kanner1

Does anyone know for sure if the VVT will work without using the factory oil pressure sender in the back of the block running to the ECM on a LY6?

I am running aftermarket gauges / sending units. I have heard from some that it wiil, some that it won't.

1989GTA

I don't know but I did not take any chances. I tapped into the oil cover with the two bolts down by the oil filter for my after market oil pressure guage.

85MikeTPI

iTrader: (9)

The PCM has upper and lower oil presure limits for VVT activation, so I would say yes. I haven't tested this though.

kanner1

Thanks! I guess I'll be tappin mine too!

casias

iTrader: (1)

[QUOTE=kanner1;16976841]Does anyone know for sure if the VVT will work without using the factory oil pressure sender in the back of the block running to the ECM on a LY6?

I guess you could unplug the pressure sensor and try driving? Maybe I will do that tomorrow on mine.

85MikeTPI

iTrader: (9)

... and scan it to see if the cam is being commanded and is actually retarding, otherwise you're just pissing in the wind.

kanner1

Casias.... Let me know wait happens if you try it out!!! Thanks.

casias

iTrader: (1)

Sure, no problem. I am curious too after the issue we had with the cam phasing being affected by the aftermarket oil cooler.

1989GTA

I am sure you would get a low oil pressure warning to the dash board. Then if the ECM "thought" there was no oil pressure would the software even try to adjust the camshaft? I guess that is the question at hand.

casias

iTrader: (1)

OK,

so here is what I found out from my informal research and testing.

1) Is it safe to run a VVT engine without an oil pressure sender?

Yes. After researching the question, primarily from this site http://www.diagnosticnews.com/tech/g...-valve-timing/, I determined from reading the fine print that the variable timing of the camshaft is actuated by a stepper solenoid. The ECU gives a command to move the camshaft to a desired position, and the solenoid responds by opening 100%. Kind of like your furnace thermostat will kick the furnace on until it reaches the temperature desired by the user. The difference is that the stepper motor solenoid will step back to a percentage allowing enough oil flow to maintain the camshaft at the commanded position. This is dynamic, and changes constantly with engine load.

Here is a screenshot from a scantool that has "commanded" the camshaft to a position for diagnostic purposes:



2) Can my pistons hit my valves if the vvt is not in the correct position?

No. The system is designed, with the original cam to always maintain a safe clearance within the vvt phasing range. In engines that use both variable valve timing and variable valve lift, it may be possible, but I didn't research these motors.

3) Is my VVT working correctly without the oil pressure sender information?

I couldn't find any technical bulletin that related failure of vvt to failure of oil pressure sender unit. I believe the system is very simple, as is described above. The camshaft is commanded to a position, and when that position is reached, the solenoid closes to maintain the position.

4) Will drivability be affected?

My engine is running exactly as before without information from the oil sender. I haven't done any testing to determine if the vvt is moving where it is supposed to, but I haven't noticed any difference in 2 days of mixed driving.

5) What codes can appear?

If the camshaft does not move where it is supposed to, or the solenoid fails, the ecu can send codes P0011 and P0012 for excessive cam advancement, and codes P0021 and P0022 for excessive cam retardation, according to http://straighttalkautomotive.com/OB...021-P0022.html.

6) How can I eliminate the check engine light if I choose to remove the stock oil sender?

A resistor wired into the connector will fool the ECU into thinking the oil pressure is in range.

I am going to drive this truck for a week or so (which should be 500 miles or more), and check the codes to see if anything appears.

If anybody has any other info?

85MikeTPI

iTrader: (9)

... pissing in the wind

casias

iTrader: (1)

Ok, so let me see if I understand what you are saying. Basically, your theory is that the vvt cam phasing only occurs when the ECU sees, at the very least, some minimum oil pressure, and possibly is deactivated above a maximum oil pressure? Kind of like a window switch.

SO

If I look at the scatterplot of an LY6 engine oil pressure:



and see that the pressure is somewhere between 30 and 60 psi (idle to 4000 rpm), and I know that the ECU looks at minimum oil pressure at 1500 rpm, and logs a dtc if it is below a minimum value, then why don't I just arbitrarily pick 50 psi as my set value.

Then I can fool the ECU, with the addition of a resistor in the original oil sender circuit, let the ECU think it sees an adequate pressure, which will allow the activation of the cam phasing system.....whew.

Then I could use that little hole in the back of the block to add my own oil sender unit, that goes to its own gauge that I can see, while maintaining the vvt system.

Is that it?

85MikeTPI

iTrader: (9)

If "it" you mean will the VVT system operate, then yes, that's
it.. If you're running an aftermarket cam without a phaser limiter, then your hack will just introduce the valves to the pistons.

Why don't you stop googleing VVT and just put a scanner
on your VVT vehicle with the Sender disconnected?

casias

iTrader: (1)

Because I have accomplished all that I promised.

HSV-GTS-300

Why not just keep the factory OP sender (to keep the factory electronics happy) and add an aftermarket OP sender at the stock location.

GEN 4.


Same swivel tee fitting on GEN3.

kanner1

Thanks for all the feedback!!! I'll post some results when I get this f'er figured out.

casias

iTrader: (1)

"Why not just keep the factory OP sender (to keep the factory electronics happy) and add an aftermarket OP sender at the stock location".

Thanks for your great pics.


I guess because that wasn't the question. I have seen this question bouncing around for a while, and I personally wanted to know.

Does it affect the operation of the vvt system?

While I haven't attached a scanner, as was suggested, we have put over 200 miles of mixed driving on our unmodified LY6 after without any noticeable drivability issues. This leads to 3 possible conclusions:

1) The ECU does not look at this signal at all with regards to this operation.

2) The ECU uses a different calculation or signal in a redundant table that allows for normal operation when the sensor fails.

3) The proper operation of the VVT system is insignificant subjectively.

The question is still open for anyone with a scanner to answer. I personally would love to know.

Thanks for all the replies.