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tbi o2 sensor, header discussion PLEASE READ
- Thread starter 89k5350
- Start date
ToddMcF2002
Newbie
I tested a few map sensors and went through the diagnostic procedures. Could be a leaky header flange or a strait up bad O2?
It's hard to know without data (from an ALDL cable setup), but you should definitely check to see if there's an exhaust leak, as that can make a good O2 sensor deliver the wrong readings. So can a vacuum leak, but that generally has the worst symptoms at idle. Another test is to disconnect the battery to clear the fuel trims. If that makes it run sort of OK, but it learns it way back to running bad, that's a sign you're getting bad O2 readings.
Before you do that, you should check for trouble codes. I don't know if it's still as easy as jumpering 2 terminals like on earlier trucks. It should have logged a code by now for O2 or lean.
Before you do that, you should check for trouble codes. I don't know if it's still as easy as jumpering 2 terminals like on earlier trucks. It should have logged a code by now for O2 or lean.
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Definitely fix any exhaust leaks,esp before O2.
Egr valves are notorious for leaking when closed at idle, which can account for random idle issues, or stalling.
Tbi base gasket also notorious for vacuum leaks. The injectors are only good for @ 100k on good day. Cheap no name injectors even less, if they work at all.
GM says 12 psi at injector, reasonable stock TBI small block with headers should be more like 14psi. Most TBI pumps are capable of @22 psi dead headed.
Need to cover the basics before getting into mods.
What size ties and ring gear does this truck have? Overdrive ?
Egr valves are notorious for leaking when closed at idle, which can account for random idle issues, or stalling.
Tbi base gasket also notorious for vacuum leaks. The injectors are only good for @ 100k on good day. Cheap no name injectors even less, if they work at all.
GM says 12 psi at injector, reasonable stock TBI small block with headers should be more like 14psi. Most TBI pumps are capable of @22 psi dead headed.
Need to cover the basics before getting into mods.
What size ties and ring gear does this truck have? Overdrive ?
And exterior color...
I vote whatever they said
I vote whatever they said
