Waterless Coolant

[reklipz]

I suggested to double check the wiring diagram. Do you see such circuitry and sensor in the diagram you posted? Does the service manual describe such system?

Ah, I see. Sorry I misunderstood.

Here is what I could gather for all of the temperature sensors:

1. TA sensor -- intake air temperature sensor
2. TW sensor -- water/coolant temperature sensor
3. Thermoswitch (water jacket cover) -- cooling fan switch B
4. Thermoswitch (thermostat cover) -- cooling fan switch A
5. Coolant temperature sending unit -- coolant temperature sensor for dash coolant temperature gauge

The item in question is number 2, the "TW sensor." I only have the JDM manuals that are available online, not one for the USDM. As part of that, I am missing the page troubleshooting the TW sensor for the PGM-FI engine, and I have instead uploaded the PGM-CARB troubleshooting.





There appears to be a CEL code for "coolant too hot," and it's code 6.

If all the ECU does with this sensor is turn that CEL on and off, I suppose we could alter the circuit to shift the new operating temperature so that it signals as though it was the lower temperature. That said, I have a feeling Honda is smarter than that, and does some actual calculations with this temperature. As far as what, I suppose that's for me to determine, being the "ASM guru" and all.

[oyajicool]

That said, I have a feeling Honda is smarter than that, and does some actual calculations with this temperature. As far as what, I suppose that's for me to determine, being the "ASM guru" and all.

OK, "guru"!!. Have at it.

Looking at the diagram, does ECU directly control cooling fans to compensate for overheating condition?

Did you know the word "Guru" is Indian (not American) word?
I didn't know that till my Indian friend told me many years ago.

[reklipz]

OK, "guru"!!. Have at it.

Hah, I wasn't trying to be a snob. In fact, I was trying to state the opposite. Sure, I can understand individual instructions from the ECM, but in the grand scheme of things I am apparently just as lost as everyone else. If we're serious about attempting this, I will sit down and try to find out where the temperature signal comes in to play.

Looking at the diagram, does ECU directly control cooling fans to compensate for overheating condition?

Below is a quick drawing I made. It looks like the ECM has the potential to ground the relay (turning it on) from anywhere from zero times, up to twice, depending upon the model of the vehicle. Again, remember that these images are from the JDM factory service manual; I do not have the USDM manual, though the circuits should be nearly identical.



The fact that some vehicles don't have any connection to the ECM would lead me to believe that the ECM only uses these lines as signals, but I could be mistaken. Does the condenser fan come on when the A/C system is switched on? My A/C system does not function, so I am unaware. If it does come on when the A/C is on, the only way this could be is because the ECM does so, and by doing so, it would also switch on the radiator fan, regardless of whether or not the "thermoswitch A" was activated or not. Also, by my count, once "thermoswitch A" activates, both fans should come on as well. Is this so?

Lastly, the KY and KQ systems, as well as the non-KY and non-KQ systems that don't have the "fan timer system," both have the independent signal (BLU, blue in my coloring) to the ECM. Again, this is either so the ECM can detect the fan load (it's not there on models without A/C, with only a single fan, where the load is less), or to actively switch the fans on. My guess is the former, as it can switch the fans on via the A/C diode (BLU/BLK, pink in my coloring) wire.

Did you know the word "Guru" is Indian (not American) word?
I didn't know that till my Indian friend told me many years ago.

I did not know that; interesting.

[reklipz]

don't worry about the ect sensor. the code is mainly for checking if the sensor or circuit is open. egr will most likely function in closed loop which is pretty much any time the CEL isn't on, 30 seconds after cold start-up and not in a WOT condition.

I found the above on the forum. It looks like Wes knows more about this sensor/circuit. In the above, he claims that the circuit is more of an auxiliary "oh shit" circuit; perhaps he can shed some more light on the situation?

A thread on pgmfi.org also says that while the ECM can control the fans, they don't appear to ever do so (the JDM ones at least), or if they do, the trip point is extremely high. We could test this theory fairly easily if needed as well.
http://forum.pgmfi.org/viewtopic.php?f=2&t=20605

These posts also allude to the ECM being able to control the fan(s) via that wire (A12, apparently). They also state that some ECMs/chassis do not have the wiring or driver to do so.
http://hondata.com/forum/viewtopic.php?f=19&t=10486
http://www.hrtuning.com/forum/viewto...bf3aa976e34ca7

Either way, if someone is serious about attempting to increase the operating temperature, I will take a stab at the PT3/PT6 ECM code and see what, if anything, the program does with the readings. I may attempt this myself at a later date once I have the funds.

[cloudasc]

One main reason the ECU uses the temperature sender input is to know when the vehicle is "warmed up" to switch from open to closed loop mode. The ecu's I'm also pretty sure use the coolant temperature input to control the effectiveness of combustion. It can tell the fans to turn on as it takes input from the A/C switch if I am correct to adjust for the load of the compressor on the engine in regards to the IACV, etc; also the both fans come on when you press the A/C switch. In systems without A/C I'm pretty the only thing that controls the fans would be the thermo-switches. One switch activates the radiator fan at around 190*F, and the other activates both fans at around 220*F, which acts as a redundance/failsafe and kicks on both fans.

In regards to the code 6, I've dealt with my fair share of cooling issues due to a leaky headgasket, that would like to overflow all my coolant out the overflow bottle by substituting it with exhaust gasses, and I've never seen a code.

In regards to the waterless coolant, they have been using something similiar to it in computer water cooling setups, where it could leak all over your componenents while its running, and not cause any issues. Then there were some manufactures that took that to a different level, and started making devices submerged in it. I believe Koolance made/makes a power supply as an example.

