ptuomov

I am playing hookie from work and trying to install the MSD 8918 tach signal gmr pickup. In case you have installed it, can you please post installation photos? I am trying to figure out where to install it and with how many washers. I need to get a tach signal but can't / won't hook my Rube Goldberg machine to the ECUs.

ptuomov

Ok, a broader question. What's the most convenient location to find the positive 12V wire to the ignition coil?

Hilton

Pins 11 and 12 on connector Q in an '87 are the left and right coil 12v supplies. (bottom left pin on Q as you look at CE panel, and the one above it)

I had to pull an old alarm out of one of my 87's the other day and that was how it immobilised the ignition.

ptuomov

Hilton -- What do you think, can I pick up the tach signal from that using the MSD pickup? Does the current move there with rpm and with rpm only?

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In any case, I've spent a couple of days dealing with performance junk. First, I wanted to test the Aeromotive 16306 pump controller. I just need it to convert the rpm pulse to pwm signal. It has a nicer box than what my own hacks have so I though what the hell let's give it a shot. It's "billet" after all.

On the test bench, I tried to feed it rpm signal from a function generator. It flatlined the signal in the tach input to +12V, what's up? Then I wired a 0.5k resistor and a led (which maybe needs about 10 mA?) from the tach signal supposed input to the groud -- the led lights up bright. Now, I don't know much anything about how electrons move and can barely hook up my toaster, but this is not what I am used to with signal inputs asking for 0-12V pulse signal.

Ok, suspending my doubts, I hook the thing up to the tach signal that I am picking up from the ECUs for the boost controllers. The controller doesn't recognize the pulse signal. The tach signal led in the billet case is dead.

Well, so maybe it needs some serious current flow to pull the input down and drive whatever is inside the billet case. I proceed to providing it with a tach signal with more muscle behind it. Enter MSD 8918, the rpm pickup. I read the instructions and start to suspect that whoever wrote them ate an entire bag of mushrooms. They don't describe how the sensor works and they are full of internal inconsistencies.

My coils are under turbo pipes, so I am having a hard time figuring the wiring. It took me a solid five hours last time to take off and reinstall the turbo pipes, so I am not contemplating taking those off at this time. Boroscope, camera, smoke and mirrors. I am finding one thickly shielded wire or cable coming out of the coil, which I think (but do not know) is the high voltage side. There's a ground strap on the coil bracket. There's also one other harmess of three wires coming out of the coil. I assume that this harness of three is the low voltage side. Two of the wires are black and one is brown with black stripes. I am trying to think like the Germans do and guess that the brown-black wire feeds the coil. I try it first, but then I try the two black wires as well since I can't think like the Germans.



The instructions / documentation that came with the pickup are either a part of a multi-day punkd episode or it was really the magic mushrooms talking when they were written. I assume that the operating principle is that at normal rest state, the green signal wire is grounded to the black wire. When current passes thru the wire inside the loop formed by the metal claws, the semiconductor inside the pickup switches and connects the green wire with the 12V (or so) red wire. In the rest state, the green and black are connected according to my multimeter.

I tried the pickup on each of the three wires and did not get an rpm signal or anything like that as measured on either a multimeter or a scope. This is a powered sensor, so I tried both the power from the car which I measured to be about 13V and also an external 12V power supply. No luck.

Maybe the sensor is busted. So I go on Amazon and order a new one. I pay extra for one-day shipping. The confirmation page says the expected delivery date Sep-27. What the F, by what math 27-22=1? Another scam.

To complete the day, I looked at my Autometer fuel pressure gauge. Haven't installed it yet, but have to do that before starting to noodle with the fuel pump speed. It had decent weatherpack (or like) connectors on the wiring loom, shiny pressure sensor, etc. They even included a grommet, that's nice. Except I can't figure out a way to pu the grommet on without completely taking apart and wrecking the wiring loom? Who comes up with this ****e?

Bill Ball

Is this an 87? You can access it at plug W11 (bue/white wire) on the CE panel after it goes from EZK pin 13 to pin 1 on the LH. Or if you have a 5-speed, pin 31b of the unused kickdown relay or CE plug J11 (green wire) which goes to the tachometer. There are other access points, but any of those should work.

ptuomov

I tried a signal from the CE panel. I use it for my boost controoler already, so it was easy. The problem is that the Aeromotive 16306 controller that I have doesn't work with that signal. It's either broken or requires a lot of current to flow to draw the input pin to ground. That's why I wanted to try the MSD pickup, which allows me to forcefully pull the controller input pin to the ground without a chance of hurting the ECUs. As I said, I have trouble hooking up a toaster so my logic may be flawed.

Bill Ball

George used one of those points with his Aeromotive controller. Must be broken.

struan

just today I have fitted a shift lite in my car, 84 4.7ltr. The instruction said to get a pulse from the neg side of the coil. It wouldn't work like this, so after a bit of trial and error I eventually tapped into the GREEN (tacho feed) wire on the plug for the instrument cluster. This worked great. I don't know if this will help you any to try that.

ptuomov

I am using this for my boost controller. There has to be a way to drive the pump speed controller from that signal, either the pump controller is busted or I have some rookie wiring error in my test bed.