spark Plugs?

[mikes94q]

I had a engine knock and I found that on the compression stroke the number 8 piston and number 5 piston were getting stuck at the top of the compression. I pulled the spark plugs. All seemed normal with very little indication of use BUT the number 8 spark plug was absolutely spotless. It looked like it was brand new out of the box. What would cause this? Could this be what is causing the knock in the Engine?

[Infinitiguy19]

http://img151.imageshack.us/im...0.jpg

http://www.ngksparkplugs.com/t...d.asp

[qship96]

Those are some ugly pictures!!! The plugs t3 took out of my Q with 133,000 miles on them looked better than the pictures of the "normal" one in your above post!!!!

[mikes94q]

yeah 7 of them looked Normal, but one was brand new looked like it was never used? Why would this happen?

[Infinitiguy19]

Show us a picture because all I can assume is that that cylinder is running rich from a leak injector (O-ring usually).

[Q451990]

This is a new one for me... I have had badly fouled plugs (to the point of causing a dead miss) after injector failures - but I've never heard of one looking brand new. The only thing I can think of is that both your injector and coil aren't working, but that's pretty unlikely on a '94.

I would check for the three things you need on that cylinder... spark, compression, and fuel and attack it from that angle.

Heath

[mikes94q]

ill try to get some pics up tomorrow, I called it a night today. Beyond the nice and clean spark plug question I'm trying to figure out why on the compression stroke while manually cranking the engine I"m getting stuck with either piston 5 or 8 they seem to be at the top of their cycle at the same time. Not sure what is causing it to stick. It takes alot of force to turn it past that point.

[jamm220]

im not sure but last summer i picked up a cheap 02 Q45 for 5k with 180k miles on it. First thing i did was change the oil, transmission fluid, air filter, diff fluid and the plugs (used Denso) before doing my research. Im not sure if it was the plugs are not but the car was running mint before i switch the plugs but after the engine had a knock on cylinder 8. After i removed the plug i cold see where piston was hitting have no idea why if they were to long or not. I torque them to the correct specs also...morale of story i guess its true not to use denso plugs in the Q45

[maxnix]

...morale of story i guess its true not to use denso plugs in the Q45

While your morale might be lowered by your recent discovery, I think the moral learned is RTFSM unless you know something the Nissan engineers didn't.

[silkysmoothyjud]

Knock is caused by gas in the chamber due to leaky injector/failure to properly change injector. Also, that knock (a guess without looking) is a tell tale sign of a pre injector failure. Rod knock like lifter tick happened in 6 of 7 failures on my car. Plus its a Q, if its not the injectors, its the injectors...

[mikes94q]

the number 8 and 5 not sure which they both hit the top of their stroke at the same time are still sticking with the plugs removed. This is while manually cranking the engine. Not sure what is hitting everything looks to be within spec.

On the injectors what seems to be the best way to check them? Since I have them pulled from the engine and main harness.

Thanks for all the help, The Q is a bit more complicated than first expected.

[Infinitiguy19]

With the plenum off test them with a Volt/OHM Meter directly.

Are there any sort of weird noises heard when cranking?

[mikes94q]

No strange noise at all, just gets real hard to turn, have to use a helper bar to turn the crank at that point. As soon as you pass the top of the stroke it is very easy to turn with a standard size ratchet.

So do I just make sure that they are getting continuos current? Or am I measuring a certain amount of current?

[Infinitiguy19]

Checking fuel injectors: http://q45.org/ohminjectors.html

I don't want to say something and sound stupid (happens A LOT) but maybe its a problem with the chain guides....

Was this always a problem?

[mikes94q]

Im not sure I just acquired the car. Got it basically free, has only 60k miles on it.

Ill check the guides in Monday, the chains seem to stay nice and tight as I turn the engine.

[Infinitiguy19]

If you have the timing cover off make sure the timing chain guides are metal and not plastic.

How clean is it in there?

[jamm220]

While your morale might be lowered by your recent discovery, I think the moral learned is RTFSM unless you know something the Nissan engineers didn't.

haha either way i know i did it right, i ve done em many times on all my previous vehicle but either way something went wrong not sure what....im only human

[silkysmoothyjud]

Unfortunately, Paul is probably right. The guides will lock it up. Please update...

[mikes94q]

Spark plugs ended up not being the issue. Turns out that after a lot of work and pulling motor, taking it down removing heads.

One of the pistons skit is hitting the crank. Not sure what caused it after 60k miles or the long time that it wasn't run. So i'm trying to decide if I need to machine the crank or piston or scrap this whole car and part it out.

[silkysmoothyjud]

Is the interior brown? Heated seats? Do you want mail?

[mikes94q]

Tan interior. Still working on it just ordered the rod. Gonna see how it goes back together than I will decide if I'm going to keep it or part it.

[dsagers]

Sad to say about such a magnificent engine, but they are cheaper to buy good used condition than to rebuild.

[silkysmoothyjud]

I feel guilty for suggesting parting it out for my own purpose. You can get a used one, guaranteed for under a grand delivered on ebay motors right now....

[Infinitiguy19]

Hey Mike (mikes94q) if you see this you have PM disabled so you need to go to your profile to enable PM's.

And here is the list of stuff you wanted: http://spreadsheets.google.com/ccc?key= ... CV1E&hl=en