Chevym84

hey i was wondering if lt-1's are known like the mustag 5.0's for loosing compression(i know it depends on the history and millage and number of different things) but i have a 95 trans am lt-1 m6 and it has a rough idle....put new dist., plugs wires(basic tuneup and it was hell) and it still has the rough idle.....also misses alil...

96capricemgr

iTrader: (1)

No they are not known to lose compression, quite the contrary actually.

LM97Z

iTrader: (4)

Double check your tune, IMO, if taken care of, these LT1s will go along time before they wear out, i'm at 160K on mine, & it has rock solid compression & runs great, detecting a miss can be a hassle sometimes & you can't get any real solid answers, running a compression test doesn't hurt, i would check fuel pressure 1st.

Chevym84

ok...i mean i know i should check it but DANG the tune up alone was a pain never mind putin a gauge on some the cyl....maybe its colapsed lifter( i know i have a loud one...)

Chevym84

yea good idea with the fuel pressure...only has a miss every now and then...mostly just rough idle....now i know the check engine light comes on and the code is (32 EGR) i havent done real diag.. but the EGR is cool to the touch and not stuck open....( i know if EGR is stuck open it could lead to a rough idle)

moderate Z28

170,000 miles and I still have good compression. Is your car stock?

Chevym84

you know i dont know i've only had it 4months and yes i thought bout maybe a mild cam but it sure doesnt feel like it has any mods....

speed_demon24

iTrader: (6)

I tested a few cylinders I could easily get to and they were all within a few psi. It was around ~237 cranking psi iirc. A stock compression car will obviously be less.

Chevym84

yea im trying everything else besides checking comp. for abvious reasons(pain in the ***) people have been askin me if it has a cam and so on but it shakesat idle(thas bout it) i mean its a fast car but doesnt feel like it has an mods....

LM97Z

iTrader: (4)

Know offence, but know matter how hard something may seem, you really need to get down to it & do it!! You mentioned noisey lifters, this can cause a rough idle, if it runs "strong" wot & feels that its hitting on ALL 8, then most likely its something simple, how did the old plugs look like?? This will give you a VG idea of what shape the engine is in, was there any oil on them? Were any fuel foiled, or carbon foiled?? Knowone is going to be able to give you a solid "this is what it is " answer, especially a rough idle, have you checked injectors, one could be parcially blocked ornot working right, vacuum leaks, have you checked voltage, make sure its charging good, or that the battery doesn't have a weak cell, all these little things need to be checked. I will go out on a limb & say it sounds like a vacuum leak somewhere, thats the simplest thing too check 1st.

Chevym84

no yea voltage is good(only reason i know is i had a bad alt. and replaced it a month ago) the plugs all looked good(alil white but not much..about average). now i have not listed to the injectors and no i didnt not think about vacuum leak and i should of thought to do that. but thanks for the info i'm goin to check those things this weekend.

lifeisgood

iTrader: (4)

yea not known for loosing compression.
the lt1 i just pulled apart had 4 spun rod bearings. (yes i said 4 lol)
but had good compression in all cyl

Chevym84

damn yea i got one in the garage apart from a 96 impala with 1 spun bearing and the rod is in pieces in a bag(about 8 pcs)

Chevym84

yea i have one in the garage from an impala that has 1 spun bearing and i rod in about 8 pieces

Chevym84

well there is no vacuum leak, all the injectors sound the same (has a crisp hard tap) the only thing i have left to do is check fuel pressure but i dont think thats the problem..i'm just thinkin that loud liffter has something to do with it..