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93 gmc k2500 need help with live data from ecm

Gregg C
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Gregg C Enthusiast

Gregg C

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I was wondering if there is someone that can help me with this truck. It has a rebuilt s&j engine (5.7l 4 bolt main) that I have been fighting to get running well.  It has had all new sensors put on it except one thing to note is I received a bad engine with a cracked block installed the first go around and it was ran for a day to work and then next day back to the mechanic so it may have affected the new o2 sensor put on the good engine but I'm not sure. Well this 2nd engine runs really rough when its cold out and the colder it is, the rougher it runs.  It takes like 5 to 8 revolutions before it starts and it runs good for about 2 seconds then it just hits the floor, back firing and missing like crazy.  Another thing it does is once in a while the volts will drop from 14 down to 10 like the alternator stops working for 1 second then it jumps right back up. I've tried 3 different alternators and nothing seems to change it. It's like something gets turned on for 1 second thats shorted to ground and then shuts right back off but I'm not sure what it could be or if it has anything to do with the other issue. I've put new plugs and wires, rebuilt throttle body with injectors, map sensor, distributor, spark control module, knock sensor with pigtail, ignition coil, fuel pump, both coolant sensors, egr valve and solenoid, iac valve with pigtail, ecm and 3 different alternators. It really lacks power when it is warmed up and its getting bad gas mileage compared to the original engine.  I used a red devil river aldl cable and tuner pro rt to pull some data off of it but I need help figuring out why the blm is so low. Is it because of my o2 sensor or what could it be? What could be causing my voltage to drop off like that? I can't get it to drop voltage with the tuner pro connected either. Any help would be greatly appreciated as I am new to this tuner pro data stuff.  Thanks!

truck2.xdl

Edited by Gregg C
clarification of cracked block engine
grampadirt Senior Enthusiast

grampadirt

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Posted (edited)

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

Edited by grampadirt
Gregg C Enthusiast

Gregg C

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Thank you for replying. First thing I should mention is this screen shot was from a restart after warmed up. I had tried recording the whole warmup cycle but tuner pro crashed and didn't save. I used all ac delco sensors and the o2 sensor does fluctuate up and down like in your video but being in open loop, it shouldn't be using the o2 sensor signal. Even after it changes to closed loop the block learn multiplier is between 90 and 109 the 2 separate times I pulled the live data. It is the same block its learning from both times at idle and it will only switch blocks if I rev the engine. I was hoping it was the o2 sensor but it does go up and down and also the integrator is always between 125 and 128 so I am lost why the blm is so far off from 127? I'll try and upload a video and post a link.

Gregg C Enthusiast

Gregg C

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Posting a video below

Edited by Gregg C
double post
Gregg C Enthusiast

Gregg C

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Just now, Gregg C said:

 

Here is a complete warmup from start. Skip to 33:17 to get to closed loop.

grampadirt Senior Enthusiast

grampadirt

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Posted (edited)

 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.

Edited by grampadirt

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