Engine Vibrations / Codes PO171/PO175
05-31-2011, 07:48 PM
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Engine Vibrations / Codes PO171/PO175
I have an 03 F150 Supercrew 4.6 43k miles, that is vibrating. Vibrations only seem to be present when the truck is put in Drive. It is not bad upon intitial start up, but more so when I come to a stop light and am on the brake. The truck drives fine, accelerates well, and idles smoothly. The tachometer does not move at all, so Im certain the vibration does not come from a rough idle.
After I pulled the codes (PO171/PO175) I started looking on the net to find the cure. Things I have done so far :
Changed spark plugs
Fuel filter/injector cleaner
cleaned K&N air filter and Mass Air Flow Sensor
Replaced PCV valve/hose/elbows
Replaced another cracked hose from throttle body to the brake booster
changed oil/tranny fluid/filters
The codes dissapeared once I replaced the PCV hose and the other hose from the throttle body to the brake booster. The codes remained gone for about 300 miles, and then came back with avengance! The vibrations seemed a little better once I replaced the two hoses, but were still somewhat present. I finally came to my wits end and took it to Ford. I paid a $99 diagnostic fee to have them tell me what the culprit is. Ford tells me the codes they pulled (PO171/PO175) which I already knew! Then they tell me they couldnt trace it to a plug or coil, but proceeded to tell me my compression in bank 2 was low (only about 5% low across all the cylinders on that side) He told me they needed to do a manual compression test to really know and wanted $380 for that...... I drove the truck home! He did tell me that the manual compression test would only confirm what the computer test revealed, and likely I would need a new a new motor!
I am not convinced I need a new motor. There is no gas or coolant in my oil, it does not overheat, or miss or even idle rough! It runs great (only 43k miles), other than the annoying vibration, and constant check engine light! Any wisdom that anyone could impart would be GREATLY APPRECIATED! HELP!
After I pulled the codes (PO171/PO175) I started looking on the net to find the cure. Things I have done so far :
Changed spark plugs
Fuel filter/injector cleaner
cleaned K&N air filter and Mass Air Flow Sensor
Replaced PCV valve/hose/elbows
Replaced another cracked hose from throttle body to the brake booster
changed oil/tranny fluid/filters
The codes dissapeared once I replaced the PCV hose and the other hose from the throttle body to the brake booster. The codes remained gone for about 300 miles, and then came back with avengance! The vibrations seemed a little better once I replaced the two hoses, but were still somewhat present. I finally came to my wits end and took it to Ford. I paid a $99 diagnostic fee to have them tell me what the culprit is. Ford tells me the codes they pulled (PO171/PO175) which I already knew! Then they tell me they couldnt trace it to a plug or coil, but proceeded to tell me my compression in bank 2 was low (only about 5% low across all the cylinders on that side) He told me they needed to do a manual compression test to really know and wanted $380 for that...... I drove the truck home! He did tell me that the manual compression test would only confirm what the computer test revealed, and likely I would need a new a new motor!
I am not convinced I need a new motor. There is no gas or coolant in my oil, it does not overheat, or miss or even idle rough! It runs great (only 43k miles), other than the annoying vibration, and constant check engine light! Any wisdom that anyone could impart would be GREATLY APPRECIATED! HELP!
Last edited by bencamdohm; 05-31-2011 at 07:52 PM. Reason: Left something out.
05-31-2011, 09:00 PM
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ouch, i'm having vibrations in the rear of the truck, and i'm also trying to get it figured out. it's at the dealer right now. 
but dang, 43K miles on a 03 motor? not bad, but sucks cause there's only 43k miles on it.
but dang, 43K miles on a 03 motor? not bad, but sucks cause there's only 43k miles on it.
06-01-2011, 01:01 AM
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Shaking/vibrating -- Codes PO171/PO175
Yeah, it is a mystery to me how this could happen with only 43k miles. My vibration/shaking is most definately not coming from the rear though.
06-26-2011, 05:17 PM
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Fixed!!!!!!!!!!!!!!!!
So, I figured I would update those of you who may come across this same issue. After talking to a retired Ford Mechanic who I found via Craigslist, I found the culprit.
He told me the reason for the viration I was feeling was because my truck jumped time. One of the timing chain guides broke (they are made of plastic) allowing slack in the timing chain which caused the chain to jump a tooth on the sprocket. Because the truck jumped time, it was causing the valves on that side of the motor to hang open a little (just enough to cause the check engine light/codes PO171/PO175) and the loss of compression on that side of the motor. The mechanic who informed me of this was not who I got to fix it. I found a mechanic who currently works as a tech @ Long Beach Ford who does work on the side. I paid 260.00 for parts and 600.00 for labor. He ended up replacing both timing chain guides/tensioners and all the gaskets and seals that were involved with the repair.
Truck is fixed! The codes are gone and check engine light is off. The truck doesnt vibrate or shake at all! And he hooked up his Ford scanner and laptop to show me the compression had been restored across all cylinders. Hope this thread helps any of you with similar issues!
He told me the reason for the viration I was feeling was because my truck jumped time. One of the timing chain guides broke (they are made of plastic) allowing slack in the timing chain which caused the chain to jump a tooth on the sprocket. Because the truck jumped time, it was causing the valves on that side of the motor to hang open a little (just enough to cause the check engine light/codes PO171/PO175) and the loss of compression on that side of the motor. The mechanic who informed me of this was not who I got to fix it. I found a mechanic who currently works as a tech @ Long Beach Ford who does work on the side. I paid 260.00 for parts and 600.00 for labor. He ended up replacing both timing chain guides/tensioners and all the gaskets and seals that were involved with the repair.
Truck is fixed! The codes are gone and check engine light is off. The truck doesnt vibrate or shake at all! And he hooked up his Ford scanner and laptop to show me the compression had been restored across all cylinders. Hope this thread helps any of you with similar issues!
Last edited by bencamdohm; 06-26-2011 at 05:19 PM. Reason: forgot something
