Ok, so as I posted a couple weeks ago, I had 19lb. injectors in my stock 2.8. So, I took the injectors back out (and returned them to jegs cause I found out one was busted) and replaced them with the old injectors. GOOD NEWS! The car runs. I got it home from my shop and it has power, but it's got a miss that you can hear and it smells VERY rich. I need to know which cylinder is missing so I can go from there, and what I can do about the running rich. My check engine light isn't on, so I don't think it's an O2 sensor, but it's possible (if those things can go bad without tellin you).

Is there a way to tell which cylinder is missing? Please don't say "start it up and start pullin wires" cause I did that and got a nice shock right through the arm. Thanks!

 

Well, If you have a timing light (inductive type) then you can clip it to all to of the wires one at a time and see which one dosent flash the light. If all the wires are hot, then its your plugs. Bout the only was to test them is to check them one at a tme on a vehical that runs correctly. Plug them into a wire and lay it on the manifold if it's metal, or anything else that might make a good ground, should produce a visible spark. If all the plugs are hot then I'm sorry, you probably have a head gasket that's leaking water into that cylinder and causing it not to ignite properly. Last ditch, hail marry resort is to borrow one of those laser heat guns and see which header/exhaust manifold tube is drastically cooler than the others...

Good luck!!

~Max

 

Pull the plugs and look at the color of them. Look for the one that is darker then the rest or might even be wet. I'd say put new plugs in first, run it for awhile and then check them. Hope this helps?

 

cool, thanks. I'm going to start pullin plugs tomorrow to hopefully get to the bottom of this. Is it possible that a damaged fuel injector would cause it to miss? also, what can I do about the running rich part?
Thanks.

 

You may be running rich due to your plugd, i would replace plugs and DOUBLE check wires and go from there. I don't think its a head gasket, you would know it. Mine did the same thing, worse when it was hott though. $400 later i put plugs and wires in, problem is gone

 

A damaged fuel injector will MOST DEFINITELY cause a miss if it's bad.

Now why were you running 19 lb/hr injectors in a little 2.8? 19 is much larger than stock. My Mustang has over 300 hp and I'm running 19 lb/s....which is stock for this car...but 19 pph is supposed to support up to around 400 hp with fuel pressure tweaks.


Also earlier you asked if it's possible for an O2 sensor to go bad without a check engine light. Yes, it's possible, and actually PROBABLE. Most of them seem to go bad because of a rich condition or they just get old...or gunked up, etc. But when they begin to read faulty, they have sluggish response times for engine condition changes, and they also more often than not tell your computer that you are running LEAN. Which means, engine dumps more fuel. Which is why poor mileage is a symptom of O2 sensor failure. For $20, hell, if you even THINK it could be bad, replace it. Cause if you remove your current one, theyre so sensitive that chances are you may have just f----ed it up. And O2's pay for themselves in the gas mileage they'll end up saving you. My buddy's Olds with a 3.8 went from 12-14 mpg city to 18-22 mpg city with just an O2 sensor swap. He finally listened to me.