Over the past year or so, my truck's throttle response has been lacking quite a bit. It's not the lift because I've had it on for about 4.5 years. Sometimes when I press on the gas, nothing much happens, I then push a lttle further and the engine and rpm's suddenly surge and accelerate like crazy. Other times, I press on the gas and nothing much happens and I keep pressing further and eventually bottom out the pedal, all the while the truck is accelerating at a very slow pace. Though it may not sound like it, I am a conserative driver and do not have a "lead foot". The truck is well tuned and just got it's 60k checkup. Any help y'all can give will be greatly appreciated.

 

I also have a 1998 4.2L, just replaced the engine and transmission.

I also have hesitation when I punch the throttle from idle. I don't know if the computer is still re-learning the engine or what.

Steve

 

I see you have a K&N filter. Your aftermarket filter may have got some filter oil on your MAF wires, causing your ECU to recieve false info from the MAF sensor. Which can cause a "hesitation" or lack of sudden acceleration when you push the GO pedal. Try cleaning the two MAF sensor wires with electrical contact cleaner. Just give them 3 or 4 quick blasts and they're clean again. These wires are very flimsy and fragile, so do not touch them. Just spray em'.

Also, I'd clean the throttle-body out with "throttle-body cleaner". Not "carburetor cleaner", because it will melt the protective film on the throttle-body blade.

Just a few suggestions.

 

My 4.2 was getting noticably sluggish. then it began having starting problems. It turned out to be a weak fuel pump.

 

Mine was getting sluggish and slow then I replaced the fuel filter and I'm runnin strong again.

 

^^^^Yep, that will slow your throttle response way down. You might want to run some fuel injector cleaner through your gas tank too. I use Chevron Techron. Wal-Mart and just about any parts store carries it.

 

I don't mean to be ungrateful for advice, but I just tried blasting the MAF in my '02 F-150 with electrical contact cleaner and I ended up getting a code telling me that my mixture from the MAF is too lean. Is there anything I can do to fix this problem? I think that it is starting to give me problems throughout the system now. I am not sure if it is related, but my cat convertor is now rattling like a madman...

Any help would be appreciated...

Thanks
Bill

 

Oh man, it sounds like you touched one of the wires with the Electrical cleaner spray tube and broke it. That's gonna be a little pricey. The wires are very hard to see if you don't have good eyes, and they are very fragile. So spray from about an inch or two away from the wires. Sorry to hear about your problem.

 

Peacemaker

I am positive that the tube never came into contact with the wires. I know that they are fragile, and that is why I made sure there was no contact made. If they are not broken, what else can I do? I saw something online from Parts America for some kind of MAF for $86 bucks. It was made by Python??? Any other possiblitiies (up to and including replacing with an aftermarket FIPK)?

Not trying to be a jerk, just stating my facts...

Thanks again for any and all help...

Bill

 

I understand man. If your for sure that the maf sensor is the problem. I'd replace it. I'm not sure about online places, but if you want a quality maf sensor, I'd get it from the dealer. Your taking a gamble on anything aftermarket. Cleaning the maf wires shouldn't have thrown any codes. I do it about once every season and never had any trouble. I've been studying what could have gone wrong in your situation though. After you sprayed the wires off, did you allow enough time for the cleaner that puddles up in the little pocket behind the maf wires to evaporate? When I do this, I usually have to turn the part of the airbox that the maf sensor sits in downward towards the ground to let any leftover "cleaner" that has puddled up in there drain out. See what problably happened is that you sprayed the wires and then left a puddle of cleaner in there, and then put everything back together. And then the puddle of cleaner back inside the maf sensor goes across the maf wires and shorts it out. When you turn the key on, there is five volts that goes across the maf wires. What I think happened is that you shorted the wires with the cleaner by not allowing the "puddle" to evaporate or drain out before you started your truck. I'm not sure this is what happened. I'm just guessing. But for future reference, this may come in handy. Sorry to hear of your misfortune.

 

Thanks for the advice. I just pulled the MAF out and the wires are not broken, but I think you might be right about not allowing the gunk to evaporate. I am going to hit it one more time since I pulled the entire piece out just now.

Thanks for the sympathy...