Girlfriend just picked up a '94 T/A auto last night with 125K on the clock. Car is in real clean shape and rides and drives like new. The only problem is one I've just noticed today, and upon WOT acceleration the car pulls strong and smooth up until 4800RPM where it pops and sputters, as though it hit a rev limiter. In neutral it will rev to right around ~5K where it does the same. It's 100% bone stock. Any clues what it may be or where to first start looking? Just found out the gas in there is 87, could the computer pull out that much timing to act as a limiter?

 

I don't know if the Aluminum Head LT1s share the same valvesprings as do the Iron Headed LT1, but on my car I was developing valve float at 4800 rpm and the car just basically fell on it's face.

Matt

 

Well, its cooled down a lot since earlier today. Just got back from floggin' the car a little bit (shhh... she doesn't know, hahaha) And so I got on it cold, car pulls hard, bangs second and car went a lil sideways. As car got warmer, up towards 210, it started to hesitate a little bit towards redline. Leads me to believe that the 87 octane plus todays relatively warm temps made for a bad combination. I'm actually a bit more impressed with that "measely" 275 HP now.

 

sounds like the optispark to me

 

Yeah...I'd stay away from a relatively high CR, low octane fuel and high temps.

Puts some 91 or 93 in there and see if it stops....the higher the octane the better. I had the same problem on my old Camaro (95) and it turned out to be an intake leak that ended up in the opti.

Eliminate the possiblity of knock and then start looking at the ignition.

 

Puttin 87 octane in your LT1 is probably the first mistake here . As it warms up, it will knock more and more. You're lucky that the engine didn't jump out from under the hood and kick you in the nuts for feeding it that cow **** . Try some 93 octane, and see what that does for ya.

 

Sounds like the optispark unit, their kinda known for that. My car has a bad opti in it right now, but mine makes it to about 6500, although if its damp out, it will only pull about 4500 to 4800.

 

Really? The opti is affected by temp, as well? BTW, I didn't put the 87 in there. The previous owners girl did. He had her fill it up, and well... ugh.

 

Sounds like the gas. before jumping to any conclusions about opti this or whatever, change the fuel, run through maybe 2 tanks of 93, and then you can be sure its not the fuel.

i hope the previous owner didnt put 87 in there all the time..

 

I'm not sure how people feel about it, but for a quick attempt to fix this, perhaps a little octane boost would be a wake up. Not to say that this is the right answer for the problem, but it will help reduce the KR a whole lot. It will also help to reduce the amount of time that it takes to get the fuel up to 93 octane spec.

Kevin rive: