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Coolant temp drops when moving

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Old 05-09-2010, 08:00 AM
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Thumbs up Coolant temp drops when moving

Hello S2ki,

I recently got Greddy E-Manage Ultimate pretuned by Giles and manual says that in order to run it with aggressive setting I need cold plugs, cold thermostat and cold fan switch.
I bought everything and installed few weeks ago, NGK Iridium plugs with Mishimoto thermo and switch.
Now the problem. Car warmed up ok a driveway, but when I start moving temperature drops significantly.
Normal operation temperature on MY05 is 7-8 bars on a gauge, when warmed up with new thermo it is sitting withing the same 7-8 bars. But when moving it drops to 4-5 bars which is IMO too cold. When I stop on a traffic light it goes up to 6-7 bars and so on.
My assumption that probably thermostat stuck opened and that is causing this behavior.
I removed Mishimoto thermo from the car and boiled both, oem and Mishimoto and looks like they both work fine, Mishimoto opened a bit earlier (60C) and stock opened around (80C).

Please advice, if this is normal temperature drop with cold thermo and switch.
Old 05-09-2010, 08:49 AM
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i would assume this is normal and that the lower temp t-sat is doing its job...
Old 05-09-2010, 12:41 PM
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http://modifry.com/products/ect/ap2.htm

seems a bit low to me too. cars operating temp should be around 170ish with the new tstat.

mine lives in the 178-190 range. stock tstat.
Old 05-10-2010, 09:59 AM
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could be air in the system causing bad readings of temps. beyond that it might just be working as intended.
Old 05-10-2010, 10:09 AM
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I would ask Giles what the desired temp (amount of bars) is optimal for the aggressive setting. Keep in mind, under "normal" driving conditions your experiencing slightly low temps... but have you ran it hard yet? If it's getting up to 6-7 bars at a stop then I'd say it's getting plenty hot. While moving, the radiator is able to really do it's job with that new switch, but what if you were above 6k nonstop for 20 minutes? As long as Vtec is not disabled from getting too cold, I'd say your cool. (pun intended
Old 05-10-2010, 12:54 PM
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Yes, this is normal because of your themostat. It opens waaaay early so your coolant is passing through your radiator earlier than before. When you start moving your radiator is working to remove the heat so your temp gauge will drop. You lose the effect of your radiator at a stop (unless your fans come on) so that why your temp gauge goes back up at a stop.

I would not recommend the thermostat mod for street cars in cold climates (had a Spoon one in but then taken out--I live in Seattle). During the winter, it would get so cold that I would sometimes get no heat on the freeway.
Old 05-10-2010, 04:03 PM
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Do you recommend stock thermostat and cold fan switch?
All I want to get a bit more advantage with aggressive ignition mode from EMU.
Will oil cooler + stock thermo and cold switch put me a bit on a safe side with aggressive ignition?
Old 05-11-2010, 12:06 PM
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The fan switch was designed to work with the lower opening point of the thermostat. So if you have the fan switch without the thermostat, then be prepared for your fan coming on a lot since your themostat is going to stay closed longer (keeping your engine warmer).

I don't know the answer to your aggressive ignition question. I've been through the bad experience with the themostat and wanted to share that with other members (might be shooting myself in the foot because I'm going to be selling my Spoon thermostat ). Personally, I would only do the thermostat if I lived in warm climates or if it's a track car.
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