Ok, so I have a 2000 Type R, with about 72K miles. For the last 2-2.5 years or so it sits in the garage and I drive it about 4-5 times a month at least 20 miles during the month. Sometimes I drive more often and for more miles. It was a daily driver from about 2002 to about 2005 I have been using Mobile 1 Synthetic for the last 2 years, and change the oil ever 3-4 months at the dealer and they top off all the fluids and last year I had them do a 30K to keep the car up, and I had the 60K mile done about 18 months ago. Only mods to the car are suspension, HID lights, stereo system, had a AEM cold air intake but removed that about 2.5-3 years ago and put the stock one in.

I have two issues. My 1st issue is the temp gauge in the car seems to do something odd before it reaching normal operating temperature, which takes about 10-15 mins. The gauge basically seems likes it goes up close to normal operating temp after about 4-5 mins but them goes back down if I get on the freeway or hit a stretch of road that I am assuming is cooling the car back down or could this be related to using synthetic oil (I am under the impression synthetic oil lubricates the engine better so it could take the engine reach normal operating temp and could be causing the odd thing with the temp gauge)? I didn’t pay much attention to this when I first switched the car over to synthetic oil, also the thermostat is the original if that matters. This odd thing with the temp gauge goes away after about 15 mins or driving, which I don’t know if is related to my second issue? My 2nd issue is there is black junk coming from the exhaust and the readings on my last smog test for HC at 15mph was very high, 1 more point and it wouldn’t have passed. Here are the emission readings from the smog test back in November of 2006.

_______CO2% 02%
_______Meas Meas
15mph 15.00 0.00
20mph 15.00 0.01

______HC HC HC______CO CO CO_____NO NO NO
______Max Ave Meas Max Ave Meas Max Ave Meas
15mph__60__9__59__.53__.02__.14_459_57__26
20mph__43__7__28__.51__.03__.05_746_50__13

I haven’t had the spark plugs replace, unless that is done at 60K at the dealer, and haven’t had the 90K done yet. All the readings look good except the HC measure at 15mph and the black junk coming out of my exhaust. The person at the smog shop said it might be the oxygen sensor but the check engine light has never come on. So before I take it to the dealer, what do you guys think it is? Is it the oxygen sensor, catalytic converter, exhaust, spark plugs?

So what I want I need your help with is 1. is this normal with what is happening to my temp gauge and 2. what should I do to stop whatever is causing the black junk that is coming out of my exhaust and reduce the HC readings at 15mph. Anybody with suggestions, comments, thoughts, recommendations, ideas, stories, experience with this or something similar? Thanks in advance.

 

hmmmm one thing at a time...

your temp gauge i wouldnt worry about, but it sounds like your thermostat is stuck open. you mentioned that your car takes forever to warm up which is a tell tale sign.

synthetic vs standard oil wont really affect "cooling", if at all.

i ran no thermostat in my teg since my engine bay got pretty hot, especially during the summer.

dont go cheapo and get some autoparts store one, just go to the dealer. the one for a 99-00 civic Si will work, should be cheaper than going to an acura dealer.

the black stuff coming out your exhaust can be a number of things...

i would start off by changing your plugs. high HC numbers means that theres unburnt fuel getting passed your cat. if your engine is healthy, then its your cat...if its not the cat, look into whats going on with your air fuel mixture. theres tons of things that contribute to high HC's....

did u smog your car with a fresh oil change?

 

Thanks Spec R for the reply.

The thermostat is only $24 at the dealer so I'm going to just use the OEM part and have it changed out.

If I have the dealer change out the thermostat I might see how much they will charge to take a look at the car and determine what the black gunk is. I'm trying to decide what to actually do becaue I'm might just get the 90K done on the car sometime this year, so I can have the spark plugs changed and have everything done all at once.

I got an oil change about 1 month before the smog test.

Any additional comments regading my situation from Spec R or anyone else?

 

just change the spark plugs yourself, its a no brainer. if you're not confident with that kind of work, just get a random friend to help you. its very very easy on your car.

the thermostat, while a bit more complex, is far from rocket science so you shouldnt be stressed out there either. holy cow i just came up with something...

okay here you go:

because your thermostat is stuck open, your engine has been running tooo cold, or been exposed to non-operating temps (cold) for prolonged periods of time. many consequences can occur because of running too cold. i'm rusty on this stuff so if anyone can chime in please do.

first, your piston rings wont seal as good as they should because your pistons/rings/rotating assembly were designed to expand/contract and optimally operate within certain temperatures. this will cause some blowby...(let me know if u need to know what that is)

second, your ecu will think your car needs to be "warmed" up, and will run rich for "coldstart" conditions. while not exactly harmful in the short term, excessively rich conditions will eventually foul out spark plugs, oxygen sensors, and catalytic converters (possibly why your HC's were so high, even though your engine may have been warm).

good luck sir.

 

Thanks Spec R. when you refer to running rich conditions not harmful in the short term but in the long term. Are you reffering to miles or actual time. I think my car has been like this for the last year or so. Any thoughts on this? I plan on having the thermostat changed with in the next week or two and car will be driven very little until then.

 

mileage more than actual time. good call.

there are things that see time over mileage, namely rubber parts. ozone deteriorates the hell out of rubber over time.

 

Ok, I got the thermostat changed along with my oil change. It warms up sooner now and I'm gonna give it a month or two to burn out all the gunk that maybe left in the exhaust then smog it. Hopefully this ends up being the cause of the high HCs. Thanks Spec R.