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Discussion Starter · #1 ·
So I am new to this forum and to the Altima. So here it is I recently bought a 07 3.5 Se with a six speed and the previous owner had the firewall cat replaced and then he started having trouble where the car would just bog down and stall out when u give it gas. He was under the impression that the right front cat was no good. But when I got the car home I did not have a p420 code I did have a p1156 code that was the upstream O2 sensor and a p335 code so I replaced both O2 sensors and the crank position sensor and a new battery. I now have no codes but still can't drive the car. Any ideas ?
 

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Discussion Starter · #2 ·
Any ideas anyone? I can trade heating air conditioning duct work info or roadstar warrior info for Altima info please help. I love this car and I haven't even driven it yet
 

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09 Altima 3.5SE 6MT Sedan
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Out of my league, but the '335 code points to a misfire in cylinder #5 (rear bank, driver side) which makes sense with the rear precat getting plugged. I would pull the plugs and do a compression test to see if the car is worth saving first. Then start worrying about what's actually wrong with it. A VQ killed by a disintegrated precat is an expensive proposition.

My guess, and I admit it's a wild assed guess, is that your main cat is totally clogged with all the gunk from the rear precat and whatever was going on in cylinder 5. So open up the exhaust at the Y-pipe/converter junction and try to start it again...it'll be loud and run rough, but if there is fuel and fire it should go.

Oh, and if you replaced the OEM sensor with a new 'plastic' one, try putting the old one back in for your tests. These cars are crazy finicky about the cam and crank sensors (yes, there are 3 of them, and it's recommended to only use the metal capped Nissan ones)
 

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Discussion Starter · #4 ·
So ur. Saying there is a cat at the y pipe and disconnect the y pipe. That sounds like good advice also ur saying the motor might be junk I hope not the car is really clean and I spent all my money on it and haven't even driven it yet ugh now I'm worried
 

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09 Altima 3.5SE 6MT Sedan
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Welcome to Nissan land..if you aren't worried, then you clearly don't know what you're driving. Heck I've been worried for almost twelve VQ years now...but I still manage to have a lot of fun and get a lot of places in-between all that angst.*

The VQ has precats on each exhaust manifold, front and back, that drop to a bizarre looking Y-pipe. The Y-pipe actually incorporates the 3rd 'clean up' converter at the back end...so I misled you a little (head cold...my bad) so it won't be as easy as splitting the pipe before the 3rd converter, instead you have to separate it at either exhaust manifold/precat where it joins the Y pipe. You just have to break the seal enough to ensure that no significant backpressure can form due to blockage further down. Even breaking the seal on just one bank should be sufficient to let the gases out from both.

If the car won't crank or cranks and won't start/run then there's a good chance the crank and/or cam shaft position sensors are to blame. If the engine bogs down with extra rpm that sounds like exhaust blockage to me. You obviously need to get back to step 1 before you can debug step 2.

*Full Disclosure: I did get one new engine courtesy of Nissan in this time
 

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Discussion Starter · #6 ·
Great at least now I got an idea of how to trouble shoot this thing. When u say run if it's the cam sensor. What does that mean exactly? It isn't just a sensor that can be replaced and ok ?
 

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Discussion Starter · #7 ·
By the way I just wanna say thank u for taking the time to educate me a little I really appreciate it
 

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09 Altima 3.5SE 6MT Sedan
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Great at least now I got an idea of how to trouble shoot this thing. When u say run if it's the cam sensor. What does that mean exactly? It isn't just a sensor that can be replaced and ok ?
You will quickly learn that with the VQ, somethings are NOT to be messed with...ie only use OEM iridium spark plugs (you can buy them elsewhere...but don't expect some triple-pronged Hellfire plug from fleaBay to actually work well in this engine) Same goes for the crank and two cam position sensors...the tolerance is really critical, the new plastic body sensors often work worse than the old ones. The only consistent path to success when the engine has no start conditions (and you know you have fuel and spark) is to replace the sensors with the metal body (Denso?) sensors..and yes, it's recommended to replace them all at the same time. Don't clean your throttle body unless you know exactly how and what to do...you'll wind up buying a new one. The list goes on...
 

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I only run platinums in mine. Never noticed a difference with the iridiums except I was mo po after buying them. Maybe it's different on the 05 VQ.
 

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09 Altima 3.5SE 6MT Sedan
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FYI I fibbed...the correct sensors for Gen4s don't have metal caps.
 

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OEM plugs for the 2005 VQ is the NGK Platinum - it's all I ran...Of course they were only changed once as the interval is 100K.

