1.3 1998 ford fiesta runs fine on tick over but missfires when under accelaration

SOURCE: Ford Fiesta 1998 Finesse 1.3 - imobillisor / ecu fault

hi mate i hade this problem and it were the catlicconverter

SOURCE: not firing right on no.4

First check plug and make sure the right plug for this vehicle,make sure that the heat rating for this plug is correct. Your problem could be a wrong heat rating plug been installed. Also make sure that the misfire is due to a bad plug and NOT a bad injector or injector wiring or uneven compression or even bad coil. Check injector wiring and make sure it not shorting or broken. To check injector pulse use a NOID light can be bought at almost any auto parts store like Auto-zone etc. Also compression can be checked with compression guage. A rule of thumb to go by is if any cylinder has more than 10 PSI in difference in compression there is a problem like a burnt valv etc. Here is a n example cyl# 1 170psi cyl#2 176 psi cyl#172psi cyl# 4 150 psi, there is a problem with cylinder # 4 and will cause a miss from cylinder #4. Good luck and thank for using FIX YA

SOURCE: miss firing engine and black spark plug

Is it a two stroke machine , do you mix your own fuel.

If so over dosing on the oil component will cause your problem, check for the right mix levels and follow them.

Is the choke going full back to zero ?

Are you running the right type pf plug for that engine, some run hot some dont

Is the engine running smooth or lumpy.
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For a four stroke engine

Your engine may either be running very rich or there is wear on the bores causing oil to get to the electrode.

You can obtain a spark plug extender which takes the plug out of the direct line of fire

SOURCE: ford fiesta,1996,petrol,fails to start.

either your fuel pump relay or the safety shut off switch

SOURCE: engine runs like it has a miss fire fault code is

The fault code appears to be telling you the 02 Sensor nearest the exhaust manifold. You have two on yours. You very safest bet is to verify with your local dealer. The New Car Dealer will give you the code meaning over the phone if you give them your VIN number and the CODE.
Be sure to check on recalls as well. This can save you thousands of dollars on some cars.

Remember if you install the new 02 Sensor to be sure to use a thread compound to save trouble for whom ever has to replace it again.
ALSO - have a stone cold engine to do this. You will want to invest in a pair of gloves for removing the old unit as busted knuckles is legend when doing these types of repairs.

Once the new part is installed; remove the negative battery cable for 3-5 minutes then replace and let the car run for 20 minutes driving time and it will 'reset' your on board computer.