Map sensor??? - Toyota Nation Forum : Toyota Car and Truck Forums

nadaok · 09-07-2011, 03:45 PM

hi there ...i have toyota corolla 1991 . 5A-FE engine .....i want to know how i can check the MAP sensor , becuase the engine not staring ....so is there any way to check this sensor ???...and if it is bad sensor , can i unpluged and start the engine ,???

thanks in advance

Blof-fan · 09-08-2011, 10:27 AM

Have you already eleminated every other possibility?
Because MAp sensors can break, just like everything else, but it is very unlickly it will.

Is the starter turning over the engine? Is fuel comming into the cylinders? Is air comming into the cylinders? Are you getting good spark?

I think the MAP sensor is one of the last things you could check

If you still want to check the MAP sensor. You can check the voltage on the connector of the sensor. With the contact of the car on, it should read between 4 and 6 Volts

nadaok · 09-08-2011, 02:35 PM

thank you fan for your reply ....i did check the map sensor and i saw the voltage 4v and 5 v across the terminals ...and applied little vacuum and i saw the voltage decreased ...so do you think that it is correct ???

i have checked the spark and it is white color not yellow so is it good ??

after some help from my friends that have told me that my car has foolded with pertrol and that what it caused misfire and weak spark ..they siad it is internal leak injector ....??the coil on the injector is reading perfectly and correct with multimeter ....so should i start to clean the injector ....??? can you please tell me how to do that ????

best regard

Blof-fan · 09-09-2011, 10:03 AM

You can always add an injector cleaning additive to your fuel. There is no harm in that and it might help.
But if you are getting fuel from the injectors, I don't think they are at fault.

The colour of your spark doesn't always say anything. The colour of the tip of the sparkplug does. it should be a greyish/brown colour. That indicates that your air/fuel mixture is correct and you have a nice detonation in the combustion chamber.

If the tip of the sparkplugs are white (engine is running lean) or black (could be a number of things) or show any disformation, that would indicate that something is wrong.

nadaok · 09-10-2011, 12:30 AM

thank fan for your reply ...i did replaced my injectors with used one from junkyard ...and the engine still flooded with fuel ...my friend said there is leak pressure between the fuel pump line and the injectors ?? and with out this pressure the injector wont work ..instead the injector will keep dropping fuel even if i turn the engine off ...so is that right ?? and how to fix this leak?

thanks in advance

90 GP · 09-10-2011, 01:58 PM

Fuel Pressure regulator is probably shot allowing too much pressure in fuel rail. That would account for engine being flooded. Should be at far end of fuel rail with a vacuum line attached.Check to make sure the vac lines are attached and not leaking. Here is a pic for a 4afe , yours should be similar. Did you ever remove timing belt cover to insure it is intact and hasn't slipped on cogged pulleys?

http://shop.advanceautoparts.com/web...1817751354____

nadaok · 09-11-2011, 03:27 PM

thank you 90 GB for your reply .....my timing belt is ok i have checked that now ......you mention that the pressure regulator need to be check..how we can do that ???...

i forgot to mention that i have replaced the O-rings for the injectors ...so do you think if the O-rings is incorrect size will impact on the pressure on the injector???

thanks in advance