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We are trying to rule out any sensor problems and look for evidence of a vacuum leak.
Looks like your cold and hot ECT and IAT readings are good
Your cold MAP is 28.9 Hg". I was trying to find out if that was the reading on that day, its a little low.
CMP retard is good
When you have a vacuum leak thats unmetered air and it causes the fuel trims to go positive (compensating for a lean condition) at idle and then they go less positive at 2500 rpm because the leak becomes less significant as the engine starts to breathe. You have the opposite of that . Your trims are good, just dont indicate a vacuum leak.
Your key on voltage seems low, is your battery in good shape? Charging voltage is good
Another sensor that can cause problems is the throttle position sensor which is what "TP Angle" was supposed to be and that should not be 0 at 2500 rpm. In case I picked the wrong PID I hooked up to my 2006 GMC Sierra (Blazer not at this house right now) and found 3 related PIDS. Not sure which one is right but they all read greater than zero at 2500 so something may be wrong here. Try all 3 PIDS (screen captures attached).
The date was Oct 13 around 1:30-2:30pm that i did that test.My postal code is M6N4X7.
The battery and alternator was just replaced and replacing the alternator made a huge difference.
The throttle position sensor was swapped with a Chinese one I bought off ebay and didn't make any difference so I put the original one back on.
I also replaced the idle air control valve with a aftermarket one and it made no difference so I put the original one back on.
The 2 screen shots you sent me. Do you want me to set those up and take those readings?
I still see TP zero. It must be a wiring problem because I changed the TP sensor and it was the same as the old one.
sorry about the first pic with the ringer volume lol
I did my testing on a 2006 GMC truck because my Blazer is not at this house. I would like to get to the Blazer and verify that we are working with the right PIDS. I would like to get a reading, disconnect the TPS and watch it go to zero. If these are really your TPS values at the computer then we might have a wiring problem. You can start by checking the 5V ref circuit by measuring voltage from gray to black with the plug connected to the TPS with a back probe and put the truck through some paces to see if the voltage is correct and stable. Then watch Dk blue to black with the voltmeter and see if voltage moves smoothly as you move the throttle back and forth.
Ya I watched a youtube video today on testing the connector. I'll have to see if I have a good ground and 12v and the connector and see if I have variable voltage at the signal wire. It's weird that the pid is showing zero.
Thats why I have to make sure I have my "PID's" together so we dont wind up chasing ghosts. I don't use that software and I checked it out on a different truck.
10-14-2022, 09:37 PM
