Misfire or CVT failure imminent?

[VStar650CL]

Put a steth on it, at least it will narrow down the potential sources.

[Ilya]

Okay, will need to procure one.

I also just realized where those 4 extra bolts came from - the donor plenum when it arrived had the VIAS solenoids and vacuum rail connected. So at least that's answered.

Otherwise I'm facing a tear down with a shop charging thousands...right? Wife is going to kill me.

[VStar650CL]

If something got into a cylinder then things are already a mess in there, but it wouldn't sound that way. The few times I've heard crap stuck in a cylinder, it sounded like marbles and screwed up a valve almost immediately. That sounds more like a tap, metal repeatedly rapping on metal in exactly the same spot at exactly the same time each rotation. The puzzle is, there isn't really anything in the induction which should be able to make a noise like that.

[Ilya]

If something got into a cylinder then things are already a mess in there, but it wouldn't sound that way. The few times I've heard crap stuck in a cylinder, it sounded like marbles and screwed up a valve almost immediately. That sounds more like a tap, metal repeatedly rapping on metal in exactly the same spot at exactly the same time each rotation. The puzzle is, there isn't really anything in the induction which should be able to make a noise like that.

AI had me unplug the TB and start the car and the noise was still there, albeit a bit slower as the RPMs were lower. It's RPM dependent for sure.

I ordered a steth and thin magnet from Amazon, will be here tomorrow. AI says to check in the intake ports with the magnet and also to check in the spark plug hole as well and see if it grabs anything.

I don't get the codes though...if something was preventing the combustion process from occurring due to being in the way, causing a misfire - P03xx makes sense. But why these?

P0113 - Intake Air Temperature Circuit High Input
P0223 - Throttle/Pedal Position Sensor/Switch B Circuit High
P2101 - Throttle Actuator Control Motor Circuit Range/Performance

[VStar650CL]

The IAT is built into the MAF, usually you get that along with P0102 when you disconnect the MAF with the ignition on. Those other two are from the throttle motor and sensor, so maybe you do have some version of the Chevy problem. Your new TB definitely isn't feeling good.

[Ilya]

The IAT is built into the MAF, usually you get that along with P0102 when you disconnect the MAF with the ignition on. Those other two are from the throttle motor and sensor, so maybe you do have some version of the Chevy problem. Your new TB definitely isn't feeling good.

Hmm...interesting. I was getting those with my old TB (looks like the shop my neighbor took it too might have used a dremel or something to cut a slit and then get it out - could vibration/etc. damaged my OEM throttle body)? I only swapped to the LKQ TB at the very end yesterday.

I should get the magnet and steth shortly here and will be removing everything after work...hopefully I can find the missing piece. Google says if I can rotate the engine manually (clockwise) with the spark plugs out and don't hit and stops, etc. that there isn't a chance that the piece-of-stud fell in. Would that be your assessment as well?

If that proves to be the case and I didn't drop anything in the intake, what would be the next move? Google thinks I pinched a wire somewhere but there really isn't anything in the way like that over the intake.

[VStar650CL]

Google is probably right about that, the VQ's are interference engines and there won't be much room in there at TDC on the exhaust stroke. If it spins clean then chances are nothing got into a cylinder. That doesn't mean something couldn't be camped on the back of an intake valve, but your magnet should resolve that. The perfect regularity of the noise is what makes me doubt it's debris, anything bouncing shouldn't be that perfectly repetitive.

[Ilya]

Okay, so I just removed spark plugs #2, #4 and #6. #2 and #4 look normal, but #6 is very dirty AND the tip is crazy bent. This means the stud did fall in the intake runner to #6, I imagine.



Magnet isn't grabbing anything so going to try the vacuum trick and order a borescope on Amazon to assist with figuring out where it went.

Crazy to think that all of this could have been avoided if I had just heard the little piece of stud fall in. I heard zilch.

[VStar650CL]

Yowch. If you don't find it in there then it may have bounced out through the exhaust valve or bounced back into the intake. More importantly, that rapping is exactly the kind of noise you'd get from a valve that can't return all the way, so the cam lobe is "slapping" the lifter instead of sliding over it. Best case for that would be that the stud lodged between the intake valve and the seat and is simply holding the valve open. Next worst case is it's lodged in the exhaust valve, and worst case is that one or both valves are bent. I hope that isn't it, but this isn't looking good. You can tell something preliminarily by putting #6 on TDC (it's 360 deg from TDC #1) so both valves should be closed. If you don't have a borescope, blowing compressed air through the spark plug hole will do the trick. If the intake is stuck open then the air will come out the intake manifold, if the exhaust is stuck open then it will come out the exhaust pipe.

