how to set up the cam angle sensor?

[evilmiata]

Yup, I'm putting a 3.4l into a miata.

I have a new 3.4l GM performance parts motor and intend to control it with a Haltech. However, none of the sensors/electronics were included on the engine. The cam does have a lobe that appears to be aligned with the hole for the CAS. Is this the trigger? Am I ready simply lacking the sensor? If so, doesn't it seem strange that the CAS is triggered every 720 degrees? Or do I need a completely new cam?

Pictures/links would be great!

[Anonymous]

Hmm.. Finally the cute sporty car with a REAL engine sounds awsome.

[evilmiata]

If you check my homepage, you'll see that the car was already stupid fast (see engine1 & 2). I just hope that GM doesn't let me down.

Now, how 'bout that CAS?

[SappySE107]

Its been a while, but I believe it uses the 24x CPS as well with the Cam Sensor. I know the SFI DOHC engines only have the 1 notch on the front intake cam, so 1 reading every 720 degrees for the cam itself, with its reference being used with the 3x crank at higher RPMS and the 24x at idle and lower RPM.

[RacerX11]

If this is one of the 3.4 Hi-torque crate engine GM sells for S-10 swaps, it should have a crank position sensor hole in the block, and the crankshaft should have the timing wheel required for a DIS system. If this is the case, you should go with a stock GM DIS system, and trigger the Haltech from it. Depending on what model Haltech you have, you can control both spark and fuel with the MPFI/DIS system. I am using a Haltech E6GM on my 3400.

Ben is right. The stock GM SFI ECM uses the high-resolution 24X pattern on the crank for timing contol, but it needs the single cam pulse to tell it what cycle it is on for sequential control. The 7x crank pattern for the DIS system doesn't provide any crank position reference.

Marty

[evilmiata]

If this is one of the 3.4 Hi-torque crate engine GM sells for S-10 swaps, it should have a crank position sensor hole in the block, and the crankshaft should have the timing wheel required for a DIS system. If this is the case, you should go with a stock GM DIS system, and trigger the Haltech from it. Depending on what model Haltech you have, you can control both spark and fuel with the MPFI/DIS system. I am using a Haltech E6GM on my 3400.

Ben is right. The stock GM SFI ECM uses the high-resolution 24X pattern on the crank for timing contol, but it needs the single cam pulse to tell it what cycle it is on for sequential control. The 7x crank pattern for the DIS system doesn't provide any crank position reference.

Marty

Hmm. I didn't use a Crank Angle Sensor for the miata motor, only a cam angle sensor. I found the 24x in the middle of the block and the 7x on the timing chain cover. So I should use the 24x to signal the Haltech (E6K)?

[bszopi]

You got them backwards... 7x is in the middle of the block and the 24x is on the timing chain cover.

[RacerX11]

First of all, what type of ignition are you going to run (GM DIS, Distributor, or three coils direct driven from the Haltech)? You have to figure this out before you worry about triggering the Haltech. Also, what model Haltech do you have? Both of these will make a big difference.

Marty

[evilmiata]

First of all, what type of ignition are you going to run (GM DIS, Distributor, or three coils direct driven from the Haltech)? You have to figure this out before you worry about triggering the Haltech. Also, what model Haltech do you have? Both of these will make a big difference.

Marty

I plan to trigger three coils directly from the E6K Haltech (I ran GM coils on the Miata). I briefly looked over a Haynes repair manual and couldn't find much information on the GM DIS equipment. I haven't actually SEEN a 3.4l equiped with a DIS, so I'm sort of running blind at the moment.

From what I understand, I need to take a signal from the 7x in the center of the block. The 24x at the pulley doesn't seem to have a home position.

[RacerX11]

If you are not concerned about running sequential injection, I would recommend using the GM DIS system. Here is how it work in a nutshell.

The 7X crank sensor feeds an input into the DIS module. The 7X signal consists of 6 equally spaced pulses every 60 crank degrees, with an extra sync pulse 10 degrees after cylinder #1/4 TDC. The DIS module uses this sync pulse to determine crank position. The DIS module then sends a reference signal to the ECM. This reference signal (Ref Hi and Ref Lo) consists of a square-wave pattern with three pulses per engine revolution. The ECM uses this to determine engine speed, and as a timing reference to send the EST pulse back to the DIS module to control aprak advance. The ECM advances or retards the EST pulse in relation to the reference pulses to chagne the spark advance. On a MPFI setup, the ECM never knows the actual crank position, and it doesn?t need to. The DIS module handles all of the cylinder firing order issues.

The Fiero guys have a site with info on using the Haltech E6K with a 3.4 DOHC. The DIS system is the same for all 60 degree V6?s, so the info is the same. http://www.dohcfiero.com/haltech%20E6K.htm You end up with 4 wires from the Haltech to the DIS module: Ref Hi, Ref Lo, EST, and Bypass. The bypass line is used to tell the DIS module to run a 10 degree spark advance during startup conditions. Once the engine RPM is high enough, the Bypass line is toggled and the ECM controls spark advance.

If you want to run sequential injection, it gets harder. On the SFI engines, they added the 24X cranks sensor, and the 1X cam sensor. The 24x signal is 24 equally spaced pulses every 15 crank degrees. The ECM uses the 24X signal for high resolution fuel injection control at low rpm, and the 1X cam signal is used as a TDC reference pulse to determine crank position (I don?t know the exact location of this cam pulse). I don?t think the E6K can support the 7X crank signal as an ignition trigger, so to use the Haltech in direct fire mode, I think you would need to use the 24X signal as the primary trigger, and the 1X signal as the secondary (home) trigger. I don?t know of anybody who has done this, so I wouldn?t be much help.

Here are a couple pictures showing the crank reluctor, and the DIS signals.

Marty

[RacerX11]

Marty

[evilmiata]

RacerX11, you're the freakin' man! You seem to really know your stuff, and I can't tell you how much I dreaded that this forum might be more about 18" wheels and AL wings. I really appreciate your help.

I ordered the 7x equipment this morning. I think you're right about the E6K sequential abilities; I believe that it's limited to only 4 cylinders/2 rotors.

[RacerX11]

Not a problem. I think you will find there is quite a knowledge base on this forum to draw from. I know a lot about the Haltech/DIS interface because I researched it a lot before I decided on my E6GM setup. Plus, I have considered building my own stand-alone ECM that will use the GM DIS setup. Keep us posted on the progress of your project. I know there are others on here working on using the FWD engines in RWD applications. For your Miata, you might want to consider swapping to the later Gen3 aluminum heads. It is worth about 30-35 pounds over the iron heads, plus they flow a lot better. Check out Raven's project in the member's rides area if you haven't already..I think you might like it.

Marty

Marty

[bszopi]

If you are interested in the waveforms (or pulses) for the 24x setup, I can get that diagram up as well. I have it in one of my books at home. At least then you would know where the cam trigger point is (although I'm not sure it references a particular degree or not... I'll have to check).

[evilmiata]

For your Miata, you might want to consider swapping to the later Gen3 aluminum heads. It is worth about 30-35 pounds over the iron heads, plus they flow a lot better. Check out Raven's project in the member's rides area if you haven't already..I think you might like it.

Marty

Marty

I thought about that, but my iron heads have already been opened up by Brian at www.totalengineairflow.com . This includes the intake and exhaust porting, unshrouding the combustion chambers, a competition multi-angle valve job, a custom grind Comp Cams Xtreme Energy camshaft specced by Brian just for this engine, upgraded valve springs and special retainers to extend valve spring installed height. Oh, I also threw on a set of Crane Gold Race 1.6 ratio roller rocker arms for good measure.