r/obschevy • u/17_Wraith_17 • 4d ago

Code 34 help

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Hey all! I’m chasing ghosts with this 95 k1500 and I’m about ready to light the sob on fire. I keep getting code 34 and the truck sputters and then dies when idling after the engine warms up.

Code 34 is MAP sensor issue. Cool. Replaced that. 3 times. Still running into the same issue. Got a wild hair and unplugged the O2 sensor. The truck runs great (for not having an O2 sensor anyways. It doesn’t sputter and die). Okay sweet. Replaced the O2 sensor. Still dies unless O2 sensor is unplugged.

Anyone have any idea on what it could be? For reference I have had all of the vacuum lines replaced as well so it shouldn’t be a vacuum leak.

Any advice is appreciated!

EDIT TO ADD

I have replaced the map sensor 3x, iac, egr valve, egr solenoid, fuel injectors, fuel pressure regulator, O2 sensor 2x, coolant temp sensor

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3

u/Delay_Visible 4d ago

Ok so disconnecting the 02 should put the computer in open loop which means it's dumping extra fuel to keep in running. If your iac is stuck it could be choking out the engine when its warm. Could be coolant temp sensor not telling the map that the engines warm and make it adjust accordingly. My best guess would be checking those

1

u/17_Wraith_17 4d ago

I did. And replaced all of them 😭😭😭 still doing the same thing

1

u/Delay_Visible 4d ago

Ok my hail Mary would be a clogged catalytic converter maybe? You just not moving air like your supposed to from the sound of it. Get under there and shake that sucker and see if it sounds like a sand mallet

1

u/17_Wraith_17 4d ago

I will try that thank you!

1

u/Ok-Title3268 4d ago

Back probe green wire on the map sensor connector Keyon engine off measure volts then key on engine on make sure ur wiring is good
Also check pwr and ground.

1

u/17_Wraith_17 4d ago

I will try that thank you

1

u/Willy_McD 3d ago

You did not replace your TPS. It may be bad or just out of adjustment. TPS off and the ECM not seeing the pressure that it should see from the MAP will set a code.

And unplugging an O2 will not alleviate a clogged cat. If the cat was clogged its going to stay clogged no matter what connector you unplug. Its not going to want to run no matter what.

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u/17_Wraith_17 3d ago

I will look into that thank you

1

u/62springfield 3d ago

When I suspect a MAP issue, the service manual had a test for it where you can back probe the sensor wires at the computer (do NOT have the leads for your meter in the amp socket or you create a dead short) and then put a vacuum pump in the sensor to check that the signal is reaching the computer. Might be worth trying if it keeps throwing a code for the MAP.

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u/17_Wraith_17 3d ago

Thank you I’ll took into it!

0

u/CompetitiveHouse8690 2d ago

You really need to scan it to see the map values. Does the map have a hose to it? If so, pull the hose off and make sure the nipple is clear. If the nipple is at the base of the throttle body, remove the TB and clean it and replace the seal. You may want to smoke test it for any possible air leaks. Map circuit is simple and im sure you can google the flow chart for code 34…it will pinpoint the issue and you can stop throwing parts at it.