The 2007 user manual has notes on Platinum plugs "If-so-equipped", but specs the NGK DILKAR6A-11 Iridium for the QR2.5 and the Denso FXE20HR-11 Iridium for the VQ35. Go figure - gotta love Nissan ambiguity.





 

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09 Altima 3.5SE 6MT Sedan
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Had the dealer run my VIN to make sure before I bought them. 2009 VQ uses Denso 3442 Iridius, aka FXE-22HR11's

Go to the parts counter and ask for a quote, no obligation to buy.
 

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Discussion Starter · #15 ·
Hey dougmac1 I just want to thank u again I took ur advice about removing the cats from the y-pipe what I found was a huge chunk stuck in the front pre-cat blocking the exhaust I took that and the y-pipe down in one piece and was able to give the car gas. So I'm on the right track thanks man. Now next question does racing line have a phone number I can call I emailed them and didn't get a response so I would like to call them thanks in advance.
 

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09 Altima 3.5SE 6MT Sedan
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Racingline is in orgainizational transformation (ie chaos) right now...probably should budget 2-4 weeks for any order at this point. If you are in a hurry to get things going, then I would use what you have right now, with plans to swap in (I assume the RL ypipe and possibly high flow cats) when they arrive.

Curious about that 'huge' chunk of 'stuff' in the front precat. Was it black? Should give you some kind of clue whether it was antifreeze or oil or unburnt gas that caused the solid matter to appear. Was the catalyitic matrix in good shape on the engine side? If so, you may be well on your way to getting her back in tip top shape. If the #5 plug looks different than the others, then you could try replacing the plug, coil pack and injector for that cylinder and test drive it like that. That may resolve it, or if you have the compression test results, that should help you isolate fuel/air mixture issues vs cracked/burnt/worn valves or rings.

PS You're welcome, and welcome to the Nissan family :)
 

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Discussion Starter · #17 ·
No it wasn't black it was ashy grey and it was the honeycomb material like a round ball of it just lose sitting on the bend just before the y-pipe. What I did was took it apart at the manifold because those bolts were in much better shape. Thought process being it would be easier to work on out from under the car. But with the cats removed and y-pipe my bogging down issue was gone. So now I'm gonna replace that pre-cat and y- pipe for now I guess I'm gonna just go with a stock one I can't wait four weeks for the nice one. The reason y I'm replacing the pipe is it is in bad condition and full of the grey ash from the pre-cat
 

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09 Altima 3.5SE 6MT Sedan
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Ok, that's not great news. I'm going to recommend the following:

Take a compression test. If one or more cylinders are low, you need to decide whether to bail or go forward.

Hypothetically, and not that I am suggesting you actually proceed, but theoretically one could:

Gut the precats. Using a hammer and a big piece of iron, destroy any remaining material in the precats (front and back). Remove all of the ceramic honeycomb matrix and discard. Wear a mask and eye protection. Make sure the front area of the main/third clean up cat (post y-pipe) is clean. Some compressed air might be useful here. Paint a large 'For Offroad Use Only' on the side of your car :) Just kidding.

Purchase some 'anti-fouling' sparkplug adapters and insert them between the lower pre-cat O2 sensors and the headers, these are the bungs BELOW where the cat material would have been (leave the upper ones alone, they are your air/fuel sensors). You will need to remove the lower O2 sensors to do this. This should allow you to run without the SES/CEL light annoying you.

Drain the oil. Drop the lower oil pan (you'll need some gasket making material to reassemble). Clean out as much grit/dust as you can from the pan and lower engine. Change the oil and filter and use some kind of antisludge/detergent additive. Drive it a few days and change oil and filter again. This is the best you can do to ensure as much of the abrasive dust that may be in your engine gets flushed away. What's done already is done.

Decide if you want to keep gutted cats, or replace with RL HF cats and Y-pipe as you see fit.
 

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09 Altima 3.5SE 6MT Sedan
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To be honest with you, there's a pretty good chance this engine is toast already. The fact that the precat material has disintegrated so far to the point that it's detached and been spinning around inside the pipe like a ping pong ball is an indication that it's been breaking down for a long long time. Long enough that enough dust has been sucked into the engine to cause excessive and very premature wear.

Symptoms: high oil consumption (1 quart+ per 1000 miles), low compression/poor fuel economy, premature deterioration of engine oil (more rapid changes required). Eventually all moving parts will have too much slop to function properly (timing chain, cams, etc etc)

You need to keep this in mind as you figure out what you want to spend. For example, it might be better to have a new long block put in rather than buy a new y-pipe (though it does cost 10-20x more).
 

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09 Altima 3.5SE 6MT Sedan
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