code po155 -running lean-
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Cross-Country
Joined: Feb 2004
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From: Boston transplant to Nash
code po155 -running lean-
hey everyone, i got one that is really stumping me. i keep getting a 155 lean code after changing the following: fuel filter, plugs, ran injector cleaner, changed all the oxygen sensors, had to fix a leaky exhaust, did the cap and rotor 10,000 miles ago. i have 188,000 miles on my 351. it idles fine, no loss of power, but my gas mileage SUCKS!!!
Any ideas?
1996 bronco xlt 188,000 miles and counting....
Any ideas?
1996 bronco xlt 188,000 miles and counting....
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Cross-Country
Joined: Feb 2004
Posts: 82
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From: Boston transplant to Nash
I checked the vacuum line at the fpr, no gas and no smell of gas there. i prob should have that checked. i am guessing(i hate doing this but it saves money guessing) that the injectors might need a full cleaning. i was using bosch platinums+4 and just changed them to the regular plats. i got 100,000 miles out of them.
Two things i need to note. when i pulled the plugs, they had a frosty white coating on the edges. this was also found on the 02 sensors, but not as much.
if the injectors are fine, however, i might have to check the vacuum at idle. those cheap plastic lines that are all over the engine bay are starting to look shady. i found a cracked one yesterday... but it always starts out with a 0155, then it adds a 0135 and a 0141.. thx
Two things i need to note. when i pulled the plugs, they had a frosty white coating on the edges. this was also found on the 02 sensors, but not as much.
if the injectors are fine, however, i might have to check the vacuum at idle. those cheap plastic lines that are all over the engine bay are starting to look shady. i found a cracked one yesterday... but it always starts out with a 0155, then it adds a 0135 and a 0141.. thx
Hotshot
Joined: Jul 2002
Posts: 14,285
Likes: 12
From: Bend,OR
ok first, our trucks dont like platinum plugs period. install some cheap autolite or motorcraft copper plugs. copper is a better conductor of electricity anyway. plat plugs just dont run right.
also check your timing.
you should also go to a muffler shop and see if your cat converter is plugged.
and definatly get the fuel pressure checked at the rail both with key on and with engine running. if you spray carb cleaner around the vacum lines and the rpms increase then you found part of your issue as well.
also check your timing.
you should also go to a muffler shop and see if your cat converter is plugged.
and definatly get the fuel pressure checked at the rail both with key on and with engine running. if you spray carb cleaner around the vacum lines and the rpms increase then you found part of your issue as well.
Posting Guru
Joined: Nov 2004
Posts: 2,155
Likes: 1
From: sunny fla sometimes windy
http://www.ngksparkplugs.com/techinf...q/faqread2.asp
Which one did it look like? A real heavy coating or just like polka dot splotches.
Replace your vacuum lines they should be done just like rad hoses since they are
only rubber and the heat/chemicals/ozone eats away at them. Get silicone hose
and you can cut the number of hose sizes you have to buy since the silicone will
stretch to fit a number of size nipples, Plus it lasts longer and can be had in colors
if you wanted. The hard plastic lines can be replaced with the pest tubes in the
walls tubing if you have any new construction check the garbage pile they usually
throw out feet at a time, Just check that they didn't punch the holes in it. A leaky
vac line will make your motor run lean!! You could pull out your Intke air temp sensor
and clean that since a bunch of build up won't allow the computer to get a good
reading on the temp(temp=density) If your IAc ever needed to be cleaned your IAT
is also probably covered with more crap than the IAC was.
Which one did it look like? A real heavy coating or just like polka dot splotches.
Replace your vacuum lines they should be done just like rad hoses since they are
only rubber and the heat/chemicals/ozone eats away at them. Get silicone hose
and you can cut the number of hose sizes you have to buy since the silicone will
stretch to fit a number of size nipples, Plus it lasts longer and can be had in colors
if you wanted. The hard plastic lines can be replaced with the pest tubes in the
walls tubing if you have any new construction check the garbage pile they usually
throw out feet at a time, Just check that they didn't punch the holes in it. A leaky
vac line will make your motor run lean!! You could pull out your Intke air temp sensor
and clean that since a bunch of build up won't allow the computer to get a good
reading on the temp(temp=density) If your IAc ever needed to be cleaned your IAT
is also probably covered with more crap than the IAC was.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
I looked up PO155 on several sites and it said (Bank 2)O2 heater circuit failure. This doesn't indicate a lean condition, it's telling you that sensor isn't getting power to the heating element. PO141 and PO135 are the same code for the other sensors, and since you have changed them we know the sensors are not at fault. If all these sensors are getting power from a common source(which is very likely the case) then that's your problem. Start by checking the fuse for the O2 sensors. Just for giggles what is your milage?
