I have noticed for a little while now a little drop in power with what seems a stuble in the engine while it is under load, Highway driving or especially while climbing a hill. After getting my exhaust i can clearly hear what sounds like a misfire/small backfire I guess you could say, any way a slight pop. Could this be my Coil gone bad or should I have the car in shop for diagnostics. Have recently changed wires (autolite) and plugs (Champion copper).

 

Go get it checked out is all i have as an answer.

 

if it's what I'm thinking, it's normal after getting an enlarged exhaust. There's a sample of what I'm talking about here

I'm not a fan of that gurgling or popping sound, but if it's not all that often, I wouldn't worry about it. If the car is lurching or jerking while it makes that popping sound, then I'd start worrying. When did you first notice the popping? Was it after you installed the exhaust or after the spark plug/wire job? Have you changed fuels recently? When's the last time you cleaned your fuel injectors with a bottle of the in-tank mix? Changed your air filter? All of these things are something to think about or try. If you think you've found the issue, post back here to let us know.

 

The Drop in power and subtle stumble was happening prior to the exhaust mod. There is no surging, it seemed to temorarily dissapear after I re-gapped the plugs, as well as a temporary return in power. I also have the notorious piston slap or loud lifters on a cold morning that seems to last about 30 sec. No oil burn and the plugs look clean. I have had the car in a shop for diagnostics already and they could find nothing (although I sure they did not perform a compression test) 200 bucks for diags and a cleaning of the injection system. I am at a loss to what it could be. If I need to have the valve train done, then I am thinking it would be a good time to uprade the cam and valve springs. Again your opinions are greatly appreciated.

 

the backfiring is normal its just usually muffled with a stock muffler

 

May have solved the small backfire, found a small exhaust leak in one of the Weld beads, which is good new's the bad new's is just after leaving the muffler shop went to the post office just to get rear ended. Not much damage probably will be getting a new rear bumper and the exhaust got bent some. So glad the guy has insurance, would hate to have to eat it. But still worried about the subtle stumble under load and the loss of power - again this started happening before the exhaust. My gut feeling is the coil, but still may be a valve train issue. Your thoughts on this as usual greatly appreciated.

 

Mine has done this a few times. It seems as though it happens most in 1st gear. You step on the gas pedal and you can just hear a deep sound...but it doesn't accelerate. Then all of a sudden it just unleashes the fury. Its like it can't breathe for a second. Then all of a sudden it can breathe again. I've had it happen maybe a total of 4 times. Then another time my car was sputtering while driving...I thought it was going to die on me. It only did it for a second. Then it stopped...I would assume it was some bad gas because I've never had that happen ever again. The hesitation thing almost never happens. Its not regular at all. Honestly I doubt the coil pack will make a big difference, but it won't hurt anything except your wallet.

 

It's not so much on acceleration from a stop but while I am climbing a hill or going down the freeway, there is also the missing low end on first take off like you describe and then like a bat out of hell it takes off. I am more worried about the underload while I am already moving, like when going up a hill i have accelerate a lot just to keep going up the hill. but you do bring up a good point about the bad gas I will try changing gas stations to see what happens.

 

Is your car throwing any codes possibly? Did problems start happening before or after you changed your wires?

 

No codes that I can tell, and now that you mention it. I think it did start after the wires and plug change regarding the power drop but the subtle stumble has been there for a while.