Killing the car....
Thread Starter
Joined: Feb 2007
Posts: 240
Likes: 1
Hmmm....not sure what the IAC valve have to do with this. I thought it just affected your idle when they got dirty. I'll do more searching.
Well, drove all morning. Stopped by a muffler shop to remove the resonator (nice mod, stock sounded good, just a little louder), got stuck in traffic on H1. Even went to Manoa for Island Manapua Factory -- haven't eaten there in 10 yrs! I'm glad they haven't changed much...I think I saw the same kids that used to work there when I worked/schooled at UH!
Oh yeah, almost killed the car again, but this time on a steep hill..really sucks, when you don't trust your car. Sucker was surging in 2nd gear! Joy.
Well, drove all morning. Stopped by a muffler shop to remove the resonator (nice mod, stock sounded good, just a little louder), got stuck in traffic on H1. Even went to Manoa for Island Manapua Factory -- haven't eaten there in 10 yrs! I'm glad they haven't changed much...I think I saw the same kids that used to work there when I worked/schooled at UH!
Oh yeah, almost killed the car again, but this time on a steep hill..really sucks, when you don't trust your car. Sucker was surging in 2nd gear! Joy.
Registered User
Joined: Apr 2003
Posts: 1,987
Likes: 0
From: Hawaii
Sup guys, haven't been around for a long while (damn work). Anyhow I thought I'd chime in for a bit. Just a warning for everyone who don't know me, I'm known for these long posts so I apologize in advance to you all. 
The symptoms you describe may or may not be the MAP sensor at all. I don't really believe that Honda would ship so many S2000's out there knowing that the MAP sensor design was faulty, as this is a common problem for nearly all S2000 owners of every generation, both AP1 and AP2.
What is known through my testing of AP1's is that the OEM ECU has a preprogrammed function that goes into "safe mode" when it feels that the engine is about to enter a high-risk situation, mainly detonation, it triggers this mode. Stop and go traffic doesn't allow enough airflow to keep things as cool compared to when you're moving, thus you'll experience higher coolant temperatures and such. When the ECU detects higher coolant temps, it tries to control the heat by retarding the ignition timing. The combination of increasing coolant temps and intake air temps are what's forcing the ECU into its paranoid mode. In my opinion, it is far too sensitive in its settings and I'm actually quite shocked that Honda doesn't understand this.
For anyone who has tuned old-school cars with distributors where you turn them to either advance or retard timing may already know this. Retarding the ignition timing can lower combustion temps to some degree but it also increases the risk of engine stumbling, especially under load. Advancing the ignition timing often times increases low-end torque, and in some cases comes at a cost of increased heat. This is not so much of a rule as the results will vary from engine to engine, but that's the general idea. If there was a way for me to let anyone drive an old pre-ECU car up a hill where I could retard the ignition timing while you drive, you'll notice that the torque will be less and the engine will sometimes stumble if the timing's too far retarded for the load that's being applied.
What can you do? Make sure you're using high quality synthetic oils like AMSOIL for example to keep temps down. Remember, there's never a good reason to use conventional oils in our cars. Second, make sure you opt for a low-temp thermostat + low-temp fan switch and higher pressure radiator cap, Mugen has them for the AP1 (not sure about the AP2). The cost is very reasonable and it's an inexpensive way to say to someone that you have a few Mugen parts in your car, hehe. This will not solve the problem, but it may help to delay or reduce the frequency of the stumbling.
Is there a complete solution to the problem? Yes, but it's not cheap. Since the problem lies in the ECU itself, the only solution I know that is a 100% fix is the Mugen N1 ECU which Steve and I both have because it bypasses a lot of the safety features which actually contributes to the stumbling. I have no idea what options the AP2 owners have especially those who own the new stuff with the flashable ECU's.
I hope this helps and hallo to everyone, I really miss hanging with you guys!
P.S. I was merely guessing that Steve still has the Mugen N1 ECU... I figure at the rate in which he was modding his ride last time I checked, he might have some full blown AEM system by now.
The symptoms you describe may or may not be the MAP sensor at all. I don't really believe that Honda would ship so many S2000's out there knowing that the MAP sensor design was faulty, as this is a common problem for nearly all S2000 owners of every generation, both AP1 and AP2.
What is known through my testing of AP1's is that the OEM ECU has a preprogrammed function that goes into "safe mode" when it feels that the engine is about to enter a high-risk situation, mainly detonation, it triggers this mode. Stop and go traffic doesn't allow enough airflow to keep things as cool compared to when you're moving, thus you'll experience higher coolant temperatures and such. When the ECU detects higher coolant temps, it tries to control the heat by retarding the ignition timing. The combination of increasing coolant temps and intake air temps are what's forcing the ECU into its paranoid mode. In my opinion, it is far too sensitive in its settings and I'm actually quite shocked that Honda doesn't understand this.
For anyone who has tuned old-school cars with distributors where you turn them to either advance or retard timing may already know this. Retarding the ignition timing can lower combustion temps to some degree but it also increases the risk of engine stumbling, especially under load. Advancing the ignition timing often times increases low-end torque, and in some cases comes at a cost of increased heat. This is not so much of a rule as the results will vary from engine to engine, but that's the general idea. If there was a way for me to let anyone drive an old pre-ECU car up a hill where I could retard the ignition timing while you drive, you'll notice that the torque will be less and the engine will sometimes stumble if the timing's too far retarded for the load that's being applied.
