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HDGENE, Ford Senior Master/Diesel/Trans
Category: Ford
Satisfied Customers: 4782
Experience:  25 years Auto experience, Ford ,GM, Chrysler, Asian & European
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2004 f150 V8 4.6lt new body style. When you come to a stop

Customer Question

2004 f150 V8 4.6lt new body style. When you come to a stop and even while driving there is a ideal problem. When at a stop it idles very low and the whole truck shakes, no check engine light! I cleaned throttle body, replaced air and fuel filters. Also replaced EGR valve, TPS sensor, the purge canister also has been replaced with no luck, help I am a disabled veteran and my truck is my primary means of getting around???
Submitted: 5 months ago.
Category: Ford
Expert:  HDGENE replied 5 months ago.

Hello, a low idle can be caused by a vacuum leak. Check all vacuum connections and the air inlet tube connections to the throttle body. If this is ok, remove the mass air flow sensor from the air cleaner and inspect inside the sensor for a bug or any debris on the sensor heater wire. Tap it out and use a can of mass air flow cleaner or brake clean, not carburetor cleaner, that will mess up the sensor. Disconnect the battery for awhile and drive the vehicle and recheck.

Customer: replied 5 months ago.
Sorry should have included more info with my original question, no vacuum line leaks, cleaned mass air sensor and had a mechanic looked at it with no luck. Have good fuel pressure. Just really confused, is it bad exhaust system?
Expert:  HDGENE replied 5 months ago.

Ok, how many miles are on the engine? WHat is it doing while driving besides the low idle?Good power running down the road? Passes a Key On Engine Off & Key On Engine Running Test with a scan tool?

Customer: replied 5 months ago.
Has just about 113,000 miles, AMD the mechanic hooked up his scanner and everything checked. It has good power while driving but at certain speeds above 35 it shutters and just feels wrong??
Expert:  HDGENE replied 5 months ago.

Ok, a shudder at highway speeds can be either an engine misfire, or torque convertor shudder. Check the trans fluid level and condition, if it looks brown to black and smells burnt, a transmission service/flush should be done to see if the shudder goes away. The mechanic that looked at the truck may not have found any memory codes stored, but I dont know if he did on demand testing (Key On Engine Off & Running Tests). Also a special OBDII test called mode 6 data will show if there are any misfires happening below the threshold of it turning on a check engine light. Take a vacuum gauge and hook it up to the engine and see if the needle bounces around, with the mileage on the truck if all diagnostic checks out ok it could be a worn or burnt exhaust valve causing the rough idle. A broken valve spring will show a bouncing needle. Remove all spark plugs and inspect how they are burning, check for any coolant in the spark plug tubes and perform an engine compression test. All the cylinders should be no more than 10 percent difference otherwise it is indicating an engine issue

Expert:  HDGENE replied 5 months ago.

Hello, do you need more help with this concern?

Expert:  HDGENE replied 4 months ago.

Hello, do you need more help?