intermittent Missing

[powrck32]

OK guys,

I have another question for you. 98 Explorer OHV engine The engine misses intermittently at idle (every 5-10 seconds or so). Have just put new plugs and wires at 88'000. The engine starts up just fine, and no check engine lights, no problems whatsoever, it just misses once it is warm and once the tank gets down to about 3/4 of a tank. I was wondering if a fuel pressure regulator could cause this, or am I looking at a sensor or something. I have also cleaned the Throttle body and the IAC motor. It didnt seem to help any. Any help you guys could give me would be greatly appreciated.
Thanks

 

[punkbek3886]

i tried this and it seemed to work pretty well. take the sensor out of the mass air flow and clean the filaments with a q-tip soaked with denatured alcohol. the reason this works is because the filaments get buildup on them and the engine does not know the correct amount of fuel to inject into the engine. also make sure you do not have any vacuum leaks in the intake system.

 

[SWLathrop]

Gee, I had the exact same problem with my 97 Sport's 4.0 SOHC at 71,000 miles. Amount of fuel in the tank made no difference. I cured mine with new FoMoCo double platinum plugs and wires.

 

[Opera House]

It is a brave man that cleans the MAF fliments with a Q-tip. Besides, it is easier to use a spray with a nozzel that you can stick through the screen rather than to pull the sensor out. I use a circuit board cleaner that I always have aound though I thibk a carb cleaner spray would be better. Just use the head and tube from an unused bottle of WD-40. I've heard that the oil from a K&N filter can sometimes get on these filiments. Just by rubbung your finger on the protective screen, you can see what can build up on the sensor.

 

[punkbek3886]

did replacing your plugs and wires totally eliminate the problem? ive been chasing after this annoying problem since i got the car and the maf trick doesn't seem to have worked. it helped a little bit though. ive been suspecting the plug wires and i think i will try that idea next.

 

[SWLathrop]

Yep, my problem was and still is totaly gone. don't forget to use dielectrical grease (light coat) on both ends of the wires. This eliminates any potential of "SPARK LEAK".

 

[punkbek3886]

cool thanks ill try that. do you think it was the wires or the plugs that made the difference?

 

[SWLathrop]

In my case it was probably the plugs. 3 of them were burnt to a .070 gap and 4 of them had no platimum left on the tips. Now mind you, the factory installed plugs are single platinum plugs only. I figured, since I was going thru the PITA headache of changing the plugs, I might as well do the wires also.

 

[punkbek3886]

i think i replaced my plugs with non-platinum ones, do you think this might have caused my misfiring problem?

 

[MattHarrell]

and in my case it was definitely the wires. I must have had a bad set of wires. I brought it to a friend of mine who did some kind of scan and determined that at least one of the wires was having problems. put new wires on there and it worked fine

 

[SWLathrop]

punkbek3886, What brand plug did you install? And are they the correct heat range? Also, if you haven't replaced the wires yet, you could have a flakey one out there as the plug ends can come loose from the center core when pulling them off of the old plugs. The boots get crappy from heat and age allowing spark leakage also causing misfires.

 

[punkbek3886]

the plugs were motorcraft and i havent replaced the wires yet, so i think ill try that before i replace the plugs. i just modified my intake and i have gobs more torque now but i still have that problem with missing at idle and hesitating during acceleration. thanks for the idea.

 

[SWLathrop]

Yup...I'd try the wires also. I personally would use either FoMoCo wires or FILKO wires. The FILKO wires are made with genuine PACKARD wire and also carry a lifetime warranty. I have a set of FILKO's on my 92 Aerostar's 3.0L (Extended window van) with 145,000 miles on it. Put them on in 94 with about 25,000 miles on it with a set of BOSCH platimun plugs. Hasn't stuttered once and still gets 26-30 MPG on the highway. Engine gets washed (Or should I say flooded ) once a month. I ran the same setup on my 88 Ranger 4x4 S/C's 2.9L untill I sold it last year with 109,000 miles on it. It was netting 25-28 MPG when sold. I put the FoMoCo double platinum plugs and wires on my 97 X-Sport. Good luck

 

[punkbek3886]

if the plug wires dont work do you think that maybe i have a bad sensor somewhere and it might be doing this to my engine?

 

[SWLathrop]

Was your miss there before or after your intake modification? Also, what type of modification(s) did you perform?

 

[punkbek3886]

it was there before and after i did the mod, but i changed the wires today and it fixed the problem completely. it still has a rough idle though but i think the problem is a leaky grommet from the intake manifold to the brake booster.

 

[mrorayus]

The platinum plug thing did it for me too. I thought "ahhh- whats the difference" and got regular plugs. The truck was missing really bad in about 6000 miles, and all the plugs had bad carbon tracks on the insulator. It has something to do with the way the DIS ignition system works. Sucks that they are 5 bones a pop, but its the only way to not feel like a big dummy after installing regular plugs...