Cleaning TB + IAC valve - will liquid cleaner do?

[addyguy]

I know I've been posting stuff about my 02 Cavalier and its rough idle forever on here, but I need advice on another approach.

Got an 02 Cavalier, with a constant CEL on, and a surging/rough idle when car is warmed up. Pretty sure it is a gummed up IAC valve.

I'm not that handy mechanically, so I'm not rally comfortable trying to get the valve out in my parking lot (where I'm not supposd to work on my car), and if it isn't the IAC valve that is causing the problem, I'm no further ahead.

Have a local shop with decent prices that will a) read the CEL code for $48 (half-price to anywhere else), and if it is the IAC valve, they will do a 'throttle body cleaning' for $59, which 'will clean the IAC valve'. No idea if they will actually remove it and clean it, I'm assuming its just a vacumn-induced solvent cleaning. Not too bad a price if it does fix the problem.

Big issue is I am having really serious financial problems these days from numerous factors, and I simply can't afford even that anytime soon. If their procedure IS simply to vacumn-solvent clean the TB, a la Seafoam, I can do this myself (yes, the neighbours will be [censored], ) with a can of seafoam, a bottle of MMO, etc.....

Question: do people think a heavy solvent cleaning through a brake booster line will clean the IAC enough to shut of a CEL? I wouldn't do a light cleaning, I would do a massive, 1-2 can treatment if I had to...and change the oil after....

 

[TooManyWheels]

The brake booster line and the IAC are completely separate entry points to the engine. Inducing liquids through one will have zero effect on the other.

Edit - Let me say - "on any car I have ever known of". Is your IAC IN the brake booster line?

 

[addyguy]

Thanks for that - I have since e-mailed the shop, and they confirmed that they do actually remove and clean the IAC by hand in this procedure. This is good to know, but it will still be a while before I can have it done.......

 

[Islandvic]

The surging rough idle may be from the EGR valve also. From what I know, you should replace the IAC solenoid, not try to clean it. Same for the EGR. I recommend AC Delco parts.

Cleaning the TB is easy, take a screw driver and remove the air intake tube off the TB. Spray aerosol Seafoam on the TB and wipe down. Then start the car and spray the rest of the can in the TB to de-carbonzie the combustion chambers.

Try disconnecting the battery and let sit for 5 min to clear the codes.

Do you have Auto Zones in Canada? They check CEL for free

 

[addyguy]

I don't think we have AutoZone in Canada...but I could be wrong.

Good idea about the battery....hadn't thought to try that, but I have heard it works....when we got a CEL at W-M doing injection cleanings, we would do this, and it often worked. I might do a good, strong TB cleaning myself, do the battery trick, and see if it helps.....anything that may fix it at minimum expense at this point is worth trying!

 

[addyguy]

TMW,

No, my IAC is at the back of the TB housing. Its very awkward to get to, as it is right up against the firewall. So I was hoping to be able to clean it w/o trying to wrench it out.....

 

[mechtech2]

You could clean the throttle body bore and plate yourself, and see if that fixes it. A few common hand tools, and a rag and solvent [less than an hour].

 

[Vilan]

Since money is an issue, it seems the best option is to get some kind of throttle body cleaner and spray away (in the air intake, not the brake booster!). If it works, you've saved the day, if not, you're only out $5-10.

Incidentally my car has erratic idle issues too. I'm going to try spraying out the TB and IAC tomorrow. Will report on success/failure.

 

[va3ux]

Originally Posted By: addyguy
I don't think we have AutoZone in Canada...but I could be wrong.

Good idea about the battery....hadn't thought to try that, but I have heard it works....when we got a CEL at W-M doing injection cleanings, we would do this, and it often worked. I might do a good, strong TB cleaning myself, do the battery trick, and see if it helps.....anything that may fix it at minimum expense at this point is worth trying!


No Autozones here in Canada. You cand find of similar cleaners from Canadian Tire, Parts Source, etc. You'll need a small Torx bit to get the IAC off. Clean the pintle, but don't apply any force to it or you could damage the small plastic rack and pinion gears inside. You also really need to clean the Idle air passage in the throttle body, and the seat the throttle body for the IAC pintle. Just cleaning up the throttle plate and throat won't do much (if anything) for the idle.

For what it's worth, I just did this whole affair on my daughter's Z24. The warm idle really sucks on that vehicle. A through cleaning of the IAC and all throttle body passages made no difference at all. I'm now speculating that the lousy idle is either due to the injectors - there's a lot of miles on this car and the Multec II injectors are notorious for fouling on the tips - or the rack and pinion in the IAC are worn so badly that it can't control the pintle position accurately enough to produce a smooth steady idle. I'm going to start with the injectors : remove them and take them in for a full ultrasonic cleaning and flow testing. If that doesn't fix it, then I'll try a new IAC (which is expensive, but about the same cost as the injector cleaning).

 

[The_Jeff]

Take off the long plastic air intake hose.

You'll see the throttle butterfly and a dime-sized hole that goes around it, this is the idle speed controller passage.

Buy a can of throttle body cleaner, start the car, and spray some down this hole.

Now here's the best part: Cover the ISC passage with your thumb! The computer will try to compensate for the lowering idle by exercising the ISC motor to full open position. Remove your thumb and the engine will race, then the ISC will close. Spray some more solvent down and repeat a few times.

When done you may as well shut the car off, open the main throttle butterfly, and clean around in there as well. I like to spray on a paper towel then wipe with the towel, keeps too much fluid and goo from falling down the intake manifold. A little is okay but too much is too much.

For cheap code readers one cannot beat ebay. Even in canada you should be able to get something cheap or shipped across the border semi reasonably.

 

[Kestas]

I use gasoline and a toothbrush to clean throttle bodies. It works, doesn't cost anywhere near $5, and there's no worries about chemical compatibility.

 

[addyguy]

Thanks for all the suggestions and help! You guys are great!

At some point, possibly this weekend, I am going to try to open up the TB and clean it, and if I get adventurous, try to get the IAC valve out, and clean it. Might be going to BIL place this weekend, and he's an apprentice mechanic who loves tinkering with cars, so this would be a lot easier with his help...I'll post on how it goes.....

 

[mechtech2]

I would never do a running spray cleaning. With the engine off, clean it by hand. The seating area of the TB where the plate sits is critical for a good consistent idle.
This simple cleaning cures a lot of idle problems in the shop.

 

[Shaman]

Don't know if this will work for J-bodies, but with w-bodies, if you have a friend, you can rock the engine forward, then hit the parking brake, and the engine will lock forward. Makes it easy to change plugs, or to get to the IAC valve you are talking about.

 

[Vilan]

Originally Posted By: Vilan
Incidentally my car has erratic idle issues too. I'm going to try spraying out the TB and IAC tomorrow. Will report on success/failure.


Update: I gave it a good spray out today. High rev, low rev, smoking out the neighborhood.

Previously, it would sometimes stall out at idle, sometimes it would recover.

Now, thanks to my skillful cleaning, it *always* stalls out.

Oh well. Off to the stealer it goes. Cleaning out the TB or IAC by hand is beyond me.