[GhostAccord]

The 2 wire ECT sensor is an ECU specific sensor. It is used in conjunction with the other main PGM-FI sensors to adjust the timing and fuel injection. Timing is advanced or retarded based on the coolant temps. All these sensors can be fully configured to act as you want with a chipped ECU/tunable EMS.

Nether ECT sensor has an effect on the rad fans. The cooling fans are controlled via the two temp switches and the fan control module.

Also you should know that raising the temps on an all aluminum engine could possibly cause problems. The 0.5mpg that you might gain from running hotter probably isn't worth the trouble.

This is the same reason why an all iron block can actually have lower emissions and better MPG than most cast aluminum blocks. The combustion chambers can be run at a hotter temp, in turn having a more complete burn. The same can only be said for aluminum up to a certain temp. Best not to go raising engine operating temps beyond what they are calculated for....but that's just my 2¢.

I'll stick to changing the coolant regularly, does the same thing. You can see the same gains in MPG and performance after a regular coolant flush.

[GhostAccord]

A brief description of an OBD1 PGM-FI system.

[illinois_erik]

besides boiling points and that stuff Im gonna rock it just because its electrolytically inert. After seeing that aluminum plate from Jay's duze and seeing how crusty my radiator and water necks get, why not. Also if I take the time during my restore and put in a new heater core, it should never need replaced again. Ill see how crusty the stock one is and maybe let it soak in vinegar for a week if its salvageable.

[reklipz]

Also you should know that raising the temps on an all aluminum engine could possibly cause problems. The 0.5mpg that you might gain from running hotter probably isn't worth the trouble.

This is the same reason why an all iron block can actually have lower emissions and better MPG than most cast aluminum blocks. The combustion chambers can be run at a hotter temp, in turn having a more complete burn. The same can only be said for aluminum up to a certain temp. Best not to go raising engine operating temps beyond what they are calculated for....but that's just my 2¢.

Thanks for your input Ghost, much appreciated. I hadn't gotten that far with the idea regarding issues with operating the aluminum block at a higher temperature. Honestly, the thought hadn't even crossed my mind; I was unaware of the issues.

I do know I can add a "man in the middle" device between the temperature sensor and the ECM, but that doesn't necessarily optimize whatever algorithm is embedded in the ECM program. Though, it doesn't sound like the ECM does anything major with the temperature other than some minor timing adjustments? It's not worth digging into unless someone wishes to attempt this.

Lastly, you state that the ECM doesn't control the fans, but the circuitry implies the opposite is a very real possibility, and the chart you posted even lists the fans as outputs of the ECU. From the sounds of it, the ECM indeed turns the fans on if the A/C is on (if equipped), and I assume it does this via the "A/C Diode" circuitry. We'll assume that's all that output ever gets used for. What about the other lead to the ECM? I suspect it's purely to sense whether or not the fans are actually on, as cloudasc described, and that signal is used to adjust the idle to compensate for load.

If your engine has lots of life left, or if your one that likes to change your fluid often, it looks like switching to this waterless coolant composition is nothing but a great idea.

[GhostAccord]

Sorry, I didn't mean to piss on your snake oil product.....

I can tell you that the ECU doesn't really control the Fans activation. It does power or ground the fan relays though. So I guess you could call that control. However for the most part it is the FAN CONTROL MODULE and the two temp switches (A & B) that control the operation of the fans turning on and off.

As far as the ECU doing nothing major with the ECT sensor. Here is an exercise. Go out to your car, unplug the 2 wire ECT sensor and then drive it around for a bit. Come back and tell us how well the engine works. There is a reason that the ECT sensor is #6 on the diagnostic trouble code list. It is one of the solid CEL sensors because timing control and engine temps are a major part of the PGM-FI system.

[reklipz]

°

Sorry, I didn't mean to piss on your snake oil product.....

I can tell you that the ECU doesn't really control the Fans activation. It does power or ground the fan relays though. So I guess you could call that control. However for the most part it is the FAN CONTROL MODULE and the two temp switches (A & B) that control the operation of the fans turning on and off.

As far as the ECU doing nothing major with the ECT sensor. Here is an exercise. Go out to your car, unplug the 2 wire ECT sensor and then drive it around for a bit. Come back and tell us how well the engine works. There is a reason that the ECT sensor is #6 on the diagnostic trouble code list. It is one of the solid CEL sensors because timing control and engine temps are a major part of the PGM-FI system.

Haha, I trust you, obviously. It sounds like this input is continuously variable and not just a "oh, we're at operating temperature." Thanks for the schooling, .

But, that was my whole point to begin with: in order to change the operating temperature, this would have to be accounted for and potentially tuned to take advantage of the new temperature. The ECM wants to run the engine at the temperature it was designed for (194 °F I believe), and if you don't inform it of the new temperature (which means tweaking algorithms, procedures, or writing a whole new program) all sorts of potential problems will arise. I suppose it's possible the Honda engineers implemented the "general" algorithm for the injector timing and whatever else is affected by the sensor, in which case no tweaking would really be needed and things would just work. You'll have to interpret the current code or ask someone who knows to figure this out.

[GhostAccord]

You are over thinking this way too much. The ECT would send the temps as per what they are with the new fluid and higher value thermostat. The ECU would then compensate the timing and fuel pulse widths based on the current engine temps and other related PGM-FI sensor inputs.

Now whether you will see the added MPG out of simply raising the coolant temp and thermostat on a stock ECU. That is something you will have to let us know about after you have run it for a while. The ECU algorithms will adjust timing and fuel for EC temps from -22°F to 286°F.

If you don't see any changes, as I already mentioned, the algorithms can easily be altered with any of the available tuning options out there. This is something that would most likely help if tweaked a little as well.

[oyajicool]

You are over thinking this way too much.

Is this an echo I'm listening?