If it's propping the intake valve, that's probably the only circumstance you can handle yourself. You should be able to see it with the lower manifold removed and get it out by using a veed prybar to lever the valve all the way down to dislodge it. Once it's loose you can fish it out magnetically and do a compression test to see if the valve is damaged. If it's stuck in the exhaust then the exhaust manifold needs to come off, which is a possible driveway job but just barely. Bent valves mean a new head.

[Ilya]

Welp, it's confirmed. It's in there. And it did some damage by the looks of it.

Direct top down view into the spark plug tube:



Horizontal view of the valves:





And lastly, the problem child:

[Ilya]

It's either wedged or indented into whatever it's up against...can't get to it with a magnet as it's not resting at the bottom but up against the top. It's also looking to be between two valves so prying the valves from the intake isn't going to work. Not sure I can get enough vacuum suction to get it out.

What other options are there? Is this the only one?

If it's propping the intake valve, that's probably the only circumstance you can handle yourself. You should be able to see it with the lower manifold removed and get it out by using a veed prybar to lever the valve all the way down to dislodge it. Once it's loose you can fish it out magnetically and do a compression test to see if the valve is damaged.

[VStar650CL]

If I'm reading the picture right then it looks like it's embedded itself in the head, you can see impact marks from the threads in the aluminum all around it. It looks like it might pry loose, but I think you'll need to make some sort of modified hook tool to get under it. The valves may be okay, your noise was probably from the piston smacking against it once it got stuck. So if you can work it loose and the head isn't cracked, you might be able to save it. If you can get it to turn to TDC #6 so all the valves should be closed, I'd say the first thing is to find out if they're obviously bent or damaged with a blow-through test. If that fails then the head is screwed anyway and there's no point in trying to remove the stud.

[Ilya]

If I'm reading the picture right then it looks like it's embedded itself in the head, you can see impact marks from the threads in the aluminum all around it. It looks like it might pry loose, but I think you'll need to make some sort of modified hook tool to get under it. The valves may be okay, your noise was probably from the piston smacking against it once it got stuck. So if you can work it loose and the head isn't cracked, you might be able to save it. If you can get it to turn to TDC #6 so all the valves should be closed, I'd say the first thing is to find out if they're obviously bent or damaged with a blow-through test. If that fails then the head is screwed anyway and there's no point in trying to remove the stud.

Yeah, definitely looks like it has embedded itself.

I've started reaching out to local shops to see what the ballpark is on a swap or a rebuild. It's parked in the driveway at a slope so I don't know if I can safely get it jacked up enough to get the wheel off so I can access the crank nut to manually rotate it to find TDC.

I'm coming to grips with the fact that this is either going to cost me $3-4k or it's going to cost me $40k in the cost of a replacement vehicle...major lesson learned and the crazy thing is, I had the intake holes stuffed with towels the whole time I was doing the injector, etc. Just such a freak incident to not notice the broken stud AND not to hear it fall in.

[VStar650CL]

The gen3 Murano and early R52 Pathy use the identical VQ35DE powerplant, so there are a gazillion in junkyards and I see no point in scrapping the vehicle. Looking through car-parts.com and sorting by price high-to-low, just on the first page I see six with under 100K for under $800. My question would be, is it worth yanking the head to see if this engine can be saved and then maybe needing to replace it anyway (how did the bore look?), as opposed to just replacing it out of hand with a low miles used one.

[Ilya]

The gen3 Murano and early R52 Pathy use the identical VQ35DE powerplant, so there are a gazillion in junkyards and I see no point in scrapping the vehicle. Looking through car-parts.com and sorting by price high-to-low, just on the first page I see six with under 100K for under $800. My question would be, is it worth yanking the head to see if this engine can be saved and then maybe needing to replace it anyway (how did the bore look?), as opposed to just replacing it out of hand with a low miles used one.

I'm aligned; talked my wife into it being a smarter decision to keep the vehicle than replace it. 3-4k one time is cheaper than 6-7k per year in car payments.

[Ilya]

It seems that most shops want $5k+ (more like $6-7k) to install an engine with warranty, which makes saving this vehicle a lost cause. And engine can be had for sub-$500 with around 100kmi on it, but shops are asking like $1,500-2,500 after mark up. Labor is ~$3.5k. If I could get this fixed for $3.5-4k, I'd do it...but not $5-7k.

Will likely list it for sale as-is for $5k and see what I can get for it.

Can't believe I ruined an otherwise perfectly good vehicle with a incredible maintenance history, clean interior and great body. Ugh. Such is life.

