89 Jspec engine idles high when cold

[omega]

Hello I have an 89 mr2 with 116 on the chasis and a swapped in Jspec engine. I bought it like this and since I did it always idles at 2-2.5K when cold but after about 5 minutes of driving the idle at a perfect 900. This car's engine only has 50k and runs very strong.
This high idle is annoying and not good for the car, I know the timming is correct and I dont think I should adjust the idle screw.
Maybe some sensors arent working or plugged in.

Note that since this is the jspec engine it does not have ANY EGR components, and thats a lot of stuff!

Could it have to do that the EGR (bsv) sensor has nipples that have no hoses going that becuase there is no ERG or that two of the four hoses on the throttle are plugged becuase they involve the ERG and there is none.

How do I lower my cold idle...?

[canadam]

sorry I can't help, someone should have an answer for you though !

[TheAmazingDave]

Actually, and quite honestly, that is exactly what Toyota designed it to do and it is functioning perfectly. If your car didn't do that before the swap, there was something wrong with THAT motor.

[WIWhite87]

i replied on the other board. it's normal. Mine will idle at 3-3.5K in a cold winter, 2K in summer. 800rpm as per spec after warm.

[20incher]

Is this kind of like a motorcycles choke? where it raises the rpm's in order for the engine to properly heat up? My smallport does this also so im stoked that its a good sign

[CpuZapper]

From an e-mail I wrote to MotoMan:
The old carburetors used to partially lock the throttle open and restrict the intake above the throttle butterflies to create the vacuum around the venturi necessary to cause a rich condition with slightly opened throttle. Motorcycles didn't usually hold the throttle open, but just cut off most of the intake. Some also had a dual stage vacuum unit on the distributor that would retard timing when a thermal vacuum switch sensed a cold engine. Many new fuel injected engines function in the exact same way, and I have yet to see one that doesn't do something like it.

The way new systems work:
The computer recognizes that the engine is cold, so it retards timing for easier ignition and cranking (on models that have electronic fixed timing distributors - some use the thermal switch like a carb'd motor), then it increases the injector pulsewidth (giving more fuel) and also opens an [auxiliary] air bypass valve (some are thermostatically controlled by coolant physically passing over a "waxstat" - What our MR2s have in them). In essence this produces the same result as the carb'd choke holding the throttle plate open, only with without physically opening it. Many also adjust the warm idle this way - a screw that allows air to bypass the throttle plate.



And yes, the high idle is completely normal. If it drops down to spec'd idle, everything is fine. If it doesn't drop to between 750-1K, it's likely you have a vacuum leak somewhere, and/or a toasted waxstat on your throttle body. You don't need to adjust anything. It is perfectly fine, and won't hurt anything. It may be annoying, but it really really helps cold drivability. Imagine trying to drive a 1967 Charger without a choke. They're impossible to start even with the choke on! My MK1 idles about 2.4K when its cold out, and about 2K when it's warm when I first start it. Once the engine is warm it pretty much always stays at 800-1K. The waxstat is why our engines are so great for MegaSquirt-N-Spark in a plug and play setup. You don't need to wire in an Aux Bypass Valve. The throttle body is already setup to use the coolant to control warm idle. It just heats the incoming air, unfortunately. I'm doing some testing to see what can be done to keep the intake manifold, head, and throttlebody thermally separate.

[bob12312357]

Yup CPUzapper summed it up. Mine idles at about 2.5k for 5 minutes during winter and about 1700 during summer for 5 minutes. I thought it was a problem 2 until other people said it was normal.