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Steady Eddie · 01-30-2008, 04:37 AM

Does anyone know if the PCM/ECU brainbox looks at oil pressure BEFORE allowing power to the ignition system? My Vortec BB starts so fast it is scary...

Steady Eddie · 01-30-2008, 04:37 AM

Does anyone know if the PCM/ECU brainbox looks at oil pressure BEFORE allowing power to the ignition system? My Vortec BB starts so fast it is scary...

edgray · 01-30-2008, 04:45 AM

Steady Eddie: I don't claim to be a mechanic, and certainly could not rebuild a motor, so please forgive if this sounds stupid. HOW can there be ANY oil pressure before the motor starts? Isn't the pump that produces the pressure shaft driven?

ED

Steady Eddie · 01-30-2008, 04:51 AM

Ed---
As the starter, which is a very hi-speed gear reduction motor, spins the engine over to start it, there is indeed oil pressure created in the oil galleys...

edgray · 01-30-2008, 06:36 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">spins the engine over to start it, there is indeed oil pressure created in the oil galleys... </div></BLOCKQUOTE>
I don't have any dis-agreement with the above. BUT, your OP asked the question "oil pressure BEFORE allowing power to the ignition system?" The starter does not spin until AFTER the ignition system gets power, right? ED

Steady Eddie · 01-30-2008, 06:43 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by edgray:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">spins the engine over to start it, there is indeed oil pressure created in the oil galleys... </div></BLOCKQUOTE>
I don't have any dis-agreement with the above. BUT, your OP asked the question "oil pressure BEFORE allowing power to the ignition system?" The starter does not spin until AFTER the ignition system gets power, right? ED </div></BLOCKQUOTE>
Ed--
Exactly--does the ignition switch and brain-box, turn on the power to the ignition primary side right away, or does the brain-box wait until it sees, for example, a
positive oil pressure, thus preventing a dry cold start??

Jeepster47 · 01-30-2008, 06:59 AM

Steady Eddie,
Doesn't the PCM/ECU Brainbox take a second or two or three to analize the oil pressure? If so, by that time the engine has started.

Ed

Steady Eddie · 01-30-2008, 07:13 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by jeepster47:
Steady Eddie,
Doesn't the PCM/ECU Brainbox take a second or two or three to analize the oil pressure? If so, by that time the engine has started.

Ed </div></BLOCKQUOTE>
Jeepster--
I think that I can find out if I disarm the oil pressure sending unit and attempt a cold start. Don't know if it'll throw a code, but I can clear it with my Scan Tool.
If it DOESN'T start, then we'll all know for sure. The rig is in storage right now and it is snowing outside so I doubt if I'll do the test anytime soon. I hoped someone would know, right off the bat.

exrench · 01-30-2008, 09:55 AM

If the ECM held off until after the oil galley was pressurized,we would not be able to start after an oil change with an empty filter until the oil pressure came up.In fact,the engine will start immediatly and show NO pressure for a scary length of time.Best to fill the filter first however which is not news to you.

Steady Eddie · 01-30-2008, 10:11 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by exrench:
If the ECM held off until after the oil galley was pressurized,we would not be able to start after an oil change with an empty filter until the oil pressure came up.In fact,the engine will start immediatly and show NO pressure for a scary length of time.Best to fill the filter first however which is not news to you. </div></BLOCKQUOTE>
exrench--

You are right..100%...and, you already know that I always pre-fill my filters. But there is a method to my madness here. I would not have posted if I wasn't going somewhere with this thread. I have been looking at Pre-luber Systems in the interest of preventing dry starts and having the engine last a very long time. But the price--

--really backed me off. But then I remembered "fork trucks"...

The Hysters we had at work (when I had a real job and was not retired) would crank a few revs and then fire off and run. Their oil pressure sending units had a set of two contacts, one of which closed at 5 PSI (rising) and it brought in the 12v to the
primary side of the ignition coil. Hyster figured that was a real easy way to prevent the cold, dry start problem. I think I can "T" one into the oil pressure sending unit on my Vortec BB and have a Pre-luber System for about $14....

rgrstndgby · 01-30-2008, 11:10 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Their oil pressure sending units had a set of two contacts, one of which closed at 5 PSI (rising) and it brought in the 12v to the
primary side of the ignition coil. Hyster figured that was a real easy way to prevent the cold, dry start problem. I think I can "T" one into the oil pressure sending unit on my Vortec BB and have a Pre-luber System for about $14.... </div></BLOCKQUOTE>
SE, I'll admit I generally read your posts with a lot of interest, and a little caution, but I'll also say that you are a free thinker, my kind of guy, and this sounds like something that is worth a further look, please keep us posted...rgr...

Avalondanes · 01-30-2008, 11:22 AM

Steady Eddie,
The Hyster and Yale lift trucks, mfd. by NACCO, had a "revolution switch". It is a sealed PC board that went to the second oil pressure send unit, then to the ign coil and module. The OP unit would close with pressure and make the circuit to power the revolution switch, then ign. would fire the engine. In the engines used since 2005, the ECM will see oil pressure from the second OP sender and send power to the coil and module.

Richard

Steady Eddie · 01-30-2008, 12:49 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Avalondanes:
Steady Eddie,
The Hyster and Yale lift trucks, mfd. by NACCO, had a "revolution switch". It is a sealed PC board that went to the second oil pressure send unit, then to the ign coil and module. The OP unit would close with pressure and make the circuit to power the revolution switch, then ign. would fire the engine. In the engines used since 2005, the ECM will see oil pressure from the second OP sender and send power to the coil and module.

Richard </div></BLOCKQUOTE>

Here's the very low tech, old school hardware to do this Mod. The black object is the rubber boot that slips over the sender to protect the naked terminals.

http://tinyurl.com/26qze9

And a pic of the sender, showing the ground terminal for the oil idiot light and the other two, are the NO contacts. The idiot light ground is not used.

http://tinyurl.com/2xzg34

TandW · 01-30-2008, 01:20 PM

Unless a timer delay is incorporated after proving pressure this system is useless, as that portion of the running gear that is farthest from said pressure switch is still not positively lubricated. Oil of proper multi-vis rating is your best protection and is endorsed by the engine manufacturer. Good luck!!