This question isn't about my '84 F150, but since there seems to be plenty of knowledgeable people visiting this site, I thought I'd post a question about my sister's '98 Ford Contour.

The Contour has a 4cyl DOHC engine and it is misfiring badly. It is also throwing a misfire code. I changed the spark plugs and spark plug wires. I guess the coil is next to be changed.

Does anyone have any other suggestions as to what can be the problem? How can I test the coil to see if it is bad before I spend $45 replacing it? How do I tell if it isn't a fuel-flow problem? Maybe a bad injector or a sticking valve?

I'm definitely an amateur, so I can only tell you all that it idles a little rough and it bogs down and runs really rough when I put a load on the engine (like by turning on the AC). By listening to the exhaust, it sounds a little like a tractor (a very noticeable "ba-ba-ba-ba-ba-ba").

 

find out what cylinder is missing.
clear codes.
swap that coil and boot to another cylinder.
fire engine.
if the misfire code comes up to the cylinder you swapped the coil and boot to, than it is either the coil or boot.
i always change the $5 boot first, and 95% of the time that saves me from buying a $55 coil.

 

Thanks for the response, tjc transport.

Cylinder #4 is misfiring according to the diagnostic tool. I checked the spark plugs in cylinders 1, 2, and 3. The spark plugs were all fairly clean (they're new). The #4 spark plug was very fouled (dark brown to black). I replaced it with a new spark plug and let the engine idle for ~30 seconds. It was still misfiring and throwing a code. I checked the new #4 spark plug again and it is clean.

How do I check for spark? I pulled the spark plug out of the head and (with it attached to the spark plug wire) turned the engine over. I didn't notice any spark. Does the plug need to be grounded to check for spark?

I drove the car a little today and noticed that it was very underpowered and felt like it wasn't running on all four cylinders, so cylinder 4 probably isn't firing at all. The transmission is also acting funny. It seems to rev a few 100rpms higher than it should when it shifts and it seems to be slipping (it feels like you're popping the clutch if it were a manual transmission). I was told this is probably caused by the engine running the way it is.

I was also told by that same person to try to reset the ECU by disconnecting one of the battery leads. They also said to leave the lead disconnected for a half-hour because there is a capacitor onboard the ecu that needs to be depleted. Any thoughts?

 

you done a compression test on the cylinder to see if it's carrying anything ? you could possibly have a burnt , or bent valve . if i'm not mistaken aren't these lil' 4 poppers also a close tolerance motor ? if so just winding it a little tight once might have been enough to make contact between a valve and piston and do some damage . i had a 2.3 once skip a tooth on a worn belt and play havoc with the internals ........................ maybe even a flat cam lobe . so many things . do the compression test and see what ya get .

 

I checked for spark again by using two vise-grips. I attached one vise grip to the engine hoist (the steel eye that is bolted to the block and is used to pull the motor out). I used the second vise-grip to clamp the spark plug to the first vise-grip. Using this method of gounding the spark plug, I checked for spark on all spark plugs. I got spark on cylinders 1,2, and 3, but not 4. Just in case it was the plug or wire, I used two different spark plugs and spark plug wires to check for spark in #4. Still no spark.

I then changed the coil and it seemed to fix the problem. I have good spark now on cylinder 4 and it runs pretty good. However, I drove the car a little and whenever the car is sitting and idling while the AC is blasting and the transmission is in gear, it still misfires a little. When I put the transmission in park or neutral (take a load off the motor?) the idling smoothes out. The transmission still seems to be slipping a little, but not nearly as bad as it was before I installed the new coil. So, next up is a transmission oil and filter change.

55 f350, I haven't checked cylinder compression yet, but I plan to just to satisfy my curiosity. I've been told the biggest thing to look for while doing a compression check is that all cylinders have nearly the same compression (within 10%-15% of each other). How do I find out what numbers I should see? Around 130psi at each cylinder?

For anybody who wants to know, I found out that the #8 relay in the power distribution box is for the fuel pump. I took this out when I checked for spark. Along with unplugging the coil, I'll also take out the fuel pump relay when I do the compression test.