Intermittant code 41 errors....

[clm2112]

Still a fail.

Started out by removing the cam signal pin from the wiring harness weatherpak connector (F) so the ECM couldn't see the cam signal or drag it down in any way. Still only seeing six volts. Of the three ICM's I have (the original, the spare, and a new replacement) the highest voltage I can get on the cam signal line is 6.7 VDC. It is supposed to be 8 to 10 VDC with the cam sensor disconnected, same as the supply reference voltage.

Cut the wire at the ICM connector and installed a different contact in the connector shell... now I can see the cam signal voltage right at the ICM...still showing the same 6 or so volts.

Took the coil packs and ICM off and sanded the heck out of the aluminum parts...top of the engine bracket, mounting plate, and underside of the ICM. I was thinking of a possible ground path through the underside of the ICM to the alternator bracket. Still right back where I started. Cam signal voltage with the sensor disconnected is 6vdc, signal output going back to the ECM is fluctuating around 4vdc with the engine running.

BTW, there is an amplifier circuit in the cam signal within the ICM. I tested the continuity between the cam signal input and output pins. The pins show 1M ohms resistance, so there's some circuit between the input and outputs. Not sure what, but I'm guessing it's a linear amp. Similar to the two crank signals. Amusing, but doesn't get me anywhere closer to solving the problem.

Never got to take the cam sensor out and check the magnet... though is seems unlikely it is missing if I can't get the basic voltage tests to pass with the cam sensor completely disconnected.

Edit: Could the frigging manual be wrong on the test voltages??? Can someone check their cam sensor voltages to see if the manual values are real world? (basic test: Key in run, no engine start, cam sensor disconnected. Three pins on the connector: A=Cam signal output, B=Signal Ground, C=Ref Voltage. Per manual voltage across pins B and C should be 8 to 10 VDC, Across Pins A and B the same 8 to 10 VDC.)

[crzydmnd72]

Curt, I am off work and home today. I can PM my cell number and do the test. I just disconnect the cam sensor wire right?

ETA...went out and winged it.

Battery voltage key off was 12.29v

holding the cam sensor connector with the lock tab at 12 o'clock and assuming the middle pin was "B"

From left pin to middle was 11.59v

From right pin to middle was 6.71 volts...

Just for smiles, from the 2 outside pins it was 4.88 volts

Car is code free, timing chain, sprockets, magnet and sensor were replaced about 30k miles back.

Delco Ignition if that matters

[clm2112]

Thanks Glenn... yours is doing the same thing as mine, voltage wise. Right pin (A - Signal) to Center pin (B - Ground Ref) is about where mine is, yet manual says it has to be 8-10 vdc. Yet you don't have the code and I do. The two outside pins, signal to ref voltage (C) being 4.88 makes perfect sense. 6.71 + 4.88 = 11.59. So the ignition module circuit is trying to hold the signal voltage floating between the ground and ref voltages.

Perhaps the manual is out to lunch where the flowchart is concerned. If I've fixated on the voltages, then they may not be an issue.. back to popping the cam sensor out tonight and watching pin F while moving a magnet past it. Perhaps it is time to break out the O-scope and watch the actual signal wave form to see the voltage on the signal get yanked down to zero as the magnet passes the coil in the sensor.

The cam magnet I ordered yesterday is here, picked it up at lunch. So I've got everything I need to remove and replace the timing cover is there is something wrong with the cam magnet.

Gawd I hate doing this... I'm supposed to be on the road to PA tomorrow. Guess I'll be pushing the departure off a day and spend tomorrow on the Bonneville. I still have to load up the motorcycle and pack the trailer for the trip. It would be a load off my mind to have this solved before leaving on a road trip.

Heck, this is like the run-up to a Bonneville Club meet...you know, where everybody is trying to get everything fixed before the road trip starts. Only difference is when I get to where I'm going, there isn't going to be a pack of gearheads handy to fix what got broke along the way.

[crzydmnd72]

I am interested in what the fix is too. I am wondering if its indeed a magnet issue, like maybe its slipped back in the sprocket and not passing close enough to sensor face?

FYI, in our case, ours failed when wife merged onto interstate at redline, cam walked forward just enough and magnet contacted sensor. Still ran, but required all the above replaced lol. Found the magnet in 2 pieces on face of block and plastic retainer in front of oilpan.

ETA, I know that SES light has to be getting old. They are so big and "In your face" on the 90...at least the newer models just has a small symbol that isnt hogging up all the attention

[clm2112]

I am interested in what the fix is too. I am wondering if its indeed a magnet issue, like maybe its slipped back in the sprocket and not passing close enough to sensor face?.....<snip>......They are so big and "In your face" on the 90.

Got me thinking the same thing. The plastic holder covers the end of the magnet, so I can't say for sure that what I saw and touched wasn't just the shell of the holder. Not really sure if the magnet is still in it.

I want to re-letter the SES lamp.... "DON'T PANIC" should light up on the dash in big friendly letters.

[00Beast]

Or, "FIX ME"

[crzydmnd72]

Well, considering how the problem began...intermittently...the magnet may not be culprit either.

The whole intermittent thing in beginning has me doubting the magnet, but I guess making absolutely sure its there is another step...

[clm2112]

We have a winner.

I took the cam sensor out again, and rotated the motor by hand until the magnet was showing in the hole. The plastic capsule for the magnet is still there, but the magnet is either gone or no longer magnetized. Nothing ferrous will stick to it.

