Background is the listed above has a Zetec engine. The car had low idle problem, it would stall after to coming to stop. I started checking for vacuum leaks and found collapsed PCV hose. Also checked PCV valve and found it was sticking and then IAC check revealed zero resistance at motor terminal so that was replaced too. Idle is now fixed.
After the repair on test drive, it has high rpm problem. Car starts and runs fine until I take it above 45 mph. When I let my foot off the gas pedal, the car keeps going. When I stopping the rpm stays around 1,700, and then suddenly drop to its normal idle shifts down.
- I have checked throttle cable and it is not sticking.
- I do not notice any vacuum leak, sprayed propane and starter fluid, no change in rpm.
- Scanner reading shows throttle position 18% at idle and changes with throttle movement. While driving when I let foot off gas, it drops immediately to 18% indicating closed throttle.
- MAF is another story. At normal idle its at.2 lb/min. Goes up and down as I give it gas and let my foot off. But MAF reading stays constant at 1.7 - 1.8 lb/min after I let go of the pedal after speeding over 45 mph. It stays at this number even when I come to stop, rpm shows around 1,700 and idle eventually comes to its normal reading suddenly as described above.
- STFT and LTFT both are positive at idle. While driving LTFT remains high, around +8, while SF fluctuates between as +1.6, 0, and - 2. Xx.
- o2 sensor reading looks normal.
Do you have any guidance how to go about diagnosing the problem?
have the same problem?
Saturday, August 27th, 2016 AT 3:31 PM