Idle dropping when on the brakes.

[Jeremy_K]

I've been having a problem lately with my 03 AWD Vibe. When I come to a stop and sitting at a red light in drive with my foot on the brake, the RPMs bog down to like 500. This also causes my charging voltage to drop. Could this be a problem with the brake electronics or should I be looking into a sensor problem? If I put it in neutral at the red light the RPMs will climb back to normal idle and charging voltage will go up.

[sideshowalan]

Does it give you the problem only while the brakes are pushed? Like if you were to stop, put on the e-brake and then lift your foot off of the brakes, would it go back to normal?I'm guessing the brakes are unrelated. Common problem is for the intake manifold gasket to go brittle and let excessive air in. Toyota has an updated gasket b/c the originals were prone to failing. Also try cleaning the MAF sensor.

[Jeremy_K]

It only bogs down under load while on the brake pedal. I'll try cleaning the MAFS. I cleaned it the last time I cleaned my K&N panel filter. Maybe it got a little oil buildup on the wires. How much of a job is the intake manifold gasket? Any good places to get the gasket?

[sideshowalan]

Get the gasket from a Toyota dealer either online or just go to the parts department. Make sure it's red in color, that's the updated part with better materials. Tell them you have an 03 base matrix.It's not too bad of a job, just involves removing the air tube, lossening but not fully removing the throttle body and then the intake manifold. Took me about 2 hours start to finish and I had never worked on that part of the car before.

[Jeremy_K]

I called the local Toyota dealer and they have the updated gasket in stock for $5.XX . Just for the heck of it I took the throttle body off today. The air intake hose that goes into the TB had a slightly loosened clamp. The TB had some gunk in it but not too bad. I cleaned it all up. I popped a hose off of what I thought was the IAC valve on the bottom of the TB and coolant poured out. I quickly clamped it back up. I put everything back together and fired it up. I couldn't get the idle to bog down like it was before. It stays right around 1000 RPM under load with accessories on. We'll see if it stays like that. I may have wiggled something just right and bought myself some time.

[chadhgraves]

I was having the same issue. After I got an oil change, I cleaned the MAF sensor, put a new PCV valve on, and changed out my spark plugs which had about 117,000 miles on them. Put in a full tank of 93 premium gas that was ethanol free and a bottle of the Chevron Techron complete fuel system cleaner in it. That helped tremendously and I haven't experienced any weak idling since. I haven't checked the gasket, but I'm going to have my mechanic do a drain/fill on my transmission fluid and coolant when I get my new brakes put on in a few months. I'll probably have him check the gasket too. I'll probably go ahead and replace the engine air filter as well. I know how you feel though. Felt like my car was drowning and about to stall out when I stopped at a light.

[Jeremy_K]

I drove it to work today in 20 degree temps and by the time I got to work it was bogging down at a stop again. I'm just gonna start with the cheapest fix and work my way up from this point. I'll get the new gasket and install it. Hopefully that will fix it. I swear this car knows it's on the chopping block for a replacement.

[Charles (in GA)]

Does anyone know when the new gasket was introduced into production?I have a low mileage (55K) '04 base model and if it has the old type gasket, I'll at least want to procure one and have it on hand.Charles

[sideshowalan]

Looks like it came out around 2007. That's when the TSB was made.http://www.toyotapart.com/M.I....7.pdf