Stumbling acceleration no codes QR25DE

General discussion area for the L31-chassis Altima, including the 05-06 SE-R models.
fmorelli
Posts: 7
Joined: Thu Dec 21, 2017 5:20 pm
Car: 2003 Nissan Altima 2.5S

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Hi all, I'm at a loss on this one. Did a head gasket on an '03 Altima. Ran great for a week or two. It's now running rough on acceleration. Idles fine. Even in park, slow and constant acceleration with no load gets some hesitation. No check engine light is being set. Hesitation is hard enough that, when driving, the car struggles to accelerate up hills.

I'm used to something like this setting a code, and this is baffling me. New coils, spark plugs, cam sensor, and it was running fine.

On the head gasket, recall the car ran fine for a couple weeks. There is no bubbling in coolant, no overheating, head was milled, and Fel-pro gasket used, all work done right. Remember it ran smoothly for 1-2 weeks before we started having this issue.

No codes with rough acceleration is the key. What could cause that?

Thanks!

Filippo


macgiver
Posts: 1612
Joined: Wed Jul 04, 2007 10:21 am

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mac , hate to say it , but sounds like the H-gasket repair "didn't take" . Longshot is that not necessarily the typical bubbling into the overflow or coolant into the oil supply . Something like "adjacent cylinder" compression / powerstroke blow-by , or blowing into the crankcase (where you may notice LOTS of SMOKE & Commotion whilst oil cap removed) . :eek:

fmorelli
Posts: 7
Joined: Thu Dec 21, 2017 5:20 pm
Car: 2003 Nissan Altima 2.5S

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Interesting. I had the head milled. Did not have guides/seals done as it is a 150k car that just needs to run not last forever. Consequently there is some positive pressure at the oil cap, which is most likely do to blow-by on the guides (and we know the seals must be non-rubber at this point). I changed the PCV tube and valve as well. Felpro torx studs, all done to spec. Adjacent cylinder ... I could do a compression check and see what I get ... that should point out an adjacency issue I believe.

Filippo

macgiver
Posts: 1612
Joined: Wed Jul 04, 2007 10:21 am

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mac , I'm going to do a head gasket on 3.1L GM in a couple of weeks - same "boat " . Pray tell?
How if any treatment , cleaning , spray tack , Permatex etc. on block or heads - anything like that did you do ??

fmorelli
Posts: 7
Joined: Thu Dec 21, 2017 5:20 pm
Car: 2003 Nissan Altima 2.5S

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Not to digress, but find a good youtube video for your specific 3.1L. That helps. If a head comes off, IMHO, it should go to the machine shop to be checked out. Let them tell you what it needs. Prep is straightforward. The block surface should be completely clean. I also soaked the tops of the pistons with upper cylinder head cleaner (GM product) and with a bent toothbrush and rags cleaned everything up. A thin coat of oil spray helps keep the cylinder walls from rusting if you do the cleaning days before the head install. I suggest using Fel-pro products ... pay for them, quality is good. Head gasket goes on dry. Permatex may be used at gasket corners, like on the cam cover, or transitions points of covers, but otherwise you should not need it. Again head is installed dry on the gasket. Religiously follow torque guide. Note you may need an angle torque wrench or angle adapter (unless the spec is 90 degrees, which you can figure out without a gauge.)

If putting stuff back together in the cylinder head, coat liberally with Assembly Lube.

Filippo

macgiver
Posts: 1612
Joined: Wed Jul 04, 2007 10:21 am

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mac , heard anything about SD (severe Duty - Fel Pro ) Head gaskets ? I'm seriously considering those , same job was done 85k ago , motor is notorious Lower intake and / or blown head gasket , wife drove home and I got lax in weekly checking overflow / rad. cap and SHE MADE it HOME :rotflmao The car had reservations after that :spitout:

nando989
Posts: 29
Joined: Mon Nov 06, 2017 11:15 pm
Car: 2002 Nissan Altima S

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IF your compression test checks out good. Check all your grounds specially the ones on the timing chain cover. Have you tried to clean the mass air flow sensor. Check the connectors on the fuel injectors. Also make sure the coil pack connectors are secure. Those tend to fall apart and the wires pull out and car will run like a 💩. Check for vaccum leaks with a can of brake fluid specially at the intake where the head is. Also make sure the knock sensor is secured. Double check everything that was removed. I’ve had to chase a couple of issues on my 02 Altima with no check engine light. What a pain!

nando989
Posts: 29
Joined: Mon Nov 06, 2017 11:15 pm
Car: 2002 Nissan Altima S

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Did you change the catalyst converter ? Possible that could be clogged restricting flow. Get a thermo temp gun and check the temp before the conveter and after. Temp should be higher just after the conveter. Also check fuel pressure. If all checks out check the timing.


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