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3.0 Intermittent Stumble then Quit

RonD

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Wouldn't be PCM if you have tried a second one, so wiring
 


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97Ranger3.0

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So, this has got me wondering. How come the PCM isn't able to realize that things don't add up and overcome this issue? I just would think that using TPS data and O2 sensor data that it should be able to realize that the MAF readings are incorrect and adjust somehow. Because I know the truck will run and drive without the MAF sensor plugged in at all, since like RonD had said that the PCM already knows the basic calculations for AFR. So I guess I'm just surprised that the PCM can't adjust for this issue, and I'm also surprised it never throws a code related to the MAF sensor.

Also, I know I'm getting a little ahead of myself here. But, if it ends up pointing to the sensor itself being bad, I would like to replace it with Motorcraft if possible. But all I can find for Motorcraft are remanufactured sensor assemblies. I usually avoid reman parts because they're 99% of the time junk. But, would a Motorcraft reman MAF still be a good option? And if not, what would be a good brand to look for?
 
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97Ranger3.0

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PROBLEM (seems to be) SOLVED

This is crazy, but I think I've fixed the problem. So this problem was very intermittent originally, but lately it was getting worse and worse. The truck was getting almost undriveable, the only way I could drive it was to drive with the MAF unplugged. So for kicks, I bought a used OEM maf and threw it in the truck a few weeks ago. I haven't had one issue since. I honestly didn't expect it to make a difference, however when I did some quick visual inspections of the wiring I couldn't see any obvious issues. So I figured I'd try this as a last resort before attempting to dive into diagnosing some sort of wiring issue.

I'm kind of dumbfounded that I could somehow end up with multiple bad MAF sensors, even brand new ones of a supposedly good brand. I guess the moral of the story is to only buy OEM when possible.
 

ColtR7

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Hey guys,

About a month ago, out of nowhere when I started my truck (97 3.0 Ranger) it started stumbling/misfiring and then stalled out on me about 30 seconds after running. When I tried to start it back up, it would start after longer than normal cranking and run for a very short period of time, misfiring and stumbling until it would stall out. After a few tries then it would not start at all. I scanned to see if it set any check engine lights, and there were no new ones. (I've had a P1443 (evap) and a P0175 (running rich) for a while that I haven't been able to fix yet but I haven't had any issues for as long as I've had those codes until now). I tried several times spraying starting fluid into the intake to determine if it was a fuel issue, but it made zero difference. Also, I replaced the fuel pump about 30k miles ago so it shouldn't be failing. After letting the truck sit for a few hours, I tried one more time and after a rough start, it quickly smoothed out and acted like nothing had happened. I drove it for another month with no problems, but then again this happened to me.

However, this time it acted a little different. It did stumble and die out, but it took way longer for it to happen and I was able to keep it running for probably 30 seconds misfiring and stumbling before it just finally would quit. I could keep getting it to start up and run normal for a short period of time, then it would repeat the stumbling and dying process. Again though, there were no new check engine lights. I really thought that having it misfiring and running so bad for an extended period of time should have at least thrown a misfire code, but to my surprise, still no new codes.

It's hard to diagnose this issue because it is intermittent, but I have a few suspicions. I'm guessing it's possibly the camshaft or crankshaft position sensor failing, or possibly the coil pack starting to fail. But, the fact that it's not throwing a misfire code after running like that for a long period of time is making me concerned that the ECU could be on its way out. What I'm wondering is, does anyone have information on how I can test the cam & crank sensors, the coil pack and the ECU? I haven't been able to find any voltage and/or resistance values for testing those sensors and circuits in my searches. Or, does anyone have any insight into what else could be causing the issue?

I know I should fix the other two codes that I have as well, but I don't believe either of those are causing this issue. I did try to fix the P1443 code, but didn't have any luck after basically going through the entire EVAP system. I also did have a P0172 code a long time ago that I was able to fix by replacing the intake manifold gaskets, so I'm surprised I now have a P0175 code for running rich on the other bank, but haven't been able to diagnose the issue yet.
Hey guys,

About a month ago, out of nowhere when I started my truck (97 3.0 Ranger) it started stumbling/misfiring and then stalled out on me about 30 seconds after running. When I tried to start it back up, it would start after longer than normal cranking and run for a very short period of time, misfiring and stumbling until it would stall out. After a few tries then it would not start at all. I scanned to see if it set any check engine lights, and there were no new ones. (I've had a P1443 (evap) and a P0175 (running rich) for a while that I haven't been able to fix yet but I haven't had any issues for as long as I've had those codes until now). I tried several times spraying starting fluid into the intake to determine if it was a fuel issue, but it made zero difference. Also, I replaced the fuel pump about 30k miles ago so it shouldn't be failing. After letting the truck sit for a few hours, I tried one more time and after a rough start, it quickly smoothed out and acted like nothing had happened. I drove it for another month with no problems, but then again this happened to me.

However, this time it acted a little different. It did stumble and die out, but it took way longer for it to happen and I was able to keep it running for probably 30 seconds misfiring and stumbling before it just finally would quit. I could keep getting it to start up and run normal for a short period of time, then it would repeat the stumbling and dying process. Again though, there were no new check engine lights. I really thought that having it misfiring and running so bad for an extended period of time should have at least thrown a misfire code, but to my surprise, still no new codes.

It's hard to diagnose this issue because it is intermittent, but I have a few suspicions. I'm guessing it's possibly the camshaft or crankshaft position sensor failing, or possibly the coil pack starting to fail. But, the fact that it's not throwing a misfire code after running like that for a long period of time is making me concerned that the ECU could be on its way out. What I'm wondering is, does anyone have information on how I can test the cam & crank sensors, the coil pack and the ECU? I haven't been able to find any voltage and/or resistance values for testing those sensors and circuits in my searches. Or, does anyone have any insight into what else could be causing the issue?

I know I should fix the other two codes that I have as well, but I don't believe either of those are causing this issue. I did try to fix the P1443 code, but didn't have any luck after basically going through the entire EVAP system. I also did have a P0172 code a long time ago that I was able to fix by replacing the intake manifold gaskets, so I'm surprised I now have a P0175 code for running rich on the other bank, but haven't been able to diagnose the issue yet.
You might want to change your idle control valve
 

97Ranger3.0

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1997
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2WD / 4WD
4WD
You might want to change your idle control valve
I had already tried that at some point during the time I had been dealing with this issue with no change. Thank you though.
 

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