Hey guys,

I got a miss when engine under load at under 2000 RPM (i.e. 6th on highway at 55 and I jump on the gas I get a miss until RPM's come up, also happens anywhere else where I'm under 2000 and load up the motor). Once RPM's are up, no problems.

Car fires with 2 turns every time. Decent Idle. No smoke or other problems. Runs real good except the miss.

Anyone got any ideas? I'm stumped?

On a positive note, my LS1 brakes are in and they ROCK!!!!

mudkat

 

How many miles on the car?

 

got the exact same problem. Has it shown any codes yet? Mine showed a bad O2 sensor, so i changed it and it helped somewhat. I checked all my plugs and wires and the looked ok, my new opti came today, so i hope that's what it is.

 

Might also want to check your fuel pressure. When my fuel pump was going out the car would miss around 55 -60. Replaced the pump and it took the problem away.

 

gonna check codes next week...man I hope it's not the Opti...it's definitely not clutch slippage and it doesn't just happen at 55-60, but always at 1500 R's when I load up the motor...usually in a higher gear like 3,4,5, 6 at lower speed.

 

I know exaclty what you mean. It feels real rough up until about 2500 then it smooths out and feels fine. Ive been telling people that I HAVE to go fast or it won't run well

 

if i was allowed only 1 guess, i'd say spark plug wire(s)

 

You should NOT be in 6th gear going 55. You should be in fifth. If you have it in sixth gear and are going 50-55 MPH, the car will hesitate until it gets into a better RPM range for that speed. Downshift to fifth, get up to your desired speed, and chill it in sixth.

I never use sixth unless I'm going at least 65-70.

 

Thanks for the driving lesson...sure appreciate it! I'll try not to let it down to 55 in 6th...geez, was just describin the problem and it is a miss for sure.

 

wish it was plug wires...they're new...only 3x miles on em...hey, it still cooks when it's on the pipe!

 

Did you ever find out what the problem was??? I've got the same thing going on

 

well, I know it's something in the tranny. I haven't gone to the drivetrain forum but i will now. I know it's the tranny because if i'm drivin gin 5th and it feels rough, i'll just shift to 6th and back to 5th, but won't actually hit the gas while in 6th, and when I go back to 5th, feels fine. I'm thinking just a tweaked shift fork....

 

I had the same problem,
First time I tried to fix it, I changed the plugs and wires including the wire from the coil to the Opti. Problem fixed.
After six months it started again, this time I bought a scantool and I got strange results on my IAT sensor, it was showing 155F when the outside air was 40, so I pulled it out and tested it, it came out just fine, I checked the voltage on the connector and it was fine as well (5V)
So I decided to just disconnect the IAT sensor, guess what.....car pulls great, no more miss/hesitation/stutter.
I put a new one in and teh car pulls great