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Old 05-28-2010, 07:19 PM
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Join Date: May 2010
Posts: 2
Exclamation what does engine diagnotic code po174 and po171 truly means?

i have a cadillac deville 2001 standard edition that i've been having for the last 8 years and i have kept in good condition and taken care of it maintenance,mechanical stuff ! but recently i have been getting this loud weezing noise that comes on when the engine is cold and i just turn the car on ! this noise comes from the left driver side of the car under the left headlight area and air filter area! then just the other day,my service engine soon light came on so i had an engine diagnostic done at a professional auto mechanic spot "PEP BOYS" and they pulled these following codes : PO171 AND PO174 ..these codes were showing numerously ! stating that the car was running too lean and the pep boys technician also stated that fuel system too lean bank 1 and bank 2
he said that the car either is getting too much oxygen or not enough fuel ! but yet there were no oxygen sensors codes showing !
i also recently had done these following maintenance services on the car :
complete engine flush with oil change semi-synthetic and filter, power steering flush, brake flush, radiator cooling system flush, fuel injection system cleaning service
while doing the engine diagnostic,the technician found where the weezing noise was coming from which was the secondary air injection auxiliary pump which was containing water inside of it ! so at this point, i would like to know do i need to change that pump and if by doing so would it take care of the service engine light! also i keep finding no parts named secondary air auxiliary pump on the internet when i am doing my searches for pricing and info ??
thank you very much for any help provided !
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Old 05-28-2010, 08:29 PM
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Join Date: Apr 2009
Location: Seattle Area
Posts: 108
Default P0171 and P0174

The first thing to check with those codes is your plenum duct. Check it for a tear in the bottom by running the car at low idle and spray a little starting fluid under the bottom. The plenum duct is a short rubber connector between the throttle body and the intake manifold. Observe the idle while you spray a short spurt of starting fluid under it and if the idle raises, then the plenum duct must be replaced. All plenum ducts will develop a leak at this location due to the design of the vehicle. You would be lucky to get 100K miles before it goes.

Other causes include vacuum leaks at the air incuction system, intake manifold, and injector o-rings; leaks at the crankcase ventilation system, and missing, loose, or leaking exhaust components. The secondary air pump is an exhaust component. It is about a $150 part and includes numbers 12 - 17 in the attached picture.
Attached Images
File Type: jpg air-pump-part-2-6k0303101.jpg (12.5 KB, 26 views)

Last edited by 2001_Seville_SLS; 05-28-2010 at 08:32 PM.
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  #3  
Old 05-29-2010, 12:44 AM
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Join Date: May 2010
Posts: 2
Default

when you say run the car at low idle, can you explain how is that done ?
do i just turn the car on and let it run, is that considered low idle if nothing else is applied to the car?
also as far as spraying the starting fluid, where do i exactly spray it? at the connection of the throttle body and the intake manifold?
also i'm having a hard time finding air auxiliary pump product on any sites because for some reason it says that it doesn't exist! is air auxiliary pump another name for air injection pump or just simple air pump ?
i would greatly appreciate for any input and help provided ?
thank you !
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Old 05-29-2010, 01:24 PM
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Join Date: Apr 2009
Location: Seattle Area
Posts: 108
Default

Quote:
Originally Posted by ALIHESSAM29 View Post
when you say run the car at low idle, can you explain how is that done ?
do i just turn the car on and let it run, is that considered low idle if nothing else is applied to the car?
Yes, wait for the car to warm up and the idle will fall to low idle.
Quote:
Originally Posted by ALIHESSAM29 View Post
also as far as spraying the starting fluid, where do i exactly spray it? at the connection of the throttle body and the intake manifold?
Yes spray all around the connection because in addition to a hole or tear developing, the rubber ridge that contacts the aluminum at the water crossover can wear away causing a leak between the plenum and the water crossover. The throttle body mounts to the water crossover which is less than a couple of inches thick at that point. If this is your problem, you must replace the intake manifold gasket set when changing the plenum and it is a good idea to replace the throttle body gasket while you are there.
Quote:
Originally Posted by ALIHESSAM29 View Post
also i'm having a hard time finding air auxiliary pump product on any sites because for some reason it says that it doesn't exist! is air auxiliary pump another name for air injection pump or just simple air pump ?
Secondary air injection pump.

Start at http://www.gmpartsgiant.com/genuine/gm-parts.html and use their search by VIN feature.
Go to section: Fuel System, Exhaust, Carburetion, Emissions
Go to component: A.I.R. Pump and Related Parts
Look for: Pump Kit, Secondary Air Injn

Last edited by 2001_Seville_SLS; 05-29-2010 at 01:26 PM.
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Old 05-29-2010, 01:24 PM
 
 
 
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2001, bank, caddilac, cadillac, code, cts, deville, diagnostics, duct, engine, lean, plenum, po171, po174, system


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