5.4 idles rough in cold
10-16-2008, 09:57 AM
#1
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5.4 idles rough in cold
my truck has been doing this for the last couple of years every now and then during the winter. (any time the temp is around 45 or lower outside) it will start fine and idle smooth and then after a couple of minutes it starts missing like a coil is going out. they have all been replaced many times because when they go, they all go, but that is a completly diffrent problem. the truck will eventually a code will show up, which my friend who is a mechanic decodes for me with his scanner, and the code says the engine is running lean on banks 1 and 2 (so the whole engine) we have replaced the plugs with a better brand of plugs this spring, and it seemed to correct the problem but it is back and the plugs only have 6000 miles on them. we have replaced the pcv valve and the tps valve/sensor. this problem has us baffled as to what sensor is going bad and what we need to replace. there is a long list of things that could be causing this i am just asking if anyone else has had this problem. i would like to avoid replacing everything that is on the list. if anyone has any helpfull advice let me know.
10-16-2008, 11:24 AM
#2
OVERTHINKER
Have you monitored the performance of the MAF? The parameters could be off and only giving you problems that you see/feel in colder weather. The same could go for the rear O2 sensor. To take a look at these functions you will need a diagnostic scanner, not a code reader.
10-16-2008, 07:11 PM
#3
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I have no experience with the 5.4 engine. Several other posts here about the same codes. PO171 & PO174, lean bank 1 & 2. I live in the Las Vegas area, we have some abrupt temperature changes, my 4.2 thru the sames codes on cold morning starts. I never really noticed any roughness, sure had that CEL satrring at me. I was informed by the Ford techs, via a tool truck salesman, the intakes are secured in place with bolts with built in grommets. These shrink and cause an intake leak and thus a lean mixture. The composition the the 5.4 intake seems to be the same as mine. Perhaps the attaching hardware is of same design. Go to Ford parts and look at the similarity of the mentioned bolt/grommet design. I've had three mornings at 40 degrees. So far so good. I am watching.
10-18-2008, 04:18 AM
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I have no experience with the 5.4 engine. Several other posts here about the same codes. PO171 & PO174, lean bank 1 & 2. I live in the Las Vegas area, we have some abrupt temperature changes, my 4.2 thru the sames codes on cold morning starts. I never really noticed any roughness, sure had that CEL satrring at me. I was informed by the Ford techs, via a tool truck salesman, the intakes are secured in place with bolts with built in grommets. These shrink and cause an intake leak and thus a lean mixture. The composition the the 5.4 intake seems to be the same as mine. Perhaps the attaching hardware is of same design. Go to Ford parts and look at the similarity of the mentioned bolt/grommet design. I've had three mornings at 40 degrees. So far so good. I am watching.
Id MAF and The Rear O2 Sensor the non pre-heated one and also check IAC this may also cause a lean condition.I live 2 hours fron las vegas and it gets realy cold here in the winter 30ish or colder.Installed a remote start to warm things up....good luck