Ford Repair: 88 f-150 302, ford f 150, air control valve
Question
88 f-150
idle surgess up and down,drops so low the motor quits, but if you pull it ito reverse/drive it begins to idle better.and eventually clears up and idles normal.i tried cleaning the i.a.c.and it done better as far as the rough idle goes, but still surged some,and has gotten worse it seams.also need to change rear end gear to compensate for a 4 inch lift and 35 12.50's.motor lags on hills and down shifts alot.do you have any suggestions. the truck is an 88 ford f-150 with a 302/automatic(metric trans),not sure what gears are in it but pretty sure they are probally stock. Just bought the truck, and prev owner passed away. great deal on it,but it needs some tlc.
AnswerThe diagnostic plug is under the hood. Pull the codes by counting the blinking check engine light. Further instructions will be in the haynes manual for any Ford made before 1996. Please note that the oversize tires will cause excess wear and tear on the bottom end of the engine. It sounds like the idle air control valve needs to be replaced. I would aso have the TPS tested. Unfortunately both of them usually go bad at the same time. The reason for this is that they are both exposed to the blow by coming out of the engine. If you notice, the blow by pipe is located after the air filter. Clean the throttle body very thuroughly with a rag and idle air cleaner. Do not use regular carb. spray, as it will eat the enamel off the coating in the throttle body. It is a little more difficult on your truck with the dual hose inlet at the throttle body, so I sometimes will cover a toothbrush with a cotton towel to do the scrubbing. Do this with the motor off of course, and the throttle wide open.
