CEL triggers only while cruising

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Measure the orifice with safety wire or the like, and use the same size washer. or if you have a good drill index, take the smallest one and drill it to match your oem one. Or just delete the damn thing and don't worry about it.
 
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I returned that EGR valve and got a real OEM replacment. Fits great, works great, issue still present. :banghead:
I got a MAP sensor code, i'm going to try testing that.
 
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Bumping this thread again.

I went out and bought an OBD1 ALDL cord and got the WindALDL scanning software. Really cool logging, display, and analysis tool for only $60.
Anyway, I digress... everything looks in range except the O2 sensor values are kind of strange.
The scanner is displaying about 0.455v +/- 0.005v. Never any voltages outside of that range which is suspicious.
So I parked the truck, disconnected the sensor, probed the sensor lead to ground, ~0.8v with fluctuations of about 0.2v. Weird that its reading something different from the scanner but seems normal given it was disconnected. So, I probe the harness side, 1.48v. Double weird. Look back at the scanner, STILL 0.455v!!! TRIPLE WEIRD. So I think its gotta be a wiring problem, right? Completely ripped up the O2 wire all the way back to the ECM, no damage to the wire, still reading 1.48v on the harness side. Okay, ECM grounds gotta be bad, right? Nope, everything checks out on that side too. Next trick I researched was to jumper the O2 harness side to ground giving the computer a simulated lean condition. No change at all.

So I've come to the conclusion the ECM is bad..... But how? The truck runs pretty good aside from this code 13 sets only about once a week.

Anyone have any thoughts? Any other things to test?
Any help would be greatly appreciated.
 

Schurkey

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I thought the computer supplied about half-a-volt to the O2 sensor, which modulates that voltage from about 0.1 to about 0.9 as a signal back to the ECM.

Sending 1.5v to the sensor seems to me to be a problem.

I don't know what the voltage for the sensor HEATER should be, though. I have always assumed that the heater circuit was "system voltage", about 13--14 volts with the alternator charging.


Remember that most newer EGR valves are back-pressure sensitive. Some are "Positive" back pressure, and some are "Negative" back pressure. The valve won't operate properly if there isn't appropriate back pressure in the exhaust. The back-pressure sensing EGR valves will leak vacuum without the proper amount of back pressure.

You need the REAL GM service manual for this vehicle. FInd and follow the diagnostic chart for Code 13, and for any other codes that have been set.
 
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Here is the AllData diagnostic flowchart for DTC 13.
I've followed the chart and i end at "OPEN CKT 413, FAULTY ECM CONNECTION OR ECM over 0.6v [1.5v]"

The truck doesn't originally come with a heated Oxygen sensor. I retrofit from a later model truck.

EGR has been replaced with new factory-grade parts.

I triple checked the ground connections. I even tested continuity from the ECM plug to the negative on the battery and from the ECM plug to the O2 sensor. Both are good.

There must be some reason the ECM is sending 1.5v to the O2 sensor, or at least it must be some clue for whats going on.

I got a new ECM from the junkyard and popped it in, it ran the same as the other ECM, diagnostics came up with the same result.
It came with a PROM chip for a 5.0L - Code ARPC. Mine is an ANLW. Image attached.
I tried swapping chips and modules interchangeably, no change with how it ran nor the diagnostics.

There must be some all-knowing expert on this site that can help me out here.

You must be registered for see images attach
 

Supercharged111

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At any point have you replaced the sensor? You mentioned you retrofitted from a later truck and the problem persisted?
 
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This is the third sensor I’ve put in there. Currently I think it is the Bosch 13077.
The sensor seems to be reacting as it should. I did the test where I simulate a lean condition and a rich condition.
 
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