Tuning vortec to run on as little sensors as possible

[Caman96]

Maybe he's prepping for an EMP, One's gots to know how to get around in the apocalypse. lol

You don’t have a spare PCM in a Faraday?

 

[Pinger]

I'd like to hear more about both if you have the time. I'd think the cam sensor allows for better control of the ignition timing. My Saturn didnt have a cam sensor but that was a waste spark ignition which I understand has it's own peculiarities. Supposedly a value was calculated by the pcm.

On more modern engines, the cam sensor is there for start up only. Once running, data from the crank sensor is all that's needed. On start up, the cam sensor tells the ECU which stroke a piston is on. The only exception I have heard of was the Suprex engine in my smart. No cam sensor - the ECU sensed the compression stroke during firing by the slight reduction in crank speed. Maybe only possible when you are down to cylinders as few as three.

As for the knock sensor causing detonation, it absolutely can and that is the reason why it is disabled on my 383. Retarding the timing can actually cause detonation from excess heat. I did not believe others that had stated that before, until I ran into it myself. Knock sensor was picking up noise from the forged pistons and valvetrain. Retarded the timing, then it went to the low-octane spark table. Once on the low-octane timing map, it was still going to maximum retard as soon as it turned on. My ~30* of total timing became 10-15* of timing, the chambers started heating up, before long I actually heard light amounts of spark knock aka pinging.

People underestimate how damaging retarding the timing as a self-preservation method is. That Suprex engine had crap oil control rings. Oil in the combustion chamber lowered the fuel's octane (and replaced fuel). The ECU's attempt to save the engine from detonation by retarding the timing burned exhaust valves. They all did it - requiring a rebuild by 50,000 miles or so. Some no doubt suffered the double whammy of a fouled plug (twin plug heads) which would only worsen all of the above.

Back to Vortecs. The auto transmissions rely on the MAF sensor for shift quality. Remove it and the upshifts are hard.

 

[Scooterwrench]

Now y'all got my ears up. I would never had thought that an engine with crank and cam sensors would even run without them.
I may turn off the KS on ol Smoky. The tired old engine is loose and rattly and so is the A/C compressor. Think I'll datalog it today and watch for knock counts with the A/C on. My MPG sucks with the A/C on.

 

[Erik the Awful]

As for the knock sensor causing detonation, it absolutely can and that is the reason why it is disabled on my 383... Knock sensor was picking up noise from the forged pistons and valvetrain.

Back when I was a tech, Nissan had a problem on a few cars where the knock sensors were too sensitive. We were told to put a piece of notebook paper between the sensor and the block. You might consider that.

 

[slow_c1500]

Ok after hearing this new info, I’ll probably leave most of the sensors alone, even if they aren’t 100% necessary for the engine running. The only ones that I think would be beneficial to delete would be the rear o2s along with the cats, and the knock sensor. I understand why the KS is there, but from what you guys are telling me, it seems like pulling timing isn’t a good way of “correcting” whats wrong with the engine, and it’s better off without the KS.

I’m guessing to delete it, I’d just need to block off the hole where the sensor used to be, and tune it out of the ecu?

 

[Pinger]

Ok after hearing this new info, I’ll probably leave most of the sensors alone, even if they aren’t 100% necessary for the engine running.

I'm not seeing your logic here at all. Seems like you fear a sensor malfunction for whatever trouble that causes but by deleting a sensor you go straight to the trouble you seek to avoid.
You can be pretty sure that if GM could have met its objectives in improving the Vortec beyond TBI with one fewer sensor, then it would have. GM dug into its coffers and funded what they thought was absolutely necessary - by necessity not choice.

The only ones that I think would be beneficial to delete would be the rear o2s along with the cats, and the knock sensor. I understand why the KS is there, but from what you guys are telling me, it seems like pulling timing isn’t a good way of “correcting” whats wrong with the engine, and it’s better off without the KS.

Those are specific edge cases you are referring to. Forged pistons and (obviously) non-stock valve train in L31ME's case and with my smart - probably wouldn't have survived long enough to burn its valves without a KS.
Down-stream O2 sensors don't influence engine parameters, merely monitor cat efficiency so no positive gain to be had.
If it aint broke dont fix it. And if it is broke, fix it right.

 

[slow_c1500]

I'm not seeing your logic here at all. Seems like you fear a sensor malfunction for whatever trouble that causes but by deleting a sensor you go straight to the trouble you seek to avoid.
You can be pretty sure that if GM could have met its objectives in improving the Vortec beyond TBI with one fewer sensor, then it would have. GM dug into its coffers and funded what they thought was absolutely necessary - by necessity not choice.

Those are specific edge cases you are referring to. Forged pistons and (obviously) non-stock valve train in L31ME's case and with my smart - probably wouldn't have survived long enough to burn its valves without a KS.
Down-stream O2 sensors don't influence engine parameters, merely monitor cat efficiency so no positive gain to be had.
If it aint broke dont fix it. And if it is broke, fix it right.

Ok, I was a little confused about the knock sensor causing problems, maybe thats only the case for performance/non stock engines which is why L31ME deleted his.

On the topic of rear o2, I have heard that if the rear o2 sensors are faulty or if they detect the cats not doing their job, it CAN mess with the air/fuel ratio. Isn’t this why you delete the rear o2 sensors when you get rid of the cats? Because if you leave them in, they will tell the pcm that the cats aren’t doing their job, and it will subtract fuel to make the truck “pollute less”, and fuel economy and performance will suffer.

 

[Pinger]

Ok, I was a little confused about the knock sensor causing problems, maybe thats only the case for performance/non stock engines which is why L31ME deleted his.

I'll leave L31ME to speak for himself, but I think you have read it right.

On the topic of rear o2, I have heard that if the rear o2 sensors are faulty or if they detect the cats not doing their job, it CAN mess with the air/fuel ratio. Isn’t this why you delete the rear o2 sensors when you get rid of the cats? Because if you leave them in, they will tell the pcm that the cats aren’t doing their job, and it will subtract fuel to make the truck “pollute less”, and fuel economy and performance will suffer.

My understanding was that all the downstream O2 sensors could do was light up the CEL as the upstream O2 sensors were the only ones that could influence AFR. You'd delete downstream O2 sensors along with the cats but only to avoid the CEL (by programming them out). I could be wrong but that's my understanding of it.

 

[454cid]

The rear oxygen sensors don't affect your air/fuel ratio.

 

[Hipster]

I'm not seeing your logic here at all. Seems like you fear a sensor malfunction for whatever trouble that causes but by deleting a sensor you go straight to the trouble you seek to avoid.
You can be pretty sure that if GM could have met its objectives in improving the Vortec beyond TBI with one fewer sensor, then it would have. GM dug into its coffers and funded what they thought was absolutely necessary - by necessity not choice.

Those are specific edge cases you are referring to. Forged pistons and (obviously) non-stock valve train in L31ME's case and with my smart - probably wouldn't have survived long enough to burn its valves without a KS.
Down-stream O2 sensors don't influence engine parameters, merely monitor cat efficiency so no positive gain to be had.
If it aint broke dont fix it. And if it is broke, fix it right.

Ditto, all engines have some degree of inherent mechanical noise. Roller rockers, more piston to bore clearance for forged pistons make more noise. Not difficult to understand knock sensor picking that up.