With the A/C off, do the cooling fans come on correctly?
Fwiw, ECT1 does control the fans. While testing different resistance loads, I was able to get both fans to come on because the temp was reading 230.The pot is inline with the sensor. ECT sensors are thermistors, which means just a resistor that varies with temperature. As the coolant temperature increases, the resistance across it decreases. By adding in more resistance inline with the sensor, you're increasing the resistance of the circuit, which makes the PCM think the engine is cooler than it really is.
The resistance I'm using by adjusting the pot is about 40 ohms, but I may have to adjust it once the weather warms up and the engine runs hotter, I'm not sure.
As mentioned, I still need to confirm that fan operation is unaffected, but so far there have been zero issues with doing this other than the initial code I mentioned that has cleared. I'll also be checking my plugs regularly to look for signs of running rich, but I really highly doubt I'll see anything. If anything, my rear bank plugs will look way better than others have reported.
I got the same readings and documented this some time ago. Your assessment is correct as you'll have to vary the resistor to keep it in the 161-167 range as the actual engine temp fluctuates. In Fl, I see 182 coolant temps (A/C off) so you'll need to have a 17d temp offset but at 170 coolant temp, the PCM will "see" 153d temps and might throw a code.verbatim, I hooked up the scangauge to get some temperature readings and to compare them against your readings. ECO mode doesn't get enabled until the coolant temperature reaches 166-167 deg. F. And the normal operating temperature of the coolant is 170-175 deg. F. I checked this over a few days where the ambient temperature varied from ~15-35 deg. F and the heater temp was set to 71 deg. F. Do those coolant temps agree with your readings before you added the series resistor?
I also noticed that, if it's cold enough and I crank up the heater to maximum, the coolant temperature will start dropping and ECO mode gets disabled around 161 deg. F. It seems there is some hysteresis between 161 and 166-167 deg. F and the heater temperature setting could affect the optimal value for the resistor. If you wanted to go crazy with the fix, you could use a digital pot. whose value gets adjusted based on the coolant temperature. A microcontroller runs the show and uses the true coolant temperature as feedback to adjust the pot. and send the corrected temperature back to the PCM. When the coolant temp. is close to the ECO disable threshold, not much resistance correction is needed. But when the coolant temp. is hotter, more correction is applied.
If anybody lives in a cold climate and they want to temporarily disable VCM, set your heater to maximum, sweat like crazy, and enjoy the smooth ride. :29:
Like I said, I have seen 182d and upper 170's regularly here in Florida.Can those of you in really hot climates that have a OBD tool tell me what your actual operating temperatures are? I've never seen anything over 175 or 176. Certainly not 180. Some data from people in warm climates would help. I'll know more here when summer comes, but even then we rarely reach 90F outside temperatures.
I've used my simple harness in outside temps ranging from about -4F to 50F with absolutely no issues and very little change in operating temperature.
I stated very early in this discussion, that this might be a problem. To get it to work in warmer climates, you have to have a bigger temperature offset. With the bigger offset, those in colder climates might trigger a CEL due to temperature plausibility (low temperature).Just passing along my update on the VCMuzzler. Install was straight forward. Once installed the ride was great. Especially in cruise mode, except for this morning. On my way into work about 5 min. into the drive the CEL came on and said "Check Emission System". That caught me off guard cause I've been using the VCMuzzler for the last month and no issues. Now this morning we had abnormally low temps than the last few weeks. It was 35 degrees so this would have been the first time it would have run in those temps. So I unistalled the VCMuzzler and took it to Advance Auto to have it diagnosed. And sure enough it was the coolant temp out of range "too cold". So with that being said has anybody run into this scenario. I've ordered a OBDII tool to clear the code and will be installing the VCMuzzler. Hopefully it was just a fluke and everything will work out fine in the future. If it does happen again maybe an adjustment needs made to the resistor value. I know that the climate changes and there are many variables. Otherwise the VCMuzzler worked great and my gas mileage was not affected during the time it's been installed.
I've used this unit for years on many different vehicles: UltraGauge OBDII Scan tool & Information CenterI don't have an ODB reader what would you guys recommend that's cheap and does the job..
Do you have your A/C on? If not, that's normal operation. As stated earlier in the thread, I have seen 184°.I swapped resistors from your harness Verbatim. It works perfectly. What I was saying was that the indicated temp with the 100 ohm resistor while the car was moving at almost any speed (air flowing through the radiator), the indicated temp was always at 158f-160f, never allowing vcm. The only time the temp climbed was while the engine is running and the car not moving. I assume this to be normal, harness mod or not. If the engine is running with no air flowing through the radiator, the temp will always climb until the pcm commands the fans to come on. I'll remove the harness and report back the "real" temp the fans come on at idle. Just curiuos. Are you saying your temps with harness never allow vcm temps even at idle with no air flow through radiator? Again thanks for a great product. What a difference its made!