I am completely stumped . I have a crazy backfire in the exhaust and the end of every gear and I i feather the fuel towards the end of second before it shifts into 3rd it sounds like a machine gun. I have done a lot of work to the truck in the past couple months and I'm wondering what would cause this backfire as it wasn't doing it before. I have had the transmission rebuilt with sonnax surecure and shift kit installed . I replaced my entire exhaust with Pacesetter Long Tubes to 2 1/2" exhaust ending behind the passanger door with magnaflow mufflers. I replaced my O2 sensor and eliminated the EGR by pinching the end in a vise and welding it shut . I did not unhook anything else on the EGR except plugging the pipe as my headers did not have an EGR port . I also replaced all plugs and wires with NGK V POWERS and Bosch Lifetime wires.


SOLUTION ( CHANGED THE WORN OUT DISTRIBUTER CAP ) just a fluke it started backfiring when the transmission blew I guess.

 

its just unburt fuel that hits the manfolds, you will really notice it high speeds with od off! ! i love doing it with my cutout lol

 

Yeah that is great ....but I am trying to eliminate it. Just not sure why it never did it before .

 

there shouldn't be any unburnt fuel passing into the exhaust.

since the plugs fire on every engine compression stroke, then unless you've got some kind of terrible leaking injector dumping fuel on the exhaust stroke, then it should be a dry stroke.

an exhaust leak can make an impressive GA-GA-GA sound. also straight headers and/or straight headers with short glass packs that can suck that cold air back in when you let off the gas. i always loved that sound...

 

Well this is not an impressive sound....it's an embarrassing sound like it's gonna break down at any time. I would like to correct this if anyone has any suggestions . What would cause the unburnt fuel in the exhaust from the list of modifications I have done. It wasn't doing this before .

 

do you have cats ?

 

ask yourself the question in a different way.

what change(s) did you make between not having the sound and then having it?

 

well he has longtubes that make the flow diffrent i know with my longtubes it did it more

 

No cats ...I hate cats....I have 2 dogs , but what does that have to do with backfiring ? .....But really ....nope no converter .....longtubes to mufflers .

 

I have a spare set of wires at home i'm going to try just in case those lifetime bosch wires were a lemon. I'm going to install my new distributer cap and route the wires as per the DIY and see what happens. If this is being caused by the longtubes or the EGR Delete than I am going to have to live with it because they are not coming off .