CNP products for Mopars

 

Why go CNP?

Coil-Near-Plug is used on almost all modern engines. OEMs do this to virtually eliminate ignition noise from modern heavily computer populated cars. It eliminates the ignition coil and distributor, and it also allows for individual cylinder timing adjustments. Spark energy increases because the coils have plenty of time for dwell saturation regardless of RPM.  And EFI datalogging is so robust that a separate data logger is not needed.

 

A Quick CNP Tutorial

The ECU must know when to fire each coil. There are two ways to do this:

 

• Waste spark with missing tooth trigger wheel:

When the ECU sees the gap on a 36X or 58X trigger wheel it knows that the engine is coming up to TDC for either cylinder number 1 OR number 6 (assuming a 18436572 firing order). It cannot tell which coil to fire since both are coming up to TDC, but only one is starting the power stroke while the other is starting the intake stroke. So the ECU will fire BOTH #1 and #6 coils thereby wasting a spark. This is an acceptable technique that can be used if there is no cam sensor, however the trigger wheel must be a missing tooth style, and individual cylinder timing control is not possible.

 

• Sequential spark using a CAM sensor:

A cam sensor generates one pulse, or edge, per camshaft revolution. This allows the ECU to be in sync with the engine’s cycle and fire only one coil, thereby not wasting a spark, and the ECU can also control individual cylinder timing.

 

Since the cam sensor synchronizes the ECU to the engine cycle the crank trigger wheel does not have to be a missing tooth style. A typical configuration would be a trigger wheel with four magnets and the pickup. However, you can use the 36X or 58X style wheels with a cam sensor as well. In fact, the missing tooth wheel is preferred because the timing is more accurate during rapid changes in engine RPM. Using a CAM sensor is better than the waste spark method.

 

This document assumes the use of the CAM sensor.

 

* EFI with CNP benefits for racers that you may not have considered.

 

$1500 for smart coils, wiring harnesses and sensors is roughly what a person would need to spend for a conventional system. A racing carburetor is well over $1000, a racing CD box is around $700, big coils are $300, a billet distributor is $400, while a belt drive distributor is $700. So if you are building a new engine you might as well go EFI with CNP and get the benefits from the get go.

 

EFI allows you to control timing, start retard, high-speed retard, two step, multiple rev-limits, timing retard for launch control, custom spark curves for boosted engines, nitrous control, turbo control, and extra timing at high vacuum conditions, (a billet distributor does not have a vacuum advance), and if you want start retard or high-speed retard you may need to buy extra modules. All these features plus accurate air fuel ratio control are built into the ECU for free. Individual cylinder control of both fuel and spark (with CNP) comes for free whereas doing this with a conventional system is almost impossible or very expensive.

 

Plus the fact that the built in datalogging negates the requirement for adding a separate data logging system.  Some data logging systems exceed the cost of the EFI system so in that regard, EFI for a racer is actually cheaper, simpler to implement, lighter, and you can data log engine parameters that only the ECU would know about.