Fubar231 Posted March 26, 2013 Report Share Posted March 26, 2013 So i have a 1990 talon tsi and its been having this idle issue since i got it. Even when it gets to operating temp, it will still idle like its a cold start, or sometimes will randomly bounce between 1400-1000-1400-1000. A lot of the time it just idles high like its cold and wont drop down and surge unless i rev it up and let it idle down. Heres a video of it (Sorry about the music, wasnt thinking when i took the video as i just pulled in my driveway from work and it was doing it) http://s50.photobucket.com/user/SevereSarz/media/20130326_171653_zps42351586.mp4.html What do you guys think? IAC motor? I was told it could be the coolant temp sensor... But any ideas where to start? I need to go measure the resistance on the IAC and see if its good or bad. Also theres no CELs. Quote Link to comment Share on other sites More sharing options...
Browning Posted March 26, 2013 Report Share Posted March 26, 2013 just pull the IAC and clean it, see what happens Quote Link to comment Share on other sites More sharing options...
Green Bastard Posted March 26, 2013 Report Share Posted March 26, 2013 Look into resealing the throttle body, iirc there is a couple o-rings for the throttle plate shaft. Quote Link to comment Share on other sites More sharing options...
Trouble Maker Posted March 26, 2013 Report Share Posted March 26, 2013 Here... let me google that for you.... http://www.vfaq.com/index-main.html If you go to intake>throttle body you would find the article below as well as articles detailing cleaning the TB, setting the idle set screw, etc. http://www.dsm.org/how-tos/tttt/tttt3.html But really I think this can in theory happen on any car, unless new cars have some way to detect this situation and not go into a loop. The car is cold so the idle should be high, no problem. The car gets warm and it should be low. But the idle is still high (somehow too much air getting past the throttle). So the car cuts fuel to try to match target idle. But the the o2 sensor sees that the car is lean. So the FI ecu adds fuel. But the the idel is too high. So the car cuts fuel to try to match target idle. So on and so forth. Quote Link to comment Share on other sites More sharing options...
SinisterSS Posted March 26, 2013 Report Share Posted March 26, 2013 I would check these items: Throttle Body Idle Air Control (IAC) Motor <---this being the most common issue Automatic Idle Speed (AIS) Control Motor Intake Manifold Vacuum Leak Tests/Procedures: 1. Check the resistance of the Automatic Idle Speed (AIS) motor windings. Check the resistance from the center pin of a row of three pins to the pins on each side of it. All four windings should be 30-40 ohms. 2. Check the Throttle Position Sensor (TPS) voltage at closed throttle. It should be about 0.5 volts. Adjust by turning the throttle stop screw. 3. Turn the key off. 4. Ground pin 10 in the Data Link Connector (DLC). 5. Start the engine and set idle speed to about 700 RPM by turning the air bypass screw at the top of the throttle body. 6. Shut the engine off. 7. Remove the jumper from pin 10. 8. Start the engine and let it idle for at least 10 minutes. 9. If it is still idling too fast, check the secondary air valve for sticking. Quote Link to comment Share on other sites More sharing options...
boosted98gst Posted March 26, 2013 Report Share Posted March 26, 2013 If its a 1g dsm its prolly the IAC motor. Quote Link to comment Share on other sites More sharing options...
Patterson Posted March 27, 2013 Report Share Posted March 27, 2013 Is it stock? Quote Link to comment Share on other sites More sharing options...
WheelSpin Posted March 27, 2013 Report Share Posted March 27, 2013 Remember if the iac goes bad it can often blow a track on the ecu since it's an unfused circuit. Quote Link to comment Share on other sites More sharing options...
PsychoticGaming Posted March 27, 2013 Report Share Posted March 27, 2013 Fiav block off plate is an option but also check the throttle linkage that its not too tight causing it to stick and idle high or surge. Quote Link to comment Share on other sites More sharing options...
RC K9 Posted March 27, 2013 Report Share Posted March 27, 2013 BISS? Its a DSM...could be like 100 things. Some good pointers above though. Quote Link to comment Share on other sites More sharing options...
accel_is_my_drug Posted March 27, 2013 Report Share Posted March 27, 2013 Holy Mary mother of god! A link to Vfaq.com Nearly everything I ever learned to do on my first DSM came from that site. Memories for 15 years ago... Quote Link to comment Share on other sites More sharing options...
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