grampadirt

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.

Kind of looks like a blower motor resistor.Is there voltage on the red wire?Try turning on the blower motor and check the voltage then.I would think the blower motor resister would be inside the cab though... Maybe the remnants of a trailer brake controller?..dunno..

Classic Industries has what you need...p/n 5671510

You didn't use a temp sensor meant for the aux. fan in the engine temp hole ,did you?

Did you replace the sensor in the driver's side cyl. head?,that's the one the gauge reads,the computer reads the one by the thermostat.The aux. cooling fan uses the one in the pass. side head.

Sounds like you have a warped rotor.

Don't think so,the computer controls the EGR valve and will need the signals from it.

I tried this years ago.....won't work.I discovered the difference when I sat the new intake next to the engine.I looked all over the 'net for some kind of adapter and came up empty.I eventually returned the new 3764 with much disappointment.Because these 454s with that linear EGR valve got passed over when it came to performance options,no doubt because they were a two year model only.Bummer

In '94 GM went to a linear(electric)EGR valve(at least on their 454s) with several accompanying wires so I don't think the '93 will work.

I use ALLDATAdiy.com,tons of info there.

Don't thnk so.I had to raise mine several inches and then barely got it out.You might have to rotate the crank so the pan will clear the 1/2 connecting rod journal.