain and starting problem. Definitely look at checking and possibly changing out the radiator and cooling fan assembly. They tend to go around that mileage and for sure on this one considering the age. Of course drain and fill the trans fluid. What the hell did the previous owner do to that seat?!?.
 
Hey man congrats on the pick up! Great price and I’m glad you’re saving her and bring her back. I have a 2014 QX70S 5.0 with 135k miles and had the no start issue. Changing that starter should clear up your parasitic drain and starting problem. Definitely look at checking and possibly changing out the radiator and cooling fan assembly. They tend to go around that mileage and for sure on this one considering the age. Of course drain and fill the trans fluid. What the hell did the previous owner do to that seat?!?.

Thanks! The radiator blew out on the previous owner, so he had it replaced a couple years ago. I've already done one drain and fill on the trans, I plan to do two more after driving it around a bit. Not sure what he did to the seat, but it looks like there's a possibility that it can just be sewn together, as it just came apart at the seam. Since the replacement I thought I could get on Amayama turned out not to exist, I'm either going to have to get it sewn back together, or have a shop try and make a new one from scratch. Given the somewhat intricate stitching of the sport seats, I'm not looking forward to that possibility.

Question- How in the world does the starter cause the drain? I've never heard of such a thing before.
 
Thanks! The radiator blew out on the previous owner, so he had it replaced a couple years ago. I've already done one drain and fill on the trans, I plan to do two more after driving it around a bit. Not sure what he did to the seat, but it looks like there's a possibility that it can just be sewn together, as it just came apart at the seam. Since the replacement I thought I could get on Amayama turned out not to exist, I'm either going to have to get it sewn back together, or have a shop try and make a new one from scratch. Given the somewhat intricate stitching of the sport seats, I'm not looking forward to that possibility.

Question- How in the world does the starter cause the drain? I've never heard of such a thing before.
Very sorry for the late reply…my notification emails go to spam. The dealer mechanic that replaced mine said the solenoid in the starter causes a short or something over time with the heat since the starter is in the vee. It then causes wonkiness and battery drain like what you’ve experienced. I had the no starts, the interior lights pulsing, random clicking from a solenoid in the dash, and random hatch opening malfunctions. 15k miles since my replacement and zero issues like I had before.
 
Welp, got everything put back together and all seemed well. But not for long, and it looks like I need some help. Here's a quick list of what I did:

-New water pump and gasket, new thermostat and gasket. New coolant and many coolant hoses.
-New NGK Iridium spark plugs
-New OEM valve cover gaskets
-New/reman starter and alternator
-Cleaned the throttle bodies
-New intake manifold and TB gaskets

Ran the car up to temp in the garage to circulate the coolant and it idled just fine. Let it cool down, topped off the coolant and backed it out of the garage, and it idled fine. Turned it off, came back a few minutes later and it was misfiring badly. Codes for P0300 random misfire and cylinder 1 misfire. Parked it, cleared the codes. Came back later and it ran fine. Decided I would go through all of the relearn procedures since I had removed and cleaned the throttle bodies and installed new spark plugs. I followed this guide:

https://www.infinitifx.org/attachments/ecm-idle-throttle-maf-fuel-trim-relearn-notes-pdf-pdf.20658/

Car ran fine after doing the relearn for the accelerator pedal, throttle valve and idle air relearn. But after I did the MAF relearn all hell broke loose. The car ran like hot garbage for the 15 minutes I let it idle and relearn. I turned it off. Turned it on a little bit later and decided to take it for an easy drive. If I gave it more than 5% throttle it would buck and stutter REAL hard. I had to let it idle just to get it back home.

Now I have P0300 (multi cylinder misfire) and P0011 (bank 1 VVT). I did have a very intermittent P0011 before doing all this work, but it was infrequent and the car always drove fine. I checked the logs and all of the cylinders in bank 1 showed misfires, but there were none in bank 2.

It seems like the P0011 code can be caused by either bad cam sensors or bad VVT solenoids. Unfortunately the FX50 has VVT on both intake and exhaust, making this more complicated. Plus, those VVT solenoids are blocked by coolant tubes, so I need to drain the coolant to get to them, making part switching more difficult.

I do have a mid-level scan tool at my disposal, but it's still new to me and navigating it isn't exactly easy. Can anyone provide any guidance on where I should start here? I suppose I could switch all cam sensors and VVTs between bank 1 and 2, and see if the codes follow. Is there anything I can check in my scan tool that would help with the diagnosis?
 
