2001 Pathy - ignition with a twist

[AdamLowther]

Hi All ,

bought a 2001 pathfinder Chilikoot (Canada) from a colleague who had skipped the timing chain, and blown the motor. I got a donor motor, that I didn't see running (maybe first mistake).

The truck is a 5 spd and the motor was out of an auto, but I put in the new pilot bearing, and a new clutch while I was at it, and dropped it in. The wiring harness hooked right up.

It fired up fine, but have pretty bad miss. It has enough power to do a lap around the block fine, but definitely not putting out as much power as it should, and an audible pop pretty regularly.

So I swapped out the coils on the donor engine, back to the coils from the original (as buddy thought it was running fine, prior to throwing the chain) still same problem.

Ran the codes and just getting a generic P0300 and then the 1130 and 1131 for the Swirl control valve. Not too worried about the swirl valve, as I can swap it out for the one from the original engine.

I have ordered new coils and they are on the way.

Questions, basically, all the solutions for a P0300 are to put new coils on, which is what I am doing. I am just wondering if there could be other sensors that are causing the problem, but not throwing a code. Is it safe to assume that if it was a different sensor, I would get a code for it?

- If the problem was a cam or crankshaft sensor, these would throw their own codes right? I'm just getting a bit jumpy as am having the same problem with two sets of (admittedly old) coils.

- the drivers side electronic valve timing (oil channel) component had the connector snapped off on the donor engine, so I swapped the one off the old engine (which presumably worked fine). I have yet to do the same on the passenger side, but wondering if this piece would cause a p0300 code.

- donor engine, looked fine, no oil leaks, and I pulled the oil pan to check for chain guide bits and metal, and all was clean.

I suppose I will know when I get the new coils, but waiting is a pain, and I'd just as soon return them before using if there is other sensor that could be contributing to the P0300 first, as I have the old motor with presumably good sensors I can swap over. But then again, the P0300 and 1130/31 codes are the only ones it is throwing.

Thanks!

PS, the grease and a dowel trick worked like a million bucks for pulling that automatic pilot bearing out of the donor engine. Four wacks with a hammer and it was out. Anyone want any swap pointers happy to contribute. PS, the FSM is out to lunch when it says to pull the transmission in order to remove the engine. I left it in with no problems.

[4xq]

There are quite a few things to look at for a p0300 code. Possible causes:
- Faulty spark plug (s)
- Faulty ignition coil (s)
- Clogged or faulty fuel injector (s)
- Intake air leak
- Fuel injectors harness is open or shorted
- Fuel Injectors circuit poor electrical connection
- Ignition coils harness is open or shorted
- Ignition coils circuit poor electrical connection
- Insufficient cylinders compression
- Incorrect fuel pressure

(Coming from here: http://engine-codes.com/p0300_nissan.html )

The pop could be a sticking valve, or it could be a lean condition. You may want to run a compression test just to be sure your engine is mechanically sound if the coils don't fix it.

[fueler]

so much bad info. P0300 is code for random misfire. Random means an issue detected at 2 or more cylinders. This rules out coils, as you have 6 individual coils. One bad coil can not create a random misfire.

[AdamLowther]

Ok, thanks. So in reading some of the other posts there were a lot of P0300 codes that were fixed with new coils and by the sounds of some of these, a specific P030X code was not present, indicating that in those situations it may be more of a "unspecified" vs "random" misfire.

The popping would indicate unburnt fuel is hitting the cat so I am ruling out fuel issues for the present, although it could be too much fuel. Indeed, the popping doesn't start until a couple minutes after startup, once the cats are warm.

Also reading between the lines, although the P0300 has a few items (thanks) that can be tied to it, I infer that the other sensors would throw their own code if it was a cam sensor for example.

Am I adding to the misinformation? I'll update when I receive the coils.

[4xq]

Why not use the coils off of the bad engine? Doesn't sound like it was having ignition issues, so it may be worth trying.

