Can the cats be checked
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,627
Likes: 4,071
From: Cape Coral, Florida
OK. What specific DTCs are showing in your vehicle now. Current and History, as well as "pending." The tools to read that are <$125 for higher quality tools capable of data logging, and <$40 for "economy" tools capable of reading the codes and doing some rudimentary diagnostics. If you can navigate this website and use a smart phone, you're capable of using the tools to do this. My recommedation is:
https://play.google.com/store/apps/d...hl=en_US&gl=US
Optimum adapter for that is:
https://www.amazon.com/dp/B07JFRFJG6/
The "economy" adapter for that is:
https://www.amazon.com/dp/B005NLQAHS
I own both and use them with the app on a couple of different android devices. I got the better OBD-Link MX+ adapter when I found the BAFX one was too slow to provide useful data logging for diagnostic use and performance tuning.
And I wouldn't pay for a compression test if they didn't write down actual measured cylinder pressures for all cylinders and provide those results for me.
And personally, I'd never do a leak down test on a single cylinder, or only on a few problem cylinders. That's another one you want to do all cylinders to have a comparison between what's "good"/normal and what's low/problematic.
https://play.google.com/store/apps/d...hl=en_US&gl=US
Optimum adapter for that is:
https://www.amazon.com/dp/B07JFRFJG6/
The "economy" adapter for that is:
https://www.amazon.com/dp/B005NLQAHS
I own both and use them with the app on a couple of different android devices. I got the better OBD-Link MX+ adapter when I found the BAFX one was too slow to provide useful data logging for diagnostic use and performance tuning.
And I wouldn't pay for a compression test if they didn't write down actual measured cylinder pressures for all cylinders and provide those results for me.
And personally, I'd never do a leak down test on a single cylinder, or only on a few problem cylinders. That's another one you want to do all cylinders to have a comparison between what's "good"/normal and what's low/problematic.
If the shop is better and they have a scope they can do a relative compression test if you know what that is without having to remove any plugs and costing a lot of money in diagnostic time…any shop that does it with a gauge is working in the Stone Age…it takes less than 5 minutes !!…it won’t show you the actual compression numbers but how each cylinder looks relative to each other as far as compression goes.
Thread Starter
Racer
Joined: Jun 2020
Posts: 427
Likes: 54
From: oroville ca
Replace the cam
So I was told that I need a new cam and lifters and the heads redone and springs and i AM WAITING FOR A QUOTE from the shop that told me this ... I asked so what has lead you to believe that I need a cam ? And he said well those motors are known for that and my mechanic who also works for Chevrolet came over and did some diagnostics and has come to the conclusion that you need a new cam. The car runs pretty consistently sluggish so I am kind of beginning to believe him.. Although my car still has plenty of power and I notice no real loss if I get on it a little seems to be normal power except for the stumbling. I just do not know how to accept that it is the cam ..... I will say that the motor has 134.000 miles not that much but enough I guess. I thought that if the cam was bad enough to cause the motor to stumble and be sluggish that I would notice a power loss of some amount. So I am looking at replacing the cam and the valve train, Have the heads machined head gasket set and so on. How much would you think it is going to cost for a cam replacement ? 2500.00? give or take
Thread Starter
Racer
Joined: Jun 2020
Posts: 427
Likes: 54
From: oroville ca
On a repair this big I should get a second opinion right ? I am wondering if I should just tell the next shop what I have been told or should I let them try to tell me something else ?
Thread Starter
Racer
Joined: Jun 2020
Posts: 427
Likes: 54
From: oroville ca
To be perfectly honest I feel I could go to every shop in Tracy one after another and I would end up paying 150 for an hour or hour and a half of diagnostics and have a different answer from every shop and be out thousands of dollars ... really !! Am I doing something wrong here '? ? ?
