Questions about cam sensor, cap, code 41, etc. Need some help.

[ross87t]

I just purchased an 86 T-Type. I have driven the car all of 1 mile since it arrived on the transport truck on Sunday (waiting for tags, plates and inspection). Yesterday, the car had a bit of a stumble, rough idle and the CEL came on. I checked for codes and got a code #41 (Cam Sensor Circuit Failure). I pulled the car into the garage, shut it off for a minute and tried to restart it. The engine would turn over, but the car would not start. I went inside and cooled off for about 20 minutes and then tried to start the car again. It fired right up and there was no CEL. I let it idle for a couple of minutes and the CEL returned. Again, code #41.
I’ll add that the car would hesitate/stumble during initial acceleration but smooth out after. It also seems to spool quite slowly for being equipped with a Precision 6262 BB and a 10” 3200 converter which (in my research here on turbobuick revealed) is another symptom of a cam sensor related problem.

From my research so far, it appears it could be a bad cap, sensor, etc. I contacted the previous owner and he mentioned he had to replace the cap twice in the past and the sensor once. I figure I will start by replacing the cap which leads me to my first question. Assuming the sensor was installed correctly (previous owner said the car ran fine), is the cap (equipped with an LED light) a simple bolt-on and go replacement? The sensor itself is what’s adjusted, not the cap, correct?

I guess my other question would be:
If a new cap doesn’t fix this problem, where would be the next place to start? Sensor?

Sorry for this being so long. I wanted to be thorough. If you need more information to help diagnose the problem, just let me know.

Thanks,
Ross

 

[mikestertwo]

The cap is the sensor. Pull the cap and make sure the sensor ring isn't loose on the shaft. Also check the electrical connector on the cap and harness and the connector at the ignition module for loose, corroded, or damaged pins.

 

[ross87t]

So if the cap is the sensor and I were going to install a new one, I'd have to do the whole "finding top dead center and adjust cap" process or is that only done when also replacing the shaft?

Is the "sensor ring" the "cup" looking object just under the cap on top of the shaft? If so, that seems to be tight. It has a very minimal amount of rotation play in it, but I think that’s just some ever so slight play in the entire shaft it is bolted to.

Sorry if these are stupid questions. I have been out of the Turbo Buick game for about 6 years now and this is a problem I luckily never had to deal with in the past.

All wires and connectors seem to be in very good shape.

 

[ross87t]

Please note. When I mention the word “sensor” in my first post, I am referring to the shaft the cap bolts to the top of. Sorry about the confusion. I’m a bit rusty.

 

[mikestertwo]

You can just replace the cap and your good to go.

 

[ross87t]

I'm going to bump this one back up one more time before I start purchasing parts.

Any additional input is appreciated. Thanks.

 

[BlackBandit]

The actual sensor is in the cap. If you don't have any play in the cup looking ring then the cap would probably be the place to start as it contains all of the electronics. I would recommend ohming out the cam circuit while wiggling wires to check for a bad wire and checking all the connections at the ignition module and at the ECM for corrosion and what not before you start throwing money at it though.

 

[TurboBuRick]

The cap is the problem. I would not use the l.e.d. cap. Your best bet is to buy a complete new ac delco cam sensor. You can't buy just the cap.

 

[ross87t]

Replaced the the ignition module (because I had one and it was the easier job) and no change. I ran the car for about 10 minutes this morning without issue. I shut it off for about 10 minutes. Go back out to drive it again and the miss is back. Weird.
I'll be replacing the entire cam sensor soon and will post an update.

I love buying a car from out of state and having issues right off the transport truck that were never brought up in phone discussions with the previous owner.

 

[TurboBuRick]

Start the motor unplug the cam sensor. Does the miss go away?

People always get amnesia when it comes to the little problems.

 

[GNDriven]

Do not be scared of this stuff, do not hesistate to pull the cam sensor. There is enough info on the web to help you put it back in. I think Vortexbuicks has some good reading as well. Also this site does if you do some searches on Cam sensor, also GNTtype.org. PM me and Ill get your phone number and call you and talk your way though a few things you can test for. I know you are focusing on the cam sensor, but I think you need to sttep back and start with some general troubleshooting. Does it stumble at idle?, under load (put it in drive with your foot on brake and give it some gas). I like to use slap on a injector test light and then pull each spark plug wire and test spark. There are certain combinations that you can trry of cranking it, like pulling cam sensor once it running, etc. Once you understand what is doing what then the step you need to take become clear.

 

[GNDriven]

also, the brass ring (reluctor ring) unde the cam sensor will be tight because of the screw that is holding it down, but still may move around when the engine is spinning. There is a liittle piece of the base of the ring that is cut out on three sides and it bend down. It is on the opposite side of the reluctor ring window (the cutout of the brass cup) this little bent brass tab slides into a recieving hole that is drilled in the shaft of the cam sensor. It purpose is to keep the reluctor ring window in a fixed location on the cam sensor shaft that is being turned by the timing chain that is being turned by the crankshaft. anyway take the brass reluctor ring off the top of the shaft and see if this tag is gone. It can still be in the right place due to the screw that holds it down, but cause problems once the motor is turning 800 or higer rpm.

 

[GNDriven]

P.S. I really need to proof read what I type in a hurry. I sounds like I can't speak english in those paragraphs.

 

[ross87t]

Thanks. I'll be changing it out sometime this week when I get the chance. I'll follow the instructions on vortexbuicks. I got up under the car and saw 2 marked notches. I cut a 1.45" piece of masking tape and to my pleasant surprise, it was exact (notch to notch). I'll provide updates as can. Thanks again.

 

[ross87t]

Replaced the cam sensor cap with a non-LED unit.

FIXED!!!!!!!!!!!!!!!!!!!!!