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MAP sensor question

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  #1  
Old 12-01-2009, 08:32 PM
Horton Horton is offline
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Default MAP sensor question

Greetings.
My check engine light has come on twice just lately with the code 13. My manual says it's Map pneumatic signal or MAP voltage too low. Does this indicate the MAP sensor needs to be replaced? The oil pressure has been dropping with this new problem, don't know if it's related at all. Any suggestions? Thx!
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  #2  
Old 12-01-2009, 09:03 PM
landyacht318 landyacht318 is offline
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The Map sensor is located on the passenger side of the throttle body, under the air cleaner. There is a vaccuum line running from a port on the bottom/ back of the TB to the map sensor. Make sure this vaccuum line is not leaking. If I disconnect mine, the CEL lights instantly.

I don't see a relationship between the map sensor code and the oil pressure unless you've got serious internal engine problems.
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Old 12-01-2009, 09:08 PM
alloro alloro is offline
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A MAP sensor has nothing to do directly with oil pressure. Perhaps the 5 volt wire powering the sensors has a problem and is not providing full power to the MAP sensor or the oil sending unit.
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Old 12-01-2009, 10:07 PM
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Thanks to you both. I will check the vacuum line and then the wire and go from there. Is there an oil pump or oil sending unit that may be going bad causing the pressure to drop?
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Old 12-01-2009, 10:21 PM
landyacht318 landyacht318 is offline
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2 causes of actual low oil pressure are worn bearings, or a worn oil pump.

The sending unit only senses the pressure and sends a signal to the gauge.
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  #6  
Old 12-02-2009, 10:24 PM
Horton Horton is offline
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okay I checked the vacuum hose and I didn't find a leak. I also unhooked it while the van was running, the engine stops at that point. The wiring still looks good but I don't have a way to test the voltage. I'm thinking maybe the MAP sensor is going bad. The oil pressure could be related to the cold weather here and there is Lucas added in. I'll take it in to the shop I guess. Thanks!
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Old 12-02-2009, 11:36 PM
landyacht318 landyacht318 is offline
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Colder weather means slightly cooler and thicker oil at full temp which would translate into higher oil pressure. Lucas is very thick and also increases oil pressure.

A shop will be able to put a mechanical gauge on and test the pressure and determine of the sending unit is bad, or you actually have low oil pressure.

The vaccuum port where the map sensor vacuum line connects is prone to carbon build up.
If the throttle body has never been removed and cleaned. It is possible the port to the map sensor is filled with carbon, not allowing the Map sensor to read intake manifold pressure and lighting the CEL.

It is not very difficult to remove and clean the TB. The little port on the back where multiple lines run to, comes off with 3 torx bit screws. But there is a gasket which most likely tear upon removal.

I know this suggestion might get Alloro all riled up, especially with you being female and all, but pull the vacuum line off the Map sensor and see if you can easily suck or blow air through it with the other end still attached to the throttle body, to determine if it is clogged and if a TB removal and cleaning is necessary.

The only times I got a code 13 was when my ECM was failing, and causing the engine to sputter, stutter and backfire.

Harbor freight sometimes sells a digital multimeter for $2.99. Regular price $7.99. It's not a professional tool, but I've tested mine against an 85$ Fluke meter and found it to be pretty accurate. It is very worth having one.
http://www.harborfreight.com/cpi/cta...emnumber=90899

Good luck. Is your overdrive working?

Here's a mechanical oil pressure tester for 10$ while your at HF.
http://www.harborfreight.com/cpi/cta...emnumber=92687

