Well I'm stumped

[Squeegee]

well first off its a carbed 2.8. its running fine at idle, but once its in gear and i start to give it a bit of gas, i makes a popping/backfiring sound, i have no idea what it is. when just giving it a little gas it runs fine, but if i get on it at all it does it, but only in the mid rpm's. could it be something to do with the ignition system?

[34blazer]

Quote: Originally Posted by Squeegee

well first off its a carbed 2.8. its running fine at idle, but once its in gear and i start to give it a bit of gas, i makes a popping/backfiring sound, i have no idea what it is. when just giving it a little gas it runs fine, but if i get on it at all it does it, but only in the mid rpm's. could it be something to do with the ignition system?

does it free rev without the popping while in park/neutral? hows the exhaust, flowing freely or clogged cat. how many miles on the ticker?

[Squeegee]

Quote: Originally Posted by 34blazer

does it free rev without the popping while in park/neutral? hows the exhaust, flowing freely or clogged cat. how many miles on the ticker?

yea, it does free rev. odometer has 234k on it, not sure if its been rebuilt or not though. and the exhaust seems to be flowing freely, not sure how to check that though

[ap72]

sounds like a coil or a module going out- could also be the wires arcing over.

[SH-60B]

Check the timing and vacuum advance.

[ap72]

I missed the running fast at idle part- it probably is too far advanced timing. Maybe a vacuum leak but that usually doesn't result in popping. Set your timing to 10* with the wire unplugged and see how it runs. Timing rarely moves once set though- unless the clamp wasn't tightened properly.

[Deeze49686]

you overloaded it hauling the bithcezzzzz around......

its as worn out as patricia is..... time for an over haul......

[SH-60B]

Quote: Originally Posted by ap72

I missed the running fast at idle part- it probably is too far advanced timing. Maybe a vacuum leak but that usually doesn't result in popping. Set your timing to 10* with the wire unplugged and see how it runs. Timing rarely moves once set though- unless the clamp wasn't tightened properly.

What wire? It's got a carburetor, and a vacuum advance.

[ap72]

Nevermind then... I was assuming it had computer controled advance. If its vacuum and weights you may want to take it apart and make sure its all clean and moving freely, you could even do a recurve if you want to. Sometimes the centrifugal advance can stick causing it to be over advanced at idle.

[Squeegee]

can somebody explain the wires arcing over?

[Deeze49686]

its called an inductive misfire, and as my expereince shows that those always happen during the exact same criteria. Humidity, rpm, load, ETC, something has to be exactly the same as it was before. easy way to test for EMI (induction) noise. turn your radio on AM, and rev it, if your speakers pop, good chance you have spark arcing to ground.

[ap72]

I orginally guessed arcing wires- which it could be, but it usually won't pop from arcing wires- though its probably an ignition problem. I'd doa tune up with new wires, cap, rotor, and plugs. If its still doing it change the coil and module. The wires should be changed with the plugs and while some people say they'll last 100,000, miles I'm more inclined to say a few years or about 50,000 miles. A LOT of that depends on plug gap, fuel, oil, and rings.

[Squeegee]

the plugs were replaced about 2k miles ago, along with the cap and rotor, not sure if it just wans't installed right or not. is there anyway to test the coil?

[Squeegee]

damn gm and the retarded coil design, i can't get the bracket off

[SY2932]

Quote: Originally Posted by Squeegee

the plugs were replaced about 2k miles ago, along with the cap and rotor, not sure if it just wans't installed right or not. is there anyway to test the coil?

Yes there is. Like this and you won't even have to take it off the truck...


"This is a brand new MSD coil #8226. The coil does NOT have to be removed from the vehicle to perform these checks. Any connections on the terminals will have to be done with a paperclip or other small object as the test leads won't be able to reach the pins inside. This value should be infinite resistance (open). If not, replace the coil."


"From here on out, the resistive values are not "carved in stone" and are approximate. Here, the value should be very low or zero. If not, replace the coil."


"Here, the resistance should be high but, not infinity (open). If not, replace the coil. *These checks will work on a stock coil as well*"

[Raydar]

Thanks for posting that!
I've been dealing with GM stuff for many years and on many forums, and this is the first time I've ever seen pictures posted for checking the coil.
It's got to be helpful.

That's an expensive d@mn meter, too. Nice. (I'm just sayin'...)

[Squeegee]

seeing how i got a new coil, an y tips on getting it off, its held on to the bracket with to bolts and they won't budge, yes i tried PB Blaster. I did get it fixed though, i was checking the plug wires, and on the plug end, the whole metal piece that slips onto the plug came off, heh.

[dimerunner88]

you can't get it off the engine or the coil off the bracket? if you can't get it off the bracket just grind the bolts or rivets(factory ones are riveted on)

[SY2932]

Quote: Originally Posted by Raydar

Thanks for posting that!
I've been dealing with GM stuff for many years and on many forums, and this is the first time I've ever seen pictures posted for checking the coil.
It's got to be helpful.

That's an expensive d@mn meter, too. Nice. (I'm just sayin'...)

Thanks! You know what they say, "a pic is worth a thousand words" . Think how complicated it would be to try and describe that to someone without any pics. I would have have had to write a mini book. But with three pics and a description it's no biggie...

Yep after spending four years in the Air Force working of HR radios, I got an affinity for Fluke meters, Weller variable temperature soldering irons and Panduit GS2B cable tie tensioning guns.



Everyone who has never seen/used a Panduit cable tie gun think it is a pretty cool until they find out that it's a $200 tool. That's usually when they put in back in my tool box...

Regarding that "stuck" ignition coil, it depends how BAD you want to replace it. If you snap off both the bolts, you are going to have to pull the lower intake off to drill them out. Might as well replace the intake gaskets while you're at it too. Should take more than a few hours start to finish. As dimerunner88 mentioned, the brackets are riveted on. You will have to either drill or grind the heads off and punch them out to get the brackets off (that's how I remove them myself). Just use a small bolt and nut to hold them on the new ignition coil.