zakgord

Posted this on the other site....no replies yet. Thought I'd try here too

Hey I posted a while back about completing a compression test and my results on my 97 standard auto altima:

Nissan Enthusiast Forums - Compression Test

This was because of my rough idling and CEL codes being thrown. Well, I figured out how to check it myself, count the flashes on the CEL, and I came up with 0304 (knock sensor) and 0701 (multiple cylinder misfire)...finally something I can see for myself and trust.

The times before I had autozone and a mechanic scan the code and I always got different answers. Knock sensor always came up, but the other code they told me was 0302....one told me cylinder 2 misfire and the other said egr.

Well, Ive checked my egr, it works fine. And my compression readings do not indicate anything fishy with cyl 2 specifically. Im really just glad i figured this out myself and know what the code is for sure.... no more conflicting opinions.


Anyways, on to the rest.

Ive heard these high compression readings could be the result of high carbon buildup. So, I think i might try and clean some of the system. Ive read up on seafoam a lot, and get many mixed opinions (did not intend to start another seafoam debate....sorry for your troubles Asleep). I think Ill take my chances and run half a can through the brake booster vacuum line and the rest in the tank.

My understanding is to suck it up slowly with the engine warm and on....but do not allow it to stall...shut it off when done. Let it sit 20 min or so...the smoke out the neigborhood. Also, just pour the rest in the gas tank like Fuel injector cleaner.

Now i dont need to change any filters after running it through these two spots correct?

Think ill give it a shot this weekend....just might clean up this carbon buildup, unusually high compression, and ultimately smooth my rough idle and remove my CEL codes. Any thoughts/suggestions?

Altima SSS

Many car owner's use Seafoam, so if you follow the directions it's not going to hurt to try. It would be interesting if the compression test is done again after the Seafoam treatment to see if the cylinder's compression readings change at all, and also see if the engine runs smoother too.

zakgord

Alright, a reply! THanks man. Ok, I did the seafoam thing. I took it for a quick run through the neighborhood, seemed to run a bit smoother. Couldnt get that fast though, will have more feedback for that tomorrow.

However, during the grand smoke show, I found I have a leak or two. About a month ago when I did the compression test I noticed a bit of smoke coming from the front of the engine (burning off oil from wet test). I checked it out, and best i could tell it was from the exhaust manifold gasket.

So, the smoke show today showed the same thing...but even more smoke of course. As best i can tell its from where the exhaust manifold connects to the engine. Also, I noticed some smoke leaking out the rear of the exhaust pipe (im not sure what its called, but the part of the exhaust right before the end of the tail pipe is connected to the larger exhaust piece....uh, shaped like a round box).

Also, I noticed a noise randomly every 5 - 10 sec or so coming from around the tailpipe. Sounded kind like a dripping or metal ping. No signs of fluids/oil leaking anywhere.

Does this mean my exhaust system/ gaskets are faulty, and could this cause my rough idle and CEL codes?

I have a short clip of the smoke coming out the front of the exhaust if that would help.

Any advice?