Strange acceleration issue....
Thread Starter
Intermediate
Joined: Apr 2020
Posts: 33
Likes: 6
From: Ocala, FL
Strange acceleration issue....
Ok, this one is unique. 1994 LT1/Auto, all stock. Opti was replaced about a year and a half ago, ICM was replaced last week(Fun tow truck ride), BOSCH 3 injectors, plugs and wires all new. Car starts and runs smooth. Under hard acceleration it will take off and accelerate "ok" then suddenly about 3-4K rpm's, it acts like I've all of a sudden got 100 more horsepower. Doesn't buck or skip, it just suddenly pulls harder all the way to 5500. This isn't cam overlap, this is like switching cam profiles or something. It's not violent, but you can feel the difference in the seat of your pants. Its very strange. I would love for it to pull that hard at all RPMs lol. I feel like it doesn't have the power it should down low. I can't get it to do a burnout unless its a donut, just bogs and pulls through the brakes(sucky 2.59's also contribute I'm sure). I can't accurately describe it, other than it acts like the timing suddenly advances or something of that nature. It use to be once in a while, but now its repeatable every time. Torque converter issue? Opti again? I'm clueless. Thank you!
Drifting
Joined: Jun 2018
Posts: 1,678
Likes: 229
From: Michigan
VTEC kicked in yo! 
I can't tell if you think the lack of power or extra power is the issue.
How much run time is on it since the Bosch 3's, plugs, and wires were done? You say "new", how new?
Couple of things here, I believe the 94 still had the non-vented Opti. Always some water moisture away from failing. New parts don't mean good parts, still need to verify their function. Any codes?Have you verified the basics like fuel pressure, alternator health (Voltage), and coolant temp sensor? Since it broke down recently are you on old gas?
I can't tell if you think the lack of power or extra power is the issue.
How much run time is on it since the Bosch 3's, plugs, and wires were done? You say "new", how new?
Couple of things here, I believe the 94 still had the non-vented Opti. Always some water moisture away from failing. New parts don't mean good parts, still need to verify their function. Any codes?Have you verified the basics like fuel pressure, alternator health (Voltage), and coolant temp sensor? Since it broke down recently are you on old gas?
Last edited by KyleF; Aug 13, 2020 at 06:26 PM.
Instructor
Joined: Jul 2018
Posts: 165
Likes: 53
This made me laugh. I heard if you scream VTEC during each shift you gain an extra 50 HP :-)
Only 95 and 96 got the vented opti but that's irrelevant since he replaced his and the replacement could have been either vented or non-vented. Mine just went out in my 95 and it makes me sick that I replaced my stock vented Opti with a non-vented one. But I had no choice since it's currently my daily driver and I needed to get it on the road ASAP so I bought one at a local auto store that had them on the shelf.
Get a 3000 stall torque converter and then you'll always be in your power band. I had a 4400 stall in my old LS1 Trans Am and next to the cam it was the best mod I ever did to that car.
Only 95 and 96 got the vented opti but that's irrelevant since he replaced his and the replacement could have been either vented or non-vented. Mine just went out in my 95 and it makes me sick that I replaced my stock vented Opti with a non-vented one. But I had no choice since it's currently my daily driver and I needed to get it on the road ASAP so I bought one at a local auto store that had them on the shelf.
Get a 3000 stall torque converter and then you'll always be in your power band. I had a 4400 stall in my old LS1 Trans Am and next to the cam it was the best mod I ever did to that car.
Le Mans Master
Joined: Aug 2015
Posts: 6,119
Likes: 1,994
From: St. Charles MO
You should probably do some data logging. I would bet that you have some issue with timing retardation at lower RPMs, and it's finally letting it have all the timing when you feel the power increase. Maybe you have knock, or hopefully just a bad knock sensor - something like that that's causing the ECM to pull a bunch of timing.
