Definately pull the whole throttle body off and spray the hell out of it with 2+2 carb and choke cleaner. Also, while its off pull the IAC back off and clean the air bypass passage behind it. If its gummed up or even partially clogged, it will cause a rough/low idle. Good luck.I replaced my idle air control valve in my 95 lumina 3.4 and I am still having idle problems?
Check the MAF sensor and do a major tune up like spark plugs, wires, O2 sensor, coils, ignition module, MAP sensor and clean the air intake or throttle body. You are looking at about 300 dollars if you do it your self. But you can start with the cheapest parts first. After all your car is worth it.
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I own a shop, and what I think is this: Many things will cause a rough idle. The most common ones are; the engine is getting more air than it can handle; leaking vacuum hose split where it plugs on, fitting too loose, fell off, collapsing, or just leaking all over as in no good. Leaking injectors that don't close off all the way due to a build up of crud in them. On this vehicle, they are very prone to having an EGR valve that is sticking, thus allowing too much air into the engine. You can sometimes confirm this by using a metal pipe, or rod to hit the base of the EGR where it attaches to the engine. ';DO NOT'; hit the upper portion of the valve, or you may damage it. When you rap it pretty good, the engine speed will change, or go to running right most of the time if its bad. If this is the case, then replace the EGR with a new one, and your problem will be resolved. Next; You may have a bad throttle position sensor, and this will need to be tested with a meter in order to confirm it is in fact bad. Another common problem is a bad rotor button or distributor cap, and finally a bad temperature sensor.
Part 2: If you use any kind of cleaner, then use Throttle body cleaner (not choke/carburetor cleaner) as this is the ';only'; cleaner that is safe to use on your vehicle. The idle is controlled by the IAC solenoid, and what it does is allows (vacuum) air to flow into the throttle body just behind the butterfly. If when you clean this, you should stuff a long rag into the throttle body to catch the crud, or it will get into your EGR valve, and/or the O-2 sensor, and you will be replacing them too. The EGR allows (vacuum) air into the engine, and when its sticking in the open postion, it allows more air into the engine than it needs, thus you will have a rough idle. You can look for vacuum leaks with a propane torch. Don't light it, but just open the valve on it, and point it around the area's of the intake, EGR, and vacuum hoses. As soon as you pass over the leak, the engine will speed up because it will suck the gas into the engine at the leak point. Old spark plugs that are about gone will also cause a rough idle. A bad temprature sensor will cause the computer to make the incorrect adjustments to the timing and idle speed, and it won't show up on a scan tool.
Glad to help out, Good Luck!!!
well im a mechanic...i think that if you clean it out and set you throttle up a bit that should clear the problem up...your o2 sensors aint going to help you much...
tps = throttle position sensor - most common problem
MAP sensor - another possibility
And yea a good cleaning never hurts.
Look for a vacuum leak at the intake manifold. The GM 3.4 is known for that.
I WOULD RECOMMEND THAT YOUR GET YOU VEHICLES COMPUTER SCANNED TO FIND OUT JUST WHAT THE PROBLEM IS FIRST SO THEN YOU WILL HAVE SOME IDEA WHAT IS WRONG AS WELL AS WHAT TO EXPECT.
TRY FINDING AN INDEPENDENT AUTOMOTIVE REPAIR SHOP INSTEAD OF THE DEALER OR ANY CHAIN STORE BECAUSE YOU WILL BE OVERALL MORE PLEASED WITH THE PERSONAL SERVICE THAT YOU WILL RECEIVE.
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