[QUOTE]Originally posted by hoof
[B]Shamu, you bought a thermostat that causes your engine to not run at 3 bars?

 

I had this problem 2 weeks ago and since it was time for my 37,500 service I took it in the next day. They did an analysis on it and found nothing. They suspected water in the gas and the tank was on 3/8 so they drained some gas out put in more gas and the problem went away. I found out that the gas station that I got my gas from (Exxon) has had a reputation of water in their gas. Everything is fine now after about 2 tanks. I did add some dry gas when I got the car back.

 

Ok, each bar represents a range in temperatures, and I guarantee you that you can VTEC in 2-bars.

As for why why I went with a cooler running engine, well, I'm running 12:1 compression, and consequently a lot hotter engine. I'm certain that the cooler running stat and switch are key components to controlling my engine heat.

 

My concern is that the purpose of the rev-limiter when cold is to save on wear/tear when revving on a colder engine. Deliberately running the engine cool, esp. if the rev-limiter is disengaged (after driving for a while) would result in this same wear/tear occuring by my guess. So you're either a) giving up your 9k limit to run cooler, b) increasing the wear/tear on your engine while revving, or c) not really running at less than 3 bars. Since the intake air temperature wouldn't be significantly different in temperature when running a cooler engine (things happen too fast to transfer much heat into the fuel/air mixture before ignition), I fail to see the benefit of a cooler engine via a thermostat change.

Then there's the ECU, which "adjusts" to the longer-term running conditions of the engine. That's the only way I can think of for Honda to allow the engine to change its settings for different climates (settings like idle) w/o manual tweaking (like the idle screw someone mentioned). If the ECU "learns" how to idle at 2 bars over time, it might have trouble at 3 bars to run properly at idle. I'd suspect your thermostat change as the cause of your 3-bar idle problems.

 

I wrote my last post before seeing your latest post Shamu.

I also didn't realize that you were running a different compression ratio than stock. That changes everything. There's no guarantee that the ECU can handle that kind of change 100% reliably. How did you achieve the change in ratio? Header change? Piston change? You may have altered the pattern of airflow at idle RPMs in a way that the ECU cannot handle properly in all cases. Plus, the engine has a method of running at reduced power and different ignition timing when running poorer gas (less than 91 octane). Your increase in compression ratio could be tripping this system, which may result in valve timing issues that could alter idle behavior. Someone with more familiarity with the engine would know better than I.

Regardless, I still suspect that Honda designed their engine to run at a certain temperature, and you're running the risk of extra wear/tear by running cooler (especially between any parts that might have different metal components that have a tight fit).

 

I had another thought about the reason you went for a cooler engine. You said that the higher compression ratio resulted in more heat being generated (I assume you had your engine overheat and/or ran into detonation issues before the thermostat was replaced). While running cooler can help, have you considered increasing the coolant pump capacity? This would allow you to run at normal temperature without overloading the system, as more coolant could be circulated through the engine and radiator thus removing more heat without having to run the engine cooler than stock. Clearly the radiator is sufficient, otherwise your thermostat wouldn't be making a difference.

 

[QUOTE]Originally posted by hoof
[B]I wrote my last post before seeing your latest post Shamu.

 

My car was stalling quite a bit, like when I would put my car in nuetral and roll up to a stop it would just die. I replaced the map sensor and it seemed to help somewhat. It didnt stall but the rpms would still dip down pretty low. I finally replaced my spark plugs and that seemed to do the trick. You might want to check your plugs make sure all are torqued properly and check the gap.

 

None of you have the coastal metals grill on your car, do you? I have found that since I live in Texas, where the summers are extreme, I have to take the grill off in the summer. Mine was doing exactly what you are describing plus if I drove for over an hour I would hit 4 bars. I took the grill off and it all stopped. I only use the grill at cooler times of the year. I also put some insulation over the radiator, up to the air intake. That helped as well.

 

[QUOTE]Originally posted by Nelson
[B]I don't know about the S, but on my old car their is a Idle Speed Adjustment Screw for the engine. I don't know if their is anything similar on the S but it might be worth checking out.