grampadirt

Look for something like CMP ****** Offset,probably under the live data heading.That's where it is on my Autel.

Could be a leaking wheel cylinder soaking the shoes and making them lock the drum.Pull the wheels and have a look.Of course it could be a bad diff...time to open it up and have a look.

Why did it take over a half hour to go to CLOSED LOOP?It should happen in a few minutes.It took forever for your engine to get up to almost 190°,operating is 195°.Is there a thermostat in it?If there is it looks like it's stuck open.Looking at your O2 sensor it never fluctuated betweeb 100(or so) and 900(or so),all I saw were steady numbers...400s,500s,600s and then finally 700s....not the way a O2 sensor works.Change that O2 sensor gauge to a graph and you'll see what I mean.Pay close attention to the voltage values on the side.The O2 Sensor will start in the 450 range and as it warms up the numbers will start to jump from low to high and keep doing it.The O2 sensor plays an important role in supplying the correct amount of fuel to the engine.What's with the knock counts? Why is it pegged at the high end of the gauge? Something looks wrong there.

Do a search for A/C conversion valves,I just found a bunch.

Did you use ACDelco or Delphi sensors? Any aftermarket parts are suspect to their quality.Also,with the coolant temp being what it is the fuel system should be in CLOSED LOOP,check to see if the O2 sensor is ranging from low .100mV-.900mV.If you can snap a pic of the O2 sensor's voltage,it should be an up & down zig zag pattern. Here's a video I did a long time ago(not so good camers :(),look at the lower left gauge \,the voltage is constantly changing....is yours doing this?It should take a few minutes for it to warm up enough to start ranging,when it gets warm enough your fuel system should go into CLOSED LOOP.When that happens the ECM will start using the sensors to regulate the fuel,timing etc. https://youtu.be/30K9GwMqxC0

Re-install the driveshaft and try again,I'll bet the tailshaft is spinning and not letting the parking pawl engage.

Know anyone with a good scanner? I'd check the fuel trims first,they'll tell you alot.Check the MAF sensor,might need a cleaning.Got a clean air filter?Does it have the correct spark plugs?

Is this what you're looking for? https://www.originalair.com/91-93-chevygmc-truck-ac-compressor-upgrade-kit-v8-stage-1

Thanks bud,i don't often post but i do browse the site occassionaly. I bought an Autel MaxiPro808 scanner which helped a lot.

Well,got her running pretty good now,hopefully it will last. Removed the #3 connector to the PCM and tested all the wires from the throttle body connector to check continuity....all were good.Noticed a split on a vacuum connector coming from the air box down to a fitting on the engine,replaced that.Went to AlldataDIY(been a member for years) and found that vacuum tube went to the fuel pressure regulator.Not sure if it had any bearing on the problem.I put it all back together and bingo!! The main dtc was p1512,correalation between the requested throttle body % and the actual %.So my son's pretty happy he has his car back

So,this is my son's Trailblazer....it went into reduced engine power one day on his way home from work and barely made it to my house.Plugged in my scanner and came up with P1512,P1515 & P1516.A friend of ours,after checking out You Tube installed a new throttle body,no change.It still has an erratic idle...goes up and down from 500rpm to about 2000rpm.Re-installed the old one and returned the new one.For some reason it got better and now only has a P1512 code.Did a idle relearn procedure but not sure if I did it right,no change.Both O2s acting funny so replaced them,no change.Tugged on the wires at the connector,no change.They seem fine.One odd thing though,the actual throttle position is at 22 and the throttle position desire changes as it should.Also when stepping on the gas pedal shouldn't the throttle blade move accordingly? It is fixed closed. Any Ideas? I'm thinking of getting another throttle body. Posted here because I saw nowhere else to post it.

You're Welcome,glad I could help.

There are three temp sensors....the one one the pass, head is actually a switch which will close at approx. 220*(I tested mine in a pan of boiling water with a thermometer) and turn the aux, fan on.The one in the drivers side head runs the temp gauge,the one under the thermostat housing sends a signal to the PCM(this one has a direct effect on how fuel is delivered to the engine).Remove and clean the EGR valve of any carbon build up on the valve and in the intake manifold(I use a vacuum cleaner as I scrape and clean).Check the TPS to make sure it sends a smooth signal to the PCM,a DMM will work here.Also,the ICMs are a known weak point on these distributors,check that.one more thing,be sure to check the timing with the connector(under the glove box)disconnected,it should be 4* BTDC.You can try a reset precedure on the IAC,might help. Do yourself a favor and subscribe to alldatadiy.com,I've subscribed for years and it has helped me immensely.Good Luck.

Sup Nick

I put my little cb in the cubby where the cd player would be on GMT400s,fits well.Not a lot of range but works well when off roading with other trucks.Magnetic antenna with cable going down the rear door jamb behind the rubber seal.