Hey guys, brand new member here! I just bought a 99 E-150 4.2L, and it just started having this problem......It idles pretty good, but when you hit the gas, it just kind of cuts off all acceleration, and feels like you just came off the gas with your foot. But, it happens only after you are on the gas for about a second. So weirdly, I can drive it no problem if i just hit the gas for only exactly one second, then come off for 1, then back on gas for 1, then off again 1 second, and so on. And on and on, all the way up to easily 50 mph with no problem, but as soon as you forget to come off the gas, it just does it for you! Then, if you wait a second, you can hit the gas for on 1/ off 1 again....
So, it seems to happen in all gears, because it doesn't matter if im on the highway, or taking off from a stop. So, I'm not sure what this could be. It seems rather like a minor problem, but the owner said he was gonna junk it because he thought it was the tranny, but I'm pretty sure the tranny and motor are fine. It idles fine, and revs fine and strong, with 150k, and the owner was a friend so i know good general upkeep on her.
Again, it is hard to explain, but the best way i can describe it, is if you just give it some gas, a lot or a little, it accelerates fine for about a second, maybe 2, and then does what feels just like coming abrubtly off of the gas, jerking you a bit forward. And, the only way im driving it is by doing that annoying on for 1 off for 1 second pattern, and thats getting old fast. And, it never actually stalls out. It just cuts off gas, and lets it pick up again a second or two later......really weird. So, im hoping I can fix this and its something stupid, instead of having to junk her.
So, any ideas on what this could possibly be? Everything else seems to be running fine. I know he just changed the belt too, so I don't know. It seems almost like a sensor maybe? Any advice or ideas would be greatly appreciated. I have been working on cars for a long time, but this is my first truck, well van.... Thanks in advance for any help, and thanks for letting me into your forum. This place seems like it will teach me alot, and i am hoping to. So thanks.

Dave

oh, and the Service enging soon light came on the same time the truck started doing this weird thing(a few weeks ago and then got parked but now im trying to drive it). Im trying to borrow a universal diagnostic thingy from my friend, so yea.
Oh man, i hope its not the fuel pump.....

 

Okay guys....So, got the diagnostic. The code is reading P0102. When i check this online, it says "Mass Air Flow Circuit Low Input." So, I guess thats better than the fuel pump....but, i think these things are pretty expensive too? Any advice so far?
Do you think I can get by with a cleaning? Or you think Im gonna need a replacement.....
Thanks again

dave

 

Okay...UPDATE!
I cleaned the MAF with maf cleaner spray. I took her down the block, ran perfect for about 30 seconds, then the problem came back. So, tried again, same thing, good for a few then back to the annoying gas cutting off.
So, is there anything else I can do to clean it better? Is it hard to remove it from the big round air intake cylindar thing so I can maybe soak it in maf cleaner? Or is this a bad idea? And finally, if I was forced to buy one (still hoping to perhaps get this one cleaner...) then this has to be the problem right? Maybe I can locate a used one at a junk yard. I saw some on ebay for like 25 bucks plus 15 shipping. Would that be okay?
Thanks again for any help you can give me.

dave

 

Anyone?? Nobody wants to comment on my thread?.......

 

I have had the same issue on other vehicles. I tried cleaning the MAF sensor with very limited success, but inevitably it needed to be replaced.

What happens is the sensor heats up like a tiny coil and the air passes by it and cools it down. That voltage is measured by the computer. Well, heating and cooling thousands of times wears out the resistor and it stops sending a good signal.

Save the trouble and just replace it. Ebay is the best place to get one-

 

thank you Sir.

 

Sounds like the MAF sensor is bad.