Engine pings under load, power loss
Thread Starter
Drifting
Joined: Aug 2004
Posts: 1,327
Likes: 5
From: 2010 C6 Grand Sport Convertible
Engine pings under load, power loss
Ok, being new to this LT1 world, I'm wondering where I should begin to remedy a few situations.
Here are the basics.
1995 LT1, 49,000 miles.
Best of my knowledge, original plugs, wires, coil and opti.
Here's the symptoms:
1) A pinging condition(6th gear low engine rpm's, heavy load). The engine does not pull to increase mph's climbing a long hill at 60mph.
That is one scenario.
2) When the A\C is on, the engine seems to occasionaly misfire when accelerating. Otherwise runs smoothly, especially at idle.
3) When outside air temp is very hot especially humid...ie Carlisle during the Sat. evening parade, After revving the engine a few times, the engine ran very rough at idle and misfired horribly for a several miles. The engine finally smoothed itself out throughout the evening. I think a high speed run on the highway helped. I did smell sulpher from the cats just before it ran well again.
The engine threw no codes at all.
Any thoughts?
Mike
Here are the basics.
1995 LT1, 49,000 miles.
Best of my knowledge, original plugs, wires, coil and opti.
Here's the symptoms:
1) A pinging condition(6th gear low engine rpm's, heavy load). The engine does not pull to increase mph's climbing a long hill at 60mph.
That is one scenario.
2) When the A\C is on, the engine seems to occasionaly misfire when accelerating. Otherwise runs smoothly, especially at idle.
3) When outside air temp is very hot especially humid...ie Carlisle during the Sat. evening parade, After revving the engine a few times, the engine ran very rough at idle and misfired horribly for a several miles. The engine finally smoothed itself out throughout the evening. I think a high speed run on the highway helped. I did smell sulpher from the cats just before it ran well again.
The engine threw no codes at all.
Any thoughts?
Mike
Racer
Joined: Feb 2006
Posts: 269
Likes: 0
From: Vancouver B.C.
Just a thought here........it should have thrown a C12 code. (meaning no codes, of course). In case you're not throwing ANY codes the diagnostic is incomplete.
Only reason I'm mentioning this is with your symptoms, I'd imagine SOME fault codes should display? (However, if you're getting a C12 code, then please ignore this.
Only reason I'm mentioning this is with your symptoms, I'd imagine SOME fault codes should display? (However, if you're getting a C12 code, then please ignore this.
Instructor
Joined: Aug 2007
Posts: 212
Likes: 0
From: www.C4guru.com Everywhere!
Melting Slicks
Joined: Dec 2004
Posts: 2,954
Likes: 2
From: Obama=death for America
How long has this been occurring? It almost sounds like you're running bad gas or gas with too low an octane. Next time you're on that hill, shift down into 4th. You should be able to accelerate quickly. If you can't, then post that and we'll go from there.
Thread Starter
Drifting
Joined: Aug 2004
Posts: 1,327
Likes: 5
From: 2010 C6 Grand Sport Convertible
This as been the same way for several months, altho more noticable now(A\C on) ? I've been using 93 octane all along, so I doubt its that.
There absolutley no codes thrown. If I downshift to fifth and floor it, it's fine. The pinging takes place in 6th gear under a load with low rpm's. Shouldn't the knock sensor retard my timing and stock the pinging? The misfires happened under extreme humidity and heat. I should probably tune her up, but I wanted to see if while I was in there getting cut up, if it made more sense to replace that damned opti-crap and water pump at the same time. I really do hate throwing parts at it to maybe solve a problem. Now, with the glowing headers.....They would glow only when the engine was acting up, or always?
Thanks,
Mike
There absolutley no codes thrown. If I downshift to fifth and floor it, it's fine. The pinging takes place in 6th gear under a load with low rpm's. Shouldn't the knock sensor retard my timing and stock the pinging? The misfires happened under extreme humidity and heat. I should probably tune her up, but I wanted to see if while I was in there getting cut up, if it made more sense to replace that damned opti-crap and water pump at the same time. I really do hate throwing parts at it to maybe solve a problem. Now, with the glowing headers.....They would glow only when the engine was acting up, or always?
Thanks,
Mike
Burning Brakes
Joined: Nov 2005
Posts: 871
Likes: 4
From: Pembroke Pines Fl.
ping
sounds like a basic tune up is needed, your getting hot spots in your cylinders and the hot spots are firing the gas air mix before your spark plug ignition takes place. Make sure you change the sparkplug wires with a good set.
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Drifting
Joined: Aug 2006
Posts: 1,326
Likes: 18
From: Los Angeles California
This as been the same way for several months, altho more noticable now(A\C on) ? I've been using 93 octane all along, so I doubt its that.
There absolutley no codes thrown. If I downshift to fifth and floor it, it's fine. The pinging takes place in 6th gear under a load with low rpm's. Shouldn't the knock sensor retard my timing and stock the pinging? The misfires happened under extreme humidity and heat. I should probably tune her up, but I wanted to see if while I was in there getting cut up, if it made more sense to replace that damned opti-crap and water pump at the same time. I really do hate throwing parts at it to maybe solve a problem. Now, with the glowing headers.....They would glow only when the engine was acting up, or always?
