Backfiring through exhaust

[fordfreak300]

I am getting a backfiring through teh exhaust as soon as I let off the gas. It does nto have a rythem to it. Just pops in random order. Now these are the things I changed when i noticed the popping started. I went from 70 Jets down to 86 yets. I went from a 28 squirter to a 31 squirter aned adjusted my timing back up to 13 degree's initial. Now I had gotten gas a few days before and only drove the car once before and did nto pull enugh rpms to notice if it had poped or not. So to try to recitify the situation I went back up the 70 jets and put the 28 swuirter back in and droped back down to 12 * initial timming. This is where I was at when i started changing things. My total timming was at 38*. So i figured I would drop my total timing to 34* (MSD distro so i changed the bushing.) no change. I was still at 12* total where i was when i started out where I normally drive my car at. So in short I am back to 70 jets a 28 squirter and 128 inital timming with 34* total. (i did have 38* total before) I can't see ading more advance back in helping my situation. Any ideas? I am wondering if I got a batch of bad gas but i have to drive this all out to test that theory. I have not pulled a plug yet to chedck them as the car is still hot. Any other ideas?

[Marz]

What about if you give it a quick tap on the throttle... does it back fire then? If so... sound like you have a lean backfire.

Mine has that and is getting adjusted tomarrow.

[fordfreak300]

nope doesn't do it if I just give it a quick tap. I have to pull above 3,000 rpms for it to take place. It will do it while in neutral sitting or driving down teh road. Embarassing to go to change gears and everyone behind you htis the brakes cause they hear pop pop poppoppop pop. I am going to pull a plug after dinner to see what they have to say.

[fordfreak300]

ok i pulled a plug. it told me other than the bit of oil I am burning that everything with the spark plugs are fine. The spark plugs appeared normal with a bit of residue from some oil. Nothing I didnt;p find lat time i changed the plugs.

[fordfreak300]

Nes spark plugs did not help. It was worth a try. i aklreayd had them here and ready to go anway. The backfiring is happening where my fake cats are and after where the airpump pumps air in. Could this be part of the problem?

[frankiesaysrelax]

Nes spark plugs did not help. It was worth a try. i aklreayd had them here and ready to go anway. The backfiring is happening where my fake cats are and after where the airpump pumps air in. Could this be part of the problem?

Uhhhmmm yeah!!!!!

Backfiring on deceleration is often caused by air entering the exhaust system and reacting with the unburned fuel. Typically this is caused by an exhaust leak as what happens when the throttle plate snaps shut is that the exiting volume of exhaust gasses has inertia which actually pulls air in through the exhaust leak. However if you have the air pump pumping air into the exhaust, there's your answer.

[fordfreak300]

tguess it is time to block that sucker off. I just don't rememebr havign this problem before... i will check further for exhaust leaks too that may have developed while I get rid of that extra air being pumped in.

[fordfreak300]

it turns out I had an exhaust leak at my smog cross over tube. i pulged up the holes in the back of teh head and all was good.

[v8only]

good deal. I wanted to input, when I had my 77 powerwagon 360, the thing had giant craters all over the exhaust pipes. Every time I let off the gas, especially on the freeway, it would bang as loud as a gunshot, and literally shoot flames out the pipes. Boy did that scare the living crap out of me the first time It happened.

[anthonydalrymple]

"Anther one bites the dust. hey! Hey! Another one bites the dust. Yeeeeeooooow! Anotherone bites the dust....Heyyyyyyyeeeeeeyyyyyyaaaaayyyyyyyaayyyyyee ee....

[fordfreak300]

mine sounded liek an m-16 with someone playing with teh trigger. it is all good now.

[frankiesaysrelax]

mine sounded liek an m-16 with someone playing with teh trigger. it is all good now.

So why did you fix it? LOL.

Glad to hear you solved the problem.

[fordfreak300]

cause I didn't want to attract the two cops this little town has lol....