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Discussion Starter #1
Hey guys, I fired the chevelle up this weekend since it was so nice out. It's been asleep all winter and today was the day. But I noticed somewhat of a popping coming from the drivers side exhaust. All my specs are in my signature. I only drove the car once after the roller cam swap in the Fall and maybe didn't notice the popping. What I did so far was pull the plugs. In the pic, from right to left is 1-3-5-7 and you can see #1 is far darker. I cleaned up the plugs, started and no change. Thinking #1 is the culprit for the popping, I then replaced the plug with a spare, no change. I made a new ignition wire and no change. I also took a vid and put my hand in front of the exhaust so it amplifys the popping. Towards the end of the vid you can really see the popping moves my hand. Any thoughts or next steps in diagnosing? Could my valve adjustments be off? I used the EOIC method..


https://urldefense.proofpoint.com/v2/url?u=https-3A__youtu.be_LZ9F-2DhnOn3Y&d=DwICaQ&c=Nsle4b03kZ2S_ovlEw5wRUTtxP5tjUPhc45wKFbOgsI&r=huf8IwBLTuwm4enfLjTpJJLFvwDdlMmF2jtiAzJi8RY&m=Zd7TQKH99IQUJmWIngT3DNzIecIzi0Q9OGBWoXLRcjo&s=_pTQCOANiXftFsKLDobUHbb5kWgpmkSgAL1bQ9qF3lM&e=




 

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Did you notice if one of the headers is colder than the rest? Maybe you should recheck the valves since you only drove it once awhile ago.
 

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Mike,

Do you know anyone at a modern auto repair shop that could hook up a scope to it and take a look ? That would at least tell you if it is an ignition issue or something else. If it was running fine before you parked it then I doubt it has anything to do with valve adjustment. If it is a hydraulic roller you would have to be way off to make it pop.
 

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Discussion Starter #4
Did you notice if one of the headers is colder than the rest? Maybe you should recheck the valves since you only drove it once awhile ago.
Unfortunately I broke my infrared temp gun. I just ordered a new one.



Mike,

Do you know anyone at a modern auto repair shop that could hook up a scope to it and take a look ? That would at least tell you if it is an ignition issue or something else. If it was running fine before you parked it then I doubt it has anything to do with valve adjustment. If it is a hydraulic roller you would have to be way off to make it pop.

I don't know anyone at a shop and I think around here, if they can't hook a scan tool up to it, they probably wouldn't know.

It's a nice rainy dark day here in New England, maybe tonight i'll check for moisture in the cap or look for some arching?
 

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Discussion Starter #6

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I'm north of Boston, in Hamilton

Thats a ways up there. I consider Medford my second home :) Spent summers there till I was 19 and still visit a lot. My Mothers family is up there.
 

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Discussion Starter #9
No luck last night. I pulled the cap hoping to find some moisture or tracking and nothing, it was clean. I ran the car at dusk and couldn't find any arching either. My temp gun should arrive today and hopefully see what header is off. I did pull the plugs again after the engine warmed up. The color looked more consistent. There wasn't one wet plug like before. If the popping is due to a valve adjustment, think a comp test would tell? Thinking if one is stuck open a bit? Because popping would be fuel bleeding into the exhaust stroke, right? And my concern is how this is effecting my AFR. With the Fuel injection, my one o2 is in that header
 

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Any chance it is something in the injection ? I guess that is throttle body injection ? Does it clear up any if you raise the rpm ?
 

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a spray bottle with water on the exhaust after a cold start (or your bare fingers) will let you know if a cylinder isn't warming up as fast as the others.
 
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Discussion Starter #12
I didn't have enough time last night. All I was able to do was a cold compression test. And all the holes pumped up to 175-180. I pulled the valve cover too and the rockers were pretty loose. I can't imagine a valve being held open at all.

Bill, if I can find a helper I'll try running the rpm up and seeing if theres still popping
 

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Hey bud why not start by firing it up and then pull #1 plug wire. See what that does to the pop. At least you can verify the cylinder. I’m thinking ignition...go around your cap and make sure your firing order is correct. I’ve seen sillier things happen. I’ve also seen wires backwards and not backfire so worth a check.
 

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Discussion Starter #14
Hey bud why not start by firing it up and then pull #1 plug wire. See what that does to the pop. At least you can verify the cylinder. I’m thinking ignition...go around your cap and make sure your firing order is correct. I’ve seen sillier things happen. I’ve also seen wires backwards and not backfire so worth a check.
I don't know how, but I put the timing light on it and it was at TDC at idle. I put it back to 16* where I thought it was before the winter and the popping seemed to go away. I wonder if the engine being 16 degrees off from what the Fitech thought it was at, was messing with the system?
I did do a drop test and I didn't hear any change. Weather still isn't too nice here, so I'll play with it more. The little that I did mess around I still don't think it sounds great.
 

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Maybe just bad gas? My car sits a lot and the fuel quality around here is not great, I kind of had the same issue on a carbureted engine, lots of pops and back fires at random, put sea foam in the tank and cleaned the carb and the problem went away. Perhaps your problem may just be something simple like dirty injectors? Might be worth a try.
 

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Discussion Starter #16
Maybe just bad gas? My car sits a lot and the fuel quality around here is not great, I kind of had the same issue on a carbureted engine, lots of pops and back fires at random, put sea foam in the tank and cleaned the carb and the problem went away. Perhaps your problem may just be something simple like dirty injectors? Might be worth a try.

A good possibility with the gas'ohol that has been sitting in the tank all winter. I think I did put some stabilizer in there, but who knows how effective it is. As far as the injectors go, I don't know if you can see it with the naked eye, but the spray pattern in the TB seems consistent between the 4 injectors
 
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