I think I have a adnormal problem in that everything about my car has decreased by 500 RPM in about a month. I have a 91 CRX Si with a b16a swap. I noticed the problem first when i would start in the morning, i had a cold idle of 2k but is now 1.5K. Now all my shift points appear to be decreased my 500 RPM as well as my curising speed and when my Vtec comes in. i.e. 70mph at 3k in 5th, now its like 3.5k in 5th. bought car in july, oil change in october, replaced within the last month the spark pulgs, radiator hose's and thermostat, and air filter. Also ran one of those fuel injector cleans though my car. now i have decreased MPG of what appears to be form 30 to 25-20 mpg. any thoughts on this problem?thanks if you do.

 

hey - i had something similar with my 92 accord 2.2l, which was fan switch and thermo sensor. it caused my car to trigger ecm into thinking it was running cold all the time, so the overdrive in trans would never switch on. once i replaced the 2 (sensors) the car ran as it should at speed/rpm. well, that's just my 2 cents.

 

Did you have an auto trans?

 

If the cold idle dropped its probably just the Fast idle thermo valve. Located on the intake manifold next to the throttle body on the b16a motors. Either take it apart and tighten the screw holding the wax plunger in place or buy a new one for $60. Thats a cheap fix.
Mine did the same crap, first got the motor it cold idled at 2k then eventually cold idled at 1k rpm. Its not a big deal. Your VTEC can't be adjusted because its controlled by your ecu. Vtec does not kick on a stock ecu at 3k,lol, try 5500 on stock ecu. What tranny do you have?

 

I have a normal manual transmission as far as i know. maybe my teacher was right, now that i don't have a broken thermostat anymore its actually operating normal now...

 

First, whats a normal manual transmission? Each tranny has a sticker on it, there is a code on it. Write it down and post it here. That identifies which manual tranny you have. Each tranny is geared differently so the revs are different.

Second, Your thermostat does not have anything to do with your cold idle!
You have a fast idle thermo valve that controls cold idle. You have coolant lines that run into the FITV. When cold, the FITV wax plunger allows air to pass though raising your idle. As your car starts to warm up, your coolant slowly heats up the wax plunger causing it to slowly expand. This causes less air to flow past the valve as you'll notice the slow drop in idle. Once your car is fully warmed up, the wax plunger is fully expanded and no air is passed through the valve. Now your FITV is no longer in operation. But now your EACV or electronic air control valve takes over and regulates the idle and compensates for the idle for any accessories you turn on, like lights and ac/heat that pull from your battery and cause your idle to drop slightly. The EACV adjusts the idle so it remains normal.

 

yea, it's auto. i couldn't figure out what was going on, it drove me nuts and nearly got talked to having a guy tear apart my trans! good thing i sense he was just trying to rip me off...by the way, never go to aamco or cottman.

the reason i noticed it was because of poor fuel economy...although, it's still not great - around 22-23 with 50/50, but i drive like a madman so...

 

thats what mine is cold start is any where from 1500 to 1570 sounds like its running right to me as for gas don't go past where VTEC hits and you'll get more mpg what tranny do you have

 

thanks Alscrx that is one like the best desricption of the operation of the fit vavle that i've heard. As far as that part, you said its 60 for a new one but i don't really have any cash i can spare. so can i pull one off a junk car and use it? Oh and that transmission code is Y 1 -1027594. So what does that mean? thank you!