1998 yukon Mystery p0300 and rough idle still

[east302]

I took a look at the P0300 diagnostic table in the manual, is your MAP sensor voltage over 4.0V at idle?

 

[OilBurner2003]

I took a look at the P0300 diagnostic table in the manual, is your MAP sensor voltage over 4.0V at idle?

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Let me throw that PID up if I have it, I’ll go take a look.

Edit: Can’t seem to find the MAF voltage gauge or PID. Is there a specific thing it’s called?

 

[east302]

It’s the manifold absolute pressure sensor, may be under some variation of that.

 

[OilBurner2003]

Strange. I can't find voltage, only thing I can find MAP KPA: was 94, probably not the reading we're looking for.

 

[east302]

Yeah, you’d think it be buried in there somewhere. Here’s a way to manually test it just to make sure…

MAP Sensor Test (P0106, P0107, P0108) (GM 4.3L, 5.0L, 5.7L)

How to test the GM MAP Sensor (4.3L, 5.0L, 5.7L). Symptoms of a BAD MAP Sensor. Troubleshoot and test codes: P0108 (OBD II) or codes: (pre-95 OBD I). Testing The MAP Sensor. Multimeter MAP Sensor Test.

troubleshootmyvehicle.com

 

[OilBurner2003]

Yeah, you’d think it be buried in there somewhere. Here’s a way to manually test it just to make sure…

MAP Sensor Test (P0106, P0107, P0108) (GM 4.3L, 5.0L, 5.7L)

How to test the GM MAP Sensor (4.3L, 5.0L, 5.7L). Symptoms of a BAD MAP Sensor. Troubleshoot and test codes: P0108 (OBD II) or codes: (pre-95 OBD I). Testing The MAP Sensor. Multimeter MAP Sensor Test.

troubleshootmyvehicle.com

Looks like the next step for me now is the intake gaskets. Looks more time consuming than hard, Just got to pick a day I wanna do it. This is a good step even if it's not the problem, I would hate to fix the misfires only to dump coolant down the road!

 

[OilBurner2003]

Yeah, you’d think it be buried in there somewhere. Here’s a way to manually test it just to make sure…

MAP Sensor Test (P0106, P0107, P0108) (GM 4.3L, 5.0L, 5.7L)

How to test the GM MAP Sensor (4.3L, 5.0L, 5.7L). Symptoms of a BAD MAP Sensor. Troubleshoot and test codes: P0108 (OBD II) or codes: (pre-95 OBD I). Testing The MAP Sensor. Multimeter MAP Sensor Test.

troubleshootmyvehicle.com

Hello sir, I decided to do that test and have verified that there is a vacuum coming out of the oil dipstick.

Edit: I know a little is okay, but there is a clear suction on my thumb when I felt the dipstick tube.

 

[exp500]

Make sure you have eliminated or plugged vacuum source/PCV.

 

[OilBurner2003]

Make sure you have eliminated or plugged vacuum source/PCV.

Roger, plugged the PCV valve and the breather tube when test was done. From memory, I think that’s what I was told to plug lol.

 

[east302]

Oil cap opening plugged too?

@exp500 Thinking out loud, are there any other openings?