Hissing sound in engine

CHEVYGUY18

MEMBER
2002 CHEVROLET SILVERADO
4.3L
V6
2WD
AUTOMATIC
165,000 MILES

A service engine soon light came on and I took it to a shop and they gave me a code for the MAF. I replaced the MAF and the light went off, the next day it came back on again. I took it to the shop again, and gave me P0171, P0174. He told me that can be caused by a vacuum leak, or bad O2 sensors. I came here to ask what do I need to do to find a vacuum leak and if I do find one how do you fix it? What do we need to buy? And if it is the O2 sensors well I already know how to fix those.

2 Replies

HMAC300

MECHANIC
48,601 POSTS

Use choke cleaner for small stuff like cracks, but check hoses for crack/broken etc. Also because it is a 171/174 code check fuel pressure as it may be low causing it as well you should have 60-66psi with 60 being minimum with key on auto parts rent gauge.

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Sunday, May 29th, 2016 AT 3:32 PM

RENEE L

ADMIN
1,257 POSTS

Hi Chevyguy18,

Here is a link to an article from this site that features written instructions and pictures showing and explaining the process of checking the fuel pressure yourself. If you decide you would like do this yourself you can purchase a fuel pressure gauge online from sites like Amazon.com.
Please re-post with your findings so that we can further assist you.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Thank you for visiting 2CarPros.

Kindest regards,

Renee
Admin

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Tuesday, May 31st, 2016 AT 3:27 PM