Woops I got it backwards. Thanks for the correction.

 

Oh man I was doing fine, but now I have a headache!

 

Cleatus, do you still have the waves stored and can you check the time shift, assuming timing difference is linear, we are only looking @ 1/2 of the 0 to 0 duration skew.

Anyone overclock their PCM? That could change everything.
Just kidding, you're on a good track here.

 

It would be interesting to measure the signals at different speeds to see if there is an effect due to the speed. If the time shift is constant, than the advance will vary with speed.

 

What is your approximate cutoff point of light and heavy? is 9K considered light or heavy?

 

I do have the waveforms still stored. I will take my scope home this weekend and fiddle around with it. It's not like it will be hard to determine actual advance on the BASE injector timing because it's just a matter of time and speed (I have both of these on hand). I haven't had a lot of time to mess with the stuff on work hours due to the uncorny flood of 4L60 rebuilds I've had to do this week.

Cody

The injector timing will always change with engine speed/load, but that is a function ONLY by the ECM based on load, RPM, and fuel rate. The CMP sensor does NOT change dynamic timing. Static or BASE injector timing is all that we are changing. Yes, the injector timing will be changed across the board due to the different CMP sensor, but it will only be off by our new offset afforded by the different CMP. For example:

Say the ECM commands injector firing at 15 degrees BTDC at 2400 RPM with a fuel rate of 93cc while throttle position is at 75%. With the black CMP sensor, the firing of the injector happens at 15 BTDC. With the blue CMP installed that advances BASE timing 1.5 degrees(hypothetical number for all intents and purposes), the firing event actually happens at 16.5 degrees BTDC.......but the ECM doesn't know any different and thinks the timing is still at 15 degrees BTDC. This will be the same no matter the RPM or load on the engine. The engine computer DOES NOT KNOW that the CMPsensor is actually sending the RPM signal before it is supposed to.

I think I just confused myself but reading it over again makes sense to me......... .

Cody

 

Yes Cody, yer right. If Kwik's theory is correct, it would actually be a retarded situation (no pun). So although we know the pulse is of shorter duration, we can do all the hypothetical math in the world, and still not know if the timing is actually changed. Say for instance the on/off differance is not linear, and it's really just the on time that changed due to the narrower pick-up, and the off time stayed the same?

I'm gunna ask again, does anyone know how to hook an inductive timing light to the #1 injector to see exactly what the real change to base is?

 

Me too until I read the above posts. I even majored in math in college (but then, we were still using slide rules then)

 

I really dont understand all of this so it is like reading greek to me just a little gives me a headache. am reading trying to understand and learn more, but to tell the truth I am waiting for all of you to decide if the blue is the way to go, or stay with the stock black

 

It's more like reading GEEK. I'm with ya. I needed to replace mine as it was doing the momentary off thing, so I went Blue. We all know black is safe, and the blue seems to help some users. Nobody knows exactly why. Since I'm there, I want to see what is really happening so I can revert if that is better for the motor. And thanks again Cleatus, you've gone alot further than anyone else.

 

I understand your post, makes sense to me.

I understand that there is an advance curve in the ECM, similar to spark advance in a SI engine. My question was whether the timing change due to the CMP would change as speed changes. For example, if the time shift from the CMP is the same at various speeds, the advance would actually be changing with speed. For the advance to remain constant, the time shift would need to be smaller as engine speed increases, as measured on your scope.

I pose the question about processor I/O speed before, because this change may be smaller than the controllability range of the ECM. This may be why some motors see a change, others don't.

As mentioned, the easiest way is to hook up a timing light.

 

I guess I don't see what you're saying. I've ALREADY got a base reading from the crankshaft itself. I KNOW that the CMP's switch to "off" is earlier in the compression/power stroke of the piston's cycle. Overlaying the waveforms with the same trigger point yields a [blue cmp] waveform that sits perfectly inside the other [black cmp].

I don't see why you couldn't easily hook an inductive timing light around the no.1 injector wire (once it's separated from the loom). There is easily enough amp draw through the wire to induce a magnetic field for the light pickup.


I'm going to take my scope home and do some math with the time/RPM I have and see if I can't make heads or tails out of what the actual timing change is. I want to see if I can do it mathematically.

Cody

 

I don't see how it's possible to have any reference to the crank position.
I at this point am thinking you are assuming the timing is advanced.

 

Wow... I do think that headache is contagious.

 

Now that my headache is gone and I can think clearly again I think I will wade into this pool of insanity and throw a small dose of reality in if for nothing else to keep this archaic thread alive. Law of averages = one of these responses: 'worked in my truck', 'didn't work in my truck', 'didn't notice any difference in my truck'. Just as a Presidential race with 2 candidates and a Zebra or it may even be an animal of your own choice but, the zebra will eventually and historically receive about 12-15% of the voter turnout. Not unlike telling 100 people they are on a diet while giving some the actual diet pill, some getting nothing but a sugar pill, and others getting nothing at all during the test. Some with the pill will lose weight, some with the sugar pill will lose weight, and even some doing nothing at all will lose weight which means the flip-side to this equation is that some may actually stay at the same weight or gain weight. Not to bash anyone that is using the blue cps (more power to you){NO PUN} As my forum signature says: "You can always tell whose a pioneer with the amount of arrows in his back". You guys using the blue cps are pioneering through areas that others are interested in and may want to try but only after a guaranteed result. So back to the logic that if 100 members on this forum are using the blue cps the law of averages will equate to what is stated above. Just as all of us using the black cps have the same law of averages for us such as some of us never having to have changed one yet, while some are on their third one or more, and others that may only be on their second one even though the trucks mileages could be very similar. I personally will stick with the black cps just for the same reason that I wouldn't use an oil filter designed for a 6 cylinder engine even though it has the same threads that would allow it to fit my truck.
All the guys using the blue cps with better results must live up north as the earths magnetic pull along with the cps's magnet send a stronger signal to the pcm. Now just calm down and relax - we don't need everyone chiming in that this guy is an a-hole even though that might be the case! We know who we are. $.02