What can you do? Make sure you're using high quality synthetic oils like AMSOIL for example to keep temps down. Remember, there's never a good reason to use conventional oils in our cars. Second, make sure you opt for a low-temp thermostat + low-temp fan switch and higher pressure radiator cap, Mugen has them for the AP1 (not sure about the AP2). The cost is very reasonable and it's an inexpensive way to say to someone that you have a few Mugen parts in your car, hehe. This will not solve the problem, but it may help to delay or reduce the frequency of the stumbling.
Is there a complete solution to the problem? Yes, but it's not cheap. Since the problem lies in the ECU itself, the only solution I know that is a 100% fix is the Mugen N1 ECU which Steve and I both have because it bypasses a lot of the safety features which actually contributes to the stumbling. I have no idea what options the AP2 owners have especially those who own the new stuff with the flashable ECU's.
I hope this helps and hallo to everyone, I really miss hanging with you guys!
P.S. I was merely guessing that Steve still has the Mugen N1 ECU... I figure at the rate in which he was modding his ride last time I checked, he might have some full blown AEM system by now.
Registered User
Joined: Aug 2001
Posts: 2,625
Likes: 1
From: Honolulu/Kona,HI
My engine runs too COLD! 
I have the Spoon thermostat, switch, radiator cap, Hondata IMG, and Spoon snorkel. My CEL came on a couple times and when the code was pulled, it read that "Engine Coolant Temp. is too low" Correct me if I'm wrong but this can't be good since it would take the oil longer to get to temp? I might have to switch to the Mugen mods since it'll run a little warmer than the Spoon. When running at a constant speed on the freeway, it goes back down to two bars on the temp gauge (AP1 normally runs 3 bars).
I have the Spoon thermostat, switch, radiator cap, Hondata IMG, and Spoon snorkel. My CEL came on a couple times and when the code was pulled, it read that "Engine Coolant Temp. is too low" Correct me if I'm wrong but this can't be good since it would take the oil longer to get to temp? I might have to switch to the Mugen mods since it'll run a little warmer than the Spoon. When running at a constant speed on the freeway, it goes back down to two bars on the temp gauge (AP1 normally runs 3 bars).
Registered User
Joined: Apr 2003
Posts: 1,987
Likes: 0
From: Hawaii
The bars on the instrument cluster are very vague from my experience, I've found more success by using a scan tool and monitoring the coolant temps that way.
However your concern is a big one. The rule of "cooler is better" isn't entirely true when it comes to engines. The motor must reach a certain temperature range to ensure proper combustion otherwise you'd lose power and risk dumping unburned fuel into the exhaust.
I have zero experience with Spoon cooling products but I haven't found any successful coverage of their products in both normally driven and race driven cars back when I was shopping around for cooling solutions. Mugen products are proven to work on both the track and street by just about every successful racing team back when Jason Saini was the guy to beat in autocross have used it with success. It also helped that Steve was the unofficial Hawaiian Mugen Supermodel, sporting Mugen headers, Mugen ECU, Mugen Intake, Mugen G-String, Mugen Toothpaste, Mugen Hairspray, Mugen Car Wash, Mugen Air Freshner, etc. so I had the chance to see how well it worked first hand before I made my purchases. There's no guesswork with Mugen products, they definitely work.
The IAG is a more involved project considering how small and simple the product is. Ask Colin and Rick Stark how "fun" it was putting it into Steve's car, lol. That contributes towards lowering your IAT (intake air temp) which helps to reduce the risk of premature detonation due to heat soak of the intake manifold. The Hondata IAG is an incredible product, this is something I wished that Honda installed at the factory. The IAG is not responsible for making your car "too cold", as a matter of fact it's probably doing the most efficient work by ensuring your incoming air charge stays cool. A cooler (denser) air charge is never bad.
However your concern is a big one. The rule of "cooler is better" isn't entirely true when it comes to engines. The motor must reach a certain temperature range to ensure proper combustion otherwise you'd lose power and risk dumping unburned fuel into the exhaust.
I have zero experience with Spoon cooling products but I haven't found any successful coverage of their products in both normally driven and race driven cars back when I was shopping around for cooling solutions. Mugen products are proven to work on both the track and street by just about every successful racing team back when Jason Saini was the guy to beat in autocross have used it with success. It also helped that Steve was the unofficial Hawaiian Mugen Supermodel, sporting Mugen headers, Mugen ECU, Mugen Intake, Mugen G-String, Mugen Toothpaste, Mugen Hairspray, Mugen Car Wash, Mugen Air Freshner, etc. so I had the chance to see how well it worked first hand before I made my purchases. There's no guesswork with Mugen products, they definitely work.
The IAG is a more involved project considering how small and simple the product is. Ask Colin and Rick Stark how "fun" it was putting it into Steve's car, lol. That contributes towards lowering your IAT (intake air temp) which helps to reduce the risk of premature detonation due to heat soak of the intake manifold. The Hondata IAG is an incredible product, this is something I wished that Honda installed at the factory. The IAG is not responsible for making your car "too cold", as a matter of fact it's probably doing the most efficient work by ensuring your incoming air charge stays cool. A cooler (denser) air charge is never bad.
Registered User
Joined: Mar 2001
Posts: 4,562
Likes: 0
From: Honolulu
whoa! Talk about back from the dead! long time no see buddy.
If you really came back, you know you have to show up to the Ward Ave. Starbucks this Wednesday.
Gotta see all of the sick mods that everybody is doing nowadays
If you really came back, you know you have to show up to the Ward Ave. Starbucks this Wednesday.
Gotta see all of the sick mods that everybody is doing nowadays