Frustrate with my Chevy Tahoe 5.7 vortec

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MystyD

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2000 Chevy Tahoe Z71 5.7l vortec
There is several issues I am trying to get help with. It's important too. It's a competition between the guys and I. The guys think I can't figure out what is wrong with my Tahoe. They have thrown so many wrenches in my way trying to tell me what I should and shouldn't do. I am almost feel a tiny bit of it made the problem worse. This is a guys vs girl competition. We all own either a Chevy pickup, Tahoe, or Suburban all with 350s in them. Some vortec some not. But mine is the one this little competition is over.
A little history. I bought the Tahoe very cheap because the guy I bought it from couldn't figure out what was wrong with it. I had it figured out by the next day. It was the firing order. Boy was he mad as ever. A girl getting it figured out in no time at all compared to his weeks of troubleshooting trying to figure it out. Lol. So that's how this competition began because of me boasting and him not ok with it.
The firing order wasn't the only problem come to find out.....the symptoms.
1. Sluggish.
2. Backfiring through the exhaust originally.
3. Poor fuel efficiency.
4. Smell of fuel in cab intermittently.
5. Exhaust backing up into cab (only happened once though but it was really bad, couldn't get it over 35 that night either.
Parked it to work on it. Been parked since October 20, 2021.
Parts I have replaced. And work I have done.
1. Changed oil. Running 10/40 full synthetic.
2. Changed spark plugs ( the spark plugs I took out had alot of carbon build up an were not gapped correctly )
3. Changed spark plug wires ( was told to do so when purchasing used vehicle the first time spark plugs are changed)
4. Replaced distributor, cap and rotor ( cap and rotor I took out had lots of carbon build up and the cap had a broken screw hole)
5. Replaced the heater control valve ( the other one was broke and bypassed so I just replaced it and took the bypass out)
6. Serpentine belt (under direction of the local auto part store)
7. Replaced fuel pump ( one of the guys broke the fuel line adapter so I had to replaced the assembly, when I did the fuel pump quit working so I replaced that as well)
8. Replaced the fuel pump relay. ( Reason the fuel pump stopped working)
9. Replaced the cam shaft sensor and the crankshaft sensor ( the computer was blowing codes that were related to these sensors so I changed them out)
10. Oil pressure regulator sensor( because the first person I allowed to help me thought that's where the crankshaft sensor was and ended up breaking the sensor )
Now the Tahoe just cranks but I can't get it to turn over. There is a back fire in the intake. After a few adjustments the sound changed and now it sounds worse. Several backfires from the intake. I think the cats are clogged but I don't think that would be the reason the Tahoe will not turn over.
My question is ok well it's not a question it's a plea for help. Any ideas on what can be wrong. I am so frustrated I am about to let the guys when and sell this stupid Tahoe. I love the truck and really love the fact it's a 4x4. It sucks I can't drive it though. I have had no vehicle since I parked it and I am over the walking thing. I seriously work on this truck trying to figure it out so much that one of my neighbors gave me another Chevy but a trailblazer with the whole top end taken apart needing a head gasket replaced. I jumped on it but that's for another post. Anyways I have adjusted the dotributor like 9 times so far trying to find TDC could that be the problem. Also the vacuum lines crumbled in my hand when I went to move it out of my way. Working on trying to get them routed correctly to. Could that be an issue? I don't know anymore it's driving me nuts. Anyone have any ideas on what I need to do to get this thing running and to also prove these guys wrong. I am worried they are going to put a time frame on me next since I have another Chevy to work on now as well. HELP PLEASE. Sorry it is so long but there is a lot going on with this Tahoe.
Thank you for any ideas or advice anything will help at this point I am at my wits end with this Tahoe and I can't let the guys be right on this.
Ps. Someone said something about a lobed cam???? I don't even know what that means or how to check it. ?????
 

