Alright, I was out at my mom's last weekend and decided to pop the hood and look around on my 97 4.6L. I removed the plastic cover and air intake thingy from the Throttle Body and took a peek inside. I opened the butterfly and wiped my finger across the backside of it. It was coated in a sticky almost burnt oil looking substance. I took a clean white napkin and Wiped a littel more of and it was indeed BLACK and kinda gummy. I was going to hit it with some parts or brake cleaner or something but noticed the small sticker that said not to clean it as the TB internals was covered in some special coating. What exactly is that crap and how do I get it off?

Also sometimes when the trucks warmed up and in gear but stopped at a light or stopsign the rpms will fall to 500 or so and the engine wil shudder a littel bit. I think it may have something to do with the IAC valve, but I'm not sure. Any help would be appreciated.

 

I take my TB off every once and a while and clean it with dish soap and water. Dry it with the dish towel just like the dishes. If your TB is that dirty you can bet the IAC valve is also dirty. TB cleaner will take care of that. Just take it off and spray. BTW you can use TB cleaner for the TB too.

Regards

Jean Marc Chartier

 

make sure you check and/or replace your PCV valve. JM is right only use an approved throttle body spray or soap and water (Only if TB is off the engine) do not run the engine while cleaning that is the OLD way and if you run your engine while cleaning the TB you can cook your cats. Also DO NOT use carb cleaner.

the film on the TB plate is normal.

 

Thanks for the help guys. It'll have to wait till this weekend as I can't work on my vehicles in my apartment complex. I figured it was somewhat normal, however I don't really want it building up unchecked. What's the best way to remove the TB and where exactly is the IAC valve/how should I go about cleaning it?
Can I just spray the TB cleaner in it if it's still attached to the truck? If so how long do I have to wait till I can fire her back up? TIA!

 

I added a picture, diagram actually, of the IAC in my gallery. See https://www.f150online.com/galleries...6255&anum=3442

JMC

 

Great pic JMC thanks!

Yes you can spray it all down with everything still attached. Depending on how much you spray is how long you wait but it shouldn't take more than 10-15 min to evaporate. It won't hurt anything if you start it up before it is all gone.

What I was talking about was the old way of spraying carb cleaner in and reving the engine at the same time. A big no no on modern engines!

 

I don't think the coating is very durable. The first time I looked at my TB I noticed lots of the coating was peeling. It was a light brown transparent color. I'm sure my engine had eaten some. I wiped out what I could and cleaned the rest with carb cleaner. Even without the coating the TB won't need to be cleaned very often.

 

Well I used TB cleaner to clean the gunk out of my TB and IAC valve (which was surprisingly clean). It wasn't particularly hard, but it didn't fix the problem! My truck will run rough for a little while when I first start it up. Also at stoplights/signs etc the rpm's will drop to 500 or so and the engine will kinda knock/shimmy (when in gear and warmed up). All vibrations are gone if you press the throttle, what gives? It's got fresh oil, and new plugs/wires (9k miles on them). It's a 97 4.6 w/ 94k on the clock. TIA

 

It sounds like you need a new IAC or TPS sensor because your problem is related to idle and nothing else.

Do you drive a lot of the same roads at the same speed for long distances?

 

Hmmm, might be right! I drive in the city for the most part, short stints on the interstate up to ~70mph or so about daily/every other day. When I go out of town it's usually 200 miles @ ~65mph.