I know this topic was discussed in a previous post but I have a couple of follow-up questions. I have a 1998 blazer. Two weeks ago the diffuser came loose causing the throttle to remain slightly open and the car to accelerate on its own. I pulled over and when I tried to remove the diffuser with a pair of pliers it dropped into the throttle body. I then drove the remaining 2hr home with no problems. A week later, after no problems and only light driving, the car began to misfire badly, with rough idle and noisy muffler. I essentially got a tune up and the misfire was solved. I asked to mechanic to look for the diffuser, he removed the throttle body and used a camera to look inside the manifold and could not find it. He suspects the diffuser passed through the exhaust because one of the spark plug tips was broken off, like something hit it. Two days after tune up, the SES light came on. Car still runs smooth, no weird sounds or anything. My questions are:

1-What material is this diffuser made of?
2-Is it possible for it get in the engine and damage a piston or something?
3-Is it possible for the diffuser to pass through to the exhaust?
4-What other concerns should I have knowing that this piece fell into the throttle body?

Thanks for any help you may provide.

 

1 - Aluminum
2 - It wouldn't have a prayer of making it into the cylinder. It will get stuck in the intake runner long before it would make it down to the intake valve. Even if it were to make it to the valve, there is absolutely no way it could get past the valve or even into a position to damage the valve. The rivets that held it on originally, maybe, but the deflector, no.
3 - See #2
4 - That it is stuck in the intake runner for a cylinder, starving that cylinder for air.

Also, your idle is likely off. The IAC may be able to account for it now, but the hole in the throttle plate is MUCH larger than the hole that is in the deflector. It may be gummed up by junk right now which may be why you haven't experienced any adverse idle effects.

Bottom line, you need to figure out where that thing went and get it out of there. At a minimum you will need to pull the upper plenum off. But you may end up pulling the whole lower intake manifold off as well. It just depends on where it went and how far in it is.

 

Thanks swartlkk, that's good info.

Just today it started driving rough again, but only momentarily. It would make a rattling sound, seemed to be coming from the muffler, and would hesitate on acceleration. This would last for a few minutes and then it would drive fine again. I imagine that thing is in there and it's moving around and sometimes it gets in a bad place. Maybe starving a cylinder for air like you said.?.? Knowing this, any guesses on where it may be?

Thanks again

 

It could be in any one of the LIM runners. As I said, you will likely have to pull the upper plenum off as a start to be able to locate it.