The past couple days, maybe a total of about 5 times with no pattern whatsoever i have noticed my car back fire. It sounds like it back fires in the intake, and it will only do it once. It has been at night, during the day, hot out, cold out, after running hard, when gently crusing, coolant tempurature 170, coolant temperature 200. The only similar thing i notice is it happens after cruising at a set speed then pressing the gas down to accelerate. I can be light acceleration or hard, but just as long as its an increase it will do it, not when i let off. I dont know if this is making any sense, but it does sound like its almost back firing in my intake. I'm probably wrong but does anyone know what this could be?

 

Have you noticed anything else like poor gas milage or fuel smell about the time this started to occur? Had you done anything around the time the problem started? Have you done any tune-up type things recently like fuel filter, plugs or the like? How many miles on the tune-up parts since the last time they were changed? Are you using platinum plugs? A lean condition can cause back firing, how old is the fuel filter? Sorry I ask so many questions.

Dave

 

I have have had the care for 4,000 miles. Since i have owned it i have, replaced the fuel filter, replaced the oil and oil filter with 5w 30 synthetic, replaced the transmision mount, replaced the transmission filter and fluid, flushed the radiator and added a hypertech 160, bypassed the TB coolant - no leaks, added the cowl hood, and removed the flowmaster muffler.

I dont know what type of plugs are in there. I just purchased some NGK TR55's and im gonna get some over the valve cover wires along with Pacesetters. I have noticed that my gas mileage is a little bit worse. I went from about 27 highway to around 22-23. I cant smell unburnt fuel sometimes, especially when i park my car after driving it for a while. I plan on replacing the 02 sensors when i put in the headers so hopefully that will fix the problem. Any other ideas?

 

I have heard this when new rockers where put on and the valves were not able to open maybe one of them is getting stuck. I would try running a cleaner thru your fuel system to see if they are gummed up or something. Atleast its a easy inexpensive place to start.

 

Usually when this happens its because the car is lean.

Check the fuel filter

 

Might try retorquing the intake, the one time I had a problem like this it was an intake manifold gasket leak allowing fresh air in and causing the lean condition. The LT1 intake is known to loosen up, at least worth a couple minutes with a wrench to check.

 

What causes it out of curiousity?

 

It could be a week or broken intake valve spring. Does the car have a factory stock cam? It could be a lot of things.Could be a cam lobe going out.
You need to check a bunch of stuff till you find it,starting with the simple things and working to the harder things.Could just be a plug wire jumping to another wire??????

 

It hasnt done it in a long time so i havent really been worried about it too much. Fuel filter is new, but i did descreen my MAF so that's probably why it's running lean.