|WYG|SS

93 f1504.9l 5spd 4x4 126,k. i was on the high way the other day and my truck ran fine before that. so i was on the highway and went to go pass some1 so i threw it in 3rd gear and as i was passing the person it seemed like my truck didnt have much power. so i ignored it until i got off the high way and it felt like truck was going to stall. drove home ran fine. i did go mudding with my truck andd dented the front gas tank pretty good right where the pump is at so i thought it was possibly the pump so i filled the back tank and still ran like the truck was missing. the only thing is that the truck will run fine idleing and then when im going in either reverse or forward it feels like it is missing. when im in 1st starting out i go the truck floored and am getting up to 30mph in like 4 sec. i checked the cap and rotor, coil and wires. ill check plugs tmrw.

what could have just caused the truck to start missing all of the sudden?

dr_bowtie

did you take the cap off and look for water...you did go mudding right..? my guess would be you either got water in something or you revved it too hard and the plugs didnt like it...

|WYG|SS

i did take the cap off and their was carbon build up on the end of the rotor so i sanded it off. their wasnt any water in the cap.

|WYG|SS

well the truck seems to idle rough.(shaking back an forth while idling) then when i go down the road it just shakes as the the truck misses. no power at all. how do i check the timing? my dad says it isnt advancing the timing as i step on the gas.

dr_bowtie

in a 93....how does he know...you cannot tell if it is or not..the ECM does it..

even if it stays at the base timing it will run the same but use more fuel...thats all...

you have a spark issue or other issue...


beings you had carbon on the cap and rotor I would do a tune up...cap/rotor, plugs and wires....after you do that and if by some wierd chance it still misses come back and we'll go from there....

no reason to chase a miss when the spark system is sub-par at best...

|WYG|SS

the thing is the computer will adjust the timing btdc if you step on it. ive seen that in my car i set the timeing and as was using a timing light it kept advancing and and then going back to normal when we let off the gas and that was a 91 pontiac sunbird.

its just a guess. my dad does know about cars. it does seem like something with the spark. we guess it is something with the advance cause you step on the gas and thier is no power like the computer isnt adjusting the spark for the increassed pressure on the pedal. like i said it seems to run fine sometimes idleing and other times it will shake while idleing. i had replace the cap, rotor, plugs, wires, like 5k miles ago.

i bought a spark plug tester that shows the spark as it jumps across the pins. i plugged it into the coil wire and as my dad was turning it over it was like an orange spark at first then went blue. then he stoped and samething. is their a way to test the ignition modual or the stator, or pickup coil without taking them of? im thinking one of these might be the problem cause it just started acting up after a drove it for 700miles after mudding it.

dr_bowtie

that sounds more like the coil....

spark wont necessarily advance under load...the ECM controls it and as long as it is moving under a timing light the ignition module and ECM are working...timing should be the highest at light load and drop down under throttle and down lower when you let off teh gas...

under full throttle passes the timing is lower than at cruise...

spark should be blue all the time...only thing that regulates the spark is the coil...

all the ECM and Ignition module regulate is WHEN it sparks...

if your coil was/is weak it will eat the terminals on the cap/rotor....if there was any build up on it you need to replace it...

gr8dane

clogged cat converter?

|WYG|SS

thanks dr_bowtie. the cap did seem a little worn so it is posibly the coil. im looking at replacing it with a accel or a msd. can i do this with stock cap and rotor? no the cats are fine just something with spark.

dr_bowtie

I would highly recommend using any cap and rotor with Brass terminals...for this helps stop the carbon formation and is a better conductor of the electrical current...IE: easier on the coil....

as for the coil any of the performance coils are fine that are direct replacement....even the cheaper Jegs and Summit coils are fine and even ones from Professional Products are good...

Accel makes good coils as well...

the last one I used was a generic red one from Jegs and it is still holding strong...

other than that I swear by the Autolite double platinum plugs...even with the 3year warranty I am going on 9 years with them and they still look great...

Autolite plugs have the least amount of resistance also and that builds a better spark as well...

you can also find out if it is the plug causing the issue by using a test light and shorting out the terminal at the cap...

with teh test light hook teh alligator clip to ground and test the light to make sure it works by touching the hot terminal on the battery...

now with the pointed end of the test light puncture the plug wire at the terminal on the distributor cap...when you touch the terminal it will cut the spark off to that cylinder...you should hear the engine drop RPMs slightly...that means that cylinder is working....

keep going cylinder by cylinder until you find the one that doesnt alter engine RPM...trust me you'll notice when you kill a cylinder...

if you have a dead one you should notice 2 of them not making any power...narrow it down from there....the reason for 2 not making the difference is when you drop one cylinder it take another to make up for the loss...basically loosing power in that cylinder as well...

EDIT...

here is the web page for Advance Auto parts....Accel coil for my 95 f150 4.9L should be the same for your 93...

http://shop.advanceautoparts.com/web...|GRPTUNEAMS___