2000 Oldsmobile Alero My 2000 Alero fails within 10 mins of

Tiny
RLBUTTA16
  • MEMBER
  • 2000 OLDSMOBILE ALERO
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 161,500 MILES
My car is a 2000 Olds Alero, 2.4L, 4 Cylinder. Auto trans.
When I first start my car and drive, as long as the engine is cold, has no problems. Within 5-15 minutes of running I run into some problems. Normal operating temp is mostly where my problems occur. Temp never goes over the middle, no overheating.
The problem I'm having is very low/loping idle (600-900rpms), and when in gear, rarely but sometimes also in park, the car hesitates and wants to stall out. It starts right back up though most of the time. I have to press the gas while turning the engine to make it start up smoothly. Otherwise it sometimes catches itself but idles very rough, rumbling. Revving up eliminates that.

Normal RPMs for being in gear during cold engine is about 1000 - 1300 rpms. Once its been running a few minutes, as engine temp climbs to normal problems get progressively worse. When driving the car hesitates and tries to stall when my rpms are around 1100 - 2000. Steady acceleration is fine, no stalling over 2000rpms, no highway stalls, no mid driving stalls. I can press the accelerator and rev high to push through most choking and rumbling and theres a slight delay then car catches and drives fine. Only low speed, low rpms cause engine failure. Like redlights, stop signs, in bad traffic, etc. Anything over 20mphs runs like new.

Have replaced spark plugs, coil housing, fuel injectors, fuel filter, catalytic converter, IAC valve, air filter, fresh oil change and filter. Used 4 bottles of fuel cleaner over 3 weeks. Replaced an O2 sensor a few months ago when having similar symptoms, seemed to temporarily fix problem. Checked vacuum hoses over and over, every way except with a guage. No cracks and all firmly attached that are accessible from checking topside. Checking fuel pressure today if I can figure out how to use guage (car has specifics for this test).


SVS, ABS, TRAC OFF are on and ding when they come on (from off to driving 30 feet comes on), Check engine light is always on. Did an OBD diagnostic. P0420 catalytic threshhold below efficiency (we just replaced 3 months ago, had to cut exhaust and use 3 C clamps to attach). Also getting a code saying I'm running too rich in my fuel mixture. (I forget the code)

One other thing is a small buildup of carbon deposits in exhaust pipe past CatConverter, rattles occasionally when revving and letting off the gas. Spits out little black drops of residue occasionally.
Had a slight constant oil leak the past few months, oil stabilizer seems to have fixed that at least for now. Was going through appx. 3 qts of oil every 2-4 weeks. Have not needed oil for over a month now. Coolant is full, full power steering fluid, brake fluid full. I did notice the other day after driving appx 30+ minutes when I turned the car off, I could hear a boiling sound coming from the passenger side under the hood. Went away after about 10 seconds or so.

ANY and all help is very much appreciated! If you need more info I can provide it.

Me and my stepdad are both kinda baffled by this problem.

UPDATE! Went to Advance Auto Parts and ran another OBD diag.

Info is as follows:

Codes
P0172 System Too Rich Bank 1
P0300 Random/Multiple Cylinder Misfire
P0420 Catalytic Efficiency Below Threshhold Bank 1

Freeze Data
Cause P0172
RPM 1962
Load Value 68.2%
MAP Sensor 62KPA
Coolant Temp 167F
Short Term Fuel Trim 1 -5.1%
Long Term Fuel Trim 1 -8.0%
Short Term Fuel Trim 3 -42.4%
Long Term Fuel Trim 3 -30.1%
Vehicle Speed 39mph
Fuel System 1 Closed
Fuel System 2 N/A

Side note? Oxygen Sensor Monitor INC
the rest are N/A or OK
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Saturday, January 23rd, 2010 AT 10:09 AM

4 Replies

Tiny
BRIAN 1
  • MEMBER
I would start by checking fuel pressure, the 2.4 doesnt have a shrader valve to check fuel pressure, on these you have to tap into the feed line on the fuel system to get a pressure reading. With the key on engine off pressure should be (52-58 psi). Also pull the vacuum line off the fuel pressure regulator and see if gas comes out of the regulator or the vacuum hose. Last thing use a scan tool and see the IAC counts, see if they are more or less than 100, if they are less Turn off the ignition.
Disconnect the MAP sensor connector.
Start and operate the vehicle in Closed Loop operation. You may have to drive the vehicle in order to get Closed Loop Status. See if the long term fuel trims increase more than -46% if they do you have a bad MAP sensor.
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Sunday, January 24th, 2010 AT 5:52 PM
Tiny
RLBUTTA16
  • MEMBER
Just got back from the meachnic and found out my fuel pressure regulator is faulty. Dribbling fuel was coming out of the port where the vacuum plugs in. Just replaced it last year so hopefully I just got a faulty regulator. I'll be installing a new one by tomorrow to see if that makes any difference. I was told that I could also have a bad fuel pump and may need to replace the cat converter (installed last year) due to the improper fuel mixture which could cause the cat converter to burn itself out. I will repost with updates thank you.
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Tuesday, January 26th, 2010 AT 3:57 PM
Tiny
ELRODANGELA88
  • MEMBER
I have the same car. And also had similar problems. My car started to run hot, so I changed the thermostat. Then the car started leaking alot of water, so I changed the water pump. Then the car started misfiring and occassionally shutting off at stop signs and reds lights and it got to the point, if I had to drive it, that I had to keep it above 2000rpms. Eventually found out that the problem was the timong chain had broke a tooth. After the timing chain was replaced, it rode smooth again!
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Wednesday, January 11th, 2012 AT 5:46 PM
Tiny
HOMER1967
  • EXPERT
You may still have a bad or failed cat due to all the rae gas dumped by the regulator.
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Sunday, January 15th, 2012 AT 10:32 PM

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