29 replies to this topic

[JehovArob]

Well, I cleaned my TB, and it made the idle a lot smoother. Was really rough before that. But, now it feels a bit hesitant and rough around 2000 rpms or so when I accelerate. Any ideas?

[Adam Franke]

Plugs.

[jda2000]

don't forget to clean the IAC valve.

[JehovArob]

I did the plugs not too long ago.

What's the IAC valve? Is that the thing attached to that elbow piece attached to the throttle body?

[Bay13]

What's the IAC valve? Is that the thing attached to that elbow piece attached to the throttle body?

Yes

[JehovArob]

Ok, yeah. I cleaned that first by accident thinking it was the throttle body, and then later realized that it wasn't, so went back and actually cleaned the throttle body. I think I may have gotten some cleaner farther into the engine, as it stuttered when I started it up.
Still, shaky when starting to move, actually closer to the 1500 rpm area. Maybe engine mount(s) need(s) replacing?

[550]

carburator cleaner is usually reccomended, I use carb and choke cleaner

[jda2000]

It's a good idea not to spray carb cleaner into the TB, as some might find its way into the TPS electrical connector and create problems. Use a wet rag to wipe the inside of the TB and plate.

The same goes for the IAC valve, keep carb cleaner away from the connector.

[JehovArob]

Well, idle isn't too great anymore, atleast if it's in drive. If it's in park, it's not so bad.
I don't remember if anyone said anything about this yet, but could it be a problem with the engine mount(s)? It's worse at the lower rpms and in the lower gears. I would think that that would be when the engine would be prone to shaking it worse. Any comments would be greatly appreciated.

[jda2000]

the problem could be a failing IAC valve.

Do you have a spare IAC valve? If so, then swap valves and see what happens. I doubt is the engine mounts.

[JehovArob]

No, I don't have a spare valve. Doesn't seem like something that would be too common to have...
The IAC valve is that little plastic piece with the other, yellowish colored piece inside with all the holes in it, right?

Ok, I looked up what IAC stands for, and thought about where it was positioned, and that pretty much answered my question.

I sprayed plenty of carb cleaner in there and poked out the dirt with a paper clip. It should be pretty clean. Should I just buy a new one? Are they expensive?

Edited by StarmanDXE, 29 November 2004 - 01:29 AM.

[freeskier8585]

put it in neutral and see

[jda2000]

Starman,

No, the IAC valve is not plastic.

Its a silver metal electrical motor that controls the idle of the engine, thus its name Idle Air Control (IAC) valve. With time, the inside of the IAC gets gummed up with varnish and gunk and won't allow the little flap inside to open and close properly, thus you get a rough idle. One end of the valve connects to the intake's vaccum tree and the other end connects to the TB large intahe hose.

[JehovArob]

I suppose what I saw wasn't it then, as this didn't have any power. Any more information as to where the IAC valve is exactly? Sounds like it needs a cleaning next time I'm at home (in like 3 weeks).

[Nebor]

No, I don't have a spare valve. Doesn't seem like something that would be too common to have...
The IAC valve is that little plastic piece with the other, yellowish colored piece inside with all the holes in it, right?

Ok, I looked up what IAC stands for, and thought about where it was positioned, and that pretty much answered my question.

I sprayed plenty of carb cleaner in there and poked out the dirt with a paper clip. It should be pretty clean. Should I just buy a new one? Are they expensive?

That was your flame trap that you cleaned. The IAC is something totally different.

[JehovArob]

Interesting. It's nice to finally learn what all of these things everyone has mentioned are...

[josh_S70GLT]

No, I don't have a spare valve. Doesn't seem like something that would be too common to have...
The IAC valve is that little plastic piece with the other, yellowish colored piece inside with all the holes in it, right?

Ok, I looked up what IAC stands for, and thought about where it was positioned, and that pretty much answered my question.

I sprayed plenty of carb cleaner in there and poked out the dirt with a paper clip. It should be pretty clean. Should I just buy a new one? Are they expensive?

They aren't cheap, looks like $108 from FCP.

[JehovArob]

No, I was corrected by Nebor. So, what exactly is the throttle body? And where is the IAC valve?

From what I understand now, the throttle body is the part with the circular flap with the bar going through the middle. Is that even correct?

Edited by StarmanDXE, 29 November 2004 - 03:39 AM.

[Alston850]

Starman,

Here are a few suggestions that might help.

Get a manual for your car. It can help you identify the parts you are working on.

Go to Volvospeed and look at the Repairs and Maintenance section. There is one titled "Replacing the Flame Trap" that has pictures of all the parts you are talking about.

Go to the Performance Modifications Board and read through the pinned post, "Before You Ask A ? Please Check Here First". There is a ton of information there on getting your car running at its optimum. I have been working on my Stage 0 for a couple of weeks now and it has made a huge difference, including my idle, it is so smooth.

Among other things I cleaned and polished my Throttle Body, but my car is turbo so I dont know if the process is the same for yours. I took it off the car, not a very difficult job, cleaned it and reinstalled it in about an hour. If you do the same make sure you replace the gasket, I have read some posts where people dont but a leak there will cause you problems.

Good Luck,

Tim