Question about 1994 Pontiac Firebird

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MAP sensor reading at idle 1994 Pontiac Firebird with a 3.4 V6, 5 speed manual and air conditioning A/C (just passed 150K miles). I'm not getting a check engine light but it will suddenly runs rou

I'm having a intermittently rough running issue. If anybody can help, Does anybody know which of my emissions systems, ignition parts/sensors, and/or solenoids ONLY start functioning after my 1994 Firebird (3.4ltr./manual) is fully warmed up and driven for about 10 minutes to a 1/2hour or more of driving? The on-set of the symptoms most often seem to start happening when I drive it on the freeway 3 miles or more miles...then park and let it sit for 15-20 minutes or more. Then...it starts happening when I re-start it (and it's already been warmed up and driven (WOT) like that). It also seems to be triggered sometimes by a little extra load...like a freeway hill or something). It feels like my timing advance (for higher speeds/hotter engine/higher load. or as in on a hill) on the ignition coil module just clicks to open circuit (or close circuit),..? or maybe a solenoid opens (like my EGR)...? Whatever it is, I lose lots of power and MPG. It also makes my car sputter and pop. I've recently checked my O2 sensors with a digital volt meter, and they seem a little lazy. They seem to go lean (about 50 mV) when I push on the gas. Then they seem to take 7-12 seconds to go back over to rich condition. When I push on the gas it surges and lags and lacks power. Could that be what's causing a symptom like mine (only runs weird when it's hot. and it happens all the sudden). I've recently replaced my Spark Plugs, SP wires, coils, ignition coil module, air and gas filters, PCV, and took my EGR off and cleaned/ put in new gaskets, cleaned out my throttle body. I've also cleaned my PCM connectors and sockets along with all the other engine compartment wiring harnesses, connectors, and grounds. Thanks in advance.

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Posted on Jan 02, 2017

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taran_2005
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SOURCE: 1991 Pontiac Firebird V6 3.1

Hi,

That code is for an IAC. Without a scan tool or something to manually drive it, you won't be able to confirm the problem is the IAC itself. Your best hope is to just take a shot and change it. See what you have after that.

Let me know,once done.

Hope i helped you.

Thanks for using ' Fixya ' and have a nice day!!

Posted on Apr 28, 2011

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What is a solution to fixing the mass air flow system, with code po121


DTC P0121: Throttle Position (TP) Sensor 1 Performance
Circuit/System Description
The engine control module (ECM) uses the following information to calculate an expected airflow rate:
?€¢
The throttle position (TP)


?€¢
The barometric pressure (BARO)


?€¢
The manifold absolute pressure (MAP)


?€¢
The intake air temperature (IAT)


?€¢
The engine RPM


P0121 The predicted air flow and the predicted MAP combined are outside a calibrated range for more than 3 seconds.
Circuit/System Testing

  1. Inspect for the following conditions:
  2. ?€¢
    Vacuum hoses for splits, kinks, and proper connections as shown on Vehicle Emission Control Information label


    ?€¢
    Inspect thoroughly for any type of leak or restriction


    ?€¢
    Air leaks at throttle body mounting area and intake manifold sealing surfaces


    ?€¢
    Throttle body for dirt, debris, and coking--Refer to Throttle Body Cleaning.

  3. Allow the engine to reach operating temperature. Observe the MAP Sensor Voltage parameter with a scan tool. Voltage should be more than 0.8 volt and less than 4 volts.
  4. ?‡'
    If more than 4 volts or less than 0.8 volt, refer to DTC P0106.

  5. Idle the engine. Observe the MAP Sensor kPa parameter with a scan tool. Increase the engine speed slowly and then back to idle. The MAP sensor kPa should change smoothly and gradually as engine speed is increased and returned to idle.
  6. ?‡'
    If the MAP sensor kPa does not change, refer to DTC P0106.

  7. Take a snapshot of the engine data list while performing the actions listed below. The mass air flow (MAF) sensor g/s should change smoothly and gradually as the engine speed is increased and is returned to idle.
  8. ?€¢
    Idle the engine.


    ?€¢
    Increase the engine speed slowly to 3,000 RPM, then back to idle.


    ?€¢
    Exit from the snapshot and review the data.


    ?€¢
    Observe the Mass Air Flow (MAF) Sensor parameter frame by frame with a scan tool. The MAF sensor g/s should change smoothly and gradually as the engine speed is increased and is returned to idle.


    ?‡'
    If the MAF sensor g/s does not change smoothly and gradually as the engine speed is increased and is returned to idle, refer to DTC P0101 or P1101.

  9. Inspect the throttle body for the following conditions:
?€¢
Loose or damaged throttle blade


?€¢
Broken throttle shaft


?€¢
Any throttle body damage


?‡'
If any of these conditions exist, replace the throttle body assembly.

Jun 20, 2015 | 2008 GMC Sierra 1500 2WD

1 Answer

Having problems with my 1998 Pontiac firebird. When I sit with the air on my car sometimes start to shake or even smoke. I don't know if it's the exhausts or something dealing with it breathing. Whatever...


