2001 ford focus had the spark plugs and wire change. Has a code po171.. ran good for two days. The spark plugs are blacker than acs of spades which is running rich. Don't know what to do next. To me its getting too much fuel at idle. Goes when get to higher rpms. When u stop it runs rough and shakes through the steering wheel. Please help.

P0301 is a engine misfire code for #1 cylinder , spark plug or plug wire problem or a bad fuel injector . Po171 system lean code . Lack of fuel , clogged fuel filter , vacuum leak . https://www.obd-codes.com/p0171 There are ways to test O2sensors before replacing . Your best bet take your vehicle to a qualified repair shop .

Check crank shaft sensor and cam sensor.

free pdf repair manual ford focus
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http://www.allcarmanuals.com/factory-service-manual-146-Ford-Focus.html

my guess
oil changer
spilt the oil filling the motor up and it ran on to the exhaust
if rocker cover gasket isnt leaking
oil smell will go away after engine gets up to temp

degreased the engine bay with something cheap
then hosed it down with a hose and water went everywhere

firing order for 4 cyl typical is 1342
the leads will be to length from dissy so its hard to mess up

water may have condensed under the dissy cap or coil plug wires arcing in the spark plug tubes

all needs to be dried out

a dry rag or metho not wd 40

car should run ok after the engine bay is dry

sounds like EGR valve and sensor this controls idle speed when at a stop. the po171 is a burn lean or rich code need to know what bank 1 or 2. also check for a vacuum leak from one of the hoses.

P0302: Cylinder #2 misfire.
P0171: System too lean, (bank 1)
The first may be a bad spark plug or the wiring to it. If it has been some time since the engine has had a tuneup, change all spark plugs and plug wiring. Check the air cleaner and replace if dirty. If it runs much better, recheck the codes again. If the car has 100k miles or over, it wouldn't hurt to replace the O2 sensors as they do wear out (even though the codes don't show that at this time). Replace the fuel filter as well. Running some injector cleaner through in the fuel will help too. If still having problems, check the system fuel pressure as the pump may be on the verge of failing. Again, the codes don't show this as a problem yet. Good luck.

ur o2 sensor is detecting a lean condition bank 1check ur maf sensor may be dirty or replacement try cleaning it with an electronics spray or brake spray cleaner --also check pvc lines and vacuum lines --not often but the fuel filer can also set this code off check fuel pressure

Gas Filter? Then scan tool on it,to look for codes set when check light came on. Most likely a senor is old and out of range.

check you put the same rated plugs in as there are a few different types they are rated from a cold plug to a hot plug which basically means the run better at the set temp

I recently bought a used 2001 zx3 with 130k miles:
1. Ran rough as a cob. Ford has a "Safety Campaign" (not a recall) on the fuel sending unit/fuel pump. Had mine replaced for FREE at the dealer. You do NOT have to be the original owner. BUT, this is only a 10 year window on the replacement (10 years from original purchase). I squeeked in by only 4 months. Afterward car ran much better, but still sickly under 1500 rpms.
2. Replaced the fuel filter (1 hour job) and spark plugs (30 min). Fuel filter was so full of garbage it felt like somebody had put a dead rat in it before sealing it up. Plugs were fouled too. Ran even better but AC was still lukewarm at around 500 rpm (where it wants to idle at).
3. Going to clean, not replace, idle control valve. This is a tricky one because of its location- on the intake manifold next to the throttle housing. I know folks are going to scream at me about cleaning it and not replacing but it runs about $50-$150 depending on the supplier. I've read a how to on one of the focus enthusiast sites and looks like a 30 min job. Counting the can of WD-40 I already have this should cost me $0.
Good luck!

you will have to read the diagnostic code that the computer is sendig for the check engine light to activate