Joe Dirte

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2000 Chevy Tahoe Z71 5.7l vortec
There is several issues I am trying to get help with. It's important too. It's a competition between the guys and I. The guys think I can't figure out what is wrong with my Tahoe. They have thrown so many wrenches in my way trying to tell me what I should and shouldn't do. I am almost feel a tiny bit of it made the problem worse. This is a guys vs girl competition. We all own either a Chevy pickup, Tahoe, or Suburban all with 350s in them. Some vortec some not. But mine is the one this little competition is over.
A little history. I bought the Tahoe very cheap because the guy I bought it from couldn't figure out what was wrong with it. I had it figured out by the next day. It was the firing order. Boy was he mad as ever. A girl getting it figured out in no time at all compared to his weeks of troubleshooting trying to figure it out. Lol. So that's how this competition began because of me boasting and him not ok with it.
The firing order wasn't the only problem come to find out.....the symptoms.
1. Sluggish.
2. Backfiring through the exhaust originally.
3. Poor fuel efficiency.
4. Smell of fuel in cab intermittently.
5. Exhaust backing up into cab (only happened once though but it was really bad, couldn't get it over 35 that night either.
Parked it to work on it. Been parked since October 20, 2021.
Parts I have replaced. And work I have done.
1. Changed oil. Running 10/40 full synthetic.
2. Changed spark plugs ( the spark plugs I took out had alot of carbon build up an were not gapped correctly )
3. Changed spark plug wires ( was told to do so when purchasing used vehicle the first time spark plugs are changed)
4. Replaced distributor, cap and rotor ( cap and rotor I took out had lots of carbon build up and the cap had a broken screw hole)
5. Replaced the heater control valve ( the other one was broke and bypassed so I just replaced it and took the bypass out)
6. Serpentine belt (under direction of the local auto part store)
7. Replaced fuel pump ( one of the guys broke the fuel line adapter so I had to replaced the assembly, when I did the fuel pump quit working so I replaced that as well)
8. Replaced the fuel pump relay. ( Reason the fuel pump stopped working)
9. Replaced the cam shaft sensor and the crankshaft sensor ( the computer was blowing codes that were related to these sensors so I changed them out)
10. Oil pressure regulator sensor( because the first person I allowed to help me thought that's where the crankshaft sensor was and ended up breaking the sensor )
Now the Tahoe just cranks but I can't get it to turn over. There is a back fire in the intake. After a few adjustments the sound changed and now it sounds worse. Several backfires from the intake. I think the cats are clogged but I don't think that would be the reason the Tahoe will not turn over.
My question is ok well it's not a question it's a plea for help. Any ideas on what can be wrong. I am so frustrated I am about to let the guys when and sell this stupid Tahoe. I love the truck and really love the fact it's a 4x4. It sucks I can't drive it though. I have had no vehicle since I parked it and I am over the walking thing. I seriously work on this truck trying to figure it out so much that one of my neighbors gave me another Chevy but a trailblazer with the whole top end taken apart needing a head gasket replaced. I jumped on it but that's for another post. Anyways I have adjusted the dotributor like 9 times so far trying to find TDC could that be the problem. Also the vacuum lines crumbled in my hand when I went to move it out of my way. Working on trying to get them routed correctly to. Could that be an issue? I don't know anymore it's driving me nuts. Anyone have any ideas on what I need to do to get this thing running and to also prove these guys wrong. I am worried they are going to put a time frame on me next since I have another Chevy to work on now as well. HELP PLEASE. Sorry it is so long but there is a lot going on with this Tahoe.
Thank you for any ideas or advice anything will help at this point I am at my wits end with this Tahoe and I can't let the guys be right on this.
Ps. Someone said something about a lobed cam???? I don't even know what that means or how to check it. ?????
I'd pull valve cover n watch rockers as you crank motor by hand. Make sure they all move. Could be bent rod. Passenger side is easiest to remove.
 

b454rat

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Whats the fuel pressure? Are the injectors clogged? Unplug the fuel pump relay and try to start it. Put some starting fluid to it and try to start it. Might need 2 people. If it will run fine with the fluid, then it's a potential fuel issue. If not then go to spark. I had a 96 that ran great, went to start it the next day and didn't start, but when it did ran like ****. Bad cap/rotor, tho they weren't that old. How is the antifreeze level? Blown head gasket? Intake gaskets could be leaking. What codes if any?
 

Joe Dirte

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I would hook up a scanner and see your cam position. If you cant do that then make absolute your not 180 out. Imo sounds like distributor is way off. Any codes?
That's a good point there. I've always lined up the oil pump with #1 in older SBCs. Doesn't work that well in the vortecs. Had hell of a time gettin it lined up right.
 

SUBURBAN5

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That's a good point there. I've always lined up the oil pump with #1 in older SBCs. Doesn't work that well in the vortecs. Had hell of a time gettin it lined up right.
Yeah any time you got it backfiring out the intake. I be worried. Shoot I've heard they wouldnt even start if it's way off. Better to do process of elimination and making sure it's all done correctly. At least imo
 

Joe Dirte

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Yeah any time you got it backfiring out the intake. I be worried. Shoot I've heard they wouldnt even start if it's way off. Better to do process of elimination and making sure it's all done correctly. At least imo
I'm getting Poppin in intake on my 98 but it's in time. I'm thinkin my updated spider may be leakin or has faulty injectors as 5&6 ports were clean in headers and motor has slight shake.
 

