IAC - BAC location and cleaning

[eddie jr]

This is on a 97 protege 1.5L. Te problem is that whenever going to neutral and returning to idle when slowing to a stop, there is a bit of a choke (actually stalled once or twice) and then after a few seconds it returns to proper idle.

I am thinking maybe the IAC needs cleaning. Are these possible to clean? From doing some reading I understand that it may be related to or integrated with the BAC valve? Is it located under the throttle body?

thanks.

[midnightblue97]

Whats the BAC valve??

[eddie jr]

Whats the BAC valve??

Bypass air control valve I believe. It is for when the engine is cold and allows extra air around the throttle plate. As the engine warms up it gradually closes. It is some wax-like thing that responds to heat and receives the heat from the coolant when it gets warm since there are 2 small coolant lines going to it.

I was looking under the throttle body today and there is a little motor-like thing with 2 wires going to it. I assume that is the IAC. The 2 screws are torx but with the little pin in the middle so I can't get it off. Is it possible to clean these IAC's? I know you can on GM's and it makes a big difference.

[mannydingo]

Whats the BAC valve??

It's the part right below the Throttle Body. It is attached to it by four phillips screws that are hell to get off. To separate them, make sure you use an impact driver. Now right next to that BAC is the IAC valve. It's held by those two torx screws he mentioned. I have seen it taken apart but you have to be very, very careful. Also, you really need to take the whole TB off so you have all three units-in-one off at the same time. Then separate them.

[eddie jr]

It's the part right below the Throttle Body. It is attached to it by four phillips screws that are hell to get off. To separate them, make sure you use an impact driver. Now right next to that BAC is the IAC valve. It's held by those two torx screws he mentioned. I have seen it taken apart but you have to be very, very careful. Also, you really need to take the whole TB off so you have all three units-in-one off at the same time. Then separate them.

So you "can" clean the IAC then? Would you agree that it is maybe the cause of the chocking when returning to idle at stoplights? Any other ideas?

And where the heck do you get the tool to take it off, because a regular torx won't work?

[mannydingo]

So you "can" clean the IAC then? Would you agree that it is maybe the cause of the chocking when returning to idle at stoplights? Any other ideas?

And where the heck do you get the tool to take it off, because a regular torx won't work?

Well, I actually don't recall it being a torx. It's that other shape. I can't recall but I have a set of those sockets also. Go to your local auto parts store and see if they have a set. If not, go to a tool supply store. My set was cheap from a cheapo unknown brand and they work just fine. I really don't think it's the cause of the choking but I don't have enough experience to tell. If you take it apart, there's a chance the parts will fall out especially a little spring that's in there. If you're careful you'll be ok. It's up to your knowledge. You can end up not being able to put it back together again if you're not good at these things.

[eddie jr]

Well, I actually don't recall it being a torx. It's that other shape. I can't recall but I have a set of those sockets also. Go to your local auto parts store and see if they have a set. If not, go to a tool supply store. My set was cheap from a cheapo unknown brand and they work just fine.

Mine is definitely a torx but with little bump or pin right in the middle (so an actual torx won't fit). I have seen them used on other things but they are not too common. I will have to look around for the tool.

So have you actually taken off the BAC before and cleaned it?

[mannydingo]

So have you actually taken off the BAC before and cleaned it?

No, I haven't. I saw a guy on ebay selling his about a year ago. He had completely separated it and had the parts individually spread out on a table. Yes, he was actually selling it disassembled. Also, on one of these Protege forums a guy stated that he had taken it apart and another mentioned having to be careful that you don't lose the little coil/spring thing-a-ma-jig inside the IAC. Well IAC or BAC. I can't remember which.

[MightyFreeCar]

If it is a torx with a "thing" or bump, that makes it a "security" torx. There are bits for those, too. I would replace it with the right size allen hardware (go to a fastner dealer, look in the yellow pages). The security feature is to keep people who shouldn't work on stuff from screwing it up....kinda like most hot-rodders!!!

[eddie jr]

So no-one has ever tried cleaning those before?

I took it out for a drive tonight after changing the fuel filter and surprisingly much of that choke at stop light is gone. Usually sputtering on acceleration is indicative of a plugged fuel filter.

But it isn't gone all together so I still wouldn't mine cleaning that sucker.

[mannydingo]

So no-one has ever tried cleaning those before?

What's the dash between the words no and one for?

[eddie jr]

What's the dash between the words no and one for?

i don't know, for some reason at the moment i thought it was one of those "2 word" scenarios where it is used........why?

[mannydingo]

i don't know, for some reason at the moment i thought it was one of those "2 word" scenarios where it is used........why?

No reason, I'm just pulling your strings?

[growe58]

Jumping in a little late here with a couple of things...

1 - are you guys sure that the 97 has a separate bac and iac? I'm thinking that both functions are combined into the iac...

2 - just fyi, eddie jr, this is a very common problem with these proteges. If you've priced iac's ($200+), you'll understand why most people try to learn to live with it.

3 - when I first got my protege, I had pretty severe shaking at idle. I removed the throttle body and cleaned it carefully, throttle plate, passages etc. While that does NOTHING to help the iac situation, it did improve the idle by removing the other problems enough that it's not particularly bothersome. You might want to try starting with that.

[eddie jr]

Thanks for the info growe58. I believe the BAC and IAC are integrated in some fashion. They always call them 2 different things in the documentation but it also says something about together????

I was actually trying to get some of those security torx bits tonight but no luck yet so i still can't take the IAC off, but as mentioned the fuel filter made a noticeable difference surprisingly.