2001 Mercury Mountaineer misfiring on cylinders 1, 2 & 8, idling rough, details in thread.

Been having problems with this thing for a few weeks now.

So, my mom's Mercury Mountaineer was idling rough, and Cylinder 1 was misfiring. Check engine light on, blinking, and so on. My dad replaced all 8 spark plugs, and the spark plug wires, because they all really needed replacing. Ran fuel injection cleaner (Lucas?) through the system. From what I understand, the ignition coils are fine, although I may double-check with my dad later to clarify (although I haven't heard that they need replacing, SO... for now, we'll labor under the assumption that they're not involved. I dunno if they would be anyway, though...)

Now, the car has good and bad rides. Some trips, it runs better than others. It seems that after my dad did the replacements, cylinders 2 and 8 started misfiring as well, although the diagnostic said the (new) spark plugs and wires looked fine. The people here run diagnostics starting at $100 (which we really can't afford to just ATTEMPT finding out what's wrong)...

Any ideas on what it could be? It idles rough, shakes some when accelerating to certain speeds (but does okay at higher speeds), and apparently isn't using the fuel to its full potential (i.e., dumping raw fuel out the exhaust pipe or something. I can't remember the exact wording). The check engine light stays on. If I'm on a long trip (going to or from work, which takes an hour and gets me onto the highway), the light will sometimes blink for a few seconds and then go back to just staying on steadily, although when I went to and from work yesterday, the check engine light didn't blink.

From what I've been garnering, it could be the fuel injector, fuel pump, or O2 sensor, at the very least. Could those be it? Any suggestions? (I know we need to get a diagnostic eventually, but we can't afford the prices the mechanic quoted... not right now, anyway.) Any idea on how much it would cost to get any of these replaced? We're in a bit of a tight financial situation right now, so it'd be nice to know what to prepare for.

Does your trip to or from work take you past any auto parts stores? At least most of the chain parts stores (Autozone, Advance Auto, O'Reilly, etc.) offer their scan tool to pull diagnostic codes at no charge. Those diagnostic codes will help guide you in the correct way. Get the diagnostic codes and search this forum for them, or reply to this thread with the codes.

A flashing Check Engine Light (CEL) indicates an emissions issue that may cause more extreme/expensive issues in the near future if no remedied soon.

-Rod

Does your trip to or from work take you past any auto parts stores? At least most of the chain parts stores (Autozone, Advance Auto, O'Reilly, etc.) offer their scan tool to pull diagnostic codes at no charge. Those diagnostic codes will help guide you in the correct way. Get the diagnostic codes and search this forum for them, or reply to this thread with the codes.

A flashing Check Engine Light (CEL) indicates an emissions issue that may cause more extreme/expensive issues in the near future if no remedied soon.

-Rod

I'll probably have to do it before work or on my days off, as I live an hour away from my job and have to work until 11 most nights right now. I'll try and get it done Saturday. AutoZone and Advance only had the Check Engine tools (since we needed to do a minor check-up on my Hyundai today), is that what you're referring to?

Could be the coil packs.

FishFind is right, my first guess is the coil packs. Pull the packs and look for "hairline" cracks in the plastic portions on the coils. Cylinder #1 and #8 are the two closest to the radiator. Cylinder #2 is the one on the passengers side, second from the radiator. Check engine light is probably also throwing the "multiple misfire". Bad coil on #1 or #2 could cause each other to misfire. Misfire on #8 has no connections with the left cylinder bank (#1, #2, #3, #4) which means that the misfire on the #8 cylinder is just that...a misfire on number 8... the computer recieves info from the coils as-to how much energy it is creating. If a coil is NOT SENDING OUT THE ENERGY TO SPARK...that is why you get a misfire code on that cylinder. The misfire on #1 and #2 could be caused by one or both coils...a bad coil could send a "spark" to a good coil causing it to fire off the air/fuel mixture at the wrong time causing the misfire code to pop up for thar cylinder.
Anyhow, beware coil packs...any coil packs are EXPENSIVE!!! I just paid $400 (PURCHASE PRICE) for the ones on the wifes CTS-V

It could be a lot of things, and since money is tight, don't try to shotgun items, but rather get the diagnostic codes read and confirm if it is a misfire code(s), codes that may point toward the DPFE sensor, an intermittent MAF sensor, etc.

Yes, the Check Engine Light scan tool is what I'm referring to. The stores used to send an employee out to your car to pull the diagnostic codes. I'm hearing more and more that they no longer do that, but rather let you take the scan tool to the car and use it yourself. That's good. As long as you can figure out how to read the codes, you will see the exact code numbers and can post them back here versus getting the employee's interpretation of what the codes mean.

-Rod