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what does a MAP sensor do??
- Thread starter HOOKER
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ab_slack
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As to symptoms I can't answer.
The sensor is used in the basic regulation of the fuel/air mix. The absolute pressure is needed to know how much oxygen there is going into the cylinder. That measurement determines how much fuel is added.
The sensor is used in the basic regulation of the fuel/air mix. The absolute pressure is needed to know how much oxygen there is going into the cylinder. That measurement determines how much fuel is added.
HOOKER
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well I ordered a new MAP sensor online,,
my old turd is spitting/sputtering when I get it @ 1800rpms,,
being a manual itsa real PITA..
I werk 5 miles straight east from my house & speed limit is 40mph..
I hafta shift at a real low rpm & gradually get my road speed up...
my old turd is spitting/sputtering when I get it @ 1800rpms,,
being a manual itsa real PITA..
I werk 5 miles straight east from my house & speed limit is 40mph..
I hafta shift at a real low rpm & gradually get my road speed up...
Last edited:
ab_slack
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- 2.9L
While you don't have a check engine light, you should be able to get codes and perform Key On Engine Off (KOEO) tests as well as the Key Off Engine Running (KOER) tests. This would indicate a bad MAP sensor.
I did a full sensor check on my 87 a couple years ago. The MAP sensor fooled me because it is a frequency output instead of a voltage output. It generates an pulsed waveform that changes frequency with pressure.
I looked briefly at the diagnostic criteria and key indicator of a MAP sensor problem is issues during acceleration and deceleration. These are the times the manifold pressure is furthest from atmospheric pressure.
Can you get to higher RPM slowly or without engine loaded?
If the issue is higher RPM, then questions come into play like can the catalytic converter be clogged and timing advance. Have you checked the timing? Verified it advances?
I guess you will find out with the MAP sensor, it is an easy swap.
If that doesn't work, one sensor that frequently gets messed up is the air charge temperature sensor on the throttle body. That can fill up with crap. That was one that improved operation of my vehicle quite a bit. O2 sensor was the other one although that one you can test for easily by just disconnecting. O2 sensor problems only show up after vehicle warms up when it tries to go closed loop. It is open loop upon starting.
I did a full sensor check on my 87 a couple years ago. The MAP sensor fooled me because it is a frequency output instead of a voltage output. It generates an pulsed waveform that changes frequency with pressure.
I looked briefly at the diagnostic criteria and key indicator of a MAP sensor problem is issues during acceleration and deceleration. These are the times the manifold pressure is furthest from atmospheric pressure.
Can you get to higher RPM slowly or without engine loaded?
If the issue is higher RPM, then questions come into play like can the catalytic converter be clogged and timing advance. Have you checked the timing? Verified it advances?
I guess you will find out with the MAP sensor, it is an easy swap.
If that doesn't work, one sensor that frequently gets messed up is the air charge temperature sensor on the throttle body. That can fill up with crap. That was one that improved operation of my vehicle quite a bit. O2 sensor was the other one although that one you can test for easily by just disconnecting. O2 sensor problems only show up after vehicle warms up when it tries to go closed loop. It is open loop upon starting.