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map sensor range

magimerlin

magimerlin

NAXJA Forum User
Location
Flatonia, Tx
Ok so I was checking my map sensor output according to the "Renix F/I book" and it states that the output should be 0.5-1.5 while running. Mine reads 1.9 to 2.2 at the highest. It says that anything out of the 0.5-1.5 range the map is bad. Well this is brand new. So my Question is how would the extra 0.4-0.7 volts signal effect the system. Or should I just bring it back into work and exchange for another. Iknow the F/I book says to replace, so thats probably what I'll do but just curiuos of what the extra little output voltage would do. Oh and the output signal while running is the only thing that is off. The input voltage and output voltage is in spec when the Jeep isn't running. Just the output signal when running is off. What might be causing this, just a bad sensor purhapse. I checked the ground and that is fine. Thank you
 
The voltage will translate to a fuel mixture difference. Those readings should make it run pretty rich. Make sure your ground from the firewall to the head is clean and tight.
 
That was the first thing I did. There was very little resistance when I checked pin A on the plug to ground. That is what I am combatting is my Jeep is going through gas really bad. I average between 9-12 mpg on an average. I am checking the exaust for any leaks that would mess with the O2 sensor in a few moments as well. Thank you
 
I just replaced the coolant sensor on the block but will ohm that out while I'm under there. The IAC I ohm'd yesterday. That was in spec. It was about 70 degrees yesterday and it ohm'd out at about 3400-3450. spec is 3400 according to the F/I book so that should be ok.
 
magimerlin said:
Ok so I was checking my map sensor output according to the "Renix F/I book" and it states that the output should be 0.5-1.5 while running. Mine reads 1.9 to 2.2 at the highest. It says that anything out of the 0.5-1.5 range the map is bad. Well this is brand new. So my Question is how would the extra 0.4-0.7 volts signal effect the system. Or should I just bring it back into work and exchange for another. Iknow the F/I book says to replace, so thats probably what I'll do but just curiuos of what the extra little output voltage would do. Oh and the output signal while running is the only thing that is off. The input voltage and output voltage is in spec when the Jeep isn't running. Just the output signal when running is off. What might be causing this, just a bad sensor purhapse. I checked the ground and that is fine. Thank you
Click to expand...

The FSM contradicts itself and says 0.5 to 1.8 volts at idle with a deep vacuum a page before the diagnostic tree drawing which says 0.5 to 1.5 Volts. I am guessing altitude variations and engine wear account for the large variation allowance at idle. Check for a weak battery in your meter first, then check for intake manifold vacuum leaks which would cause the high reading, also check the idle vacuum and see what it really is at idle!!!!!!!!!! If it's less than 18" I would look for a leak or low compression causing the high idle MAP senor reading.

Interesting post, I never thought to check the vacuum readings against the MAP sensor readings before this thread.
 
Ok. haven't changed the map yet. I ohmed the coolant sensor and that was in spec. I am going to check the vac as soon as I can get a tester from work. I did find that a few of my manifold (both intake and exhaust) had a couple loose bolts, and the exhaust is missin on on the bottom. I'll get that tonight from work along wth the vac gauge.
Kinda off topic but Ecomike where about in Houston are you. It would be great to meet someone else out here. Thanks every one for your ideas
 
SE Houston, Pasadena area between Hobby Airport and Pasadena. Also travel to NW houston near 249 & Beltway 8 each week.
 
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