Topic: Misfires and system lean

[roushben]

I recently bought a larger plenum for my 2000 gt. After installing the plenum I noticed a whistle when I would give it alot of gas. After time the car started running terribly and I figured the whistle must be a leak. Also I was getting misfire codes and a system to lean code. I changed every gasket re-tightened every bolt evenly over and over until finally I just reinstalled the stock plenum. The car was still misfiring so I disconnected the negative battery terminal to clear everything and took it for a drive. Within two miles the car was misfiring and the check engine light was blinking, I took it home pulled the codes.. p0307 ( cylinder 7 misfire) p0308 (cylinder and p0174 (system too lean bank 2) It no longer whistles but is still having these problems. I dont remember if the last time i pulled the codes they were the same cylinders and bank however, I could deffinetly use some help.

[roushben]

that smiley face is soposed to say Cylinder 8.)

[Soaring]

Yeah, normally whenever you get a misfire, the #8' cylinder coil is FUBAR.   Replace the coil and see if that doesn't fix the problem. 

[roushben]

Why the 8th? Do you think I should just switch the 8 and 1 cylinder and see if I get a cylinder one code?

[thyreaper]

no,check your firing order and pull the plugs... mine was doing the same thing but i did several things including clean the air filter and maf sensor... installed new wires and spark plugs (they where due and someone had used bosh plats which is a mistake!) then i cleared the code and my misfire/stumble/lack of power all went away runs smooth and powerfull now... but thats a good place to start... with the engine running spray carb clearner around the intake and see if the engine changes any if so isolate the leak and find where exactly its coming from.. the gasket on the plentum could be misaligned or something and causing all kinds of rukus or a vacuum leak on the back of the plentum that u missed... just a sugestion

[Soaring]

The #8 coil is usually the culprit because it is at the rear of the engine, and when you get a lot of water splashing around while driving in the rain, #8 is the one that gets the most water on it, shorting it out. 

[roushben]

i actually had water in each whole on the entire side turns out it was a leak in the hood scoop right above the canal were the plugs were.. good call

[Soaring]

Glad you found the source.