Sooooo... tomorrow I get up early and see just how fast I can remove the oil pan, balancer, water pump, and timing cover to install a new magnet in the cam gear. Not what I was looking forward to doing, but it appears that it will have to be done.

Tonight however, I think I just want a nice stiff drink and go to bed early. If I can get the magnet replaced before noon, I have the rest of the day to get packed up for the trip and leave on Thursday.

[crzydmnd72]

You? From hood open to close? 2 hours.

Unless you want to throw a new chain and sprockets on it too.

Wrestling balancer bolt will be the biggest challenge doing it alone. Not sure what torques that on originally but I dont want to meet him

[clm2112]

Two hours is giving me a lot of credit

I'm hoping it will take under 5 hours. Daybreak is 6:00 am. I've gotta drain the block and radiator of coolant and lock the crank in place at the flex-plate end. I hope the balancer comes off with the same ease as the two series II motors I've taken down.

This is the first time I've opened this motor up. At least I don't have to work around a torque axis mount. No Dexcool to deal with and the motor is still pretty clean on the outside. Should go well (I hope.)

[RJolly87]

If you are going through all that, just plan on doing the timing set as well. How many miles do you have on it? It is my understanding that timing chains beyond 100k miles welcome an excuse for replacement.

[clm2112]

If you are going through all that, just plan on doing the timing set as well. How many miles do you have on it? It is my understanding that timing chains beyond 100k miles welcome an excuse for replacement.

I agree with you, and if I had more time to get this done, I would. I checked three parts stores, all had the timing set as special order parts, not in stock locally. I got lucky with the magnet, it only had to come from Orlando overnight. If I wait for a timing set, It will be Friday before it gets here and I need to be on the road before then.

So, this is just going to be emergency surgery. $45 in parts, in and out as quickly as I can. My own fault for not figuring out the manual was B.S. and was pointing me in the wrong direction. Cost me a week of tracking down an electrical problem that was probably never there to start with.

I'm still looking forward to getting the blower motor in the car some day in the near future. Part of this trip is to empty out the garage of a few large objects to make room to work. Before I head out, I will have one side of the two car garage open as work space. When I get back I can focus on the truck (first as it is the closest to being a daily driver), the Camaro 2nd...which is getting the LT1 motor (going to try to get it to pass PA inspection too) and then blower motor in the Bonneville...before surrendering it's keys to my daughter.

[clm2112]

Well.. 6:44 am. On my second cup of coffee and in gear-head mental mode... finish up this cup of coffee and a bagel, then under the car I go to drain the fluids.

[RJolly87]

Carry on, and may the gwartz <gearhead schwartz> guide your wrench.

[Jrs3800]

Hope you are knee deep in it Curt, and everything is going well.. Its not too bad without the Torque Axis there..

[clm2112]

Coffee break for cigarettes and a dry shirt (already up to 86 degrees out there.)

So far, smooth sailing. Dumped the oil, noticed a hose leak on the tranny cooler line (fix that later today), dust covers off, oil pan off, block of pine to lock the crank in place on one of the counter weights, and off the came the balancer bolt. Not as bad as I thought...must have been well over 100 ft-lbs. Used a 15/16th socket, 1/2" breaker bar, plus three feet of steel pipe over the handle ("with a big enough lever, I can move the world") Balancer slid right off the end of the crank snout. No fuss, no muss. Balancer is pretty clean, no rot in the rubber. Does have a wear ring on the seal, but I'm going to leave well enough alone at this point. It wasn't leaking oil out the crank seal.

Motor is really clean inside. Not what I expected for a 120k mile motor. No sludge in the pan, castings just have that brownish tint from baked on oil. I did Seafoam the motor a few weeks ago, but still didn't expect this. Still have not located the cam magnet yet. I figured it would be stuck to the oil pan baffle.







Ok, break time is over, gotta go drain the coolant and remove the water pump and timing cover.

[clm2112]

Halfway point...*dang* is it hot out there. On my fouth t-shirt.

Found the magnet. It was still inside the capsule and still locked in the hole in the timing gear. Only problem, it is no longer a magnet. It has turned into a grey paste and no longer has a magnetic field. Only visible damage to the capsule was that it bulged out and has cracks across the top (like the magnet expanded as it broke down.) I broke the plastic capsule open and can stick a toothpick into the magnet like it was putty. No sign that it made contact with anything inside the timing cover.

I have no friggin clue as to what can dissolve a magnet like this. The only thing I ever used inside the motor was engine oil. The treatment with Seafoam was after the problem started. I was getting intermittent code 41's before I did that.

Got a new magnet installed in the gear. 30 minute epoxy is drying now. I have to go scrape the gasket surfaces and get ready to put it all back together again.

[J Wikoff]

Weird. Maybe that's what happens to most of them though?

[crappiefisher]

I believe I will pull cam sensor from the LN3 on the stand and poke gently at its magnet and see if its still solid. Thats strange as anything.

[clm2112]

Ok, car is done. I finished up at 5:30. Started right up and no codes. Had to mow the grass before it got too late. Now it is time to run over to Lowes for a couple of eye-bolts for the trailer (to tie down the motorcycle.) Also give me a chance to take it for a little test drive to se if there is anything I missed. No extra bolts left over, no fluids leaking out. Pretty good sign it is all put back together.

Run...run..run...