Hi, Nice post on everything! I have a 3.7 but still love reading about full builds and seeing the process. Im doing almost a full build since my qx had rat chewed wires and was disgusting inside. Also have a wheel hobble in what im assuming is the front right. Im coming with knowledge from the q50 and g37 platform so I have a idea of what to do with everything. Wish I could help you with your current issues but not familiar with your platform. I will say this, going with the cheapest solution option first is always best and working your way up. Maybe new maf sensors? I know maf sensors are finnicky, and if your getting a issue at startup and then it settles out thats a clue that maybe somethings clogged or not making a proper connection so it forces its gotta struggle first? How did the fuel rails look? I know the fuel rails in the 3.7 are prone to getting eaten by rats due to the soy in the cables they used. I personally have seen it in 3 3.7's that iv worked on already where the fuel rail cables were chewed slightly causing multiple random missfires.
 
-Cleaned the throttle bodies

if the car ran fine before you took everything apart, I highly doubt the vvt solenoids and such are bad. I DO know that on these 5.0s, basically touching the throttle bodies is a no-no outside of a dealership. Read somewhere that they are SUPER sensitive to adjustment and any little thing like cleaning them by manually opening the plates will throw them way out of whack. Didn’t it run fine when you brought it home other than that solenoid issue that corrected itself?
 
Ċant wait to see the final product. I sometimes wish i still had my fx35 every time I see the honeycomb style qx70 I still have in the garage and old red tail lights.
 
Alright, time to finish off what I started! I cleaned up the throttle bodies, being very careful to not let them slam shut.

DSC03023.jpg

DSC03026.jpg

I also replaced the original Denso spark plugs with NGK Laser Iridium 1406 plugs, but it doesn't look like I took any pictures of them. :(

Because it was all so cheap on Amayama, I got new sway bar bushings, brackets, and hardware for the front and rear:

DSC03032.jpg

DSC03037.jpg

I'm kind of skipping over a lot of details here. Removing the furthest two bolts from both of the valve covers was a minor nightmare, and there were times when I questioned whether the job could be done with the engine in the car. I've got what I consider to be a very complete set of tools, but I was unable to get anything on the rearmost bolts, so I bought a couple specialty tools with the hopes they would work. Thankfully they did, and I was able to remove the valve covers. Be on the lookout for a video that goes more in depth of how I did certain aspects of this job, as they don't appear to be well documented anywhere.

I spent many hours scraping off every last bit of caked on grime and old RTV from the heads so the valve covers would hopefully seal up without leaks, being very careful to not let anything fall inside the heads.

DSC03047.jpg

Like most things in the engine bay, the valve covers were filthy. I needed to thoroughly clean them before reinstalling.

DSC03057.jpg

New OEM VC gaskets and new PCV valves, just in case.

DSC03065.jpg

After some purple degreaser, some brushing, and some power washing, the VCs came out looking real nice!

DSC03067.jpg

And because I hate rusty hardware, I got new bolts for the valve covers.

DSC03068.jpg

I also preventatively replaced the plastic coolant tee with a metal one:

DSC03069.jpg

DSC03070.jpg

The intake manifold (which is surprisingly heavy for being made out of plastic) got cleaned up as well:

DSC03010.jpg

DSC03071.jpg

It too got new hardware, as one of the bolt heads rounded off when I was removing it and I didn't think I would be able to torque it properly.

DSC03073.jpg

New hardware is pretty :)

DSC03075.jpg

I will say that torquing down the valve covers to the right spec and in the correct order was pretty challenging, especially on the driver's side where the AC line is in the way of a lot of things. Once again, my new specialty super shallow wobble 10mm bit saved the day. Then it was on to the cooling system:

DSC03086.jpg

The main radiator hoses had some janky hose clamps on them before, so I replaced everything with new OEM hoses and spring-type hose clamps.

DSC03087.jpg

DSC03089.jpg

As you can see, I replaced all of the hard lines for coolant. I'm sure they would have been fine for another few years (they weren't rusted through or anything) but new ones were cheap from Amayama, and they sure look a lot better!

DSC03090.jpg

Unfortunately, there was one hose that goes to the oil cooler/heater that simply isn't available anywhere in the world, 21306-1CA0C. I decided to replace it with a length of generic heater hose, but had to add a reinforcement where it rubs up against the frame rail so it wouldn't get a hole in it.

DSC03092.jpg

Anyways, due to my other cars needing attention, and the misfire issues described above, I haven't really driven the FX since I did this big job, so I can't comment on how it drives. I can say that when it idles without misfiring, it's very smooth and quiet, quite the change from before!
 
Thanks for the updates - I've a feeling my parasitic drain my be my starter too. Do you have part numbers for that and the alternator? Or did you just pull them off Amayama?
 
Thanks for the updates - I've a feeling my parasitic drain my be my starter too. Do you have part numbers for that and the alternator? Or did you just pull them off Amayama?

I did not use OEM parts for the starter or alternator, they're simply too expensive. I bought those on RockAuto and my local parts store.
 
I made some videos of the work I've done, hoping they may help someone else!

How to fix a clunking rear diff bushing on an Infiniti FX50

How to replace the valve cover gaskets on the Infiniti FX50

How to replace the starter on the Infiniti FX50

Infiniti FX sunroof drain tube permanent fix DIY
 
Back
Top