I was thinking of a backfire into the intake when you said there was a pop noise. You could be right about fuel getting into the cats if you are sure thats where the noise comes from. That would mean a leaky fuel injector. Fuel injectors could be a problem if the new engine was sitting for awhile. Altho I would expect some type of code from the O2 sensors if that were the case - p0172 or p0175 (rich condition) perhaps.

The crank sensor does sometimes cause problems without setting a code. You might try swapping the crank sensor off the old engine and see if that helps.

Nice to have all those spare parts from the old engine sitting there if you need them!

[4xq]

OOps, sorry I missed where you had already swapped the ignition coils. Pretty slim chance those are the problem at this point if there was no change.

I think I would swap the crank sensor next just to eliminate it as a problem - its easy to do.

After that, if it were my truck, I would do the compression test.

[AdamLowther]

Thanks for the thoughts all.

Last night I pulled the injectors off the old (blown) engine, thinking I would try swapping those into the donor because the donor engine had been sitting for a year or two.

While doing that I noticed that the donor engine has the power valve and the original engine does not.
The power valve is activated by vaccume, and had a connection to the left of the swirl control solenoid for some sort of solenoid of its own (as the stock engine didn't, there was no connection in the wiring harness for this). I capped this tubing on the donor engine, to match the capped tubing on the stock engine. So the power valve on the donor engine, has not been hooked up to anything.

So I am going to switch the intake manifolds to get rid of the powervalve, as there is no connection for it on the stock wiring harness. This has probably been causing some sort of air leak, and could be the culprit. Then I don't have to locktight the powervalve screws either. I wonder if no powervalve is why the standards got 10 extra HP compared to the auto?

As for the injectors, when I pulled them off the old motor there is the O ring, then below that a plastic collar that sits in the injection port. A few of these collars cracked when I pulled the injectors, I will get new ones along with new o rings, but anyone have any ideas for slipping these little collars back on the injector without cracking them?

Thanks!

[atraudes]

I had the injectors collars pop off when I was working on my injectors the last time. They should snap right on and hold firmly. If you can't find new ones, try contacting a shop that does flow testing; they could probably get you some replacements.

Be sure to coat the o-rings on both sides of the injector with engine oil (per the FSM). This will ensure they slide in properly without bunching up the ring. The reason I was working on mine and the collars popped off was I didn't use oil the time prior to that and when I pushed the injector into the intake one of them bunched up and ripped, causing a vacuum leak. When I pulled them out the rings didn't want to let go so the collars did instead. A few others had minor rips and tears as well. It wasn't fun pulling the lower intake and retrieving them off the valves (I was SUPER lucky that none of them went past that).

[AdamLowther]

Yikes! Thanks for the tip!

On the old engine the collars didn't juyst pop off, a few of them cracked north to south. They still click on the injector fine, but I am worried that they need to be not cracked. I guess I can baby the ones that I take out of the donor engine and hopefully have 6 uncracked ones beween the two.

Should the collar sit in the engine, then slide the injector with oring in, or should I put the collar on the injector and slide into a "naked" port?

Thanks

[atraudes]

Ahh, gotcha. As I understand it, their sole purpose is to keep the o-ring on the injector. If they're not doing that, then they're trash I remember reading that a couple of people did without them in a pinch, but that was on different engines so I'm not sure how effective that'd be. I'd just buy new ones if in any doubt in the interest of not having to go back and do it again (or the engine having to digest it if they get sucked off).

They snap onto the injector, then the injector is installed in the port. They're small enough that they'd fall right through the port opening.

I just remembered they're called "pintle caps"

[AdamLowther]

Beauty. Thanks!

[4xq]

Well, you saved some money on new coils!

Let us know what happens on p1130.

On another note, I just missed a 2001 Pathy with 123,000 miles - body and paint almost new condition, no real rust underneath - for 700.00 dollars. It sucked a power valve screw. Would have been a great truck with a new engine. Another guy got to it before I did.

