Rebob5

iTrader: (3)

I have a 95 firebird, I got it with 50,000 in 2001 and now currently has 100,000 miles and I think that the opti may be going on me. Im pretty sure its the stock one so its seen a few miles. The car has always driven fine and pulled hard through the rpm band but have noticed that towards the end of last year while you were driving if you got on it hard it would break up pretty bad as it went through the rpm's. It will break up real bad and backfire through the exhaust. It has 3 year old msd plug wires and new ngk's at the time of the wires and has been fine till last year. I planned on getting a new coil and also checking fuel pressure for starters to see if it solves the problem. Last year the catalytic converter plugged up and the car would barely run at all so I gutted the cat and all seemed to be fine at the time, Could that issue possibly have anything to do with the problem?

Thanks for the help

96z28_lt1

iTrader: (3)

100,000 miles could have something to do with the cap and rotor on the opti, these things are just like a normal vehicle where cap and rotor are wear tear items, althought if one was to go and replace those might as well replace opti with a gm one while your in the area. do your fuel pressure checks and such though

Rebob5

iTrader: (3)

If it were the opti would it start, idle, and run 100% normal when you aren't hard on it? It seems to me like if it were the opti it wouldn't run right the rest of the time and then break up under a hard load, I drove it today and 1 time it broke up bad at 3500 rpm and the next time was 5000 rpm. Im going to get a fuel pressure gauge and check that out and make sure thats not my problem.

96capricemgr

iTrader: (1)

So you alone have put 50K miles on the cap and rotor which were frankly likely original when you bought it yet you want to think it is a potential issue with the "opti" or wonder about other things rather than just DO A ******* TUNEUP AND SWAP THE CAP AND ROTOR as anyone would do with any other distributor equipped car.

The stupid people on the internet will tell you how "terrible" the opti is but never consider that no other distributor would be expected to last as long between cap and rotor swaps, those are tuneup parts, but this community is full of raging morons who will swear the "opti is bad" when all that went wrong was the cap and rotor wore out or got water in them. any distributor will act up if it gets water in it or the cap and rotor are left unchanged indefinitely and this is exactly what you and so many other LT1 owners do.

The only other reply you got pointed out you likely have 100K on a cap and rotor and your reply amounts to not want to accept that answer.

Then there is the fact you have 3 year old mediocre plug wires and you didn't say what NGKs but if a basic TR55 I would consider replacing them as basic plugs wear out fairly quickly. You probably thought the MSD wires were great but that is not what people here have found, many a high rpm or peak torque miss has been resolved by swapping away from the MSD wires.

I do understand you only put 50K on it 12ish years but things AGE besides just mileage.

Go ahead and check fuel pressure and such but if you want to believe the "opti is dying" rather than worn out cap and rotor or are hellbent on figuring out how to blame this on fuel pressure rather than doing a complete tuneup then just sell the car.

The LT1 gets a lot of bad press because it's owners are too stupid to understand distributor caps and rotors are tuneup items.

leadfoot4

iTrader: (1)

I agree. Based on what I've read both here and the Corvette Forum, I think people are under the impression that the Opti is a "sealed unit", that gets replaced as a complete assembly.

96z28_lt1

iTrader: (3)

needsless to say my last opti(a cheap one from orielly's because i was in a bunch) lasted maybe 1000 miles before the rotor started to arc to the cap instead of the actual post terminal. This caused a low rpm misfire but once rpms went higher then around 3k rpms it would clear up and run like a top. i noticed with a bad pump my car was hard to start and fell flat on its face in the higher rpms.... but hey thats just personal experience. I think a good tune up would do it well personally if your fuel pressure check out.

Rebob5

iTrader: (3)

96capricemgr, Its not that I didnt believe his answer I was just looking for options on other things that I could "try" beforehand, changing the cap and rotor isnt exactly easy on these engines. I understand that it has alot of miles and just like everything else things wear out and need to be replaced it just didnt seem right to me that it would run right under normal conditions and the not run right under harder acceleration but i guess that is what it will do. I guess i will just DO A ******* TUNEUP AND SWAP THE CAP AND ROTOR as anyone would do with any other distributor equipped car. LOL

leadfoot4

iTrader: (1)

It's not that difficult. You DO NOT have to remove the Opti from the engine. The GM engineers anticipated this operation, that's why the harmonic damper is a 2 piece unit. Remove the serpentine belt, then remove the 3 bolts on the damper, and remove the outer ring. You may have to rotate the engine to get the "arms" of the damper aligned correctly for clearance, but when you do, remove the plug wires, then the 3-4 screws that hold the cap in place. (they're a small Torx head screw, I don't remember the size, off hand.)

96z28_lt1

iTrader: (3)

the size is t-4 or reverse t4 or whatever its called, problem is sometimes they aren't long enough. The one i got from autozone about a year ago had to be sanded down a bit on the sides so i could get it in the holes to get 2 of the 4 screws

Rebob5

iTrader: (3)

Thanks for the reply's guys, I wasn't aware that it was not a all weekend project to change it out. I was under the impression that the waterpump and balancer had to be removed to change it out. I will definitely be changing the cap and rotor asap and hopefully my problem will be fixed. Thanks again

96z28_lt1

iTrader: (3)

the balancer does have to be removed but not the hub that its mounted too, technically even an opti shouldn't be an all weekend job, maybe a day. Be surprised how good you get at changing those things haha

BTC

The length of time required for the repair is directly proportional to the complexity multiplied by the number of beers you drink.