muffins

So I'm making my 2 hour trip home and everything is going accordingly, truck is shifting fine nothing out of the ordinary. I have a 2008 STX with the 4.6l. I had the cruise set at about 64mph and out of nowhere the truck jerks. Only way I can explain it is it was as if I hit a pot hole, except there were no pot holes around. I ignore it and brush it off, but not too long later it does it again. Now I'm concerned and I decide to take it off cruise to see if I can replicate it and it happens again. I couldn't pin point it down to a specific RPM or speed this was occurring at, but eventually at one point I notice a lit up wrench dash light. Not sure when or how long it was on but I looked in the owners manual and it said it's the electronic throttle control.

Well I take it into the shop and they take a look and I get a call few hours later and they said they cleaned the throttle body out, replaced the air filter, and reset the computer. I was confused what was going on with my air filter because it was replaced within the last few months, but he showed me it and it did have some damage on it...and said it could have played a part on why things went haywire today.

I left the shop and drove it home mixing in some highway and local streets, everything seems normal...my question is is there anything to be worried about? I researched around online and the consensus says that when the ETC dash icon is lit the check engine shortly follows, but I didn't get one at any point...I mentioned this to the mechanic and he said it was a "stored code" and that is why it didn't pop up. Also have read that shutting down the engine and starting it again clears the ETC light but it'll come back on eventually...I couldn't tell any throttling issues but I haven't had much time to drive it extensively so it's hard to say if the problem is gone or if it will persist...

Also my mileage seems to have plummeted as it usually takes me a quarter tank to get home but it took almost half a tank...related to the problems I was having?

Any input would be nice since I'm a little nervous of what's going on and I can't find anyone who has had a similar issue

muffins

Thoughts?

Indyhead

If the tech fixed the problem and cleared the code the problem code is gone and wont effect anything unless the problem is not fixed

muffins

I hope it is :/. It's beginning to get cold and I was excited to try my 4wd

pcastal

It is possible that there could be a code and no light... There are several different types of codes, pending, current and history. A pending code is set when the computer detects a problem, and to put it simply, if it never detects the problem again, it will never become a "current" code and turn the check engine light on. Over time, after it doesn't see the problem again, it will put it in history, or what I believe is a "stored" code as he says, telling the technician that a temporary malfunction occurred at some point, but is not currently an issue.

Now, carbon can mess up the electronic throttle bodies, but I have only seen them cause problems at idle. The build up of carbon will make the computer keep the throttle plate open more and more over time to compensate for the carbon. If the air filter was damaged, which is strange in itself, it could mess up the flow of air, and create turbulence, which will create problems with the Mass air sensor, making it hard for it to accurately read the air coming though. You can also get a build up on the Mass air sensor, which can cause inaccurate readings. One of these 2 scenarios sound more likely to be causing the problem. When cleaning out the throttle body, they may have also cleaned out the mass air sensor just to be safe, and between that and the air filter, I would think that would be the fix. Keep us updated

muffins

Thanks! That explained a lot. He basically said what you said regarding the air flow, but not as in depth.

I drove it again today with varying highway and local speeds, and it actually seems to have better throttle response then BEFORE I ever had an issue. I haven't kicked it down hard yet because I'm scared to lol.

True test will be tomorrow when I take a 2 hour trip again.

Thanks for the responses so far, I really do appreciate all the input.

pcastal

Happy to help

muffins

UPDATE

I drove it on my 2 hour trip and not a single hiccup. It actually seems to be throttling a lot better then before!

packplantpath

That probably means the throttle body was all gunked up. Cleaning them can work wonders since they get dirty so gradually you don't notice the reductions.

muffins

The bizarre part was I asked the guy how dirty the throttle body was and he said "it wasn't bad," so yeah idk. Hope this fix actually fixes the issue. Got spark plugs to look forward to doing soon seeing as I rolled 70k yesterday....