1997 Pontiac Firebird

Tiny
RN1944
  • MEMBER
  • 1997 PONTIAC FIREBIRD
Engine Performance problem
1997 Pontiac Firebird 6 cyl Two Wheel Drive

I have a firebird 3.8L V6 the is breaking up when engine gets hot after running awhile. It starts hesitating sputtering, missing, when accelerating, and under load. So far new parts: fuel pump, crank sensor, plugs, fuel pump relay, fuel filter, coil pack for cyl. 1 and 4. Starts and runs fine when cold, but starts erratic breaking up when engines heats up - like out of timing, runs rich (gas smell), also lost gas gauge when tank installed. Also, does put out any engine errors codes. Please help - any ideas?
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Friday, July 30th, 2010 AT 8:40 AM

3 Replies

Tiny
MERLIN2021
  • EXPERT
If you have more than 100,000 miles, check the o2 sensors with a scan tool that reads live sensor data, also check the ECT(engine coolant temp sensor. Did you put a K & N air filter on this by any chance?
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Friday, July 30th, 2010 AT 8:43 AM
Tiny
RN1944
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Wouldn't the coolant temp sensor, and 02 sensors throw out error lights / codes? Also, my intake is factory stock with a new air filter in it! Thanks - RAY
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Friday, July 30th, 2010 AT 8:00 PM
Tiny
MERLIN2021
  • EXPERT
Many sensors can be slightly out of normal range and not set a code, Crank sensor O2 sensors ECT...Test them like this:
CRANKSHAFT POSITION SENSOR A malfunction in the crankshaft position sensor circuit will set a related diagnostic trouble code. For testing procedures, see the TESTS W/CODES - 5.7L article. To diagnose crankshaft position sensor, the following procedures can be used: 1. If a scan tool is available, scan RPM parameter while cranking engine. If RPM is indicated, crankshaft position sensor is operating properly. 2. If scan tool is not available, disconnect crankshaft position sensor harness connector. Set ohmmeter to 2-k/ohm position, and measure resistance across sensor terminals. Resistance should be 800-1200 ohms. 3. On all engines, set voltmeter on the 2-volt AC scale. Crank engine and measure output voltage across sensor terminals. Voltmeter reading should be .8-1.4 volts. If resistance reading is not as specified or sensor does not produce the specified output voltage reading, repair faulty wiring or faulty crankshaft position sensor. ENGINE COOLANT TEMPERATURE (ECT) SENSOR If a coolant sensor-related diagnostic trouble code is present, see the TESTS W/CODES - 5.7L article. An out-of-calibration sensor may not set a diagnostic trouble code. Use following procedure to test sensor calibration. Disconnect ECT sensor connector. Measure resistance between sensor terminals. Resistance should be high when engine is cold and drop as engine warms. See ECT SENSOR RESISTANCE VALUES table.


http://www.2carpros.com/forum/automotive_pictures/62217_ECT_Table_1.jpg


Also if you can scan the MAF while running it should read 159 hz at sea level.
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Saturday, July 31st, 2010 AT 7:33 AM

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