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Cross-Country
Joined: Feb 2004
Posts: 82
Likes: 0
From: Boston transplant to Nash
hey thanks guys, there is 188,653 mile on this. now the air temp sensor, is a good idea. haven't thought of that... i bet that looks like *****
the vacuum lines i am gonna check as soon as it stop raining!!
the o2's however were checked of all the voltage 9.8-12 volts to all of them. i wasn't gonna jam the tip into the plug, but when i did, the voltage went up.
now, where the hell is the fuse for those 02 sensors? i cannot find it ANYWHERE. even if they were labeled HEGO, i still can't find them. And man, there are fuses EVERYWHERE!!
maybe they are inline ones?
and you know what? there is a CRAPLOAD of vaccum lines all over the place. some chevy engineer musta designed that crap!!!
the vacuum lines i am gonna check as soon as it stop raining!!
the o2's however were checked of all the voltage 9.8-12 volts to all of them. i wasn't gonna jam the tip into the plug, but when i did, the voltage went up.
now, where the hell is the fuse for those 02 sensors? i cannot find it ANYWHERE. even if they were labeled HEGO, i still can't find them. And man, there are fuses EVERYWHERE!!
maybe they are inline ones?
and you know what? there is a CRAPLOAD of vaccum lines all over the place. some chevy engineer musta designed that crap!!!
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Cross-Country
Joined: Feb 2004
Posts: 82
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From: Boston transplant to Nash
oh-ohh
so for giggles, i removed the vacuum plastic tree. i fugured i was gonna replace the whole thing anyway.. there is this "vent" cap on the back of the valve cover which the "tree" plugs into. and guess what the entire cap just floats in its hole. tada! vacuum leak like nobodys business. now i am mad at the ford dealer. they claimed to fix the leak. why am i mad? you can't even get this stupid thing out from under the intake manifold!! i am dreading what i have to do next. remove the upper plenium just to replace a stupid vacuum cap that goes on the passenger side valve cover!! who designed this crap?!? it just sits there and doesn't snap in!! and it is rather loose too...
ggggggggrrrrrrrrrrrrr!!!!!!!!!!
ggggggggrrrrrrrrrrrrr!!!!!!!!!!
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Thread Starter
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Cross-Country
Joined: Feb 2004
Posts: 82
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From: Boston transplant to Nash
running lean still gets the 0155
well, i took out the vacuum tree and check it for leaks. there was only one broken part which was fixed with tubing. i still get that code. the pcv in the back snapped so i replaced it. what worries me is the breather cap with the small hose that comes out; it is too wiggly back there. i have two questions left:
1. initally when i replaced the passenger 02 sensor(bank 1 ,2) the wire was grounding n the exhaust. the white wire had melted in the casing. is there a fuse for this?
2. since my idle on the truck when warm is mint, not shaking or twitching i beleive the vacuum is good. what else should i be concerned with? the injectors last how long?? should i clean them? the FPR i have heard has given people problems.. would a lean condition cause this?
thanks
1996 bronco xlt
blue & white
351Eaod. quad shock setup
leather interior
188.644 miles and rollin
k&n Filtercharger. Jet Chip(removed for testing the ob2)
1. initally when i replaced the passenger 02 sensor(bank 1 ,2) the wire was grounding n the exhaust. the white wire had melted in the casing. is there a fuse for this?
2. since my idle on the truck when warm is mint, not shaking or twitching i beleive the vacuum is good. what else should i be concerned with? the injectors last how long?? should i clean them? the FPR i have heard has given people problems.. would a lean condition cause this?
thanks
1996 bronco xlt
blue & white
351Eaod. quad shock setup
leather interior
188.644 miles and rollin
k&n Filtercharger. Jet Chip(removed for testing the ob2)
Thread Starter
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Cross-Country
Joined: Feb 2004
Posts: 82
Likes: 0
From: Boston transplant to Nash
ok everyone, i have checked the vacuum on the truck. good news. it isn't that. a healthy 15-18 at idle and when you punch the gas, it goes right to zero!! i guess i had better check the fuel pressure regulator?? opinions anyone??
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