Rough idle when put in reverse

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2drhoeon4s

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gas smell seems to be only when i cold start it... It smells like I am at a car show and an old muscle car started up beside me..i attribute it to maybe a rich condition? I havent tested fuel pressure yet, but I hear the high pitch whine, and i recently replaced my fuel filter.. Can I verify good operation using a multimeter on the wiring?
 

SunlitComet

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Attribute? yes. If you don't have a tester, borrow one kit from Autozone using a refundable deposit, follow the PDF below and take note of what is wrong where. If you mean test wire continuity with the DMM, yes, by all means. What happen to the cats? sig says you got them but you said no? It does nothing but create issues as well as mess up performance when they are not in. Also because there are individual sensors on the valve body that tell the pcm what gear it is actually in, ensure the main connector on the tranny is clean inside with no bent pins and stuff. Let me ask when you removed these cats you say you don't have what happened with the actual rear sensors. Just dangling somewhere or completely unplugged?

http://www.sunlitcomet.com/pdf/automotive/tahoe/98-99/1999%20yukon-tahoe-5.7l-fuel-pressure-testing.pdf
 
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2drhoeon4s

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rear sensors are still in the exhaust.

I had the cats, but they were removed when I had the headers installed. But that has been 6-8 months ago and no problems until recently... Ill do the tests and get back with ya..
 
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2drhoeon4s

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question for you sunlit.. i think it might be vacuum/brake related... it seems to act up when im on my brakes... like when i drive it home from work. i pull in the driveway and put it in park and with my foot on the brake it wants to bog down... so i hold the brake and gas a little to keep the rpms up.. after about 10 seconds i let off the gas and it idles normal.. but when i let off the brake the idle goes up prolly 50/100 rpms.... vacuum leak in the booster? How do i test?
 

SunlitComet

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simplest way is to run your engine and very slowly press on the brakes full stroke and try to listen for hissing noise underneath the dash at the booster. Also make sure the the idle is not effected when you wiggle the vacuum line check valve a little.
 

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