Last edited by landyacht318; 12-02-2009 at 11:43 PM..
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  #8  
Old 12-03-2009, 01:50 PM
alloro alloro is offline
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Quote:
Originally Posted by landyacht318 View Post
I know this suggestion might get Alloro all riled up, especially with you being female and all, but pull the vacuum line off the Map sensor and see if you can easily suck or blow air through it
Naw, only if she lived near me!
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  #9  
Old 12-03-2009, 02:33 PM
Horton Horton is offline
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You guys are too funny! I'll blow on the vacuum hose and have the shop test the pressure of the sending unit. I'm fairly certain the TB has never been cleaned. I've only cleaned what I could get to easily. Still no OD, the next step is a tranny shop recommended by the new mechanic. The flywheel cover is missing, I have no clue why. My endless budget for this van ran out! LOL
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Old 12-03-2009, 03:32 PM
alloro alloro is offline
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Quote:
Originally Posted by Horton View Post
I'll blow on the vacuum hose and have the shop test the pressure of the sending unit.
You know...if you do that in front of them they might not charge you to test the sender.
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  #11  
Old 12-04-2009, 12:16 PM
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After checking hose & wiring I unhooked battery to clear codes. This morning the CEL came on again while the van was warming up in the driveway. At this point I'm leaning towards replacing the MAP sensor. I got the same code 12 & 13 again today.
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Old 12-04-2009, 12:39 PM
landyacht318 landyacht318 is offline
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Is the van Idling/driving smoothly? A code indicating that a sensor is getting incorrect readings, does not mean the necessarily sensor has failed, only that it is reading parameters outside that which the ECM is programmed to look for.

A code 13 could also be caused by the TB being loose on the intake manifold, a leaking TB gasket. A plugged vacuum port, or excessive resistance or a short in the wiring leading to the sensor from the ECM. Or the ECM itself. Or the diaphram inside the Map sensor has developed a leak.
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Old 12-04-2009, 04:05 PM
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The van is running fine, no sputters. This will give me a route to find the problem. Most of the plastic parts close to the engine have become brittle, some of the tabs have broken off. I will let the professionals check it out. Thanks!
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Old 12-07-2009, 05:43 PM
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Mechanic says the MAP sensor is bad. I would've blown on the hose for him except I had to get to work and it's bitter cold here today. Wind chill -20.
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Old 12-17-2009, 05:15 PM
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Hi guys. The mechanic replaced the MAP sensor last week and the hose that goes to the back of the TB. It's worse now, CEL comes on every time you drive the van. The rpm takes a dive and it starts to run rough like its not getting enough gas. They had it again today and said the voltage parameters looked okay. Within five minutes from leaving the shop the CEL was on. They fixed the oil pressure gauge with a new one.
Any thoughts on this MAP situation?
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  #16  
Old 12-21-2009, 08:26 PM
alloro alloro is offline
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What's the code now when the CEL comes on?
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Old 12-22-2009, 02:33 AM
landyacht318 landyacht318 is offline
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I wrote a response a couple days ago, but my laptop froze during, and I've only just stopped cursing each and every aspect of everything.

Assuming you are still getting the code 13 after getting a new map sensor. ( BTW did the mechanic give you the old Map sensor?) I will pose a couple hypothesisesesesss.

1. Moving the wires to the Map sensor further aggravitated a weak wire or poor connection.

2. Replacing the vacuum line to the map sensor caused an adjacent vacuum line on the TB's rear vacuum ports to fail.

3. There is a large accumulation of carbon in the TB, so the possibly new map sensor is more sensitive to the lack of proper vacuum .

4. Your ECM has gone plum Loco, causing not only your overdrive issues, but the map sensor codes and poor idle.

The only time I've gotten a code 13 is when my ECM was failing, and it caused stuttering, stumbling and backfiring for about 30 seconds on start up. It(The ECM) should have displayed this code during such an event, and it did, but it was also the issue.

Just because the ECM was able to recognize that one sensor was getting improper readings did not mean the ECM was still good in All respects. In my case.

Good luck
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  #18  
Old 12-22-2009, 08:13 AM
alloro alloro is offline
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5. The new MAP sensor isn't seated properly.
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Old 12-28-2009, 12:20 PM
Horton Horton is offline
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or #6. Hard to find a mechanic who still believes in customer service.

Thanks guys for your help. The part is being replaced this week, hopefull that will be the end of it. Happy New Year!
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  #20  
Old 12-28-2009, 02:21 PM
alloro alloro is offline
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Quote:
Originally Posted by Horton View Post
The part is being replaced this week
What part is being replaced?
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Old 12-28-2009, 02:21 PM
 
 
 
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