SUBURBAN5

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I'm getting Poppin in intake on my 98 but it's in time. I'm thinkin my updated spider may be leakin or has faulty injectors as 5&6 ports were clean in headers and motor has slight shake.
And I agree with that is timing and dizzie is right then I got to fuel next and injectors. Including pulling plenum and physically checking each injector
 

SAATR

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2000 Chevy Tahoe Z71 5.7l vortec
There is several issues I am trying to get help with. It's important too. It's a competition between the guys and I. The guys think I can't figure out what is wrong with my Tahoe. They have thrown so many wrenches in my way trying to tell me what I should and shouldn't do. I am almost feel a tiny bit of it made the problem worse. This is a guys vs girl competition. We all own either a Chevy pickup, Tahoe, or Suburban all with 350s in them. Some vortec some not. But mine is the one this little competition is over.
A little history. I bought the Tahoe very cheap because the guy I bought it from couldn't figure out what was wrong with it. I had it figured out by the next day. It was the firing order. Boy was he mad as ever. A girl getting it figured out in no time at all compared to his weeks of troubleshooting trying to figure it out. Lol. So that's how this competition began because of me boasting and him not ok with it.
The firing order wasn't the only problem come to find out.....the symptoms.
1. Sluggish.
2. Backfiring through the exhaust originally.
3. Poor fuel efficiency.
4. Smell of fuel in cab intermittently.
5. Exhaust backing up into cab (only happened once though but it was really bad, couldn't get it over 35 that night either.
Parked it to work on it. Been parked since October 20, 2021.
Parts I have replaced. And work I have done.
1. Changed oil. Running 10/40 full synthetic.
2. Changed spark plugs ( the spark plugs I took out had alot of carbon build up an were not gapped correctly )
3. Changed spark plug wires ( was told to do so when purchasing used vehicle the first time spark plugs are changed)
4. Replaced distributor, cap and rotor ( cap and rotor I took out had lots of carbon build up and the cap had a broken screw hole)
5. Replaced the heater control valve ( the other one was broke and bypassed so I just replaced it and took the bypass out)
6. Serpentine belt (under direction of the local auto part store)
7. Replaced fuel pump ( one of the guys broke the fuel line adapter so I had to replaced the assembly, when I did the fuel pump quit working so I replaced that as well)
8. Replaced the fuel pump relay. ( Reason the fuel pump stopped working)
9. Replaced the cam shaft sensor and the crankshaft sensor ( the computer was blowing codes that were related to these sensors so I changed them out)
10. Oil pressure regulator sensor( because the first person I allowed to help me thought that's where the crankshaft sensor was and ended up breaking the sensor )
Now the Tahoe just cranks but I can't get it to turn over. There is a back fire in the intake. After a few adjustments the sound changed and now it sounds worse. Several backfires from the intake. I think the cats are clogged but I don't think that would be the reason the Tahoe will not turn over.
My question is ok well it's not a question it's a plea for help. Any ideas on what can be wrong. I am so frustrated I am about to let the guys when and sell this stupid Tahoe. I love the truck and really love the fact it's a 4x4. It sucks I can't drive it though. I have had no vehicle since I parked it and I am over the walking thing. I seriously work on this truck trying to figure it out so much that one of my neighbors gave me another Chevy but a trailblazer with the whole top end taken apart needing a head gasket replaced. I jumped on it but that's for another post. Anyways I have adjusted the dotributor like 9 times so far trying to find TDC could that be the problem. Also the vacuum lines crumbled in my hand when I went to move it out of my way. Working on trying to get them routed correctly to. Could that be an issue? I don't know anymore it's driving me nuts. Anyone have any ideas on what I need to do to get this thing running and to also prove these guys wrong. I am worried they are going to put a time frame on me next since I have another Chevy to work on now as well. HELP PLEASE. Sorry it is so long but there is a lot going on with this Tahoe.
Thank you for any ideas or advice anything will help at this point I am at my wits end with this Tahoe and I can't let the guys be right on this.
Ps. Someone said something about a lobed cam???? I don't even know what that means or how to check it. ?????

You need to verify your distributor installation before you throw any more time and parts at the truck. Search for "finding cylinder 1 TDC in a small block Chevy". There are YouTube videos and written instructions on the subject. Verify that the distributor rotor is pointing at the #1 terminal when the engine is at TDC. Assuming your firing order is correct, the engine should crank and run. Check fuel pressure and make sure it's in spec both key on and engine running. If not, you may have an issue with the fuel pressure regulator, the filter, or your pump.

If you don't already have a scanner that will read live data from the engine (there are several Bluetooth adapters and apps available, or dedicated hardware) get one and find out if you have any active codes. You'll also need to see sensor data, such as coolant temp, air temp, MAF airflow, manifold pressure, and oxygen sensor status. These will help tremendously.

Your issue with backfiring and afterfiring (through the intake vs through the exhaust, respectively) is probably ignition related, but could also be a valve timing issue. If that's the case, somebody could have adjusted them poorly, or you could have a worn out timing chain causing a valve timing problem.

Plugged catalysts are also a possibility, but that very, very rarely is bad enough to cause a no-start condition. If you get the truck to run again, try disconnecting the exhaust from the manifolds and see if throttle response improves. That's a sure sign of plugged catalysts or other exhaust restriction.

You really just need some solid diagnostics on this engine to figure out the problem, instead of firing the parts cannon over and over. Good luck.
 
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