backfire

Guest · Post by **Guest** » Mon Dec 24, 2001 1:43 pm

Okay, when going down the road, my engine backfires in fourth and fifth, sometimes lower gears. I have replaced plugs, wires, coils, fuel filter, and a vacuum hose(leaking). I cannot get this thing to stop doing it, it's my winter driver, also have an 85 z28, and winter just hit yesterday, or I guess I should say snow, but anyway, no more camaro... Please help, I'll try anything to get this thing working!!!

Thanks

Kevin

Guest · Post by **Guest** » Mon Dec 24, 2001 1:52 pm

How does it run otherwise? If its sluggish, maybe the timing chain has stretched or jump a tooth.

Also check the injector -- see if its atomizing fuel properly. Those old TBI injectors can sometimes get icky and cause it to run really rich, which might be dumping gas into the cat and lighting off at inopportune times.

Guest · Post by **Guest** » Mon Dec 24, 2001 2:05 pm

no, it's actually not sluggish at all, it runs like a rapped ape starting out, but right before it starts backfiring, it kinda vibrates and that is when you know it is going to do it. It sounds to me like it's running lean, do you know what the fuel pump amp draw should be, it's 2.53A , I don't know if that is out of spec or not. Maybe I should check to O2 sensor too, I don't know....

98beretta kid · Post by **98beretta kid** » Mon Dec 24, 2001 6:12 pm

my friends truck was doing a similar thing and ended up being the timing chain, it was way to lose. im pretty sure that may be your problem

Guest · Post by **Guest** » Tue Dec 25, 2001 4:25 pm

Yeah, I was afraid of that, I'm really hoping that isn't the problem, i don't really have the tiem to do a new timing chain or a place to do it actually.... oh well, maybe I'll get lucky and see that tensioner and guides are all okay.....

Guest · Post by **Guest** » Wed Dec 26, 2001 6:21 pm

kmdrew26

I would guess your catalytic converter is bad. I had the same problem with an older Chevy Cav. They said it was plugged up. Chevy dealer said it would cost $550. Way to much. Went to a smaller shop and all was done for $150.

Hope this helps...BigMuz...

Guest · Post by **Guest** » Wed Dec 26, 2001 8:29 pm

yeah, I've been meaning to do a vacuum test to see what my gauge does from 1000 to 2500 rpm's I guess from what I've heard if the vacuum goes down by 3in. then I could have an exhaust restriction, I'll check that out and let you know!

Guest · Post by **Guest** » Thu Dec 27, 2001 5:02 pm

Quote (kmdrew26 @ Dec. 26 2001,8:29)yeah, I've been meaning to do a vacuum test to see what my gauge does from 1000 to 2500 rpm's I guess from what I've heard if the vacuum goes down by 3in. then I could have an exhaust restriction, I'll check that out and let you know!
kmdrew26
Reading all your problems I would bet my pink slip that you have a bad converter. I did the same things you did. Changed everything with no improvment. Bit the bullet and spent some money for a pro to tell me what was wrong.

Same problems, driving down the freeway and the car is backfiring, when turning car off you feel a vibration. Sounds funny. Get a new converter. All your problems will be gone!

BigMuz...

Guest · Post by **Guest** » Thu Dec 27, 2001 7:07 pm

Sounds like a good time to drop the exhaust at the header and go for a drive. Stay away from the cops of course.

Also if it is the timing chain you should be able to do it with the engine in the car. You will need to remove the oil pan to get the timing cover off however.

Dan

Guest · Post by **Guest** » Sat Dec 29, 2001 5:48 pm

Well, I have some news. I went to do a compression test and when i pulled out #3 plug the electrode and half of the arm was missing. I fixed the car for $1.46 I put a new plug in it and it runs great!?! I pulled the valve cover off and saw nothing wrong with the valves. I put a magnet down in the cyl. and nothing attached to it but some oil and little metal shavings, probably the electrode. I have no idea what caused this. Originally when this problem first occured and I put the new plugs and wires on, it quite backfiring for a couple of days, then it went back to doing it, so I figured it was being intermittant and the plugs and wires didn't help! must have been wrong. But the one thing that strikes me as strange is that the plug that i pulled from #3 the first time is the only one that had deposits on it.. Any thoughts???!!
Kevin

Guest · Post by **Guest** » Sun Dec 30, 2001 10:52 pm

What kinda deposits? If you can describe or take a pic, that would help. gnttype.org has some nice photos of plugs to give you an idea of what's going on in there.

Guest · Post by **Guest** » Mon Dec 31, 2001 3:35 pm

you may have what is called blow by which means oil is seeping past the ring and being burned in the cylinder leaving deposits on the spark plug. Any blue smoke out the tailpipe?? You may also have had a carbon deposit come lose and damage the plug or cracked the procelain when installing the plug--I have done it quite a few times. then within a few days the car starts runing like crap. If you changed the plug and the car runs fine I would not worry about it unless it starts running funny again. If it does it is time to do a compression test to see what is going on in cyl # 3.

Connect with your social network account