Chevy Tahoe 5. 7 - Misfire & High Idle Complaint
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Date: 2020-08-05
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Comments and reviews: 10
MyNewUserName47
i didn't notice if he later mentioned anything about the injector fuel pressure drop test being strange or not. that system has 2 injectors per cylinder, 1 electric injector where the harness plugs in, & 1 poppet injector right at the ports of the heads. the poppet injectors use the fuel pressure to open, it takes 5455 PSI for them to open. the pressure does vary a little, i've seen them open as low as 51. or maybe it was a problem with my gage, at any rate with the poppets working dead right, you can have a no start at 54 pounds of fuel pressure because the presssure is too low.
GM made a complete replacement fuel rail for this system because of clogging problems with the poppets, i don't remember for certain but i they may have also lowered the poppets opening pressure.
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i didn't notice if he later mentioned anything about the injector fuel pressure drop test being strange or not. that system has 2 injectors per cylinder, 1 electric injector where the harness plugs in, & 1 poppet injector right at the ports of the heads. the poppet injectors use the fuel pressure to open, it takes 5455 PSI for them to open. the pressure does vary a little, i've seen them open as low as 51. or maybe it was a problem with my gage, at any rate with the poppets working dead right, you can have a no start at 54 pounds of fuel pressure because the presssure is too low.
GM made a complete replacement fuel rail for this system because of clogging problems with the poppets, i don't remember for certain but i they may have also lowered the poppets opening pressure.
reply
Scott
Your Gopro smell detector is on the fritz. looks like oil though. A rubber glove hooks a smoker to almost anything. Add a few rubber bands and electrical tape, fits a Cox. 049 up to a Cargo Ship diesel. Totally not my idea. I've used a funnel with optional self adhesive weatherstrip foam lining.
Funny how these days we reach first for the scan tool when 30yrs ago it was the can of wd40 and a piece of fuel line to listen for vac leaks, big screwdriver for noises. We also assume high tech troubles too, although I don't thing the frequency of good old intake leaks and bad plug wires has changed much.
Good videos!
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Your Gopro smell detector is on the fritz. looks like oil though. A rubber glove hooks a smoker to almost anything. Add a few rubber bands and electrical tape, fits a Cox. 049 up to a Cargo Ship diesel. Totally not my idea. I've used a funnel with optional self adhesive weatherstrip foam lining.
Funny how these days we reach first for the scan tool when 30yrs ago it was the can of wd40 and a piece of fuel line to listen for vac leaks, big screwdriver for noises. We also assume high tech troubles too, although I don't thing the frequency of good old intake leaks and bad plug wires has changed much.
Good videos!
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Tom
I got a question for everyone. Got his same 5. 7, 30k miles since the rebuild. Just had new intake gaskets installed, has the newer spider injection design. Ran great for about 100 miles and, Is back to same issue. Bank 2 runs rich, with Bank2, sensor1 plugged in. You can smell it and the engine idles rough. IF I unplug the same sensor, engine idles smooth, doesnt run as well and obviously he engine light is on. I will do all of the injectors tests with a snap on scanner, but Im about done with the lean issue any other recommendations if all fuel system passes?
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I got a question for everyone. Got his same 5. 7, 30k miles since the rebuild. Just had new intake gaskets installed, has the newer spider injection design. Ran great for about 100 miles and, Is back to same issue. Bank 2 runs rich, with Bank2, sensor1 plugged in. You can smell it and the engine idles rough. IF I unplug the same sensor, engine idles smooth, doesnt run as well and obviously he engine light is on. I will do all of the injectors tests with a snap on scanner, but Im about done with the lean issue any other recommendations if all fuel system passes?
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Kevin
Haven't even gotten to the diagnosis yet in the video but I already know what's wrong. Intake gasket sucked in on one or both of the middle intake ports. Pretty common when someone uses cheap gaskets on these Vortecs because the only bolts holding the intake down are on the ends of the intake (nothing in the middle) The first one of these I diaged kicked my butt because I didn't know the design of the gasket and it was sucked in from the bottom side (so it was pulling vacuum on the crankcase, not sucking in from outside the engine.
