Cam position sensor

[1997ThunderbirdLXV6]

Questions...

Is this the PCM? And is it normal that it's in there sort of loose? I can wiggle it.

 

[XR7-4.6]

Yes and it’s normal. I doubt the PCM is at fault

 

[1997ThunderbirdLXV6]

Well, I added some electrical tape around those wires. Didn't help. Starting to wonder if my Dodge seat belt guides cause interference.

 

[XR7-4.6]

I'm telling you, Ford god backlash! It's the reason I won't install a pistol grip lol

 

[1997ThunderbirdLXV6]

Alright...so what next?

Btw, Joe, I owe you one for jumping on your thread!

So if the sensors are good, I guess wires and connectors must be to blame. There's absolutely no visual evidence of rodent presence though.

I just drove a few miles. It bogged again twice though the engine didn't die. It seems to happen during brisk acceleration just before shifting into third.

No code yet, neither pending nor confirmed.

I'm wondering if something completely different could mislead the PCM into thinking it's crankshaft sensor related.

The bogging is really odd. Unlike a misfire which is more like a vibration, this feels like the engine is off, with complete loss of power for the fraction of a second. It doesn't vibrate; rather it's momentarily quiet. It feels like someone pulls the plug and then plugs right back in.

I did check battery voltage both with engine off (from memory, approx. 12.5V) and on (14.4V). While driving, my app indicates 13.6V. None of this looks like a bad alternator, does it?

I'm at a loss right now...

 

[dDUBb]

See post #37 .. need a scan tool capable of displaying waveforms VIA the PCM, or tapped in at the PCM connector. You can try to do a continuity check on wiring between the PCM and sensors while unplugged or swap in a Known Good sensor to rule that out .. the CKP and CPS share a grounded wire shield from interference, check wire shielding for continuity to ground.

 

[1997ThunderbirdLXV6]

I'd like to better understand the correlation between code and symptoms.

I mean the symptoms happen first. Sometimes they produce a code, sometimes they don't (or at least not right away).

What actually causes my bogging?
I mean I can understand that this crankshaft sensor can cause the tach needle to act erratically. But that it actually cuts power and on one occasion shuts down the engine, that seems extreme (?).

 

[dDUBb]

The PCM supplies tach signal to the speedometer. So without knowing what the PCM is actually reading, it's just a guessing game.

 

[1997ThunderbirdLXV6]

Speaking of guessing game, even though I don't have a code right now, I have this freeze frame. Does that mean anything?

 

[dDUBb]

Nope.

 

[theterminator93]

If you can monitor live data, have someone watch the RPM while you drive. If it jumps around while the car is acting up, that would seem to confirm an issue with tach signal.

 

[1997ThunderbirdLXV6]

If you can monitor live data, have someone watch the RPM while you drive. If it jumps around while the car is acting up, that would seem to confirm an issue with tach signal.

I mean I can monitor it myself on the actual tach. It drops when it happens, literally to zero.

 

[dDUBb]

Do a wiggle or tap test if you can't do anything else.

 

[theterminator93]

I was gonna edit but you guys are quick!

Yeah, wiggle the connectors if you can while the engine idles.

 

[dDUBb]

Wiggle all the wires. Tap the sensors. Like you're driving down a bumpy road, maybe one of wires will short or drop signal. Those cuts in the wire may not look like much but if they've had corrosion it can wick its way up. A continuity test may not show excessive resistance unless you put it under a load like a test light.

 

[1997ThunderbirdLXV6]

I'll wiggle myself through the engine compartment tomorrow.

Thank you all!

This is a bit like several months ago when I had arcing over the coil pack and had to replace it. That was also a painfully long diagnosis until I actually saw the flashes with my own eyes.

 

[1997ThunderbirdLXV6]

...and if wiggle tests don't get me anywhere, I'll go and ask for help on TCCoA!

 

[supergordo]

Alright...so what next?

Btw, Joe, I owe you one for jumping on your thread!

So if the sensors are good, I guess wires and connectors must be to blame. There's absolutely no visual evidence of rodent presence though.

I just drove a few miles. It bogged again twice though the engine didn't die. It seems to happen during brisk acceleration just before shifting into third.

No code yet, neither pending nor confirmed.

I'm wondering if something completely different could mislead the PCM into thinking it's crankshaft sensor related.

The bogging is really odd. Unlike a misfire which is more like a vibration, this feels like the engine is off, with complete loss of power for the fraction of a second. It doesn't vibrate; rather it's momentarily quiet. It feels like someone pulls the plug and then plugs right back in.

I did check battery voltage both with engine off (from memory, approx. 12.5V) and on (14.4V). While driving, my app indicates 13.6V. None of this looks like a bad alternator, does it?

I'm at a loss right now...

Could be the actual balancer. The 3.8 balancer is similar to a 5.0 balancer and the balancer in my daughters 5.0 explorer spun the weight around. The Tone ring could move too.

 

[supergordo]

If I look hard enough I have pictures.

 

[supergordo]

If you look closely you can see how the inner and outer portions of the balancer have separated and are moving away from each other.

 

[1997ThunderbirdLXV6]

Let's hope it's not that!

 

[supergordo]

Let's hope it's not that!

Take a look at your tone ring to see if it is loose or off kilter or something. Even this repair was kinda hard to diagnose when it happened. Hopefully this isn't what you're up against. But take a look.

 

[supergordo]

I'm sure you already figured it out, but the red marks show where TDC is marked on that new balancer and where it moved on the old balancer.

 

[1997ThunderbirdLXV6]

Honestly I have neither the resources nor the skill to remove the balancer. Ugh.

Meanwhile, I checked continuity on all the sensor wires up to the connector on the firewall, and all checks out fine.

 

[1997ThunderbirdLXV6]

Also checked continuity to this connector, which also checks out.

 

[1997ThunderbirdLXV6]

Put everything back together for the nth time. Starts right up (as it did all along). Rev just a bit. Again, sudden loss of power, at about 1,500 rpm. Same code (previous code was cleared).

Let engine run. Wiggle every wire I can reach. No effect. Friend revs engine while I watch over engine compartment. Unable to reproduce - go figure.

I don't know...at this point I'm just totally puzzled.

On an Expedition forum, or maybe Focus, I read someone got this code due to issues with the PCV valve of all things, because of some blockage. I replaced mine over a year ago though.

 

[1997ThunderbirdLXV6]

...could there be some fuel delivery issue which the PCM somehow misinterprets?

 

[Kenz]

I know you said you hooked up a meter and did a continuity check. But it may be worth replacing the harness connector if you haven't already. It could be the cause of an intermittent bad connection; even if it seems to check out fine.
The 4.6's have a common no start issue because the crank sensor connector gets bad over time.

 

[1997ThunderbirdLXV6]

Just had my alternator checked. It's fine.

On my way back, some more hard hesitation. Does this mean anything?

 

[supergordo]

I'll give you another diagnostic idea. Find another 97 V6 Tbird/Cougar computer. Swap that computer in. Not hard to do. Drive it and see if the code comes back. That would at least rule out the computer.