atxking27

iTrader: (8)

I recently developed a problem of my car stalling or just shaking really bad when the AC is on. It will shake and then stall in idle. It'll run sluggish when moving and the AC is on. I cleaned the throttle body, replaced the IACV, checked for manifold leaks, The coils are good, and there are no CEL on. What else could I be missing? The only things left that I think could be the culprits are the plugs or a bad TPS. Forgot to mention I did an idle relearn. Any help would be appreciated.

maximase86

iTrader: (24)

If the issue seems to only happen when the A/C kicks in and the car/accelerate fine with the A/C off, you're barking up the wrong tree with the TPS, plugs, coils, etc. I'd be more incline to focus on the A/C compressor as that is what generates load on the motor. Is there any strange noises coming from the compressor? Did you have the A/C system charge recently?

S

atxking27

iTrader: (8)

It was charged in the summer and it was fine. It wasn't until recently that it started doing that. Sometimes it'll die on me at idle without the AC ever being on. As well as sometimes having a jerky idle that tends to smooth out after a minute or so. But yes when the AC is on the compressor clicks more than usual. Still blows cold and no squeaks of any kind.

maximase86

iTrader: (24)

Ah okay now what you're doing makes more sense. lol. I would check the cam position sensor/crank position sensors out. MAF is the other to check as well. Also check the harness to those sensor to make sure they aren't worn or have any chance of grounding.

S

Finchum

^ im thinking crank/cam sensors as well

atxking27

iTrader: (8)

Still having the same issue. I was told it could possibly be my ECU. That my IACV fried the ecu. Never heard of this, but if anyone has, could you shed some light on it?

DennisMik

iTrader: (2)

The ECU will sometimes get "fried" when either of 2 things happen - the IACV shorts out or the electric motor mounts short out.

The IACV has a stepper motor in it and it also has engine coolant flowing in it. Coolant will leak into the motor and short out the motor windings which causes the driver transistor in the ECU (type STA509A) to short out.

The electric motor mount is an almost identical situation except that there is no engine coolant used there. I don't know what causes the motor to short. Also, your car may not have electric motor mounts, they are only used on cars with auto trans. Only the GLE model has them as standard equipment, optional on the GXE model and the SE model.

When the IACV shorts out, usually the engine idle surges up and down between 1500 rpm and dying out, never steady. You can check the motor windings for shorts with an ohmmeter (it's in the service manual) but since you've changed yours, it's probably OK (emphasis on probably). Also if the IACV has shorted out, the check engine light is usually on, code P0505. No CEL for the motor mount.

http://forums.maxima.org/5th-generat...d-seconds.html

How does the engine idle, with and without the a/c on? If the idle rpm drops when you turn on the a/c, that is not correct. Idle speed should be the same whether the a/c is on or not, about 625 for manual trans, 700 for auto trans. The auto trans should idle at the same speed whether in neutral or drive a/c on or off.

atxking27

iTrader: (8)

I had a CEL, but it was for a cylinder 1 misfire, changed the coil, runs fine. No other codes. Idle is at around 750 or so. The second I turn the AC or heat on, the engine bogs down and stalls. When driving I can feel a power loss as well. Dash lights dim also. Turn the AC off and no bogging down, or dim lights.

DennisMik

iTrader: (2)

I am beginning to wonder if the alternator is failing on you. The lights dimming shouldn't happen. Nor should the a/c clutch be clicking which I interpret as energizing and de-energizing. The voltage should be around 14 volts and should not drop when you turn on the a/c or heater.

Check the alternator belt tension, too. Maybe it's loose and slipping when the alternator has a load on it.

atxking27

iTrader: (8)

Think you're right on this part here, I've yet to try it out though, ran out of time yesterday. And for an update, I bought some MAF sensor cleaner and now, when I turn the AC on it doesn't stall. The idle is still a little jumpy, like it wants to stall but it doesn't. That damn MAF is the root of all evil that happens to this car.

DennisMik

iTrader: (2)

Great! Glad to hear that progress is being made. Maybe trying the idle relearn again might help the idle. I doubt that anything would have built up in the throttle body since you cleaned it, but if you find yourself with nothing better to do (lol), check it.