idle problems on 89/90 turbo mr2

[bob stone]

hello,

my car was idleing fine till i did some radio work on it. that also coninsided with my engine bay rod ( the thing that holds the engine door open ) fell in to the engine ( i did pull it back out anf put it in my tunk for now but i was driving with it sitting in there). since that night, when i first start my car ( btw it is cold here snow and all ) it idles fine and if i rev it up it will drop right down in to idle just fine, but after it warms up if i rev it past 2500 rpm it will drop way below idle and most of the time die and it also will idle rough, it will start up again just fine but when i am driving i have to watch my rpm's other wise it will die on me. any one here have any other idea on what might have happend ?? thanks

also on a side note. i lost all my gague lights after installing the radio, everthing else still works but i got no gague lights. any ideas on that also

Thanks
Bob Stone

[HighFidelity]

check your fuses, it will probley be your parking light fused, you touched your dimmer wire to ground while installing the radio. BUt the radio has nothing to do with your funny idle, sorry cant help you there.

[bob stone]

thanks for the lights info, if any one else might know what happend to my idle please help me out, one other thing i did was my battery was dissconnected for about 2-4 hours, if that makes a diffrence

Thanks
Bob stone

[JekylandHyde]

If I recall correctly, you have an aftermarket BOV?
Make sure it is not sticking open.

It sounds to me like you have a vac leak somewhere. When you start the car up cold, the ECU is sending extra fuel via the cold start injector.

Once the car is warmed up, no more extra fuel and you are leaning out to a stall.

Check all your intercooler hoses and any other vac lines.

[bob stone]

awsome thanks will check in to that

[Mr2bliss]

When that hood prop broke did it happen to land on any vacuum lines. I did the same thing couple weeks ago and ended up pulling a vacuum hose. Hyde your heading in the right direction. What your thinking of is open loop. When the car first starts up the car ignores the 02 sensors and the computer send a rich command (dumps fuel until 02 sensors reach operating temp.) This typically doesn't even last for a minute. Cold Start injectors (Simply put thermo time switch) helps warm the fuel using a winding in the injector so it is more volital during cold starts. However I agree vacuum seems to be the problem. My first guess would be Manifold Absolute Pressure sensor or MAP. This sensor senses engine load. If the line fell off the ECU would read Low manifold vacuum and high manifold absolute pressure (Wide Open Throttle is when you would see those readings) Basically your ECU would be "tricked" It would see a rich condition all the time and try and lean it out because of that disconnected vacuum line. At idle your car would be fine but under heavy load or W.O.T it would stall due to the lean command your ECU is sending. If you have any questions feel free to IM me.

[bob stone]

ok thnka for the info mr2bliss, i have a couple of things to add, reading what you said, i have not seen any thing lose yet , but have yet to get it on a lift, doing that in 2 days with my friend, going to figure it all out. but when i said it starts to have the idle problem after it warms up, i meant to say it will be fine for like 10+ mins after i start the car, from reading what you said about the computer will go to normal fuel load after about a min? also i just thought of this, my temp gague is out, could it posably be overheating and doing this ??

thanks again

[JekylandHyde]

The OEM MAP sensor does not sense engine load or affect fueling in anyway on the 3SGTE engine.
All the MAP sensor does is operate the OEM boost gauge and control fuel cut.
There are no negative fueling affects from unplugging the vac line to the MAP sensor and CORKING it. Many people do this to eliminate fuel cut to run bigger boost.

A vac leak at that sensor, would not affect things any differently than a vac leak in the intercooler pipes (or anywhere else).

[Mr2bliss]

Thanks Hyde, my bad I retract that last statement. I was thinking of a map sensor on a typical air density system. Never really messed with the mr2's MAP.

[JekylandHyde]

Yes, the MR2 is a AFM/MAF based system so the MAP is nearly meaningless.