3000 rpm start up
 

A quick question regarding the 3000 rpm start up. After SEARCHING for this topic I gather the best method for disabling this is to pull the electrical connection on the air bypass solenoid. Is this method better than pulling the wires located on the radiator? Is there any other problems that could arise with disabling the solenoid?

Its seems the other option is to start in gear. I have a '86 n/a. It would seem that disconnecting the solenoid would be the easiest fix to eliminate this feature. I could see why this accelerates wear on the engine. After I replaced my plugged cats, my engine revs to almost 4000 rpm on start up. Dont really care for that.

yeah i wanna know to, just got straight pipe true dual. and dont want it to rev in the mornings to freakin loud!!!! i mean LOUD!!!

The best method is to remove one or both wires from the temp sensor that is located on the bottom of the radiator, left hand side, as Six Rotors suggested. One of my many wrong answers was to disable the air bypass solenoid. I was sure that this would do the same thing. WRONG. I started my 87 na one morning and it reved to the 3000rpm. I knew that that plug was off. So, hey, I was wrong. The description of the solenoid implies that it is involved in the 3000 rpm start up along with its relay. One of life's mysterys to me. The problem with the disconnect of the radiator wire, is that the relief solenoid causes the relief valve in the acv to remain in the dump position, which disables some of the functions of the acv. Putting the car in gear will indeed disable the 3000 for 17 second feature. I just let the car rev to 3000.

does unplugging the temp sensor on the radiator also disable your idiot light too?

yeah i figured the gear thing out this morning. i started it in gear and then once on shifted back into neutral. still revved has to leave it there for about 25 secs so it wouldnt rev. since i have the true dual now have to do it that way.

So the safest method to eliminate the 3000 rpm start up would be to start in gear. The mazda shop manual lists the steps to test but leaves little to how the components interact. I am stuggling to figure out the purpose of the switching solenoid valve, releif solenoid valve, split air solenoid valve, and port air solenoid valve. Notice I did not even mention the air bypass solenoid valve. I'm lost. To me it appears the 3000 rpm start up is buried in this whole system and cannot be isolated without disabling some other little vacuum/electric device.

Well, it depends. Which series are we talking about here? The S5s have neither the "3k startup temp sensor" in the rad, nor an ABSV - they've got a solenoid on the intake that switches open (can't recall the name ATM). I just got done messing around with that system today. Ask away! :) but tell me which series you're wondering about...

Brandon

I have a '86 so I guess Iam a S4

Car's cold. You start 'er up, out of gear. The thermowax holds the throttle open at ~1500 RPM. The temp switch at the bottom of your radiator reads cold, so your ECU pops the Air Bypass Solenoid Valve (ABSV), which meters air in and raises the idle to 3000 RPM. The ECU holds the ABSV open for ~20 seconds, then turns it off. As the thermowax heats up, it retracts and your idle drops to "normal".

The BAC is only responsible for compensating for loads (such as PS, A/C and electrical) that would make the engine stall.

Wanna disable it? The "best" way is to start the car in gear, every time. If you forget, a quick blip of the throttle will drop it down again. In the S4 cars, you can simply pull the electrical connection to the sensor at the bottom of the rad - the 3k RPM startup is all it does. If you wanna get REAL useful, you can make a block-off for the ABSV, pull the sucker and put a 1k ohm resistor in its place on the harness.

Note, this only applies the S4 cars. The S5s are a little different (only one temp sensor for the engine, ABSV called the Air Solenoid Valve - manual bypass procedures similar). It's also HIGHLY recommended that one bypass the 3k startup. Revving that high on a stone-cold engine may be GREAT for cold emissions, but it SUCKS how much it'll wear out the internal bits.

Brandon

NO7YET.....Thats not quite right. That water temp switch at the bottom of the radiator will do more than disable the 17 second,3000 rpm start up. It WILL disable the relief valve in the acv, which in turn means that the functions of the acv are disabled i.e the split air, the port air, aav. Been there, done that.

Why not just remove the themowax? do the throttle body mod and you'll have no more 3k start up. or you can move the thermowax solenoid can't remember which direction it goes but you can tie it in it's open position and it won't know that it's supposed to close

james

Without the thermowax and it's coolant circuit, cold morning idle is a hassle. BTDT.

Thanks for the info. What about this? Starting in gear disables the 3000 rpm start up. What controls that. Can't I just ground or jump out that sensor so the ecu thinks you are starting in gear? I'm running a hi-flo cat, so I dont want to disable the any air supply to the cat (split air). I will look in the shop book for that sensor or where it picks up that signal that you are starting in gear.

Threads like these always catch my attention. My car never does the cold start of 3k. I actually wish it would so it will warm up a little faster. My car idles at about 2k and that is because I turned up the cold start adjustment near the waterwax.

I did find that my car will do the 3k start up if I unhook the "useless" air hose which seems to be running from the bottom of the car (near radiator), then to a little filter like object, then to near the turbo. If i unhook this one inch diameter air hose, it seems willing to do the 3k start but I think it sucks in unfiltered air. I wonder what could be wrong with my system.

Car idles great otherwise.

ROCKETPOWER....Must be the neutral switch on the transmission. Never done it, but might jumper the connector and see what happens. I don't know what else it would effect. Pin 1G on the ECU. Neutral switch is on the right hand side of the transmission.

I'm at work (hard at it) right now. When I get home I will pour over the electrical schematics in the shop manual to see if its possible. Just seems it should work, but maybe not worth it if you can just start it gear to eliminate. Thanks for the info.