Please help rough idle!!
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Please help rough idle!!
Let me start with I have a 2003 f250 5.4. The motor blew on my truck and I had a 100k motor dropped in it. ive put new spark plugs, ohmd out the coils. tried both sets of injectors. cat delete and new fuel pump. it has rough idle and stalls but runs fine at higher rpms. also has basically no brakes. im thinking vacuum but ive check all the lines. scratching my head on this one please help. no codes either!! also cleaned throttle body.
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Joined: Mar 2010
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From: Upstate NY
Let me start with I have a 2003 f250 5.4. The motor blew on my truck and I had a 100k motor dropped in it. ive put new spark plugs, ohmd out the coils. tried both sets of injectors. cat delete and new fuel pump. it has rough idle and stalls but runs fine at higher rpms. also has basically no brakes. im thinking vacuum but ive check all the lines. scratching my head on this one please help. no codes either!! also cleaned throttle body.
Egr valve could also be opening when it is not supposed to causing the same symptoms as an unmetered air leak.
I have seen brake boosters rust at the bottom where you cannot see, causing pinholes that = unmetered air leak.
Also I'm unsure but its something you can look into, the older ford throttle bodies had a protective film on the inside of them and you need to specifically use throttle body cleaner to get the trash out of them, using carb or brake kleen will destroy the film, it may or may not be the same case for super duty throttle bodies.
Do you have a post cat o2 sensor on your truck?
Postmaster
Joined: Jul 2015
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From: very South Texas
I also was going to say... brake booster....
also throttle body.. maybe one of the small passages are still blocked.
does these engines have idle air control valve? if its dirty, (or bad) same problem
install a vacuum gauge.. at idle should be 18 inches.. or more. if less a leak.
also throttle body.. maybe one of the small passages are still blocked.
does these engines have idle air control valve? if its dirty, (or bad) same problem
install a vacuum gauge.. at idle should be 18 inches.. or more. if less a leak.
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UPDATE!!! so im guessing the reason I wasn't getting any codes is because the battery had been dead for a while after the motor blew and also after I had recharged it I disconnected when I was welding in the straight pipe in place of the cat. I took it to a local guy his machine says bank 1 sensor 2 02 sensor dead short. so replacing that to see if it helps?
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NashT001
1987 - 1996 F150 & Larger F-Series Trucks
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May 15, 2019 07:09 AM