A bunch of things can cause this.
It could be the engine idle speed is too low, can be caused by a faulty Idle Air Control valve. Watch the rev counter when it does it and see if it's very low. See if it rises when you turn off the air con. The air con puts a load on the engine which should be adjusted for by the IAC valve (automatically opens the throttle very slightly to keep the engine speed from getting too low).
Also possible to be fuel pressure, Mass Air Flow sensor, ignition coil, spark plugs or even a blocked air filter.
Is the check engine light on?
Try looking at Pontiac firebird forums. Google search firebird idle faults. Good luck.
https://www.google.co.nz/search?q=1998+Pontiac+firebird+idle+adjust&ie=utf-8&oe=utf-8&client=firefox-b&gfe_rd=cr&ei=YbpsWavMPOrc8weH8qDYAw

https://www.google.co.nz/search?q=Pontiac+firebird+ide+problems&ie=utf-8&oe=utf-8&client=firefox-b&gfe_rd=cr&ei=z8dsWcXfBOHDXsLtjoAN

Jul 17, 2017 | Cars & Trucks

2 Answers

1994 crown victoria engine races


Problem with idle speed. The idle is controlled by the pcm (engine computer) through the operation of the Idle Air Control valve or motor. But several other sensors are also at work, like the throttle position sensor, the coolant temperature sensor, the MAP sensor or the Mass Air Flow sensor. The computer monitors all engine conditions to optimize performance and driveability-this includes keeping idle speed correct.
Would probably help you if you could see what all those sensors are telling the pcm-so you need a scanner capable of giving live stream data. And don't forget, your '94 is OBD-1, not OBD-II like all cars since 1996 on have. A garage should have such capable scanners, but they are kind of high end, not your typical cheap code scanner.

May 07, 2017 | 1994 Ford Crown Victoria

1 Answer

Rough or high idle


are there any codes? do you hear and vacuum leaks? have you replaced the idle air control valve

Jan 07, 2013 | 2002 Pontiac Firebird

1 Answer

Which codes (OBDI or II) do I use for my 1994 Jeep Grand cherokee laredo 4.0 2wd


before 1996 they use onboard diagnosis system for jeep.

when you turn on key you need to count check engine light blinks.

here are codes taken from internet.

11* No crank reference signal detected during engine cranking.
12* Direct battery input to PCM was disconnected within the last 50 key-on cycles.
13** No difference recognized between the engine MAP reading and the barometric (atmosphereic) pressure reading at start-up
14** MAP sensor input below minimum acceptable voltage.
or
MAP sensor input above maximum acceptable voltage.
15** No vehicle distance (speed) sensor signal detected during road load conditions.
17* Engine coolant temperature remains below normal operating temperatures during vehicle travel (thermostat).
21** Neither rich nor lean condition detected from the oxygen sensor input.
or
Oxygen sensor input voltage maintained above the normal operating range.
22** Engine coolant temperature sensor input above maximum acceptable voltage.
or
Engine coolant temperature sensor input below minimum acceptable voltage.
23** Intake manifold air temperature sensor input above maximum acceptable voltage.
or
Intake manifold air temperature sensor input below minimum acceptable voltage.
24** Throttle position sensor input above maximum acceptable voltage.
or
Throttle position sensor input below minimum acceptable voltage.
25** A shorted condition detected in one or more of the idle air control motor circuits.
27* Injector #1 output driver does not respond properly to the control signal.
or
Injector #2 output driver does not respond properly to the control signal.
or
Injector #3 output driver does not respond properly to the control signal.
or
Injector #4 output driver does not respond properly to the control signal.
or
Injector #5 output driver does not respond properly to the control signal.
or
Injector #6 output driver does not respond properly to the control signal.
33* An open or shorted condition detected in the A/C clutch relay circuit.
34* An open or shorted condition detected in the speed control vacuum or vent solenoid circuits.
or
Speed control switch input below the minimum acceptable voltage.
or
Speed control switch input above the maximum acceptable voltage.
35* An open or shorted condition detected in the radiator fan relay circuit.
41* An open or shorted condition detected in the generator field control circuit.
42* An open or shorted condition detected in the auto shutdown relay circuit.
44* An open or shorted condition exists in the engine coolant temperature sensor circuit or a problem exists in the PCM's battery temperature voltage circuit.
46** Battery voltage sense input above target charging voltage during engine operation.
47** Battery voltage sense input below target charging voltage during engine operation. Also, no significant change detected in battery voltage during active test of generator output.
51** Oxygen sensor signal input indicates lean air/fuel ratio condition during engine operation.
52** Oxygen sensor signal input indicates rich air/fuel ratio condition during engine operation.
53* PCM internal fault condition detected.
54* No fuel sync (camshaft signal) detected during engine cranking.
55* Completion of diagnostic trouble code display on the malfunction indicator lamp (check engine lamp).
62* Unsuccessful attempt to update SRI (service reminder indicator) miles in the PCM EEPROM.
63* Unsuccessful attempt to write to an EEPROM location by the PCM.

* - Check engine lamp will not illuminate at all times if this code was recorded. Cycle ignition key as described and observe code flashed by check engine lamp.

** - Check engine lamp will illuminate during engine operation if this code was recorded.

PCM = Powertrain Control Module (the engine computer)
MAP = Manifold Absolute Pressure (the sensor that measures how hard the engine is sucking air through the intake manifold
EEPROM = Electrically Erasable Programmable Read Only Memory (a type of computer chip used inside the PCM)

Nov 19, 2011 | 1994 Jeep Grand Cherokee

1 Answer

High idle


Clean the throttle body inside to make sure the throttle plate closes properly. also clean the mass air flow sensor cross wires inside it's bore. If there are no vacuum leaks, this may help

Jun 06, 2009 | 1994 Pontiac Firebird

1 Answer

94 Firebird. Hesitates at 2K RPMs, surges at 3K. Low MPG, Rich.


Jen,

Some other easy items to check. Remove and clean the MAF/MAP Sensor and the inlet to the thottle body with some brake cleaner/electronics cleaner. Also may want to try some Fuel Injector cleaner as well. The O2 Sensors usually require a special socket which you can buy at the local auto parts store, and you can also use a "Crowfoot" Wrench. Usually if the O2 Sensors are bad they will set off the Check Engine Light. Some other items to consider is a Rotor and Rotor Cap if you have a distributer instead of a coil.

Sincerely,

JC

Nov 16, 2008 | 1994 Pontiac Firebird

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