91 Regal code 41

I have a 91 regal 3.8 giving me a code 41. The code is persistant and appeared after a short full throttle condition. I understand this a camshaft sensor problem, but can anyone tell me what the voltages and test procedures should be? After searching the other threads I understand it may be the magnet on the camshaft as well, which I'm afraid is going to be the case. I just want to test the sensor before replacing it. I have a digital VOM meter and an O-scope if needed. Any help would be appreciated.

I guess I should add that when I disconnect the sensor, the engine will not start, but with the sensor plugged in the car is running fine. Does this tell me anything?

CODE 41

Trouble Code 41 indicates that the Camshaft Sensor is not functioning properly.

The ignition module uses the Cam Sensor signal for timing the spark firing. The ignition module also passes this signal to the ECM to enable sequential fuel injection. The inability to properly determine engine position from the Cam Sensor will generate Code 41.

The engine will continue to run if the signal is lost from the sensor, however it will not restart after shut down. If the Cam signal from the ignition module to the ECM is lost while running, the ECM will switch to the simultaneous fuel injection mode. The engine can be re-started but will continue to run in the simultaneous mode as long as the fault is present.

The conditions for setting this code are:

the engine is running, and
the Cam Sensor signal is not received by the ECM in the last 1 second interval



Typical causes for this code include:

1) Loose or misadjusted Cam Sensor
2) Defective Cam Sensor-to-ECM connections
3) Defective ECM

Cam sensor installation and adjustment procedures call for very exact tolerances. It is for this reason that it is recommended that the service manual be consulted while performing any adjustment or replacement of the Camshaft Sensor.

CODE 41

Trouble Code 41 indicates that the Camshaft Sensor is not functioning properly.

The ignition module uses the Cam Sensor signal for timing the spark firing. The ignition module also passes this signal to the ECM to enable sequential fuel injection. The inability to properly determine engine position from the Cam Sensor will generate Code 41.

The engine will continue to run if the signal is lost from the sensor, however it will not restart after shut down. If the Cam signal from the ignition module to the ECM is lost while running, the ECM will switch to the simultaneous fuel injection mode. The engine can be re-started but will continue to run in the simultaneous mode as long as the fault is present.

The conditions for setting this code are:

the engine is running, and
the Cam Sensor signal is not received by the ECM in the last 1 second interval



Typical causes for this code include:

1) Loose or misadjusted Cam Sensor
2) Defective Cam Sensor-to-ECM connections
3) Defective ECM

Cam sensor installation and adjustment procedures call for very exact tolerances. It is for this reason that it is recommended that the service manual be consulted while performing any adjustment or replacement of the Camshaft Sensor.


Hope that helps...... I could not find any way to test it though

Cam sensor installation and adjustment procedures call for very exact tolerances. It is for this reason that it is recommended that the service manual be consulted while performing any adjustment or replacement of the Camshaft Sensor.

Andy, where do you adjust the Cam Sensor?

Jack

While this repeats what was posted above I thought I would post it as it adds "a little more" detail and applies to 1984-1994 engines.

3.8L and 3.8L Turbo Camshaft Sensor Operation:

The camshaft sensor provides one pulse at 25 degrees after top dead center (ATDC) of the number 1 cylinder for every two crankshaft revolutions. This camshaft sensor pulse is used to synchronize sequential fuel injection (SFI.)
Both the camshaft sensor pulse and the crankshaft sensor 3X pulse must be present for the ignition module to sequence the firing of the 3-6 coil and start the engine. The camshaft sensor "sync" pulse must also remain present to sequence SFI fuel delivery when the engine is running. If the camshaft signal is grounded or opened when the engine is running, the ECM stops SFI and goes to multiport fuel delivery, but the engine continues to run.
Chuggle, intermittent miss, high emmisions and stall symptoms can sometimes occur when the camshaft signal is lost. The Service Engine Soon light comes on and Code 41 is set if the signal is lost for more than one second.

Here's a little additional information pertaining to the 3.0L and 3300.

The 3.0L and 3300 engines will run without a camshaft or sync signal if the engine is running before the failure occurs, but will not start without it. However, if this circuit is pulled low while the engine is running, the module will re-sync and frequently stall the engine.
Note that some 3.0L engines may start if the sync signal is pulled low and the driver repeatedly tries to start the vehicle.