Thread Starter
Racer
Joined: Jun 2020
Posts: 427
Likes: 54
From: oroville ca
Also can they take off the valve covers and be certain it is the cam ? or do they need to take off the intake and valve covers to be certain? Or do they have to take the heads off to really be sure that the cam is bad? Is there any way to see the fault or the bad cam without actually removing it ? I just want to be sure it is the cam and see it with my own eyes if that is wrong then oh well it is not my fault the auto repair industry has made me this way .. I do not believe anyone when it comes to repairs to my car I am sorry but I did before all of this guessing and different reasons everyone has about what is the reason for my motor running like it is ... . I will not be alright if they replace the cam and so forth and find out that it was not the cam actually but a loose wire or a cracked spark plug or a clogged cat ...? No way would i not lose my cool if that happened ... lol "there will be blood"
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,627
Likes: 4,071
From: Cape Coral, Florida
Well saying that “those motors are known for that” isn’t diagnostics !!…now you say your mechanic works for Chevy…at a dealership ??…what diagnostics did he do specifically??…did he see any low compression doing a relative compression test with a labscope or one with a mechanical gauge..any misfires ??…now you can put a dial indicator on each pushrod and rotate the engine and check for wear, or actually remove the heads and lifters and physically see if a lobe is worn visually both requiring a LOT of time to do…now they could just crank the engine over and see if all the rocker arms move but using the dial indicator would be the most accurate…going into the tailpipe and intake manifold with a pressure transducer would yield a lot of info but only the more “advanced” shops do this type of testing without having to do any engine disassembly…seems to me your guys don’t even know how to use a scan tool or labscope never mind a pressure transducer…that’s all I have on this so good luck and let us know what they find.
Last edited by C5 Diag; Feb 15, 2022 at 12:25 PM.
Safety Car
Joined: Jun 2017
Posts: 4,786
Likes: 425
From: North Georgia, USA
To be perfectly honest I feel I could go to every shop in Tracy one after another and I would end up paying 150 for an hour or hour and a half of diagnostics and have a different answer from every shop and be out thousands of dollars ... really !! Am I doing something wrong here '? ? ?
Also can they take off the valve covers and be certain it is the cam ? or do they need to take off the intake and valve covers to be certain? Or do they have to take the heads off to really be sure that the cam is bad? Is there any way to see the fault or the bad cam without actually removing it ? I just want to be sure it is the cam and see it with my own eyes if that is wrong then oh well it is not my fault the auto repair industry has made me this way .. I do not believe anyone when it comes to repairs to my car I am sorry but I did before all of this guessing and different reasons everyone has about what is the reason for my motor running like it is ... . I will not be alright if they replace the cam and so forth and find out that it was not the cam actually but a loose wire or a cracked spark plug or a clogged cat ...? No way would i not lose my cool if that happened ... lol "there will be blood"
If all the rocker arms are rockin' when I turn the engine with the starter, then I break out the dial indicator and check how much lift there is on each rocker arm. If the cam is worn, one (or more) lifters won't move as much as the others.
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Thread Starter
Racer
Joined: Jun 2020
Posts: 427
Likes: 54
From: oroville ca
Absolutely thanks for the heads up Racer I am sure that if they say the cam is bad then it is bad. They said they want to take off the valve cover to make sure as you explained .. I do not see this shop telling me it is the cam then replacing it and it still has a missfire ... They just paid for a new cam for me if that happens.. ! I will not pay a shop that replaces a cam and then it is not the problem right ? No way !! They need to make sure as well just because of that. I mean right ? That is a nightmare for the shop if that happens not me ..
Thread Starter
Racer
Joined: Jun 2020
Posts: 427
Likes: 54
From: oroville ca
My torque tube was the problem
The torque tube was so bad that it felt like an engine mis or like it was running on 7 cylinders only. So after all of the diagnostics it eventually was the torque tube so I got a good deal on a brand new assembly from GM for only 1700.00 and they slapped it back in and low and behold my vette is back on the street and with a new way to lay down the HP !!! It is all done and it only ended up costing me 3900.00 total for everything done and warranty for a year ... So I am back on the road people and thanks for the help from all of you ... FOLLOW THE VIBRATION