Classic Repetitive Problems

[TurdsOfMayhem]

Give you a good history first so hopefully all the bases will be covered. I have a 2002 Firebird Formula that I bought new. Within the first year I was very concerned of knocking coming from the motor, I had taken it to several GM dealerships and was just constantly told the same stories: it's aluminum it will make noise when its warming up, its the water pump, or my fav it's normal. Well after driving it for nearly 4 years, I noticed one day the knock was very bad, so I took it to Midas that I have had all my cars serviced over the years, have a great relationship with the shop, and the GM of the location is awesome. (I live in Houston, TX it's the Midas @ 1960 & Treaschwig aka humble-westfield). He pulled up a tech bulletin issued by GM that it has been a normal problem during assembly that a seal in the oil pan/oil line (i guess the one that supplies the motor) isn't right, and I had a bad lifter cuz of it. They replaced all the lifters, I had the car back for about 2 weeks when the problem came back, but even worse. At times now, it is a really nasty knocking/grinding sound that will change speed with the engine RPM, then go away, come back ect. I can always hear the valves (i'm assuming) making noise, and my idle seems hi, and it dips and revs when you put it in neutral, and just runs rough, I can hear thru the exhaust it miss firing... It's been awhile since that repair has been done bcuz I am so busy with work and college. The GM at Midas 'Mike' told me we should try a different oil. Well, I have been running Royal Purple (5-30 I believe) for 3-4yrs, and with that recommendation also wants to flush out the oil system. I personally don't think this will do anything, and don't want to spend un-needed money. I talked to an online friend that is a mechanic and he said it could still be a problem with the lifters and a sleeve, a bent pushrod, or something really serious.

The car has the following aftermarket equipment:
3:73 GM High Performance installed by MTI
Z06 Clutch installed by MTI
SLP Loudmouth Exhaust
SLP AirLid
SLP MAF
RamAir box and RamAir Hood

so really the vehicle IMO is still practically stock.

I have had the other classic problem I understand with bearings and what not going out in the rearend, just had all that stuff replaced too at Midas, but the really bad rearend whine is still there, and still knocks under deceleration when turning left. My dads 99z28 does the samething. So any insight on this would be nice too.

And 3rd, ever since the lifters being replaced, and the rearend stuff being done, I have been feeling my gas pedal bounce underneath my foot when you hold it at a constant position, now its not due to bumps in the road... I don't hear any change in engine RPM either, but whats weird, is I here this popping, knocking sound now that goes along when the pedal is 'bouncing'. So have no idea what is going on with that.

I searched the forum for threads, and read a lot similar, sorry for someone to have to repeat themselves, but some of the problems have been going on for so long, that I'd get someone else's expert opinion.

I greatly appreciate any help in this matter, and if anyone lives in Houston, TX (I live basically I-45 & FM1960) and wants to hear my car, drive it, or has someone they hold in high standards to inspect/repair my car, cool. I fully trust Mike at Midas, but I found out he wasn't the one that did the work on my car as I thought was gonna happen. So maybe one of the lackey's at his shop made an oversight.

Thanks for taking the time to read this, and am eagerly waiting for responses.

Jonathan Zielske
TurdsOfMayhem@aol.com

[Doom]

I'm sorry I can't exactly answer your question, but I totally know what you're talking about. This is exactly the reason it's been taking me such a long time to get an ls1 car. They all have lifter taps an spun bearings. I notice it more on the high mileage car. My dads mechanic owns one an says that these motors are known for this problem an GM never bothered to fix it. Good Luck an if you find out anything let me know !

[LS1Formula01]

Your lifter knock is normal because they are hydraulic lifters, I work at a dealership and have had 3 techs (good friends) look at my 01 Formula just to have enough supporting opinions. Hydraulic lifter knock is normal under cold start up conditions. Now some LS1s off the assembly line ran into piston/valve slap. This could almost be the case causing your misfires you are hearing. valve hitting the piston starts to leave an impression in the pistion causing minor misfires or even small scale detonations. You might want to have your heads taken off and have the valve and piston faces looked at also, just my opinion.

[TurdsOfMayhem]

Your lifter knock is normal because they are hydraulic lifters, I work at a dealership and have had 3 techs (good friends) look at my 01 Formula just to have enough supporting opinions. Hydraulic lifter knock is normal under cold start up conditions. Now some LS1s off the assembly line ran into piston/valve slap. This could almost be the case causing your misfires you are hearing. valve hitting the piston starts to leave an impression in the pistion causing minor misfires or even small scale detonations. You might want to have your heads taken off and have the valve and piston faces looked at also, just my opinion.

From what I understand some lifter knock is normal. But it is after the car is completely warmed up. Sounds more like the valves to me but not sure. Say they take the heads off and see that the piston is slightly scuffed or what not from piston slap, if I were to buy new heads say from MTI like there 2R set, and even went as far as to buy new pistons (because I don't want something that isn't 100%) would this prevent this problem from happening again?

Thanks guys for your input