LT1 Idle Quality
Thread Starter
Instructor
Joined: Sep 2000
Posts: 124
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From: Hortonville Wi
LT1 Idle Quality
The idle on my '94 6 speed is a little rough. It also doesn't run really smooth when driving in 4th in town. Is this normal or is something wrong? I replaced the opti this past winter (cured the miss I was having). It runs great otherwise. Also no touble codes. Any suggestions?
Le Mans Master
Joined: Jun 1999
Posts: 6,272
Likes: 2
From: Chino Valley AZ
Cruise-In I Veteran
Cruise-In II Veteran
Currently Corvette-less
Re: LT1 Idle Quality (LSCHMIDT)
Plastic vacuum tee under passenger fuel rail cover
One of the most commonly overlooked, yet easily recognized vacuum leak occurs with a plastic vacuum “T” under the LT1 passenger side fuel rail cover. Located about mid-way between the front and back, and situated very closely to the top of the intake manifold, the “T” is subjected to enormous heat.
Visual inspection often doesn’t reveal that the vacuum “T” has failed. The vacuum “T” tends to slowly disintegrate over a period of time. The best method for inspection is to actually turn the “T” over and look at the underside. What you find may shock you. Due to heat, the “T” fitting actually decomposes on the side toward the intake manifold and develops large holes similar to Swiss cheese. Replacement is cheap and easy.
GM calls that vacuum “T” a "valve". The GM part # is 14056648. You can pick one
up from your friendly Chevrolet parts man for cost + 10% + tax = $3.00
If you don’t have easy access to a dealership, you can call Jeff Kopp at 1-800-728-8267. Jeff can help you get the part.
:seeya Purp
One of the most commonly overlooked, yet easily recognized vacuum leak occurs with a plastic vacuum “T” under the LT1 passenger side fuel rail cover. Located about mid-way between the front and back, and situated very closely to the top of the intake manifold, the “T” is subjected to enormous heat.
Visual inspection often doesn’t reveal that the vacuum “T” has failed. The vacuum “T” tends to slowly disintegrate over a period of time. The best method for inspection is to actually turn the “T” over and look at the underside. What you find may shock you. Due to heat, the “T” fitting actually decomposes on the side toward the intake manifold and develops large holes similar to Swiss cheese. Replacement is cheap and easy.
GM calls that vacuum “T” a "valve". The GM part # is 14056648. You can pick one
up from your friendly Chevrolet parts man for cost + 10% + tax = $3.00
If you don’t have easy access to a dealership, you can call Jeff Kopp at 1-800-728-8267. Jeff can help you get the part.
:seeya Purp
