Hi,

1. <snip>
2. A solenoids inductance has to fully saturate for it to pullin properly and pull with full force. After it has pulled in the driver will "see" only the DC resistance of 8Ω.
3. <snip>
4. Ifixit

I agree with #2 for a normal on/off solenoid but I think the solenoid in question is a proportional control.. The degree of proportion is set by PWM from the ECU. If it were simply an on/off control, the ECU wouldn't display such a short pulse width . Maybe the OP can observe his scope while engine RPM is varied to see if the pulse width changes.

I fail to see how modifying the VVT function outside the OEM specs will not have an effect on emissions. Modern engines have so many sensors feeding the ECU to maintain an overall balance between performance and emissions. Upsetting any of the parameters on either the sensor input or ECU output has to effect emissions. Just my opinion.

 

Hi Bill,

I believe it is also proportional control as well, as it is constantly being adjusted. The pulse width will adjust based on rpm and load.

The reason this isn't something that plays into emissions is that this is for open loop conditions only.

 

Hey Ifixit,

If I have the solenoid bypassed and the resistor is the only thing inline, should there still be .77v there, and why does it change to ~1.2v after the first "high" cycle as far as pulse width length? Is there an extra transistor turning on?

Also, which temp probe do you recommend? I was thinking last night as I was driving, how nice it would be to have a point and click laser temp probe instead of guessing at its temperature

Hi gte,

The 0.77V drop is likely as a result of a small current put through the solonoid buy the ECU to detect whether it is connected or not.

I don't have the spec for your RS 20W resistor, but I can speak in general terms.



Design considerations...

1. Power resistors are designed to operate at very hot case temperatures, which can be in the 300 to 400 °C range. That doesn't mean you should, however, operate like that.
2. The increased temperature means the temperature coefficient of the resistor will cause the resistance value to change some percentage per °C. This may be important to a design or not.
3. The materials in the vicinity of the resistor usually cannot stand that high temperature unless its steel and the joints are welded or crimped. E.g. FR4 PCB material should not be heated above 105°C, but 85 °C is better for good long term reliability.
4. De-rate the power rating (20W in your case) down to an exceptable level of dissipation where the case temperature does not exceed 85 °C.
5. Item (4) is an excuse to buy a temperature probe.
6. With a case temperature of only 95°F, that resistor will last for 1000 years (estimate).
7. This is likely more info than you need.

Good luck, drive safely and remember to buckle-up.

Ifixit

 

Hi gte,

I don't have too much experience with using the non-contact thermal guns so I can't give a recommendation, but I suspect you'll get what you pay for. I just use a thermalcouple probe that plugs into my meter directly.

I don't know why the voltage across the solenoid is different than the voltage across the resistor. I'm not sure whether you need to worry or not especially if everything works as you want it.




To investigate you can...

1. Re-measure the impedance values to see if there is a mismatch.
2. Is the fuse included in the voltage drop?
3. Check the voltage with a scope to see if it is pulsing.
4. Something is not what it seems to be... you need to probe around until you figure it out.

Good Luck,
Ifixit

 

Hey,

Day 3 of driving with the resistor, still no issues, I'm going to consider it a success.

I purchased a laser thermo gun, can't wait until it arrives


My question was why (no matter if the resistor or solenoid is in place) the resting voltage value will be ~.8vDC when I cycle power to the ecu, but after the first time it outputs a duty cycle greater than 50%, the resting voltage value will be ~1.2vDC. Just weird and I was wondering why?

 

That result would have to be caused by the program in the ECU. Like I said in an earlier post, all of the outputs depend upon the input from various sensors. A change in engine temperature, for example, could cause a change in the minimum value of the valve timing function. Software/firmware can do anything based upon any given input.