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Pathy87

1988 misfire & wont rev past 3k rpm

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Hello all,

 

I have a 1988 Nissan Pathfinder 3.0 -

 

What I have done:

 

New plugs, wires, cap, rotor, coil, fuel filter, checked and swapped MAF with my 87 daily, Coolent temp sensor, grounds cleaned, electrical connections checked and cleaned, checked all 5 troubleshooting modes of the ECU and found no issues.

 

What the issue is:

 

I start the truck up and it idles okay. If I press the throttle really slow, it will rev up to 3k and bounce. If I press the gas moderately fast, it misfires badly and still bounces at 3k. I put in drive, and the same thing happens.

 

Any suggestions would be fantastic! I do have a 1987 daily driver to swap parts off of to experiment with if needed.

 

I will say in case this helps, I found that the PTC Relay waffle coned heater mixture was burnt up which burnt some wires (small one by the battery and the small wire near the actual heater mixture),I have an extra throttle body the seller included with the truck when I bought it so I swapped it out for that good one, and replaced the burnt wires. Not sure if that thing burnt up has anything to do with my rpm and misfire issue.

 

Thank you for your help!

 

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Edited by Pathy87

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Limp mode limits the rpm to 3k

 

All those mixture heaters burn up at some point. Mines burnt and now unplugged. I doubt that's the issue.

 

Is your timing correct?

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Timing should be 12 BTDC

 

Sent from my XT1585 using Tapatalk

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^ Sounds like a timing issue to me.

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The crankshaft pulley with the timing marks was pulled off and put back on not knowing where the original position was, so is there a way for me to check that and install it in the correct position? Would I be able to correct it by pulling by timing belt covers off, match up the factory timing dots, and then match the timing arrow at the 12 BTDC? Or is there another way?

 

Thanks!

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You can find TDC without opening the timing cover. Pull the #1 spark plug and find top dead center there. Some people will put a thin rod down the hole and crank the engine over by hand until the rod is up all the way. That'll tell you top dead. A mechanic I know recommended taking the Shraeder valve out of a compression tester and putting a balloon over the end, so when the balloon inflates, you know you're on the compression stroke, and when it stops inflating, you're topped out.

 

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Thank you. So the Crank Pulley has 7 notches in it. How do I tell which mark is TDC? The pictures in the Chilton manual don't even seem to tell me which one is TDC on the pulley, it shows a totally different plate that has degree markings on it. My stationary plate has a single mark, then 7 marks on the pulley.

 

Also, I have replaced my Intake Coolant temp sensor, and am unable to located the other temp sensor that is suppose to report to the ECU... where the heck is it hiding?!

 

Thanks again for any help. I am currently looking through the Chilton manual and googling what I can

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Alright, so my #1 Piston is at TDC, I took off my cover for fun and find that my factory timing points are this far from matching up. If I roll to where it matches, my piston is already on its way down. I have not pulled the balancer off yet to check the crank timing point because I am letting it soak in Break Away because its on there so tight I am turning the engine over instead of tightening the puller any more.

 

So is this an issue? To fix this would I pull the belt, and rotate both cam gears clockwise until the timing dots match up, then reinstall the belt? Is there something much worse or different I should be checking out?

 

883018f1-7e8a-4693-8391-8ea380eeee86.jpg392cf844-eaf6-483c-bb6b-faac47eed94d.jpg

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Looks like you found your problem! Good thing you caught it before it got far enough out to eat valves. The next question is why it slipped. Loose tensioner, debris getting in between the belt and the sprockets, crappy belt? But yeah, you should be able to turn it back without too much trouble. You can take the belt off and do it that way (would be a good time to check the tensioner/water pump/etc and make sure nothing's loose) but I've also heard of slacking the tension and rolling the engine over with a dowel or a nail or something in one of the grooves on the sprocket to intentionally jump the belt one tooth at a time one way or the other. If you don't know when the belt was done last, this would also be an excellent time to do a little refreshing in there. When putting it all back together, make sure you've got the tooth count right, don't just rely on the dimples. I think it's 40 teeth between the cam dimples and 43 teeth from the driver's side camshaft to the crank but double check a writeup or the FSM to be sure.

 

IIRC the VG30I has the other temp sensor on the cylinder head somewhere.

 

As for the timing marks, it's been a while since I looked it up but I think one end of the scale is top dead center, and the other end is 30° of advance. Because the engine spins clockwise (looking at it from the front), the mark furthest counterclockwise should be top dead center.

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It's behind the back timing cover. So might as well do that too.

 

The balancer isn't a press fit, you should be able to pull it off pretty easily. When you put it back on, wipe some grease on the crank so it comes off nicely next time.

Edited by PathyAndTheJets
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Use an impact gun to get the balancer bolt off.

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So the bolt was easy to get off, and my neighbor lent be a harmonic balancer removal tool, made it a breeze because it was rusted on there good. Thank you for the location of the temp sensor, I found that location on an older post, and remove that as well. That was the extent of my work on my Red Pathfinder with the timing issue.

