...well...I may have blown my motor up...

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RacerZX
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Postby RacerZX » Wed Apr 14, 2010 1:52 pm

No test results, going to be a while, I have a back-up car so the truck is resting peacefully until we have time to wrench on it.

I recently had the CAN Transfer Control Unit (33084-ZP20A) replaced, so no I haven't touched the IPDM, I'll take a look at that thread. Once I verify that the compression is good, I may just take it to the Nissan dealer and let them debug further since it's most likely a warrantable repair.


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disallow
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Postby disallow » Wed Apr 28, 2010 6:38 am

BUMP.... any update Racer?

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Postby RacerZX » Wed Apr 28, 2010 8:01 am

Nope, no update, waiting for the lift to be clear so we can fab some simple test-pipes to rule out Cat failure.

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Postby RacerZX » Thu May 27, 2010 10:23 am

So last night I replaced the IPDM to see if that would help. Picked up the Titan unit from Courtesy Parts for like $115, not bad.

Unfortunately help it didn't. As before the truck ran perfectly when cold, but within 5 minutes of driving I was back in the no-power metallic-detonation-rattle miss-firing-at-idle blues.

What I'm thinking at this point is that since she runs fine when cold, it really can't be a mechanical problem with the engine that I can imagine. Therefore I'm thinking to just carefully drive it or tow it to my local dealer and let them debug it...thoughts?

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Postby eieio » Thu May 27, 2010 11:13 am

if it were mine, i'd do a:
1) cold compression test
2) warm compression test (for comparison, since the symptoms show up after warm-up)
3) check for codes
under the circumstances, i'd be hesitant to drive it.......

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Postby JAHBLESSINGS » Fri May 28, 2010 10:22 pm

almost sounds like a fuel issue. either a bad pump or bad fuel. good luck

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disallow
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Postby disallow » Sat May 29, 2010 6:51 am

RacerZX wrote:So last night I replaced the IPDM to see if that would help. Picked up the Titan unit from Courtesy Parts for like $115, not bad.

Unfortunately help it didn't. As before the truck ran perfectly when cold, but within 5 minutes of driving I was back in the no-power metallic-detonation-rattle miss-firing-at-idle blues.

What I'm thinking at this point is that since she runs fine when cold, it really can't be a mechanical problem with the engine that I can imagine. Therefore I'm thinking to just carefully drive it or tow it to my local dealer and let them debug it...thoughts?
This could also be a symptom of the timing chain jumping a tooth at the cam. It could also be a bent valve.

Had a similar issue on my sisters 99 civic. Their timing belt broke, and when they put a new one back on, it would run good for about 5 minutes, then it was like it was running on 3 cylinders.

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Postby RacerZX » Wed Jun 02, 2010 12:11 pm

I've never heard of the VQ40 timing chain having issues like that, but we'll keep that in mind.

Who knew O2-bung back-pressure sensors were so cheap!? We ordered one, that's how we'll check for dead Cats.

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Postby RacerZX » Thu Jul 01, 2010 1:44 am

My buddy Michael and I *FINALLY* had some time to throw the Pathfinder up on the lift and play with our new O2 exhaust pressure gauge.

Driver's side showed 3psi at idle...hmmm...

Passenger side showed zero PSI...hmmm?

Tested the tool and it was still working fine, put it back on the driver's side, rev'ed the motor to a steady 2K RPM and watched the pressure slowly climb over several minutes as it warmed up, from 4psi to 7.5psi.

Put the gauge back on the passenger side, started and rev'ed the motor and got some minor blips on the gauge but mostly was zero PSI.

We presumed at this point that the driver's side had a blockage, though we were scratching our heads a bit at the almost totally zero reading on the passenger side.

So then we had the bright idea that we SHOULD HAVE DONE like 2 months ago. We hit the exhaust cans with a rubber mallet, and found rattling rocks inside the driver's side primary Cat. Duuhhh....

We then separated the y-pipe from the driver's side primary Cat flange and found the surface of the Cat intact, no love there. So we unbolted the pipe from the pre-cat and took the pipe all the way off and found the shattered remains of the Pre-Cat in the pipe on the up-stream side, lots of gray powder and several good sized chunks of that nifty ceramic/platinum honeycomb.

Mystery solved it seems. I'll be taking a chunk of the dead cat to my local Nissan dealer tomorrow at lunch and tell their service people the story and see what they think of it :-P

I really don't want there to be risk of this happening again, so would it be possible to just gut the pre-cats and run them hollow? There are O2 sensors after each Cat, so I'm guessing that's not possible, what do you guys think?

Very very happy my motor isn't blown over here...I need to go email Stillen an apology and appreciation for their suggestion of the failed Cat causing massive detonation.

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Postby Captain » Thu Jul 01, 2010 5:53 am

Thank goodness. that would of been a horrible thing if your engine was shot. Now you have a smiple fix. :D

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Postby pawjr74 » Thu Jul 01, 2010 6:44 am

My right side cat went at 52k. I just had a check engine light though, nothing like what you experienced. I wonder what mine looked like when they pulled it off?

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Postby NVRDONE » Thu Jul 01, 2010 10:05 am

Verry interesting. I've heard that you can gut the cats, but the o2 sensors may read incorect. So then you install a resistor - I don't know the part number, but it's done on Subaru's.
Good luck.

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Postby RacerZX » Thu Jul 01, 2010 11:21 am

pawjr74, do you know which of the 4 cats died on you?

Anybody have the warranty portion of the owner's manual handy? I have 60,300 miles, so juuuust out of the normal power train warranty. I will of course yell at Nissan to try and get them to cover this regardless, but also I wonder if the emissions parts have a longer specific warranty, I've seen that before on various cars.

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Postby RacerZX » Thu Jul 01, 2010 11:29 am

Image
Image

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Postby pawjr74 » Thu Jul 01, 2010 11:32 am

@ RacerZX

I can get the part # off of the warranty invoice when I get home.

Here in AZ the "Emmisions" warranty is covered to 80K miles.

I bet yours is still under warranty.


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