You should have a great truck when you're done!

[AdamLowther]

Will do! that would have been a steal, the engine replacement has taken about 20 hours, but if I was to do it again, it would be closer to 12 I think. Its not too difficult, lining up the clutch was the biggest pain, and getting the engine mounts lined up on the reinstall is definitely a 2 man job. Might be simpler with an auto.

I'll keep you posted on the outcome. It should be a good winter car.

By the way, I bought the middle of the road coils on Rock Auto, and it was $200 CAD delivered. I thought that was pretty decent. I'll send them back if swapping this plenum, cam sensor, and swirl solenoid make it go away. I should be through it by Monday.

Adam

[rgk]

Adam, do you have any plans for the power valve assembly which you are removing?

I am in need of one butterfly valve from the lower plenum. One of mine is cracked and I don't want to risk it breaking and falling into the intake.

If you would be willing to pull and mail it to me, I would make it worth your while and be eternally grateful.

[AdamLowther]

sure thing rgk. fire me an email lowther "dot" ac "at" gmail.com and I can send you what you need.

as for the weekend, I swapped the plenum, but stopped short of the injectors cause I am waiting on the new orings and pintle caps. Thought Id try just the plenum and see what happens. Good news is that the power valve assembly wasn't missing anything. Switched out the swirl control solenoid with the one from the old engine too. Got it back together, and the P1131/30 are now gone, but the P0300 remains.

It does run a bit better, but still has that miss. I think Im gonna put the new coils on when the get here, then if that doenst work I'll do the injectors and swap all the cam/ crank sensors.

Coils should be here mid week, so will continue to update.

[AdamLowther]

Ok so the new coils came from rock auto, but I think they are the wrong ones, and think I dont need them anyway. The top of the coil is taller than the stock ones, and I heard that there were two types for a 2001. Hard to say for sure, joy of going aftermarket I guess.

Heres why I dont think I need them.

The biggest problem seems to be on the 1,3,5 bank as that is where the popping is coming from.

So I swapped these coils with some random ones (other than #1 of course) from the old previously running engine. No difference.

So i pull the plugs (new NKG plat plugs f, cvor the swap) #5 is clearly showing signs of firing, as is whiteish. plug 1 and 3 are soaking wet but other than that are brand new looking, no signs of being fired. so i swap these two plugs out for old ones in the off chance that they are bad. Fire up the engine, and same problem. I disconnect the #5 plug wire while running, big difference. Clearly number 5 is helping. Disconnect #3 no difference ence at all . disconnect #1` and the intermittent popping actually stops but still running rough. (for clarity, I only had one unplugged at a time). during this I sniff the exhaust and you could flare it, clearly unburnt fuel.

So then why dont I think it is the coils?

1) engine supposedly ran fine before throwing the timg belt . I have used these donor coils to replace the "new" engine coils with no luck.

2) I left the spark plug in the block, but pulled the coil out, put a plug in it and rested it on a ground, and had great spark on coil s 1,3, and 5. No gaps in the spark that a naked eye could detect, strong and blue.

So the coils are definitely sparking.

So what next? My thoughts are that the donor engine had been sitting a while and the #1 and #3 injectors are clogged and sticking open. My theory is that they are dumping so much fuel that the mix is too rich to fire. So I pulled the old injectors complete with the fuel rail off the old motor that had been running until a couoweeks ago, and am planning to swap the entire fuel rail assembly this weekend. By the looks of it the fuel rail wiring haness might as well get swapped to.

So any thoughts? The coil either works or dosent,, right? I am getting spark on all of them per #2 above. IF cylinder 5 is firing right, and bank 2,4,6 seem to be fine, then a cam sensor shouldnt be throwing out just 1 &3 right?

I am trying to think through why #1 ran slightly better when disconnected (no pops in exhaust) this could be late firing i suppose, or that it is slightly less rich than #3, but still too rich to get full combustion on the power stroke.

