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JO Ohio
New User
Apr 30, 2012, 7:21 AM
Post #1 of 8
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I have a 2006 Dodge Dakota SLT, with the V8 engine. It's got about 94K miles on it right now. This past weekend, the RPMs were going all over the place while I was driving it (up to 3,000 then back down to normal levels repeatedly), followed by the "Check Engine" light. I took it to the nearest auto parts store to try and figure out what the problem was. After plugging it into their computer, I found out that the MAP(Manifold Absolute Pressure) sensor was bad and needed replaced (like it did two months ago). Since it's a fairly cheap fix (about $22), I went ahead and bought a new one and replaced it. This morning on the way to work, the problem came back, but with no "Check Engine" light this time. My question is this- what's the next probable cause of the problem? Oxygen sensor?
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 30, 2012, 8:28 AM
Post #2 of 8
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Re: 2006 Dakota RPMs
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Any time an engine runs lousy or erratic it probably is dumping unburned fuel in exhaust and will mess with sensors and converter. That map sensor may not have been the problem itself but how it gets its info from the engine so check that wiring and any vacuum hoses to it if used are in good shape.
Get codes again and if the same then the map sensor itself wasn't the problem. Codes should be taken as an area to go checking and I don't know of any that plain tell you the items covered are bad,
T
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JO Ohio
New User
Apr 30, 2012, 8:41 AM
Post #3 of 8
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Re: 2006 Dakota RPMs
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Guess I jumped to a conclusion too soon on the new part. On the bright side, it was still under warranty, so I got my money back. There aren't any vacuum hoses to it, so I'll take a look at the wiring harness when I get it back home. Thanks.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 30, 2012, 9:30 AM
Post #4 of 8
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Re: 2006 Dakota RPMs
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Then if not direct manifold vacuum it must be converting that info via a sensor and wiring - same deal just eliminates the hoses. I don't own software on stuff anymore so by just winging it I'd look at wire colors and see if the same where it would pick up manifold vacuum at intake manifold.
The deal is actual manifold vacuum is an important bit of info on what load the engine is under. When you totally max out load like full throttle manifold would be near zero and engine will take that info to make other adjustments so all runs well. At idle it would show perhaps 18Hg's or so meaning no load so adjusts accordingly and quickly.
So if codes lead to that circuit that's where I'd look all the way, wiring and where it lead to on intake itself no doubt. Some codes may be lurking before CEL light stays on kinda like it will forgive for a while on certain things - others that are totally wrong come back right away with the CEL light.
Old phart here - there were days you adjusted your own timing via a stick on your steering wheel for the conditions at hand. I can just imagine people today having a clue what to do while driving if it was all manual!
T
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Hammer Time
Ultimate Carjunky
/ Moderator
Apr 30, 2012, 10:26 AM
Post #5 of 8
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Re: 2006 Dakota RPMs
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You may have a bad IAC ( idle air control) but try eliminating any vacuum leaks and cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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JO Ohio
New User
May 3, 2012, 6:32 AM
Post #6 of 8
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Re: 2006 Dakota RPMs
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Checked my wiring to the MAP sensor, all was good there. When I went to take out my IAC to clean it, it came out in two pieces- not supposed to happen. Went and got a new IAC, put it in, and everything's running smoothly so far. Thanks for all the advice, I would've done a lot more guessing before I figured that out.
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Hammer Time
Ultimate Carjunky
/ Moderator
May 3, 2012, 6:49 AM
Post #7 of 8
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Re: 2006 Dakota RPMs
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You should also clean the throttle body.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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JO Ohio
New User
May 3, 2012, 8:40 AM
Post #8 of 8
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Re: 2006 Dakota RPMs
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Will do. Thanks.
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