# CEL help

**URL:** <https://forums.speedlife.net/t/cel-help/67918>\
**Category:** NYSpeed Automotive\
**Created:** [May 17, 2009, 7:39am UTC](https://forums.speedlife.net/t/cel-help/67918 "2009-05-17T07:39:01Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![TheJackman](https://avatars.discourse-cdn.com/v4/letter/t/ee59a6/32.png) [@TheJackman](https://forums.speedlife.net/u/TheJackman)\
**Post date:** [May 17, 2009, 7:39am UTC](https://forums.speedlife.net/t/cel-help/67918/1 "2009-05-17T07:39:01Z")

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So i recently bought a 1998 Chevy 3500 van as a service vehicle for our rally team. the check engine light was on when i bought it and it felt under powered. checked the codes and got P0171 and P0174 which are lean condition codes for bank 1 and bank 2 (350 V8). After doing some research the most common fixes seemed to be cleaning the MAF and looking for vacuum leaks. I cleaned the MAF and cleared the codes. when driving around under part throttle the codes did not reappear, but when i went WOT the light came back on. It seems like i’ll be trying to track down a vacuum leak and was just wondering if anyone has any suggestions on places to start, or common areas on the engine that could be the source of the problem. The previous owner told me that he had the intake manifold gasket replaced recently, and i’m really hoping they didn’t screw it up leading to this leak.

Any input is greatly appreciated. Thanks.

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**Author:** ![TheJackman](https://avatars.discourse-cdn.com/v4/letter/t/ee59a6/32.png) [@TheJackman](https://forums.speedlife.net/u/TheJackman)\
**Post date:** [May 18, 2009, 5:36pm UTC](https://forums.speedlife.net/t/cel-help/67918/2 "2009-05-18T17:36:13Z")

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OK so i went out and did some “carb cleaner diagnostic” testing and can’t seem to find a vacuum leak anywhere. could this be a fuel supply issue? clogged injectors/fuel filter? bad regulator or pump? anyone have any suggestions?

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**Author:** ![Pauly](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/pauly/32/7493_2.png) [@Pauly](https://forums.speedlife.net/u/Pauly)\
**Post date:** [May 18, 2009, 5:43pm UTC](https://forums.speedlife.net/t/cel-help/67918/3 "2009-05-18T17:43:25Z")

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low fuel pressure will give lean codes. Got a pressure gage?

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**Author:** ![TheJackman](https://avatars.discourse-cdn.com/v4/letter/t/ee59a6/32.png) [@TheJackman](https://forums.speedlife.net/u/TheJackman)\
**Post date:** [May 18, 2009, 5:45pm UTC](https://forums.speedlife.net/t/cel-help/67918/4 "2009-05-18T17:45:49Z")

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I was thinking of picking one up. I know it’s probably a bad idea, but could i just use a diaphragm/dial tire gauge? there is a schrader valve on the supply line and it’s supposed to be 60-66psi at idle, so it would be within the range of the gauge…

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**Author:** ![Pauly](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/pauly/32/7493_2.png) [@Pauly](https://forums.speedlife.net/u/Pauly)\
**Post date:** [May 18, 2009, 5:54pm UTC](https://forums.speedlife.net/t/cel-help/67918/5 "2009-05-18T17:54:32Z")

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ummm no

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**Author:** ![TheJackman](https://avatars.discourse-cdn.com/v4/letter/t/ee59a6/32.png) [@TheJackman](https://forums.speedlife.net/u/TheJackman)\
**Post date:** [May 18, 2009, 5:59pm UTC](https://forums.speedlife.net/t/cel-help/67918/6 "2009-05-18T17:59:54Z")

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yeah i didn’t think it was a good idea, but i just thought i’d ask.