You can convert kPa to pressure in inches of Mercury using an online calculator - and then subtract the two to get your typical vacuum gauge readings

Yours at idle = 100 kPa - 40 kPa = 29.5" Hg - 11.8" Hg = 17.7" Hg (vacuum at idle)
Mine at idle (video below) = 100 kPa - 37 kPa = 29.5" Hg - 10.9" Hg = 18.6"Hg (vacuum at idle)

Not a significant difference, especially when you factor in differences in Barometric Pressure (seldom really 100 kPa). Your Map Sensor from the 5.3 is giving reasonable values at idle.

Also from Video below:
Max vacuum on revving and then letting off = 15 kPa = 25.1" Hg
2000 rpm steady = 28 kPa = 21.2" Hg

 

I done the diagnostic for the p0101 that you sent and everything checks out okay, so I’m still not sure what could be causing this problem. It doesn’t have any converters on it and not even throwing a code for that. I’m honestly getting fed up with it lol. When I don’t the tune up I didn’t but AcDelco parts because it had the miss before I changed all of it and it had AcDelco plugs with the miss. I’m just wondering if I need to have the crank sensor relearn done on it since I tried to start it with the wire cut on it in the first place. The check engine light only comes on at idle only so I’m just confused.

 

Fuel trims move around - they are never static. Remember, fuel delivered is the total of both short term and long term fuel trim for each bank, and both change with RPM and load. So if long term is -8.6 and short term is +6.7 for a bank - then at that moment total is 1.9. If total was +15, then quite a bit of fuel is being added to the factory calibration to make the PCM happy with the fuel mixture. The opposite is true for large negative totals as well. Big differences between banks can indicated specific problems (why I previously asked for your fuel trims).

But bottom line is keeping the PCM and O2 sensors happy. As long as the O2 sensor voltage is rapidly swinging back and forth across the 0.45v line, then the PCM is controlling the fuel mixture to it's satisfaction. This is seen as a plot of O2 sensor voltage (not a snapshot).

 

Crank sensor relearn will not change the way the vehicle runs - only how it detects misfires.

Looks like you are ready to give up and we are just getting started with preliminary stuff. Sorry, but I 'm apparently not your man. These Internet diagnoses can be very involved, and I just don't have a desire to waste my time and get to post #50 and have you disappear. It happens quite often. Maybe someone else can help you. Really best wishes! I hope you can get it fixed.

 

I totally understand they can be involved but the only reason I said that means I’m getting aggravated at the vehicle because I’m very mechanically inclined and normally can fix things but this one has me stumped after I unloaded the parts cannon and have no vacuum leaks. I know that it does have a manifold leak at the collector on the passenger side. I’m not going to up and leave this thread because it’s my only vehicle at the moment and I can’t afford for it to break down on me.

 

Ok if you want to go on, lets get serious. I have three things for you to do at this point.

1. Need a good video that shows your misfire.
2. Need you to report results of a running compression test per https://www.alldata.com/us/en/suppor...pression-tests. Yes it is a pain to do.
3. Need you to get the BAFX/Car Diagnostic Pro so you can do plots and view enhanced GM PIDs (specifically cam sensor retard) + post screen shots and screen records.

 

on the video that shows misfire do you need to just see it running as in the whole blazer shaking?
okay I’ll check that one out
lastly is that supported on iPhone or something else?

 

Video and sound of the engine running and misfiring. If you want to also show the whole blazer shaking, or if you want to show anything while driving please do. I find uploading to youtube with link in post works well.

Car Diagnostic Pro is Android only.

If you have Iphone only then get Dash Command and the BAFX WiFi adapter (different). Then after you install app go into app and pay $10 more for GM PIDs for 2002. Will not be able to work with other vehicle systems like in Car Diagnostic Pro but the enhanced GM Powertrain PIDs are quite good. This is probably around $40 total. I see we can do the plot functions within a gauge. I have Dash Command too (but for Android). As far as I know its the same for Iphone.

 

okay once it stops raining I’ll try to get the video for you. I’ll get that Bluetooth adapter ordered as well. Dumb question about timing. When it’s idling it’s jumping around from 13° to 20° is that normal?

 

There also a noise coming from the front of the engine when I rev it up, I’m almost certain it’s the water pump but I’m not sure if it could be the timing chain as I’m unsure of how many miles are on it. Title showed 145xxx and that was reported in 2020 but the cluster says 136xxx