Thread: Engine running now, but not very well [PICS]

So I finally got my SE-R running today
The only problem is that it's not running particularly well, and I'm wondering what the problem is.

Because the initial need for an engine swap was due to hydrolocking, I suspect some kind of bad valve in the intake manifold somewhere, maybe the AAC valve. Possibly a bad MAF as well?

Here are the symptoms:

It runs great between 1200 and 3000 RPM
If I just let it idle, it will start dying, and shut off within about 5 seconds
If I revv it past 3000 RPM, it just stutters and shakes and doesn't want to go any further. I can revv it further if I give it more gas, but the higher I go, the more it stutters

Does anybody have any input on this one?
Thanks,

how are your coolant temps?

when was the last time your aac valve was cleaned?

Funny you should ask - coolant temps are really high just from a few minutes of running, and the AAC valve has never been cleaned - that's the one that hangs out under the back of the intake manifold, kind of by the oil pressure switch, right?

Thanks for the quick response!

yes that is the AAC.

the coolant temp sensor will effect the idle, as will the idle air control valve, the idle air control valve or aac valve is nitorious for getting dirty and effecting the idling.

also signs of bad coolant temp sensor is that if you start it and it dies right away or you start it have have to continuiously give it gas to idle untill warm..my bet is both getting a new temp sensor and cleaning the AAC valve will fix this problem

Sweet thanks for the input dude! I will clean that little guy tomorrow and see how she runs. I might have to order a new one depending on how much damage the water did.

i would test the voltages to the AAC valve to see if they are in the correct specs otherwise i think it would just need a good cleaning with some carb cleaner, aac valve is pretty expensive.

Definitely. And I just realized that I have a spare in my garage from my last Sentra, as well. That's the great thing about buying a B13 SE-R 4 times in a row.

So I took apart the AAC valve and found that it actually looks REALLY clean. The only thing that concerns me is that it looks like it's not completely closed at rest - is that normal? Here are some pictures:

At rest:


Forced it to close with my finger:


Forced it completely open:

i would still shoot it with some carb cleaner anyhow

are you going to get a new gasket for it now?

Actually, I decided to swap it for this one:



I found it interesting that it was even more open at rest than the one that was in the engine previously. It's much cleaner than the old one, too.

Side by side:



Also, I decided to pull the plugs and do a compression test. Check out the plugs - this means I'm running really really rich, right? They were brand new last night when I put them in:


And somehow I managed to get 30PSI above stock on all cylinders!!! I'm pumped!!





I'm not sure why the compression is so high, but I did re-seat the rings in the right positions while I had it apart, and when I sent the head to the machine shop, they had to mill it down a bit to get it flat again.


BUT - the problem is the exact same with the other AAC valve in, so I'm not sure what's going on. Running rich makes me suspect the MAF. What do you think?