Question about 1989 GMC Sierra

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Engine will run but rough with map vacuum disconnected.connect vacuum to map it leans out fuel and shuts engine down.

Replaced map sensor no codes in ecm

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Look for vacume hoses off or cracked

Posted on Dec 13, 2014

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2006 HHR with check engine light flashing. Codes


code 300 means multiple misfire due to plugs, wires, fuel problem including injectors.. A P0106 could be caused by:
  • Bad MAP sensor
  • Water/dirt intrusion affecting MAP sensor connector
  • Intermittent open in the reference, ground, or signal wire for the MAP sensor
  • Intermittent short in the reference, ground, or signal wire for the MAP sensor
  • Ground problem due to corrosion causing intermittent signal problem
  • A break in the flexible air intake duct between the MAF and the intake manifold
  • Bad PCM (do not assume the PCM is bad until you've exhausted all other possibilities)
Using a scan tool, watch the MAP sensor value with the key on, engine off. Compare the BARO reading with the MAP reading. They should be roughly equal. The voltage for the MAP sensor should read approx. 4.5 volts. Now start the engine and look for a significant drop in the MAP sensor voltage indicating the MAP sensor is working. If the MAP reading doesn't change perform the following:
  1. With the Key on, engine off, disconnect the vacuum hose from the MAP sensor. Using a vacuum pump, pull 20 in. of vacuum on the MAP sensor. Does the voltage drop? It should. If it doesn't inspect the MAP sensor vacuum port and vacuum hose to manifold for a restriction of some kind. Repair or replace as necessary.
  2. If there are no restrictions, and the value doesn't change with vacuum, then perform the following: with the Key on and engine off and the MAP sensor unplugged, check for 5 Volts at the reference wire to the MAP sensor connector with a Digital Voltmeter. If there is none, check for reference voltage at the PCM connector. If the reference voltage is present at the PCM connector but not the MAP connector, check for open or short in the reference wire between MAP and PCM and retest.
  3. If reference voltage is present, then check for existing ground at the MAP sensor connector. If it isn't present then repair open/short in the ground circuit.
  4. If ground is present, then replace MAP sensor.

Oct 10, 2014 | 2006 Chevrolet HHR

2 Answers

I have a 97 wrangler 2.5. Check engine light is on, running lean, loss of power and high fuel consumption. I have replaced the o2 sensors, reset check engine code. light stays off and engine runs great for...


Something odd about what you posted. An engine that is running lean shouldn't be using a lot of fuel. Lean is when there isn't enough fuel going into the engine. Two other sensors that regulate fuel flow are the map sensor and throttle position sensor. Temp sensor generally would cause a rich condition but I'd test that too. Be sure to check for vacuum leaks at the manifold and lines as well as fittings... A vacuum leak will give the O2 sensor a lean reading...seeing that, the computer will try to compensate by adding fuel. Clearing codes can change the way it's running but as soon as the computer runs through it's internal diagnostics it will turn the light back on if there is a problem.

Mar 24, 2011 | 1997 Jeep Wrangler

1 Answer

Engine shut off willnot crank after heating up geting code 34


DTC - 34 MAP Sensor Circuit Error (Signal Low Indicating High Vacuum)

The ECM uses the Manifold Absolute Pressure (MAP) sensor as an indication of engine load. High voltage would indicate low engine vacuum and higher engine load. Low voltage would indicate high engine vacuum and lower engine load. The ECM uses the information from this sensor to help calculate fuel delivery and spark timing.

Fault Code Description:
* 34 - MAP sensor circuit error (signal low indicating high vacuum)

Symptoms:
* Poor engine performance
* Engine running lean (not enough fuel, hard starting, lack of power)

Common Problems:
* GM MAP sensors do not commonly fail
* Due to erratic engine vacuum, other engine performance problems can cause a code 34 to set


Good luck (remember to rate this answer).

