Halfcent

I am familiar with the Compression Sense Ignition (CSI) system of the pre-2007 L61 engines. I'm not asking about those. I am exploring what would be involved in convertering such an engine to a typical Coil On Plug (COP) system, just like the new 2007's have.

The CSI system is able to tell the ECM which cylinder is on the compression stroke through it's waste spark sensing ability. There are no crank or cam position sensors anywhere on the engine, making a mechanically simple engine.

First question: Does this system also provide the data the ECM needs to fire the correct fuel injector? I have to believe that it does.

To convert to a COP system, the ECM is going to need a new way to know which cylinder to fire. That could be accomplished via a cam shaft position sensor using the empty cam driven accessory pad on the head. I believe MSD has such a system, or something similiar.

Second question: Is the design of the coil pack and ECM such that they are dependant on each other, or can the ECM simply accept cam position data via a different source and then control an ignition system different then the OEM equipment?

Third: Back to the first question. Would the ECM still get what it needed to control the injectors?

Lastly: The new L61 for 2007 has both cam and crank sensors. Why? It shouldn't need both from what I can tell. Remember, my experience is with aircraft engines and they use traditional gear driven distributor style igntion systems. I understand enough about digital electronic systems to be able to work with them IF I know all the parts.

cobalt06ss_sc

i may be wrong but i believe the cam sensor is to tell the computer if the timing has been properly advanced or retarded and the crank sensor tells the computer what cylinder is in what position. once again i may be wrong but that's my thoughts on it.

Halfcent

A crank position sensor can only tell you if a particular cylinder is at TDC. It can't tell you if thats TDC compression or TDC exhaust. That's the cams job.

I have been doing as much reading as I can. I have learned that the crank position sensor in fact works together with the cam sensor and the ECM. The cam is only a 4x ring, basically just telling the ECM which cylinder in on compression. It then uses the 57X ring of the crank to adjust the actual spark timing. So I've made it that far.

1. Does the ECM use this information to control fuel as well?
2. Assuming the E16 ECM can use an igntion system other then the CSI pack, what kind of position sensing input would it require? I guess I already asked that above, but I'm just trying to clarify.

NJHK

Sorry but when it comes to ignition systems, I'm still somewhat in the dark but trying to learn.

Malaclypse

iTrader: (1)

Are you talking about a standalone COP ignition system or you're wanting to upgrade to the stock '07 COP? That makes a huge difference in where you have to go and what parts need to be installed/swapped out.

The crank reluctor has 6 teeth equally spaced and then one tooth to signal crank position. So the ECM -does- know which cylinder is on the compression stroke just by using the crank signal and the input from the CKP compared to its stored programming for the engine. That signal is used to control spark timing as well as injector timing in relation to the valve train.

The CMP signal is used to fine tune injector timing. If you lose CMP signal, though.. the engine will still run.