Another E041 issue. Just replaced cam sensor.

[PaulP117]

Hey y’all. 
 

A week or two ago my reatta started throwing E041 at me intermittently and would often not see an engine light for it unless I was cruising at a steady RPM and then it would go away upon accelerating or feeding the car a little bit more gas. Like other forums have said around here it could be things like the cam magnet itself, the cam sensor or the ignition control module. Since the fault was random and not a steady problem I ruled out the CAM Magnet since I know that issue wouldn’t heal or get better regardless of driving. And the ICM isn’t leaking any green goo so I figured I’d try the CAM Sensor. I got a new cam sensor and put it in this morning and the car is running WORSE! The E041 engine light is now consistently turned on and It idles a slight bit more rough (no stalling) and accelerating from a stop has a delayed response now. Could I have just gotten a bad CAM position sensor ? I figure that is most likely but why would the issue be worse now with another broken cam sensor compared to the other broken cam sensor. What do you guys think is most likely?

Edited July 7, 2023 by PaulP117 (see edit history)

[PaulP117]

Oh and I’m also curious, I couldn’t see if anyone else asked for a way to see the cam signal in the reattas onboard diagnostic. Just to verify it has a signal at all. Is there a ECM Data reading for the cam position sensor signal?

[Ronnie]

Unplug the cam sensor and see if it runs better. The 3800 will run smoothly without a signal from the camshaft position sensor. The sensor just optimizes the timing when the injector sprays fuel. It will set a code 41 while you have the sensor unplugged and the check engine light will come on.

[PaulP117]

4 minutes ago, Ronnie said:

Unplug the cam sensor and see if it runs better. The 3800 will run smoothly without a signal from the camshaft position sensor. The sensor just optimizes the timing when the injector sprays fuel. It will set a code 41 while you have the sensor unplugged and the check engine light will come on.

Interesting so the car appears to run the exact same with the cam sensor disconnected. In that case i would think it’s pointing to the ignition control module going out despite not externally looking like it failed. I did spark plugs and plug wires very recently and the car ran phenomenally for a few weeks before the e041 code popped up. and I did coil packs about a year ago so I’d have to think it’s just the ICM? Since it’s the one remaining component in the ignition system I haven’t replaced 

[2seater]

It is possible to have coincident failure of the cam interupter magnet. The item to most often fail in the cam sense circuit is the magnet, the sensor itself is more rare. I do not know of a diagnostic input for the cam signal but it does appear the 91 has a couple more data points in diagnostics, so I am not 100% sure on that. 

 

I know I keep mentioning this but I have personally observed crumbling insulation on the wires inside the front harness of a 90 and newer 3800's. It is the harness that ties the crank and cam sensor to the ICM. If the magnet proves to be in place, you might want to check the end points of the harness, ICM, Cam and Crank sensor as well as the main harness connection behind the power steering pump, not for continuity but for cross contact

[Anthon]

The first thing you should do is (with engine off, ingnition on) unplug the sensor and check voltage at the connector on each of the outside pins, using the center pin as a ground. If they are both below 8V, it's an open ground circuit to the center pin. The other two wires lead to either a splice or the ignition module. If voltage is low on either of those two pins, check for an open circuit to the splice or the ignition module (or bad ignition module itself). If voltage is ok on both (8-10V), then you have to check voltage at the ECM connector and follow some other procedures to see if it's a bad ECM connector, missing magnet, bad sensor, or faulty ECM. 

[PaulP117]

15 hours ago, Anthon said:

The first thing you should do is (with engine off, ingnition on) unplug the sensor and check voltage at the connector on each of the outside pins, using the center pin as a ground. If they are both below 8V, it's an open ground circuit to the center pin. The other two wires lead to either a splice or the ignition module. If voltage is low on either of those two pins, check for an open circuit to the splice or the ignition module (or bad ignition module itself). If voltage is ok on both (8-10V), then you have to check voltage at the ECM connector and follow some other procedures to see if it's a bad ECM connector, missing magnet, bad sensor, or faulty ECM. 

Went ahead and checked the two pins on the outside and one is reading at about 6.6V while the other is around 11V. I’m willing to bet it’s the splice leading to the ICM. I had one ordered on suspicion it might be that so once it arrives I hope that’ll be the case. Just to be sure I’m gonna try and find the proper diagram to determine which wire color it is that leads to the ICM so Ill actually know which one is the one with the low voltage.

Edited July 9, 2023 by PaulP117 (see edit history)

[PaulP117]

Replaced the ICM after the low reading and the car is still reacting inaccurately. I tested both circuits for high resistance and proper voltage and according to the 91 service manual everything I have should check out but the car still has a very noticeable delay on acceleration with the sensor plugged in. However now the car does operate a little bit better when the sensor is disconnected. Still waiting on a new proper cam position sensor to install so I’ll just have to hope when it arrives that’ll do the trick, because my cam magnet looked good when I pulled the cam sensor just recently. 