 

THIS MORNING: Started up my daily driver Pathfinder to go to work, keep in mind I didn't touch it last night, and have never messed with the pulley's or crank shaft. My freaking harmonic balancer key either sheered off, or my crankshaft blew apart near the key hole, but either way, it was making a horrible sound so I limped it back home. Tore it down to the balancer and the balancer wiggled and fell right off..... AND my crank bolt was loose as a goose. I am guessing the bolt got loose, which helped the key wiggle and sheer off?! I cannot believe this happened a day after I took apart my Red Pathfinder. I do not have the funds to do any major repairs, and my daily pathfinder was going to end up being my wheeling vehicle, so what are my options now? Anybody experience this before? Can I just weld it on and call it good until it dies one day? I have never torn down or into an engine much before, but am mechanically inclined, but I am pretty sure to change out my crank shaft, requires me to tear down my entire engine.... I could be wrong.

 

Let me know your thoughts on my new issue with my Daily Pathfinder!!

 

Crankshaft.jpg

 

I am at work right now and cannot mess with it until tonight, but I am guessing the balancer that was on it, is all gouged up and shouldn't be put back on the crank. Either the crank is ground down or the balancer is hollowed out, either way it came off way to easy, and I think even if I put a good key in there, and tight it back down, it wont last long.... I am all about back yard rigging it up, so JB Weld the crap out of it? Or actually weld it up, and if a timing belt ever goes, just say fskc it and part it out....

 

I am having such bad luck with these things, but love them to death.

 

Thanks for any comments/ support

 

 

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That's not good. Not unheard of, but not good. I've heard of welding up the damage to the keyway, or just cutting a new one on the other side. I'm not sure how people repair it without removing the motor. It looks like the crank spun inside the balancer with bits of sheared-off key grinding both sides, which I'm sure didn't do them any favors.

 

If it was my rig, and I needed to get it going for cheap... first I'd slip the balancer back on and see just how loose it is. Installs/removes by hand is fine, but you shouldn't be able to rattle it. I would expect the balancer to wear faster than the hardened crank snout, so you might get rid of most of your play just by borrowing the balancer from your other rig. My first thought would be to fill the damage with the welder, but it's hardened steel, which means the heat could weaken the crankshaft (not good). Apparently the Miata guys have a lot of issues with these and use Loctite 660 Quickmetal--no idea if this is a good idea but it could be something to look into. If you don't mind a wall of text, this guy goes over a few options and what ended up working for him on a big block Chevy.

Honestly, though, if all the red one needs is its timing belt reset, that's the one I'd be working on first. That's all wrench work, and the timing belt setup for these is pretty well documented. Seems like that would be easier to fire out in an afternoon so you can take your time on this keyway issue later.

 

And now if you'll excuse me I'm going to go and check on my crank bolt! :unsure:

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Thanks for the input. I decided to move forward with fixing the timing on the Red Pathfinder, until I removed the lower timing plate cover, and began to find TDC, I noticed that the timing gear on the crankshaft had a HUGE amount of play in it... pulled the timing belt off, and the timing gear slid right off. The key had sheered 90% of the way, and the back and forth action over time destroyed the keyhole for the timing gear and wrecked the timing gear itself. That explains why my cam gears were a couple teeth off, and why the car would sometimes run good and then not. SOO my red one is now useless as well. Case is closed on the Red Pathfinder, I am going to sell it as a parts car.

 

As for my daily Pathfinder, I cleaned out the key hole for the balancer as best I could, set the key in place and pushed on the balancer off the Red Doner. It wasn't as solid as I wanted, but MUCH better than the one that got hollowed out. It still had back and forth movement, so I used Red Loctite the crank bolt and tightened that sucker as tight as I could possibly get it. I put everything back together, made sure my belts where not super tight, and let everything sit to cure over night.

 

This morning she fired up, and drove to work just fine. I am taking it on the highway this afternoon to see how it does and try to regain some trust back with it.

 

Thank you for all the help and input from everybody! Let the adventure continue.....

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That's a shame. That body looks immaculate.

 

If it wasn't raining currently i think I'd be out making sure my crank bolt was torqued still.

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Damn, two in a row! That sucks. Hopefully the loctite fix holds up.

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Just an Update -

 

My Daily that had the balancer key break off has been running great with no issues.

 

The Red one that had the timing gear slop, I bought two new keys, one for the timing gear and one for the balancer. Both fit nice and barley moved at all. Set the timing and that one fires right on up now too. Runs smooth but still has the limp mode at 3,000 rpm. I have not replaced the coolant temp sensor on the block yet, and I can see that the driver side injector isn't putting out fuel so hopefully just a swap of that sensor makes that injector fire, if not I have a spare injector to try.

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My 1989 went into limp mode last year. Several shops attempted to diagnose it with no success. Finally took it to a Nissan dealer and they discovered one of the fuel injectors was dripping instead of spraying. Replaced the injector and now it runs fine.

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Super easy to diag. I take a slim piece of paper and make a "l" shape and while the engine is running put it down the neck of the throttle body on each side of the injectors. The injector that is firing you will feel the paper vibrate. The one that is not there will be nothing.

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