Need Help with High Idle
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New User
Joined: Dec 2008
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Need Help with High Idle
HI Folks,
I have a problem with a high idle. My engine idles so high that I have to put it in neutral at an intersection or it pushes me through it on the ice and snow. I have changed the IAC valve and throttle postion sensor. I just resealed the intake both upper and lower along with much needed new fuel injectors but in the end it still idles high all the time. The engine is getting up to temp as the thermostat is new also but this thing is kicking my butt. I need some ideas or direction on what to look for next. The truck is a 1990 F150 with a 302 EFI and a E4OD automatic. Any help would be greatly appreciated. Thanks, Fordgoon.
I have a problem with a high idle. My engine idles so high that I have to put it in neutral at an intersection or it pushes me through it on the ice and snow. I have changed the IAC valve and throttle postion sensor. I just resealed the intake both upper and lower along with much needed new fuel injectors but in the end it still idles high all the time. The engine is getting up to temp as the thermostat is new also but this thing is kicking my butt. I need some ideas or direction on what to look for next. The truck is a 1990 F150 with a 302 EFI and a E4OD automatic. Any help would be greatly appreciated. Thanks, Fordgoon.
New User
Joined: Mar 2006
Posts: 15
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I feel your pain
Been there too!
With my efi '85 F-150 5.0 I had a similar problem. The truck would idle very high when it warmed up. My problem was with the throttle position sensor. I back probed the harness and when the truck warmed up, the sensor wouldn't read the .9 volts at idle, it was more like 1.1-1.3 volts.
I changed the sensor set it so it read about .9 volts at idle and I haven't had any issues with high idle since. Since you just replaced that sensor, I would back probe the harness and make sure that it is showing about .9 volts at idle.
I hope this helps.
With my efi '85 F-150 5.0 I had a similar problem. The truck would idle very high when it warmed up. My problem was with the throttle position sensor. I back probed the harness and when the truck warmed up, the sensor wouldn't read the .9 volts at idle, it was more like 1.1-1.3 volts.
I changed the sensor set it so it read about .9 volts at idle and I haven't had any issues with high idle since. Since you just replaced that sensor, I would back probe the harness and make sure that it is showing about .9 volts at idle.
I hope this helps.
Tuned
Joined: Aug 2007
Posts: 287
Likes: 1
Pull the IAC connector when the truck is idling high. If if returns to a normal idle then one of the sensors is telling the computer to open the IAC. Probably the TPS. Backprobe for the voltage output when it's idling high. I also have had a bad ECT sensor that acted up when the truck got hot causing the high idle to start. Both the my questionable sensors came from Advance. I went back to Ford for those all important sensors hoping their mfg. standards are more stringent.