I guess tI wont know until I see what new old injectors will do on the weekend, but thoughts are welcome!

Thanks!

apologies for typos, the ads or something are causing some lag. RGK, your butterfly will be in the mail tomorrow. I threw a two in just in case.

[AdamLowther]

Ps, any issues with just swapping the injectors by leaving them attached to the fuel rail, putting new o rings with lube, and pushing in the fuel rail? i.e. do I need to detach each injector from the fuel rail, put them in, and then reattach the fuel rail?

I am hoping I can do it with everything attached to the fuel rail as it is less to open up.

[atraudes]

When you pull the fuel rail out, the injectors will come out with it as a single unit. There's little clips that hold them onto the rail. Once you remove the clip, the injector can pop out of the rail. You can definitely pull the rail, replace the exposed o-rings and reinstall it. In fact, if you don't detach the in/out lines, you wouldn't even need to relieve the fuel pressure.

Sounds like you're on the right track, but I'm interested to hear what happens after you swap injectors.

By the way, it'd be a good idea to change your oil after this is sorted out. If gas is leaking out your tailpipe, it's also washing the cylinder walls and making its way into the oil. Gas in the oil isn't fatal, but it breaks it down and will be long term.

[4xq]

Hate to be a negative Nancy, but you are basically down to bad injectors, a bad ECM or bad compression in cylinder 1 & 3. Your test in point 2 above was good - cylinder 5 is ok.

There is a possibility cylinder 1 has a bad exhaust valve resulting in low compression. You get a pop when the plug fires, but no grunt (power) because theres no compression.

Hope its just injectors, but I have my doubts!

[AdamLowther]

Crap. Hadnt thought of that. I'll get a tester on it tonight.

[AdamLowther]

Good news. I compression tested #1 and #3 and got 130 and 125. Phew. Injectors on Sat. Hoping the ECM is good as it ran fine before throwing the timing chain on the old motor. At least I got a new tool out of it.

Now as long as I dont screw up the injectors all should be good. Thanks for all the tips gents!

[4xq]

Well, glad I was wrong on that. Yea, I think the ECM is probably OK. So injectors should get you there.

Those injectors must really be dumping some fuel! Basically a p0300 by drowning the plugs in fuel.

[rgk]

130 and 125 is well below the standard 185 and minimum 142 on the VQ35DE!

[AdamLowther]

Hey RGK, yeah it could be the cheapo gauge I bought, but at this point its not zero, which is good enough. =)

Plus based on the amount of fuel that has to be hemorrhaging in there, I'd expect a 15% lift if I got some oil on those rings, which would put me in spec.

We have to celebrate the little things lads! the motor isn't blown. =)

[AdamLowther]

No luck gents. The injectors are swapped, the crank sensor, cam sensors, the variable timing solenoids and related oil channel blocks. Fires up fine and no injector leaks that I can see or smell, still same problem p0300 and a couple exhaust pops every 30 seconds or so, with a unburnt fuel smell in the exhaust. The plugs in #1 and #3 are at least dry and seem to be firing this time so that is different, but not sure what else it could be.

Im out of ideas.

[4xq]

Gettin' towards bedtime here (Denver).

In order to try and identify the offending cylinder, why don't you redo the rpm drop test on all cylinders (2,4 and 6 as well) now that it seems to be idling pretty well and hitting on all six.

Look at the tach and try to gauge about how many rpm you lose as you test each cylinder.

However, what you are also looking for is which cylinder causes the popping to stop while you have the plug disconnected. So listen carefully for the popping as you do each cylinder.

Check the plug in 5 very carefully.

Do you have a vacuum gauge and a scan tool that can do real time?

[AdamLowther]

Hey, thanks for the feedback.

I redid the drop test the day of, but only on 1,3, and 5. I'll do the rest next time, but for now, #5 still is a noticeable impact, #3 does absolutely nothing, and popping stops but nothing else when I disconnect #1.

