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Ignition Codes 12 and 13 What does that mean?

2215 Views 18 Replies 6 Participants Last post by  lN5L816TO23LAq
So my 88 318 177000 R/C puts these codes out.
Any ideas on what this could mean or how to fix it? When the check engine light comes on, it bothers me. Also, I cannot get any power when climbing hill, which I do in North GA. I don't mind the gas money to put into the beast, but I want more umph up deez hills.
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Don't worry about code 12, it just means the battery was disconnected at some point in the last 100 key-ons.

CODE 13 (CEL ON)--MAP Sensor Pneumatic Circuit problem --No variation in MAP sensor signal is detected during engine running. No difference is recognized between engine run MAP reading and the stored barometric pressure reading.

Check to make sure the MAP sensor vacuum hose isn't cracked or disconnected, then pull the hose off with the engine running and feel for vacuum. If there is none, the port in the throttle body is clogged. If you have vacuum, replace the MAP sensor. It is on the passenger side of the throttle body with a 3 pin connector and a short hose between it and the TB. This will definitely cause a lack of power, because it tells the computer what kind of load the engine is under.

Matt {peace}
janabrute said:
This thread had me thinking. I checked my Haynes book.

Its possible that the problem may not be caused by the MAP sensor. If code 12 and 13 is being shown it may be a fluctation in voltage output. SMEC/PCM receives information from MAP as a voltage signal. MAP failure should come up as a code 13 or 14 and trigger 'Check Engine' light. Code 12 should not. Check your alternator, battery and regulator as a suggestion.

Hey TaZMaNiak question? My '91 acts up when it is hot and humid weather. I believe the fuel mixture becomes so lean that it down shifts, stalls and back fires. You mentioned a 'stored barometric pressure reading'. Can that be adjusted or corrected for extreme weather?
Code 12 is nothing.. It just means the battery has been disconnected recently. He said the check engine light was on also.. Code 13 and 14 are both MAP codes, 13 means the computer is getting an unchanging output from the sensor (meaning the problem is in the vacuum side), and 14 means it isn't getting an output at all (electrical side). The "stored pressure reading" is the "limp-home" default reading that the computer uses just to make the engine run when there's no "real-time" sensor input.. It can't be changed because it's only used during a malfunction of the sensor.

As far as your problem goes, I'm not real sure... I'm still learning the whole computer-engine thing.. I've always had carbed engines.. If it's an environmentally-related problem, first thing I would check would be the air temp sensor.. Are you getting codes? Also, does it downshift because it stalls? There's no electronic or vacuum control on Torqueflites, so any shifting is through engine speed and throttle position.

UGARAM.. Did you check to see if you had vacuum to the sensor? If you don't, changing it won't help.... The MAP sensor tells the computer to adjust the fuel delivery and timing based on load on the engine. The computer isn't getting a reading off the MAP, so it doesn't know whether you are climbing a hill or sitting still. Correct the problem (clogged/broken hose or the sensor itself) and you should gain a considerable amonut of power.

Matt {peace}
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Remove the air cleaner..... ;D ;D ;D
Pull the crankcase breather out of the valve cover, and pull the intake hose off the ram air inlet. Lift the cleaner housing up and disconnect the small hose from underneath (don't forget to put it back on when you're done tho)
The MAP goes to the first (left) nipple on the front of the throttle body. Also, if you say you're getting vacuum at the MAP end of the hose, the problem is in the sensor itself. Replace it and the hose at this point.

Matt {peace}
Yeah, you have to clear the codes after you fix the problem. Carb cleaner is fine down that hose (actually it's good for it).. If you still get code 13 after resetting the computer and replacing the hose and sensor (and you have good vacuum att he hose), I don't know what to tell you.. It can't be a broken wire or bad connection because that would set code 14. 13 is only for the vacuum side of that sensor. Let us know..

Matt {peace}
{blush} {blush} See? I told you I was learning... Learn something new every day... But carb cleaner evaporates so fast, I didn't think it would be a problem to spray some in....

Matt {peace}
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