GM Truck Club Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter #1
I have a 97 5.7 Vortec with 315k o.g. miles that has a pretty bad ping even under light load. Is it normal or even possible that excessive miles and possibly low compression cause this? The truck doesn't blow noticable smoke, but it does burn some oil, maybe 2-3 qts. between every 10k-12k oil change.

I have always ran 91 octane since it was new and Delco plugs, but I usually get the cheapest option that Auto Zone's computer recommends.

Would a complete tune up help this? Timing shouldn't be an issue since the distributor doesn't have adjustment right?

I've seen many videos on youtube but I'm looking for a solution, not an explanation.

Thanks for any help,
Art
 

·
Registered
Joined
·
2,888 Posts
A full tuneup would be in order.

MyTBI engine loves the upgraded iridium plugs.
A hotter plug will help get better combustion. Start with a compression check.

Next, if you can get your hands on a scanning code reader, check the cam retard angle. It should be zero at ~1000rpm with the truck fully warmed up.
 

·
Registered
Joined
·
5,631 Posts
Also you need to be sure your knock sensors are working. You may want to replace them too. As far timing, yes, it can be set, but as mentioned it takes a code reader that can read cam retard angle. I have the same engine, same year as yours. I run ACDelco platinum plugs. Its what these trucks came with, but nothing wrong with an upgrade. Also with your miles, are you burning the oil, or leaking it. My rear main seal has a very slow leak, and has been that way for years. You have to pull the trans to replace that seal.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #5
What's up Kenny, with that many miles I think I might be burning oil. I'm going to start with changing the plugs and connecting to a scanner. I'm sure the knock sensor will display an error code if it's faulty, correct?

Thanks,
Art
 

·
Registered
Joined
·
5,631 Posts
Im not 100% sure ot will throw a code if the knock sensor is bad. You know your engine way better than I do, but I have seen a lot of these engines with over 400,000 miles on them. These engines are so dependable. IMO I think people just give upon there old trucks. They get tired of having the same old truck for a long time. I know the knock sensors are not expensive, and not hard to change. If it was me, I think I would just replace them and see if it helps, and I am not one to just throw parts at a problem. Or at least I would look at how to test them. Maybe some of these videos will help you test your sensors.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #7
Thanks for the link Kenny. I’m going to replace the knock sensor as well as they are like you stated not expensive. I’m not giving up on my truck since I had her since day 1, and I’m running that Vortec till it turns around and punches back and says she can’t go no more...hahaha!

I’ll post the outcome. Thanks again. Glad I joined this forum
 

·
Registered
Joined
·
2,825 Posts
I would do a compression check. You could have excessive carbon build up on the piston heads too. Cheap plugs? You get what you pay for in them. Probably should use platinum or irridum. Iridum will last at least 100k miles depending on engine condition. Platinum..... not so much. If you are using oil then it is possible your plugs get fouled early. Check them. A tune won't hurt either depending on how long ago it was last performed. Check the dist for excessive play as that is a lot of miles on one.
I think 10 - 12 k on oil changes is far to long. Even GM doesn't recommend that much of an interval.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #9
I would do a compression check. You could have excessive carbon build up on the piston heads too. Cheap plugs? You get what you pay for in them. Probably should use platinum or irridum. Iridum will last at least 100k miles depending on engine condition. Platinum..... not so much. If you are using oil then it is possible your plugs get fouled early. Check them. A tune won't hurt either depending on how long ago it was last performed. Check the dist for excessive play as that is a lot of miles on one.
I think 10 - 12 k on oil changes is far to long. Even GM doesn't recommend that much of an interval.
What’s up 002, she was due for new plugs so I changed to iridium. It helped and the pinging reduced but it still pings on hill climbs. Also, I have the knock sensor but haven’t replaced it yet, so if that doesn’t cure it I will do a compression check, and then look into the distributor. So How do I check for play in the distributor?

On the oil I called Mobil 1 and they claim they’re sin oil as long as it’s used with their filter is guaranteed up to 15k miles....but that’s probably more true for less mileage engines.
 

·
Registered
Joined
·
2,825 Posts
Iridum plugs are good but not if fouled. I would check them to see what they look like. Should be a light tan to almost white color for good burn. Medium gray to black is not good.
Dist check is with cap off.... See how much play you have when twisting the rotor/shaft and side to side. Best way is too pull it and check gear on the bottom to see if excessive wear as they tend to get sharpened teeth when worn.
While its true about Mobile 1 having great properties its also true that contamination does occur from fuel etc. If you are comfortable with that oil change interval then so be it.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #11
Minor update. I tend to always fuel up at Chevron with 91 oct and at the same station, only deviating from that when I have to. Well, that station was out of service so I fueled up accross the street at Shell using their 91 oct. so my hunch is, as their fuel started mixing its way into the combustion chamber the pinging deminished almost completely.....I can still slightly hear it but it’s gotten a lot better. As for difference in performance I really can’t say as I rarely get on it due to the age and wear n’ tear. Also I replaced the water pump a week ago but was advised to not change the knock sensor if it wasn’t giving that code. I was advised that usually sensors are far better from the assembly line than new, even OEM.

I saw this in another forum, similar symptoms as mine and no one could figure it out. In the end he bought a new used Silverado.
 

·
Registered
Joined
·
642 Posts
A hotter plug will help get better combustion
It will but a hotter plug can make pinging (detonation) worse. An old trick was to go a step or 2 colder if your plugs aren't getting fouled. To reduce detonation, you can pull timing (as @kennythewelder said, knock sensors may be bad) and/or add fuel (maybe your fuel pressure is low?). As you said, maybe Chevron was getting bad gas?

You could have excessive carbon build up on the piston heads too.
Yes, this will increase your CR and could cause "pinging"

You can pull your plugs and look at them, if they look like they have pepper specs on them, you're getting detonation and need to eliminate it ASAP before something gets damaged. Sometimes (not often) a loose exhaust pipe will sound like pinging.
 
1 - 12 of 12 Posts
Top