Thanks,
Mike
There absolutley no codes thrown. If I downshift to fifth and floor it, it's fine. The pinging takes place in 6th gear under a load with low rpm's. Shouldn't the knock sensor retard my timing and stock the pinging? The misfires happened under extreme humidity and heat. I should probably tune her up, but I wanted to see if while I was in there getting cut up, if it made more sense to replace that damned opti-crap and water pump at the same time. I really do hate throwing parts at it to maybe solve a problem. Now, with the glowing headers.....They would glow only when the engine was acting up, or always?
Thanks,
Mike
Thread Starter
Drifting
Joined: Aug 2004
Posts: 1,327
Likes: 5
From: 2010 C6 Grand Sport Convertible
I'll start then with the basic tune-up. What are the required parts for the tune? In the olden' days, it was plugs, points, timing, pcv and wires if needed. Now-a-days, no points, but there is a distributor cap and rotor buried behind the water pump. I can't set the basic timing, that's all been done by the general. What's left? Plugs, wires? and.....?
Mike
Mike
Instructor
Joined: Aug 2007
Posts: 212
Likes: 0
From: www.C4guru.com Everywhere!
Not including the Opti. Id vote for: Distributor cap, rotor button, wires, coil, timing, plugs, oil, oil filter, flush out the tranny, flush out the cooling system, pcv, clean out the throttle body, replace the air filter, change out the hoses, put some chevron-techron fuel cleaner thru it,....and if you meant your cats ARE glowing, chop em off and put on straight pipe.
Opti and waterpump are out of my jurisdiction......I think that about covers the basic "motor tune up" but if yoru going for more I would throw in some windshield wiper blades, washer fluid, new gas cap, radiator cap, check tire pressure, replace pads and rotors.....Thats all I got at the moment but stay tuned for more.
Opti and waterpump are out of my jurisdiction......I think that about covers the basic "motor tune up" but if yoru going for more I would throw in some windshield wiper blades, washer fluid, new gas cap, radiator cap, check tire pressure, replace pads and rotors.....Thats all I got at the moment but stay tuned for more.
Last edited by Corn Flakes; Sep 3, 2007 at 08:56 PM.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
I'll start then with the basic tune-up. What are the required parts for the tune? In the olden' days, it was plugs, points, timing, pcv and wires if needed. Now-a-days, no points, but there is a distributor cap and rotor buried behind the water pump. I can't set the basic timing, that's all been done by the general. What's left? Plugs, wires? and.....?
Mike
Mike
I had a similar symptom, after it warmed up and in high gear it would buck, kick loose power. I would have to back off on the gas to smooth out and if I down shifted, let the RPM come up where the engine was less loaded, the problem seemed to be much lessened, covered up or gone away.
It ran good cold untill 20 minutes later and it would just start to happen again. I’ll skip all the technical crap and history and just say I ended up replacing the opti. After that it ran normal again.
Plugs I doubt, wires just maybe, but optis are common. But that is the time to do the wires because of easy accessibility (and plugs to).
This is only food for thought, it reminded me of my problem.
I would think with a clogged cat, the problem would happen all the time and any gear.
Last edited by pcolt94; Sep 4, 2007 at 06:34 AM.
Pro
Joined: Nov 2006
Posts: 727
Likes: 0
From: Ocean City Maryland
Ok, being new to this LT1 world, I'm wondering where I should begin to remedy a few situations.
Here are the basics.
1995 LT1, 49,000 miles.
Best of my knowledge, original plugs, wires, coil and opti.
Here's the symptoms:
1) A pinging condition(6th gear low engine rpm's, heavy load). The engine does not pull to increase mph's climbing a long hill at 60mph.
That is one scenario.
2) When the A\C is on, the engine seems to occasionaly misfire when accelerating. Otherwise runs smoothly, especially at idle.
3) When outside air temp is very hot especially humid...ie Carlisle during the Sat. evening parade, After revving the engine a few times, the engine ran very rough at idle and misfired horribly for a several miles. The engine finally smoothed itself out throughout the evening. I think a high speed run on the highway helped. I did smell sulpher from the cats just before it ran well again.
The engine threw no codes at all.
Any thoughts?
Mike
Here are the basics.
1995 LT1, 49,000 miles.
Best of my knowledge, original plugs, wires, coil and opti.
Here's the symptoms:
1) A pinging condition(6th gear low engine rpm's, heavy load). The engine does not pull to increase mph's climbing a long hill at 60mph.
That is one scenario.
2) When the A\C is on, the engine seems to occasionaly misfire when accelerating. Otherwise runs smoothly, especially at idle.
3) When outside air temp is very hot especially humid...ie Carlisle during the Sat. evening parade, After revving the engine a few times, the engine ran very rough at idle and misfired horribly for a several miles. The engine finally smoothed itself out throughout the evening. I think a high speed run on the highway helped. I did smell sulpher from the cats just before it ran well again.
The engine threw no codes at all.
Any thoughts?
Mike
Le Mans Master
Joined: Feb 2005
Posts: 5,146
Likes: 3
From: The Motor City
I agree w/above tune, but don'e rule out bad or low octane fuel regardless of where it came from. Begining w/plugs etc. is a good place to start, from there if it persists you can look at other possible sources (cats, 02's etc).
