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chevyman70 · 02-09-2015, 01:49 AM

So got a chance to play around with this continued issue. Ltft still at 25% at part throttle, 10 to 18 at idle. I get p0171 and p0174 codes. Replaced intake manifold gasket as well. Replaced fuel pump and fuel filter. What I did noticed is that when I plug the pcv the ltft drops to 0% during iddle and isolates from 0-10% during part throttle. The original pcv is the one that has a small hole on the pcv. I installed the one with the check valve to see if it made a difference and it worked the same as the original one. What could cause that vacuum leak through the pcv? I replaced the grommet as well, but to no avail. Any suggestions?

02-09-2015, 01:49 AM	#20
chevyman70 Registered User Join Date: May 2002 Location: Lakewood, CA Posts: 194	Re: 5.3l 4l60e issues NEED HELP! So got a chance to play around with this continued issue. Ltft still at 25% at part throttle, 10 to 18 at idle. I get p0171 and p0174 codes. Replaced intake manifold gasket as well. Replaced fuel pump and fuel filter. What I did noticed is that when I plug the pcv the ltft drops to 0% during iddle and isolates from 0-10% during part throttle. The original pcv is the one that has a small hole on the pcv. I installed the one with the check valve to see if it made a difference and it worked the same as the original one. What could cause that vacuum leak through the pcv? I replaced the grommet as well, but to no avail. Any suggestions?