When launching the car or getting on the highway right about 4500 rpms I hear a popping sound and the engine will cut out. Accelerates strong up until this area. Any clue? The other day I did notice a slight random popping or sparking sound at idle close to the opti. Not sure if the problems are linked or not but it also seems as if there is some excessive fuel. If i rev it up in the drive way there will be some fuel spray on the ground, is this normal or did the guy who tuned it give it too much gas? I'm getting terrible gas mileage. Around 9 MPG in the city. I'm new to LT1's so i need some advice on where to start please. Just purchased the car about a month ago.

 

for a 6 speed LT1 car, that is TERRIBLE gas mileage. i would recommend getting a scanner and running data-logs on the car to see what is going on. also, get a fuel pressure gauge on the fuel rail and see what your fuel pressure is looking like (check idle as well as under load, like WOT on the street). together, these two things will help you solve your issues, or at least get close to them. good luck

 

What type of scanner do you suggest? There are no engine lights, and yes outright terrible i fill up atleast twice a week

 

You have a 93. You don't need a scanner to pull the codes. Shoebox has the answer:

http://shbox.com/1/dlc2.jpg

Sounds like you have misfires. Misfires cause the O2 sensors to think the engine is running lean, causing the ECM to add more fuel that the engine doesn't need. Any exhaust leaks before the O2 sensors will also result in a "false lean" condition.

How long since the O2 sensors have been changed?

When you say "If i rev it up in the drive way there will be some fuel spray on the ground," do you mean there will be drips from the exhaust pipe? Most likely, that's the water in the exhuast condensing and blowing out of the exhaust when you rev it. Most "tunes" do not alter closed loop (part load/part throttle) operating conditions. Check for misfires (look under the hood in the dark, for that spark noise you heard near the Opti), exhaust leaks and faulty O2 sensors.

 

Great advice from Fred as always. When was the last time you looked at your air filter? Low mounted CAI's can and do get wet. Then nothing can breath right. First place to look should always be the easiest.

 

Thanks alot and no its not drips, there is a spray pattern that reaches about 8-12 inches back and you can smell the fuel. A buddy got out of his car one day and after i shut mine off and got out he was like "you runnin premium? i can smell it" lol so it is definitely wasting it somewhere at idle. as for the air filters it is the slp kit that runs down in the bumper and it has been very wet here for the last month. I recently purchased the car about a month ago so as for o2 sensors i haven't a clue the car has 184k miles and still purrs, no smoking or anything runs fine up until over 4k rpms..

 

I also do have a broken exhaust manifold bolt, the drivers side closest to firewall. i recently discovered it and try to keep the others as tight as possible till i have time to deal with it because i don't believe i can fix it with the motor in the car.