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Old 10-18-2020, 02:59 PM   #8
ruley73
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Join Date: Aug 2006
Location: Is this heaven?....No, it's Iowa!
Posts: 3,055
 
Default Re: 2003 ION Stalls at Stop....Now Dangerous to Drive

Quote:
Originally Posted by GTSRider View Post
No wonder I could not find the damn MAF ! .....and yet Rock Auto is sending me a MAF for a 2003 ION ! Oh well , sending that back before I even open it....
ruley...it is the 5 speed AISIN, been a great tranny for this 4 door do everything car.
Yes drives like new, other than the problem.
It dies in a parking situation , STOP sign, or RED light.... but ONLY after it reaches peak operating temperature....will NOT do it upon cold starts , and the first 15 minutes of driving. I can only drive it with one foot on brake, one on throttle..... have come real close to having a big pickup truck in my back seat, after light changes GREEN.
Yes , idles fine in neutral or park. Battery is about 4 years old now, alternator replaced 3 years ago....but will check battery.
No never got TSB done, but did have recall ignition done 4 years ago.
No loss of power....power is good for 230,000 miles..... OH ...one thing I forgot to mention....it has the cracked exhaust manifold , with NEW one waiting to be installed... Could the loss of back pressure cause the engine to run too lean , thereby causing the stalling off the line ?
The back pressure probably won't affect too much. However, the resulting exhaust leak could be preventing the upstream oxygen sensor from operating properly. During normal operation, the difference in oxygen content between the exhaust stream and the atmospheric air around the sensor is what creates the voltage the ECM monitors. The exhaust leak lowers the oxygen content of the air around the outside of the oxygen sensor which reduces the voltage it will produce. The ECM will interpret the reduced voltage as a lean running condition and try to compensate accordingly by enrichening the fuel mixture. This could be the cause of your problem, but you won't know for sure until you fix the exhaust leak by replacing the exhaust manifold.

The fact that your car doesn't act up until the engine is warm makes me think this is a real possibility though. The ECM basically ignores the oxygen sensor's reading during cold starts because oxygen sensors are not accurate until they warm up. This period of time that the ECM ignores the oxygen sensor is known as open loop operation. Virtually all oxygen sensors used in the last 20+ years have a heater built into them to get them up to operating temperature faster to reduce emissions.

I'd check the air filter and replace it if you haven't already done so. I'm betting you've already done this by now, but just offering the suggestion because you didn't mention it.

The only two vacuum lines that go to the intake are the PCV hose from the valve cover and the brake booster line. A leaky PCV hose won't affect idle much because its connected to the air intake before the throttlebody. A leaky brake booster line would make it idle high because it's connected directly to the intake manifold after the throttlebody.
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2007 Ion 2 Quad Coupe 5-speed manual 183K miles *gone*
2007 Chevy Equinox LT 200K miles
2018 Chrysler Pacifica Touring L 60K miles

Last edited by ruley73; 10-18-2020 at 03:09 PM.
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