90 Lumina 3.1 lots of problems. HELP!!!

[samusiii]

This car was given to me andI know it is worth fixing up because my mom has one that is great, but I don't know where to start. My lumina starts up right away, idle really high (i don't know how high I have no tach) then it will level out but it still sounds too high. next thing is it take forever to engage into drive. reverse works fine. one more thing. I have a SERVICE ENGINE SOON light that is on from start up but goes away when accelerating and comes back on when i let off the gas.
I have never worked on a car with all this computer stuff or fuel injection so I am lost. The last vehicle I work on in depth was a 1973 Ford Ranger very simple. Please give me any help you can as far as what to check and why. Thanks in advance.

[jeffcoslacker]

First thing, if you can take it to an AutoZone and have the code read so we have someplace to start. I have a feeling it may relate to the idle air circuit.

The Idle Air Control motor works to meter the amount of air required to maintain a solid idle. When you let off the throttle, the throttle plate closes, and the only air admitted to the motor has to pass the IAC to get there. It is like the mixture screws on a carburetor in the respect, except it constantly adjusts according to demand.

If it gets stuck so that it can't fully seat in that passage, it will always admit too much air at idle. Seeing this, rather than have an over lean and unstable idle, the ECM will command more fuel to match the additional air. Too much air + more fuel = higher idle, so that may be what's happening. And the light coming on when you drop the throttle may be it seeing that condition each time.

As far as the tranny, you need to correct the idle first, to make sure it isn't just delaying engagement because of the idle problem.

How long is the delay? I assume you've checked the fluid level, yes?

Anyhow, that IAC can be removed and cleaned up, and the passage to it needs to be clear. Take it off and see what you can see. It's very simple to do.

[jeffcoslacker]

Oh hell. You said 1990. I think that's too old for an IAC. Get that code read, see what it says. I still bet it's related to the idle circuit.

[ACEMAN8822]

90 lumina does have iac at least mine does.

[samusiii]

I have checked the fluid i actually drained it and replace it and the filter. same with the oil. I will take it somewhere to get the code read. There is no autozone here, any other place you know of that will do it for free?

[jeffcoslacker]

No, but you can retrieve the code yourself by inserting a paper clip into the correct terminals on the diagnostic connector.

I'll see if I can find a link to one.

[jeffcoslacker]

Here ya go...

http://www.troublecodes.net/GM/

[samusiii]

Thanks Larry. I will try to check that out today

[samusiii]

all i get is a code of 12 which is just telling me its in diagnostic mode according to the link you gave me

[samusiii]

nevermind I was just impatient. it gives me the code of 12 three times then it gives me a code of 33 three times. this means MAP sensor voltage was too high for 4.8 seconds when throttle angle was less than 2%.. Could you translate that to english for me?

[XGamesJ6]

at idle speed the sensor was getting too much power, therefore causing a bad reading and telling ur engine to adjust to a higher idle. i could be wrong though

[samusiii]

What would cause this problem?

[XGamesJ6]

bad sensor. computer problem. im sure theres more possible causes, but im not exactly sure

[samusiii]

could a vaccum leak cause this?

[XGamesJ6]

yes it could. my lumina has got similar problems but not as severe, and i think a vaccume leak could cause what your describing