The plug in #5 is chalk white, and that engine has only been running for maybe half an hour since I put it in, and all new plugs. So 5 is lean as all get out, but that could be before the injector swap, and the 02 was probably leaning out that whole side of the engine like crazy. Like I said, the plugs seemed dry on 1&3 after the swap, so that seems to be ruled out (I think) now that the injectors are swapped.

#1 &3 had good compression, so I assumed its not valves. I did remember this over the weekend, for the first 30 sec after first startup after putting engine in, there was a strong tapping coming from the 1,3,5 bank and if I had to guess it was 1 or 3. I figured it was a stuck lifter after the donor motor had sat for a while, and it quieted down after 30 sec, and was gone completely within a minute. But it was a angry tap for that first 30 sec. I wonder if that pooched something, but then why would I be getting compression on those two cylinders?

Im thinking of pulling the valve cover, but not sure what that would tell me at this stage.
I don't have vacuum gauge or a real time scan tool.

I do have time though, this doesn't have to be up and running right away, its just a project to get me away from the accounting/finance day job.

Thanks

[4xq]

Okay, 1 is definitely the popper, 3 seems dead.

Take a look at vacuum gauge readings http://freeasestudyguides.com/engine-vacuum-test.html. I'm sure at this point if you vacuum gauge this engine you will get a sudden drop for cylinders one and three.

You can get that reading for stuck valve, no spark, or no fuel (Air, Spark, Fuel). Spark is easy to confirm one more time, but fuel injector operation is tougher on this engine - pretty inaccessible. You might idle the engine for a few minutes, then pull the plugs from one and three and see if you can smell fuel in the cylinders. Or stick something down the plug hole and see if you can swab fuel off the lowest part of the piston heads.

You should be getting an ECM code (maybe p0201 or 203) if those injectors / circuits are not working, so this is a little bit of overkill, but I kind of want to confirm what is happening with the raw gas going to those two cylinders. I guess I am looking for some evidence of gas, either on the plugs, or down in the cylinder, since those two cylinders are behaving like they are not firing. A few minutes of idling should leave those cylinders wet if the injectors are now working correctly.

Confirm fuel delivery, confirm spark, and I think you are left with the conclusion there is not enough fresh air moving thru those cylinders to create a proper fuel/air mixture for a power stroke. Which has to leave some unburned gas stranded in the cylinder. So that will be valves. That hard tapping noise you mentioned in your last post seems to point to a valve problem now as well.

As far as compression - the intake valves may be opening, and the problem may be on the exhaust. Kinda hard to say precisely what is going on without looking at the valve train. The pop from cylinder 1 probably means a slightly different (or less severe) problem
than 3.

I agree on cylinder 5 the plug was white because the O2 sensor was getting unburned air and fuel from the old bad injectors on 1 and 3 causing it to go hard lean on short term fuel trim.

So if you try that I think you should be able to figure things out well enough without buying more tools!

Hope that makes some sense!

[AdamLowther]

Thanks 4xq, that is a huge help. I'll work through this list this week, and circle back with an update over the weekend.

Thanks
Adam

[AdamLowther]

Ok, I fixed it but not proud of it.

I was thinking last night what I was assuming in my diagnosis so far. One of those assumptions was that #1 and #3 coils were plugged into the right leads in the harness. All the indicators have long since worn off, and #1 and #3 come out the same spot on the harness. They were bent in a way that made it pretty natural to hook them up the way I had them, but I switched them tonight when I got home and no more miss and its obvious I have all 6 cylinders now.

Pretty dumb move, shows that even if I am half decent at most of this, that im not beyond marking a few connectors when I take them off.

Thanks for all the help, thanks to you guys I think I could do a pretty decent diagnosis on a miss on one of these now. Apologies for taking a bunch of time for something that was beyond basic. Pretty embarrasing.