Edited July 17, 2023 by PaulP117 (see edit history)

[2seater]

How is your TPS? Set properly for idle position and increases with throttle and no dead spots?

[Dashmaster]

On my 88 and maybe all of the cars. The Power and Grounds to  ICM, Cam, and Crank all share the same source power and ground,  and they are spliced together under the car near the back side of the oil pan. These splices are just like the ones found under the seats.  just trace the wires back from any of these and you will find the splices.  I would check these out.

[Anthon]

On 7/9/2023 at 3:02 PM, PaulP117 said:

Went ahead and checked the two pins on the outside and one is reading at about 6.6V while the other is around 11V. I’m willing to bet it’s the splice leading to the ICM. I had one ordered on suspicion it might be that so once it arrives I hope that’ll be the case. Just to be sure I’m gonna try and find the proper diagram to determine which wire color it is that leads to the ICM so Ill actually know which one is the one with the low voltage.

If your wire colors are brown/white and white/black, these come from pin J at the ICM and splice S130, respectively. The splice is behind the engine mount and compressor. The splice gets voltage from pin N at the ICM. 

Edited July 23, 2023 by Anthon (see edit history)

[2seater]

On 7/20/2023 at 1:54 PM, Dashmaster said:

On my 88 and maybe all of the cars. The Power and Grounds to  ICM, Cam, and Crank all share the same source power and ground,  and they are spliced together under the car near the back side of the oil pan. These splices are just like the ones found under the seats.  just trace the wires back from any of these and you will find the splices.  I would check these out.

I don't believe the wiring is the same. All the wiring for the non-touch screen cars comes over the top and from the upper firewall. The wiring between the firewall, ICM, Crank Sensor and Cam Sensor is a separate harness on the belt end of the engine. It is different than the touch screen cars. The harness plugs into the main engine harness from the firewall behind the power steering pump. The year of the car is very important when diagnosing the various model years. 

[Ronnie]

On 7/17/2023 at 10:35 AM, PaulP117 said:

...according to the 91 service manual everything I have should check out but the car still has a very noticeable delay on acceleration with the sensor plugged in....

Unplug the MAF sensor and see if it runs better. The problem you describe could be caused by the MAF.

[PaulP117]

So i finally got some time to check things out again and despite the fact i know 100% for certain the cam magnet itself was intact when the problem first arose it does now appear to be missing, Based on the pictures on the Reatta owners journal i truthfully must have touched it or bumped it when i first replaced the cam sensor causing that last little bit of strength the magnet had to crumble away haha. So now i think its time to replace the magnet and go from there! Its a very delicate part it seems

[PaulP117]

Does anyone know where i can even find that cam interrupter magnet? Its out of stock everywhere i can see. (Searched EBAY and found quite a few, not sure how many are legit but ill take a chance)

Edited July 31, 2023 by PaulP117 (see edit history)

[2seater]

3 hours ago, PaulP117 said:

Does anyone know where i can even find that cam interrupter magnet? Its out of stock everywhere i can see. (Searched EBAY and found quite a few, not sure how many are legit but ill take a chance)

No idea where to find one so here we are again. Soon to be looking for another substitute. 3D printed holder for a small disc magnet maybe??

[PaulP117]

when digging out the plastic remnants of the cam interrupter where do these pieces go? Should all this plastic junk just make its way into the oil pan or should i do my best to pull these remaining plastic parts out of the cam sensor hole

[EmTee]

Probably winds-up in the oil pan (at least the plastic bits).  The magnet, on the other hand, is an interesting question!  It wouldn't surprise me it it gets stuck on the block somewhere in the timing area.  If you are lucky enough to find the magnet intact, I would simply use some gasket maker to glue it back into the cam sprocket hole.  If is is nowhere to be found (e.g., chewed-up and dispersed) I guess I would find another similar magnet and glue it into the sprocket.

[2seater]

The disappearing magnet, and broken plastic has happened any number of times in the past and I do not know of any harm that has been traced back to the missing magnet (interrupter). 

I think the part itself has been made in multiple form factors over the years. I know that I have seen what looked like small rods bundled together, one I had seemed to be filled with a magnetic paste of some sort, there were no solids inside the plastic case. I just pulled one from the 1995 donor engine for the supercharger I installed, and the plastic case is solid with no openings to see inside. The springy ears used to retain the interrupter are stainless steel rather than plastic as I have seen before. It is highly magnetic. This engine was previously overhauled, so the interrupter is likely not original.