Todd Harrington

Afternoon Gentlemen,

First let me start by saying that I am generally not mechanically inclined and do not know a ton about mechanics. However, since I purchased this truck, I have been learning a ton and I am not dumb so I can learn pretty quick. I have driven a truck pretty much since I started driving. Why am I saying this? Be gentle with me if something I say doesn't make sense.

So I bought this truck a few weeks ago. It has about 98000 miles on it and the reason I bought it was because it's very clean and was very well maintained. The first thing I did was 100k maintenance on it (brought it to a shop). They replaced the plugs, filters, and all fluids. It also needed new back brakes.

The truck runs really well generally except I have noticed that when I come up to a red light or when I have the truck in park the RPM's will bounce pretty erratically. 250-800 rpm's is typically where it bounces to/from and I can feel a pretty sporadic shake to the truck when stopped. Bit rougher than I am used to.

After researching, I decided to look up some videos on how to clean the throttle body, so I got some intake cleaner and did that yesterday with a towel and wire brush. I have to say, it was pretty clean already, so not much dirt came out and it really did not improve the condition. So at this point I am thinking of doing a reset on the battery to have the computer relearn the idle hoping that the sensor might just be off a little bit... ?

Do you think this is a good idea to try for this issue?


Also, to mention, I noticed when I was looking at the MAF tubing that right where the clamp is that clamps the air filter tube to the tube that goes to the throttle body there is a small hole where the plastic has worn away from the clamp... could that be a problem do you think? If so, can I just replace that tubing?

Thanks for any advice you can provide. It's been a fun learning process as I have always wanted to learn more about auto mechanics. I work in IT now as a Network Engineer so logical troubleshooting is very familiar to me.

BadFish523

Clean the MAF sensor. Got a picture of the hole? Does it feel like its misfiring or just fluctuating RPM?

Todd Harrington

Doesn't appear to be misfiring. The hole is pretty small and the clamp tie down mostly covers it. I think it's just worn away from the years and opening and closing it to replace the air filter. I can try to get a pic and upload it in a few. All I have noticed so far is just fluctuating RPM's and it's really not THAT bad (have not stalled yet) but I wanted to get on it before it gets to that point.

P.S. Dig the fear and loathing avatar and quote. Epic movie, lol.

EDIT: I put my hand over the hole yesterday while it was running and could not feel much air if any escaping.

BadFish523

LOL Thanks it s a classic! Just trying to figure out exactly where said hole is. Is it before the MAF sensor just on the intake hose/tube? Also check the foam seal around the air filter box. This rots away and can cause minor issues. Try cleaning the MAF sensor. Only use the stuff designed for cleaning MAF sensors. CRC makes some good stuff. Could also be a vacuum leak somewhere too.

Todd Harrington

Do you think it's safe to assume if I reset the battery and the issue continues that it's pretty much limited to the sensor and/or vacuum tube issue?

BadFish523

A battery relearn would hurt anything. I would check the foam around the air box, and clean the MAF sensor first. Those are easy and cheap.

Todd Harrington

One more thing to mention I just thought of was sometimes when the RPM goes up and down there is also a "click" I hear. Once I hear the click the RPM will then go up. I am assuming it is the throttle body opening and closing but not sure if it's tied somehow.

BadFish523

Shoot forgot were talking about the 4.6 I don't think you have the air box like the 5.4 so you wont have foam to worry. about. Click hmm, is the AC on or the truck set to defrost?

Todd Harrington

No AC or defrost and the weird thing is it doesn't do it all the time the RPM fluctuates. When I was cleaning the throttle body last night, a few times when my finger slipped off the butterfly valve (not even sure if that is what you call it) the noise it made sounded very similar to the click I heard, which is why I assumed it was the throttle body opening and closing.

BadFish523

I would start with the MAF sensor and the battery relearn. Not sure about the click.