Thanks for all of the help, VStar, but this looks to be the end of the road for this ol gal.

[VStar650CL]

Awwwwwwwwwww. Have you tried going around the back door of the garage and seeing if anybody wants a side hack? Lots of guys do that.

[Ilya]

Hah, I haven't

[Ilya]

Found a shop locally that will do it for 4k out the door with 30 day warranty on motor. Going to get it fixed.

[VStar650CL]

Found a shop locally that will do it for 4k out the door with 30 day warranty on motor. Going to get it fixed.

[Ilya]

Thought I was crossing the finish line today, but it turned into a massive diagnostic rollercoaster. Here is how the week shook out:

- Tuesday (Day 1): Dropped the car off at the shop. The guys moved fast and had the bad engine pulled out within just a few hours.

- Friday Morning (The Battery Curveball): The shop called to report that a completely dead battery was preventing them from doing final testing. The 23-month-old battery (with about 40k miles) tested completely bad. Fortunately, it was still under warranty, so I managed to swap it out for a brand-new AGM battery for free. I also learned that the engine has a 1yr warranty or 12,000 miles...instead of the previously stated 30 days. So that was good.

- Friday Afternoon (The Hand-Off): With the new battery in, the shop finished their shakedown, confirmed all was good, and buttoned it up. I went inside and settled up the bill.

- The Test Drive (Immediate Issues): As soon as I pulled away from the shop and gave it some gas, the engine started misfiring heavily under load. I turned right back around. They cleared the codes and suggested driving it a bit to let it work itself out.

- The Fresh Gas Attempt: I drove it to get fresh 93 Octane gas and added a bottle of Liqui Moly gas treatment. It idled beautifully afterward, but the exact second I stepped on the throttle to pull into traffic, the heavy misfiring returned.

- The MAF Sensor Misdirection: Back at the shop, they spent 40 minutes scanning and pinned it on a faulty Mass Air Flow (MAF) sensor (idle readings were at .2 instead of a healthy .8). They picked up a new Hitachi sensor from O'Reilly's and tossed it in. While the idle readings corrected to .8, the car still actively misfired under acceleration during our test drive.

- Where It Stands Right Now: I left the car at the shop tonight. They are currently swapping my old, known-good spark plugs and ignition coils into the new used engine, suspecting the ones that came on the salvage motor are bad.

The Financial Breakdown (Total So Far: ~$4,555)

- Engine & Labor: $4,000 (Paid)
- OEM Fluids & Transfer Case Seals: $400 (Paid—they caught some bad transfer case seals during the swap)
- Hitachi MAF Sensor: $155 (Pending—haven't paid for this piece yet since it didn't cure the underlying load issue)

Hoping the ignition coil and plug swap fixes the issue so I can finally get this thing back home. We have another trip to FL I was hoping to take the SUV on instead of M56x which we did last month (surprisingly, that old girl got 23mpg on the highway!). If it ain't one thing, it's another!

Only thing I can think of is that maybe they didn't replace the gaskets and one of them is bad either on the TB or on the intake plenum?

[VStar650CL]

If it was an induction issue I wouldn't think a new MAF would change anything, but stumble (as opposed to actual misfire) could be coming from a sticky TB. That's pretty common on JY units. Otherwise the idle should be high and unstable, but you say it idles fine. So I have to think it's probably ignition and plugs and coils will probably fix it.

[Ilya]

Car lives!

Got it back home just now. Runs great.

The issue turned out to be the #2 coil connector/pigtail...they soldered on the one from the new-to-me motor and it resolved the issue. Evidently the green wire was...less than great. Resolved all of the issues. I'm wondering if this wire was the issue all along or at least the biggest contributor. Crazy.

They swapped over the VTC solenoids, cam/crankshaft sensors and coil packs/spark plugs from my original motor. Car runs real good now. Occasionally at idle every 60-90 seconds or so I'll feel specifically one 'misfire'. Also hear a small rattle under the car somewhere that's very faint (will have to get under the car to see where specifically, doesn't feel/sound like it's motor related).

But, drives so good. All in, with fluids and extra diagnostics for the misfires, came out to be like $4,500.

[VStar650CL]

They may have dinged a heat shield taking the exhaust down. Those tack welds can get pretty fragile in old age. If that's the noise then just secure it with a stainless radiator worm-clamp.

Sweet to hear it's back on the road!

[Ilya]

Yep, our a lose exhaust hanger or something causing the exhaust to vibrate more against something.

What a saga. But glad it's over!

[Ilya]

So, last night I got a P0306 code which explains the random blip I'd get at idle.

Swapped in a fresher coil pack and spark plug and issue seems resolved.