And finally for the 3800.

As with the crankshaft sensor, the ignition module sends a reference signal to a Hall-effect switch in the camshaft sensor. A permanent magnet, attached to the camshaft sprocket, passes close to the sensor once each camshaft revolution (the camshaft rotates once for every two crankshaft revolutions). As the magnet passes beside the sensor, the Hall-effect switch is activated by the magnetic field, and its transistor turns on to ground the ignition reference signal line and pulls its voltage low (0-0.1 volts). The camshaft sensor "sync" pulse is received by the ignition module as piston number 1 (and 4) reaches approximately 25 degrees ATDC on the power stroke. The camshaft signal out is also sent from the ignition module to the ECM.

The 3800 engine will not default to simultaneous (MFI) injection when the camshaft sensor signal is not received at any time, whether in bypass or Electronic Spark Timing (EST) mode. If the camshaft signal pulse is not present during cranking, ECM/PCM signal logic begins sequencing injectors after two crankshaft revolutions or six pulses from the 3X reference signal. Code 41 is stored on the seventh pulse from the 3X signal and sequential injection begins in a random pattern.
There is a one in six chance that fuel injection will coincide correctly with valve opening. If injection is off, driveability is affected only a small amount (slight hesitation).

Source: GM Powertrain V6 Introduction to Fuel Injection, Diagnosis and Service by Ron Harlow.

Ok, I've replaced the cam position sensor, and I still have code 41. I was able to look into the hole using a mirror and turned the engine over. I can see where it looks like something should be but not sure what I'm looking at. Anyone know of a link where I can see what the magnet should like? I'm afraid the magnet is gone. The best I can describe is, I am seeing what a black circular object about the size of one of those knindergarden pencils. The end I am seeing looks like the end of a hollow point bullet. Is this the magnet or did the magnet use to sit where I am now seeing the hole? I inserted a small metal screwdriver and could'nt feel it sticking to what was there. Thanks for the replies fellas, I know enough about cars to be dangerous, but if you need help with a phone system I'm your man. Thanks again.

Andy, where do you adjust the Cam Sensor?

Jack


I'm not sure Ill go look today. I've never had to do it before so..... BTW I got my info from www.gnttype.org. I forgot to post that. Also A turbo car will defulat to MPI when cam sensor goes out. Im not too sure about the na cars though.

The best I can describe is, I am seeing what a black circular object about the size of one of those knindergarden pencils. The end I am seeing looks like the end of a hollow point bullet. Is this the magnet or did the magnet use to sit where I am now seeing the hole? I inserted a small metal screwdriver and could'nt feel it sticking to what was there.

Johny, what you describe sounds something like what the magnets look like. Picture the engine turning over, the area you describe should be in a position on the cam sprocket where it would pass "under" the cam sensor. They are black and do bear a resemblence, somewhat, to a bullet. The magnet will have four recesses around the outside diameter so its not a solid circle.

I do know this, if a screwdriver won't stick to it then it may be only part of the magnet assembly, the part without the magnet of course as these magnets are STRONG! They are the preferred method for holding things to file cabinets, metal walls etc. at the factory and have been for many years.

These magnets fasten to the cam sprocket with a thin metal type "clip" that catches when pushed through a hole in the sprocket so a "bullet type" shape is used to aid in assembly. The blunt part goes into the hole first and as the magnet "bottoms out" the clip engages and seats it to the sprocket. On the current versions, which are cut down versions of the EV6 style, those recesses that I mentioned above, at least two of them, are where parts of the clip assembly rest so they were probably designed to allow this without adding any more to the overall outside diameter of the magnet assembly than necessary.

I forgot to mention that by looking at the diagram of the sprocket assembly for the 3.8 in the 1991 factory engine description manual it shows a solid sprocket so the only hole in it, other than the one in the center for fastening it to the cam would be for the magnet. We have versions now that are somewhat different.

Time to go build some 3800's.
We smoked it last night on second with a run of over 1300!

Hope this helps!

Jack

Thanks Jack, from what you are describing it sounds like what I am seeing is where the magnet used to be or the clip that was holding it. Will I have to take of the timing cover and all to replace this magnet or is there a way to insert it through the hole under the cam sensor? Again, thanks for your response.

