I havent run an engine cover for the past 3 or 4 months, so that wasnt it in my case. I think it was just my coils where gonna go eventually. I doubt the stage1 casued anyting, unless one of the components on the extra circuit for the ignition control is bad or defective. Maurice will test that out to make sure it's OK or not as the case may be.

 

Better put your engine cover back on. It's supposed to improve air flow under the hood. Directs it out the side vents, I'm told.

Worst case for high underhood temps - high load slow speed - such as autocross. High speed will not heat it up as there is lots of natural airflow at high speeds. Pull off a highway and drive slowly up a steep hill - that'll heat it up! Heat soak is caused by the engine operating heat normally removed by the cooling system staying in the engine because you came off the expressway and stopped the engine without letting it cool down for a few minutes. Check out cars parked in rest stops on highways. You'll find at least one in twenty has boiled out a bit of coolant.

Of course none of this will damage the coils if the engine is shut off.

 

Thanks. But now I'm tempted: "So, officer, I HAD to take my front plate off to improve air flow. Yes, I'll put it back on in less stressful driving conditions. You don't give a WHAT?"

 

Maybe not. A single diode (Silicon) is good for, IIRC, a .7V drop, leaving you a potential .7V signal, which could cause a leak in the power transistor (gain mode vs saturation mode). I seem to recall that this is what Open Collector drivers are for.... OC will "shut off" the output driver transistor in the IC and you have an external pull-down resistor to ground to take the leakage current ground. You can still have a bit of voltage present (leakage current across the resistor), but you get to manage it better.
Or maybe just a second diode?

 

No, common misconception - a single diode will drop 0.7V with very low current (about 1mA or less). Check out a data sheet. Under normal operating current you will find about 1V drop. Measured it. Got about 1V. Tried two diodes, got a 2V drop and started having problems with Maurice's car (which causes me to think it's not saturating the transistor when "ON"). Switched back to one diode, problem solved. We looked at "digital transistors" too. Unfortunalty they invert the output so you need two. They take the output down to about 0.2V. Parts count went way up (regulator needed as well as the two devices plus some resistors). More parts to fail. If we can't make the diode reliable we may have to go that route, but current indications are one diode will be fine, in fact better than stock, as the electronics we are using can drive more current than the stock PCM.

Now, in truth the current units that have been shipped also had a resistor to ground to lower the drive current. We thought being closer to stock values was better. I now think those resistors should be removed (two 2K2 resistors on end of board - they can just be cut of - leave the 10K resistors alone - they are part of the tach output). This is on the small PCB beside the Main unit. Just incase any of you want to experiment.

As I said, more measurements will be done soon (with a heat gun and scopemeter).

 

Here's a stupid questiion: Does the grounding kit offer any aid for this problem?