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Haven't even gotten to the diagnosis yet in the video but I already know what's wrong. Intake gasket sucked in on one or both of the middle intake ports. Pretty common when someone uses cheap gaskets on these Vortecs because the only bolts holding the intake down are on the ends of the intake (nothing in the middle) The first one of these I diaged kicked my butt because I didn't know the design of the gasket and it was sucked in from the bottom side (so it was pulling vacuum on the crankcase, not sucking in from outside the engine.
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Gary
I have a friend with a 1994 Suburban with the 5. 7 and it has a rough idle, runs even rougher just above idle, and if you increase the throttle more it smooths out. We've replaced the map sensor, iac valve, oxygen sensor, plugs, wires, cap, rotor and it still has the issue. I have some mechanical knowledge but not enough to figure out what the problem is. I wish i could bring the truck to you but i doubt that's possible. I enjoy watching videos like yours because i strive to be good at diagnostics and not just a parts changer.
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I have a friend with a 1994 Suburban with the 5. 7 and it has a rough idle, runs even rougher just above idle, and if you increase the throttle more it smooths out. We've replaced the map sensor, iac valve, oxygen sensor, plugs, wires, cap, rotor and it still has the issue. I have some mechanical knowledge but not enough to figure out what the problem is. I wish i could bring the truck to you but i doubt that's possible. I enjoy watching videos like yours because i strive to be good at diagnostics and not just a parts changer.
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Steven
As soon as I read the description, I said. Vacuum Leak. One of the tricks we used to use, when I was a lot younger, was to spray WD40 near where you think the leak is. If it's a vacuum issue, the idle goes down immediately, and everything smooths out. YOU are the only online shop, where I actually trust the video maker. YOU actually know what you're doing. Thank You: ) for many entertaining hours. I'm retired, and just barely making it, so I don't have the means to give you any money that I don't have. So Sorry. :(
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As soon as I read the description, I said. Vacuum Leak. One of the tricks we used to use, when I was a lot younger, was to spray WD40 near where you think the leak is. If it's a vacuum issue, the idle goes down immediately, and everything smooths out. YOU are the only online shop, where I actually trust the video maker. YOU actually know what you're doing. Thank You: ) for many entertaining hours. I'm retired, and just barely making it, so I don't have the means to give you any money that I don't have. So Sorry. :(
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Atomic
You said if you could do it I could do it.
Well, I crushed my hand when the hood jarred loose and fell. Then I burned my other hand while I was frantically trying to get the hood off my hand. Then I dropped my tool box on my foot, fell back and dented the fender of my other car.
Please don't tell people they can do things like you do - it's friggin dangerous!
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You said if you could do it I could do it.
Well, I crushed my hand when the hood jarred loose and fell. Then I burned my other hand while I was frantically trying to get the hood off my hand. Then I dropped my tool box on my foot, fell back and dented the fender of my other car.
Please don't tell people they can do things like you do - it's friggin dangerous!
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Benjamin
He is a good mechanic and good mechanics are few n far between for Shure n that's why I do my own n have realized a automobile especially with computers can give a person the run around, that being said if a cam to crank sensor Miss correlation or not communicating correctly and if the wires are good and the sensors are good is it most likely the computer?
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He is a good mechanic and good mechanics are few n far between for Shure n that's why I do my own n have realized a automobile especially with computers can give a person the run around, that being said if a cam to crank sensor Miss correlation or not communicating correctly and if the wires are good and the sensors are good is it most likely the computer?
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Edwin
I swear now that I'm back on east coast I'm willing to, if my truck will make it, to bring it up to SMA to get worked on. Love how thorough and honest you are with diagnosis. Discovered you back when I lived in texas. My old 98 Chevy made the drive to the east coast but picked up some issues on the way. Need her running like new again
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I swear now that I'm back on east coast I'm willing to, if my truck will make it, to bring it up to SMA to get worked on. Love how thorough and honest you are with diagnosis. Discovered you back when I lived in texas. My old 98 Chevy made the drive to the east coast but picked up some issues on the way. Need her running like new again
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Walter
My 1996 Chevrolet Silverado issues in the morning to get starter it takes a while to get starter. After that runs good and stars good. Any help I would appreciated. Lost my job and money is low. Thanks
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My 1996 Chevrolet Silverado issues in the morning to get starter it takes a while to get starter. After that runs good and stars good. Any help I would appreciated. Lost my job and money is low. Thanks
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