Retrofit 24x reluctor to early V8

[kur4o]

There is indeed some processing inside the sensor. I found this interesting chart for a 98 ls1. An inside schematics of the sensors. I also measured the cam/crank inputs of the pcm. They are grounded, so you need to feed some voltage to the pcm to sense signal. There is also more processing in the pcm. The signal is filtered and converted to 0-5v by a special chip before it goes to the TPU. So the square shape might not be that important unless some thresholds are reached.

The crank sensor being some sort of magentic pickup will be really sensitive on magnetized engine parts and paints on the wheel.
I have been thinking about the dual pattern of the wheel. Could it be that the 2 wheels are some mirrored image 180* apart, making the the wheel to be installed backwards for reverse rotation engine.

Best way to test for valid crank signal is to bench wire the pcm and log rpms while rotating the wheel. For most of the pcms anything under 50rpm is hardly picked.

[lionelhutz]

That makes sense for the crank sensor,

I was recommending testing the cam sensor by hand rotating. It picks up the 1x ring immediately with power applied and that lets the PCM know which 180* the crank is rotating once it starts to pick up the crank signal. Otherwise, the engine might have to crank a whole rotation before the PCM even knew how to start the engine. That's why it will still run without the cam signal, the PCM will eventually try both and get it running.

[Jim Blackwood]

Since I did get a pulse train on the CKP sensor lead (C1-12) that must wired the right way. Not so sure on the cam sensor. Apparently GM used different pin arrangements for both but I think the ones I have match the pinouts used here. Whether it matches the pickup could be a different matter I expect. I get a constant 7v output. I went out and found a couple more of my cam pickups, one uses a Ford sensor and the other is 2001 Silverado which matches the sensor on the car so I'm using that one to test. It seems unlikely that I would have 2 bad (new) cam sensors. The vehicle schematic shows a 12v input.

The CKP uses a VR sensor as the pickup then adds the signal processing to it. These type pickups are very common and are essentially an AC generator. You can pretty much tell that is what it is by the operating characteristics. The cam sensor uses a Hall effect sensor, which should be capable of switching at zero rpm. So it should indicate condition as on or off as soon as power is applied. These are commonly used in aftermarket ignition systems.

I'm working on getting a signal out of the cam sensor.

The large one below is the one I'm using for testing. The smaller one is pretty much configured the same as the old Buick V6 unit but uses the Ford pickup. It outputs a single short pulse so is not the right piece for the 0411 controller.

Jim

[Jim Blackwood]

Looks like part of the problem might be what I'm using for a cam sensor since this one wasn't used in 2001 apparently I will have to see if I can find the paperwork on that. However I tried every possible combination of power, ground and signal out hooking it up and could get no switching output so I'm starting to wonder if it provides a sinking output. Maybe I should try a pull up resistor next. Or a different sensor.

[dave w]

I'm sure we all know that the trigger wheel / flag material needs to made from a metal that is magnetic. Stainless steel is not magnetic enough. The surrounding material to the sensor needs to be non-magnetic.

dave w

[Jim Blackwood]

Right. I think I must have a bad sensor. Either that or I need a better bench test setup. I'm using the front mounted LS sensor.

Jim

[In-Tech]

The front mount cam sensor(LS3) is the best cam/crank sensor(non encoded 24x) there is. No pullup resistor required and is also non directional, meaning the mounting tab can be anywhere. It is pinned different than the LS1 cam sensor so please note that. I don't have that info in front of me but can get it tomorrow if you need.

[Jim Blackwood]

Thanks Carl. I think what would be most helpful would be a good wiring diagram for a bench testing setup for the cam sensor. Been looking for something on youtube but haven't found it yet.

Jim

[kur4o]

What type of pcm you have.

Also I think that 7v volts output is acceptable. The input of 12v is only a feed to the sensor and is processed so the output is likely lower.

[Jim Blackwood]

Yes, I hooked up the cmp and ckp leads to the 0411 ECM bench simulator to test. Good feed voltage, right at 12v, good low reference, 0 ohms to ground, about 5.5v out of the signal lead from the CMP sensor dropping a tenth or two when connected to the ECM.

No change with a relatively heavy steel target against the sensor. Looks like the sensor is bad. I'll order another one. Could be the one in the car is bad too. I heard there has been a rash of bad sensors, not necessarily GM but across the board. Ordered the Delphi part for the '05 Corvette.
Jim

[kur4o]

I just made a visual inspection about the sensor position in the block vs the reluctor wheel. The mounting tab of the sensor is facing to the front of engine parallel to the block. The sensor is really close to the wheel, I didn`t have a feeler gauge to measure. #1 TDC does seems to line up with the small hole. Now the interesting part. There are 4 tabs on the sensor 90* each. There is small gap between the 2 parts of the wheel. One of the tab is perfectly centered in the gap between the 2 parts of the wheels. If you draw a line from at the center of the wheel the sensor should be in that line straight. So it is perpendicular to the center of the wheel

I will get you a schematics of the 0411 later. I will try to see what is the normal voltage output. If it is not switching it is likely a bad one.

[In-Tech]

Hi Jim,
Yes to the bad sensors, just fought one on the dyno, brand new ac delco had intermittent output, never seen that before, usually works or it doesn't.

GM spec for gap is .020" - .040"

LS1 Cam
A=Signal
B=Ground
C=12v

LS3 Cam
A=5v
B=Ground
C=Signal

LS1 Crank
A=Signal
B=Ground
C=12v

LS3 Crank
A=Signal
B=Ground
C=5v Sometimes requires a 1k pullup

>>>>>>>>>>>>>>>>>>>>>>>>>>>

Ls1 MAP
A=Ground
B=Signal
C=5v

LS3 Bosch MAP
A=5v
B=Ground
C=Signal

[kur4o]

Some good reading for troubleshooting and a schematics for 0411 pcm.

[Jim Blackwood]

Here's a new scope trace, showing the CKP output and pin C2-26 output (coil 1 logic level) on the bench simulator. It'll be a couple weeks before I can add a third trace for the CMP sensor in the same screen shot, but this one shows that coil 1 at least is firing off, provided the wires and coils are good. That gives me something to look at while waiting for the new CMP sensor to come in.

Jim

[kur4o]

Cranking without cmp is hit or miss until the correct sequence is detected. The spark will be either correct or 360* off. After that it runs strong.