Idle surges MAP sensor volt surges falls on face from 75% throttle 2 full throttle

1227747 AMUR TBI Map surges

88 K5/V10 Blazer 5.7 tbi 1227747 AMUR
Idle and Map sensor voltage both surging.


I can and did try adjusting TPS varying from .54 to .75, the best running was around .63 however it would dive, bog, falls on it's face or looses power when trying to go from 75% to wide open throttle.
IAC counts are 40-56 (depending on TPS) in park and are always 145 in gear.

BLM stays 128 most of the time.

The idle was set to 525 in gear with the IAC closed or fully extended and unplugged. The other readings were after re-plugging in the IAC.

I am kind of assuming that IAC 145 in gear means it wants more air? In which case a higher base idle would bring the IAC down? Is that correct?
Timing is set at 0. Engine is stock and has no modifications.
I did notice the MAP voltage goes up and down when the engine rpm surges up and down. Does that indicate a vacuum leak and if so how do I find it?
The only adjustable variables are base idle and TPS, so I am lost on what is out of adjustment?
I live at 5900 ft. above sea level, so it runs at high altitude.
Any help is very appreciated.
Thanks, Chris

I got the surging to go away by unplugging the air pump and plugging its vacuum.
It still falls on its face 75% throttle to full throttle.

look for some clues,

what's the o2 voltage when it falls on its face? steady high or low?

a severe ignition miss or a fuel starvation issue usually throws your narrowband o2 lean at WOT (normally narrowband should pretty much always be rich at full throttle)

you've been playing with your TPS, does it get a decent voltage at full throttle?

what's your MAP at heavy throttle like that? should be pegged at about barometric pressure, i'd hope, but is it solid or does it fluctuate?

if you post a datalog maybe someone will have some other ideas

Thanks, I will get more info posted today. I didn't know what where to check at this point.
I was going to try to datalog today but cant get my laptop/WinALDL to see the WinALDL to usb cable? Do I need an interface between them?
Is there a better software than WinALDL? It is looking for com1 and I can't find a usb option?
Thanks for Your help, Any info is appreciated.

Are you getting any cel codes? That would be a good place to start. Whether you’re using winaldl or tprt, either will be able to retrieve the codes or you could do the paper clip method.

I never did get my laptop to see the usb ALDL cable? My scanner adds aprox. 250 rpms while checking codes and viewing the data stream, is that normal?
My scanner requires a serial cable to hook up to the computer or printer. I don't own a computer with serial hookup anymore.

What are the setting values and what are there ranges that my bin is looking for?

The o2 voltage goes from the 200's to the 400's to the 800's and bounces back and forth and jumps between them. That's all the time driving or at an idle.

The always rich as You said is why I ask if the IAC always at 145 parked in gear meant it wanted more air? which could be the code 45 rich?

TPS, does it get a decent voltage at full throttle? solid 4.75 same driving as when the engine is not running and You floor it. How does the TPS effect the way it runs?
My understanding is it doesn't effect air/fuel, so what does it do? I ask after already playing with it lol and didn't learn anything. lol

MAP at heavy throttle? 3.65-3.76

The other code is the VSS vehicle speed sensor.

So, what are the value ranges that my bin is looking for?
Thanks Chris

10k resistor between a-b on aldl when hooking up scanner will send ECM into aldl mode which adds about 10 degrees spark and rpms goes to a 1000.

Take the "B" pin out of the ALDL connector under the dash. Seems like some cables put 10K across the A and B terminals and don't have a switch to disable it. Back the pin out and see what happens.

Brian

That makes sense. My usb to ALDL cable has a 10k jumper pin.

Google is your friend.

As a word of caution...read this in it's entirety and do not start throwing parts at it. Take the suggestions and perform troubleshooting checks to ensure the component is bad. This link is a good place to start and has some of those parameters that you been asking for. http://www.pirate4x4.com/forum/chevy...ing-speed.html

Thanks for Your help, and been there read that.
I also like to test the parts before changing them, but have spares for almost everything.
It would be easier if I knew what settings and range my AMUR bin expects to see from my sensors.