have a 90 f150, 5.0l, I started noticing the tach jumping up and down, now there is a miss in the engine. Replaced plugs, wires, pcv valve and filters for emissions test. Any idea what the potential prob is here?

 

Same issue here. Had it licked I thought at one point but nope. It is back and worse than ever! Good luck. John

 

it's saturday, nice and cool, a good day to do a little wrenching on the engine. never had the problem until I put the wires and stuff on. going to go back and check all the connections and whatnot. we will see from there

 

first thing I did was pull the distributor cap and it is nasty. most of the little metal tabs the rotor makes contact with are pitted and uneven in size. once the wife gets back with her van i will go and pick up a new one and see if that is the problem, hey it's a start.

 

Should always do plugs, wires, cap, and rotar together.

Adrianspeeder

 

you are exactly right speeder and I generally do, but wanted a cheap and fast fix for emissions (readings were lower than the past 2 tests). anyway, replaced the dist. cap and rotor, the miss is still noticeable during idling and 1st thru 3rd gears, went into 4th on highway and into 5th and ol betsy purred like my cat. at least half the problem is gone. time to break out the shop manual and start troubleshooting, ah life is a beach

 

Cool,

Now pull the codes and see if you have any. Bet there are one or two in there.

Adrianspeeder

 

thats an idea, havent had a "cel" come on. I have a good sunpro reader, the kind autozone uses when u go to them for cel codes. maybe tomorrow i will check it if the wife doesnt pull out her "honeydo" list thanks for the info

 

by the way speeder, I notice u r just up the road from me, we pass thru Harrisburg on our way to Canada

 

You could still have codes without the CE light on. My 92 was running like poop last year with a bad EGR system and no light at all.

Adrianspeeder

 

Make sure that the plug wires going to #7 & #8 are not touching each other anywhere. They need to be separated from each other all the way from the distributor cap to the spark plugs.

BTW, for future reference, the best way to improve your emission test results is to change your oil and filter, and get the driveline as hot as you can without overheating just prior to the test. In fact, on your way to the test center, take the long way, and never shift it beyond 3rd gear. You want that baby as hot as you can get it.

 

had a code 77 come up this weekend, doing some checking into it now

 

Code 77 just means you didn't do the KOER self test properly.

 

yeah, I tossed that question around to a few guys at work, and they pretty much mentioned the same thing, it did say operator error, something bout cylinder too. I have gotten it down to a minor thing now with new plugs. thanks so much for the reply

 

darn, I quoted myself, duh lol :o