'86 L98 has strange "popping" noise......

[ProEMTPFF]

I'm getting a strange "poping" noise from my engine under hard acceleration. When I hear the "pop" the car also shudders. This only happens when the RPM's get into the yellow. The only mods I have is K+N filter and air foil. The car only has 6500 miles on it. Any ideas??

 

[Vettefan87]

Is the check Engine Soon Light on? And sine you said that it only did it when the RPM's were in the yellow which is right around 5 grand, how did it run after it shifted if its an auto?

 

[ProEMTPFF]

No check engine soon light and when it shifts it runs great until it gets back into the yellow. I had a 454 cid once have a exhaust valve that was stuck and it made the same sound as this one. It was the exhaust comming back through the carb, this sound is similar.

 

[Vettefan87]

With such low miles and the car sitting most of its life, maybe the EGR valve is clogged? Just a thought. Someone more knowlegable will come along with an answer.



Justin

 

[G Winter]

check your fuel supply. filter pressure, etc

 

[ProEMTPFF]

Update, I thought this noise might be a valve floating? The car ONLY does this when its under a load. When I rev it to yellow or even redline with no load no "pop". Also, there is a ticking comming from the passinger side of the engine. I don't think its comming from the valve cover sounds like its higher around the fuel rail area??Vettefan87, what and where is the EGR valve? I haven't bought a manual yet but thats on the list. Also, how would I go about cleaning it?

 

[taegdh]

I would run some valve and fuel injector cleaner through it. The early fuel injectors can rattle and make you think you've got a rocker tapping on the valve base, or the lifter isn't pumped up yet. A can of cleaner and 93 Octane should let you know if it was carbon build up on the valves.

A low mileage car shouldn't really be stepped on like that. The parts still haven't been properly been broken in.

As a precaution this fall, you ought to also make certain you swap out ALL your fluids, including coolant and transmission and see if you have any crud in them. Then install ALL new filters. If you drive it or put it away for the winter, take it out for a leisurely drive to ensure everything has been properly seated. you've got to take care of them or they won't take care of you.

 

[ProEMTPFF]

A low mileage car shouldn't really be stepped on like that. The parts still haven't been properly been broken in.

What would be a good milage for the break in period?

 

[ProEMTPFF]

Found the problem awhile back. One spark plug cap not secured on the plug causing a arc and at higher RPM's losing the spark causing the power loss and smell of raw fuel. Easy fix yet embarrassing I didn't find it sooner.

 

[G Winter]

Don't feel to bad, even the pros forget the basics sometimes. Glad you found it and didn't cost you and arm and a leg.


Happy New Year !

 

[1984C4]

I had an 85 Trans Am that did the same thing. It too was a plug wire arcing on the engine block from a loose seating on the plug. Nice looking low mileage Vette BTW.

 

[vetteboy86]

What would be a good milage for the break in peiod?

You would think that the break in period for the motor, or the car for that matter was passed. Some people say 500 or 1000 or even 3000 miles. It is all in who you talk to. However if your car has 6500 miles, I would say you are okay to stomp the throttle once in a while. That is however much different then beating the car. If the car was broke in correctly then you are fine.

Craig

 

[ProEMTPFF]

I'm sure that was the cheapest fix I'll every have on a Vette. She's my baby, I bought her from my dad 6 or so months ago. So, I know she's been treated right from the start. He put the first 5800 miles on her the the rest are all me. Went for a ride today and she rolled 7900. I have ZR1 wheels on it now with 315's in the rear. Also, I'll be doing a tune up with new, MSD wire set, AC Delco rapid fire plugs and Hypertech cap, rotor and coil set. I'm keeping EVERYTHING I take off of the car for when and IF I ever sell it. I even still have the original Goodyear gatorbacks mounted on the factory wheels "in the picture".