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RJ, Ford Technician
Category: Ford
Satisfied Customers: 1574
Experience:  Ford senior master and ase master certified 19years Ford dealership experience
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1999 ford f150: cleaned the maf put..o2 sensor..shakes..acceleration

Resolved Question:

1999 ford f150 5.4l
it had several codes p0172,p0175,p1131,p1132,p1152,p0133
I have cleaned the maf put in new spark plugs replaced some vacuum lines that did not help
I then replaced o2 sensor precat on bank 1 and changed fuel filter now truck shakes so bad you cannot drive it before it was missing at idle and hesitating on acceleration but was still drivable
Submitted: 7 years ago.
Category: Ford
Expert:  RJ replied 7 years ago.
Do you have a scanner that will monitor engine parameters? What vacume lines did you replace?
Customer: replied 7 years ago.
no I do not have a scanner the one that connects throttle body to iac and the one that goes to the evap valve I have pulled the pcv valve it has lots of suction when i replaced the plugs I checked the coils they all seemed to be in spec when i checked resistance the truck had a aftermarket air intake on it I replaced with stock one from 97 expedition I am not sure about the maf sensor compatibility the one off the other intake won't fit on the intake from the expedition I think I may need to get the holder that will fit the original maf from the truck. I just don't know why it would run so rough after I put on new o2 sensor before it had a hesitation but nothing like now it I have never had a vehicle shake so bad on acceration very frustrated I am wondering if I should check fuel pressure next when I changed the fuel filter the fuel that came out looked real clean no rust crud ect.
Expert:  RJ replied 7 years ago.
without a scanner its going to be very hard to determine the fault without just quessing. It sounds to me that the truck runs worse since you put the plugs in i would suspect one of the plugs is cracked or maybe one of the coils is failing, testing resistance of coils will only indicate a coil that is completly open that type of failure is extremely rare. I would advise removing the plugs double checking for cracks and double check your conecctions to the coils and injectors make certain you did not leave one unplugged.The vacumme line from the pcv valve to the back of the intake should be removed and the rubber elbows inspected this is the most common place for a large leak to occur that can cause rough running and also lean codes. Yes checking the fuel pressure is a good idea, you should have in the realm of 45 psi.
Customer: replied 7 years ago.
it didnt really run worse with the spark plug change it made no difference it ran worse after the o2 sensor change and fuel filter change. I put the original o2 sensor back in today it made no difference still shaking like crazy when you are moving and accelerating gradually when parked the it hesitates when you punch it its rough at first then smooths out at higher rpms but when you are moving it shakes all the way through the rpm range up to about 3000. when you give it gas and it goes back to idle it drops to about 500 rpms then picks back up to about7-8 hundred rpms you can smell the exhuast. I have thought about the coils don't know how to test if one is not working is ok to just umplug them one at a time to see if it affects the engine idle. I looked at the pcv tube today with a mirror it looks ok there is good suction at the pcv valve when i pull it out . i appreciate your help Thanks
Expert:  RJ replied 7 years ago.
IF you can see the entire tube with a mirror you are better than me!! Take it off and look at the elbows they deteriate and collapse, just make sure. Unpluging one coil at a time would work if the missfire is happening at idle, or was completly constant(dead miss) The most positive test is using a ociliscope to monitor the wave form during the missfire, this is the only way to physically test the coil. However if indeed you have a missfire another tool is to monitor the power balance with a capable scanner then you could swap the coil from the missing cylinder to another cylinder and see if the miss followed the suspect coil. Do you know what codes you have now since you started this repair? You are going to need to get it tested electronically in order to come to any conclusion on this. Its just not like the old days.LOL
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