Ron

You're welcome Ron, I can't remember how they were assembled back in 1991 but I think it's pretty much the same as we do it today. I'm almost sure that the front cover has to be removed, which means that the balancer will too.
We currently insert the magnet from the back of the cam sprocket so the "blunt" nose part of the magnet that passes under the sensor protrudes out from the sprocket, which means that the "flat" part is flush up with the back of the spocket giving it clearance to clear the case back there as it rotates.

Maybe Andy can shed a little more light on this for you.

Good Luck!!
Jack

You're welcome Ron, I can't remember how they were assembled back in 1991 but I think it's pretty much the same as we do it today. I'm almost sure that the front cover has to be removed, which means that the balancer will too.
We currently insert the magnet from the back of the cam sprocket so the "blunt" nose part of the magnet that passes under the sensor protrudes out from the sprocket, which means that the "flat" part is flush up with the back of the spocket giving it clearance to clear the case back there as it rotates.

Maybe Andy can shed a little more light on this for you.

Good Luck!!
Jack


Hey I can after this week. I'm getting ready to gut a motor this week. Ill let you know.

I just found this thread through google. I seem to have the same problem. The sensor checks out. I checked voltages to the sensor. I hooked a voltmeter between pin c-5 (black wire) on the ecu and ground and got round 10 volts with ignition on and a slightly higher and steady 10 volts when I started it up. The engine starts and still runs okay but the service engine light stays on. I disconnected the battery and the light does not brighten till a half second when I start the engine.

I feel that the magnet fell off, but I haven't looked for it yet.

Can the ecu be checked on a bench or in the car?

Just how much is involved with removing the cam gear? How will it affect gas mileage and emissions?

My email is dieter@one.net

I went back out and looked for the magnet; I only had to turn it a few degrees and for three pieces of plastic that made up three sides of a protruding (17mm approx.) box; the fourth side was missing and the three remaining sides snapped off with finger pressure leaving a 12 mm recessed circle.

Is this what you remember as a magnet?

Dieter

If you figure out what is wrong with your car let me know ... I have the same problem. I have changed out the cam sensor...crankshaft sensor, some other one...water pump ... fuel pressure is good...timing chain is good...main brain and coil packs are good. And still after the car warms up which is about 20 - 30 minutes of driving it start spitting and sputtering and running rough with no power and you have to dog it to get home. e mail me I have already spent over $600 to try and fix this car.






CODE 41

Trouble Code 41 indicates that the Camshaft Sensor is not functioning properly.

The ignition module uses the Cam Sensor signal for timing the spark firing. The ignition module also passes this signal to the ECM to enable sequential fuel injection. The inability to properly determine engine position from the Cam Sensor will generate Code 41.

The engine will continue to run if the signal is lost from the sensor, however it will not restart after shut down. If the Cam signal from the ignition module to the ECM is lost while running, the ECM will switch to the simultaneous fuel injection mode. The engine can be re-started but will continue to run in the simultaneous mode as long as the fault is present.

The conditions for setting this code are:

the engine is running, and
the Cam Sensor signal is not received by the ECM in the last 1 second interval



Typical causes for this code include:

1) Loose or misadjusted Cam Sensor
2) Defective Cam Sensor-to-ECM connections
3) Defective ECM

Cam sensor installation and adjustment procedures call for very exact tolerances. It is for this reason that it is recommended that the service manual be consulted while performing any adjustment or replacement of the Camshaft Sensor.


Hope that helps...... I could not find any way to test it though

I fixed mine.
The magnet fell off.
I epoxied another on the gear without removing the timing chain cover.
Ciao!


I just found this thread through google. I seem to have the same problem. The sensor checks out. I checked voltages to the sensor. I hooked a voltmeter between pin c-5 (black wire) on the ecu and ground and got round 10 volts with ignition on and a slightly higher and steady 10 volts when I started it up. The engine starts and still runs okay but the service engine light stays on. I disconnected the battery and the light does not brighten till a half second when I start the engine.

I feel that the magnet fell off, but I haven't looked for it yet.

Can the ecu be checked on a bench or in the car?

Just how much is involved with removing the cam gear? How will it affect gas mileage and emissions?

My email is dieter@one.net

Where did you get the new magnet from?