Mar 20, 2011 | Buick Riviera Cars & Trucks

1 Answer

Check engine light code P0171 lean bank 1 replaced upstream o2 sensor and map sensor


That code is a good O2 sensor reporting a lean condition. Lazy people and part stored just say it is the O2 sensor because they don't know how to fix it. Bank 1 is the side of the engine with the number one cylinder. That bank has a lean condition meaning it doesn't have enough fuel for the given amount of air. Since this is only affecting one side of the engine, that narrows down possible causes. Possible causes would a leaking intake gasket or a broken vacuum hose on that side. Since both sides get fuel from the same pump and rail, this wouldn't be a fuel pump or regulator issue. It can, however, be an indication of a bad fuel injector on that side of the engine. The MAP sensor also couldn't cause this code because, just like the fuel pump, that MAP sensor works for both sides of the engine and the code is only for one side. I would drive it for a couple more days to see if you get any additional codes that could help point you towards the actual problem. In the meantime, I would check for vacuum leaks (look at the rubber hoses and listen for high pitch hissing or sucking sounds.)

Mar 03, 2011 | 2001 Dodge Durango

1 Answer

P0105 P0171


That is a map sensor code and a lean bank fuel code. I would suggest replacing the MAP Sensor but before you do that makes sure all the wiring connections to the sensor and wires themselves are in good shape. Also verify that the rubber hose connecting the sensor to the manifold is not split. The P0105 code sounds like the main code and the P0171 code sounds like it is a result of the first code. The MAP(Manifold Air Pressure) Sensor basically uses manifold vacuum to determine the amount of load on the engine and thus how much fuel needs to be added for proper operation. If any of the above described conditions are present it is very easy for the system to run lean. After repair use a scan tool to clear the codes and you should be good to go . I hope this helped you.

Feb 22, 2011 | Nissan Maxima Cars & Trucks

1 Answer

My mr2 is running lean and ive changed the oxy sensor what next? its still running lean. it feels like boost cut.is it the map sensor?


Lean code , lean condition is always an interesting problem to solve, if you found a vacuum leak your job is done, but if you didn't the fun begins,
First if you have an engine scanner you have to write down a o2 sensor voltage or short fuel trim value your job is to change those numbers if the fuel pump is weak the trim value would be negative -7 or less, and the O2 sensor voltage would be less than .45. Remember this part is important A good O2 sensor reads more or less .45, and short fuel trim 0 little less, little more. less than .30 or less than -5 would be a lean condition. items to check (test) Fuel Pump Pressure more that 35PSI,
Vacuum leaks including open PCV, Throttle tube for deformation and cracks, map sensor/or maf sensor that would give you a code, Bad fuel.

Dec 25, 2010 | 1992 Toyota MR2

1 Answer

Code 51 on a Plymouth sun dance. How do I fix it?


Code 51 = Oxygen sensor stuck in lean mixture mode. ( this will often cause engine to run rich due to oxygen sensor telling engine controller that it is running lean, thus send more fuel) This may be caused by M.A.P. sensor as well, so check vacuum lines and clean connections on MAP sensor first. It should be one of 2 things, Fault from MAP sensor, or faulty oxygen sensor.

Nov 01, 2010 | 1990 Plymouth Sundance

1 Answer

Engine codes are 12, 51,21,53,55 can someone tell me what these codes are. engine is running extremely rich.


12 is battery has been disconnected recently, or went dead.
51 is Oxygen sensor stuck on lean mixture reading
21- no change in oxygen sensor reading
53- internal problem with logic module
55- is end of message/codes.

51 & 21, basically telling you same thing, but I wouldn't jump at changing oxygen sensor first, as a bad M.A.P. sensor can cause a rich mixture, thus oxygen sensor switches to lean to try and compensate. Personally, I'd go with map sensor first, check connections and vacuum lines if all good, replace it, then I'd go to oxygen sensor .

Oct 21, 2010 | 1993 Dodge Caravan

1 Answer

Engine rough idle. code p1131. replaced o2 sensor.


vacuum leak in PVC line or clogged PVC. its a leak after the map sensor. o2 sensor is correcting for a lean condition so its adding fuel to your car when the o2 sensor detects the extra air.

May 15, 2010 | 2000 Ford Contour

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