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1993 dodge dakota acceleration problems
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individualizedrepair
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Dec 22, 2013, 11:17 AM
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1993 dodge dakota acceleration problems
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I have a 1993 dodge dakota v6 that I am having some issues with. Ever since it got cold out acceleration is sporadic and at times seems not to want to accelerate at all. It feels to me when this happens like it is not getting fuel. I replaced the fuel pump and filter which did not solve anything. I have cleaned the throttle body and replace the gasket also. Spark plugs and wires seem fine even though it has been a while since they have been changed. The truck runs great when idling and without being under load will rev up steady all the way. Seems like once the truck warms up the problem gets better but it is still very sporadic and happens at random times. When this happens if I floor the truck it will come out of the bad acceleration and accelerate fine until I let off the gas and rpms go back down. I am wondering if it could be the crankshaft or throttle positioning sensor but I would like some input before doing anything else to the truck since I am not exactly a mechanic. Thanks in advance for your help!
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Discretesignals
Ultimate Carjunky
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Dec 22, 2013, 11:23 AM
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Re: 1993 dodge dakota acceleration problems
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Check engine light on? If so, do the key dance with the ignition switch. (ON, OFF, ON, OFF, ON) This will cause the engine computer to display trouble codes by flashing the check engine light. Write down the numbers.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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individualizedrepair
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Dec 22, 2013, 2:34 PM
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Re: 1993 dodge dakota acceleration problems
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it displays 12-14-14 checked voltage to the uh whatever it is middle and third post both read around 5.5v. check engine light is not on though
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Discretesignals
Ultimate Carjunky
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Dec 22, 2013, 3:26 PM
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Re: 1993 dodge dakota acceleration problems
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14 code is a MAP sensor high or low voltage code. Beware this code can set if you unplug the MAP sensor with the engine running. To be sure this code wasn't set by someone or yourself unplugging the MAP sensor, disconnect the battery for 10 secs to erase codes, and then see if the code returns.
If it does, you'll need to check the MAP sensor signal voltage using your volt meter.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Dec 22, 2013, 3:26 PM)
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individualizedrepair
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Dec 22, 2013, 3:33 PM
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Re: 1993 dodge dakota acceleration problems
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This code came on after disconnecting the battery for fuel pump replacing. It was not disconnected while the engine was running. The voltage is about 5v on both terminals which through research is what it should be at. I am not sure why it is showing this code but would a bad MAP sensor cause this kind of issue anyway?
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Discretesignals
Ultimate Carjunky
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Dec 22, 2013, 4:00 PM
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Re: 1993 dodge dakota acceleration problems
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Did you make these electrical checks with the sensor connector plugged in? You need to back probe the connector using a T pin or something you can connect your meter to. Make all measurements with your volt meter negative lead connected to battery negative. Do not short the 5 volt power supply to ground.
Violet/white wire should have 5 volts (power supply for MAP sensor)
Black/light blue wire should have less than 0.1 volts. (sensor ground)
Dark green/red will have between .5-4.5 volts on it depending on manifold vacuum. With the engine running you should see around 1.5 volts. Under hard acceleration the voltage should be about 4 volts.
The MAP sensor is critical to the running of the engine and is used to by the PCM to calculate engine load for fueling and timing. It also is used by the TCM for transmission operation.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Dec 22, 2013, 4:05 PM)
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individualizedrepair
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Dec 22, 2013, 6:49 PM
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Re: 1993 dodge dakota acceleration problems
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So I should take these readings with the engine running on the back side of the connector correct? Before I looked at a tutorial and it said to take the common when off and unplugged and just backprobe the other connection while engine was off and ignition was on. Got about 5v for both readings. Is this a false way to do it? Both should be taken when engine is on and it is plugged in and backprobe both correct?
(This post was edited by individualizedrepair on Dec 22, 2013, 6:51 PM)
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individualizedrepair
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Dec 22, 2013, 7:04 PM
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Re: 1993 dodge dakota acceleration problems
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back probed using t-pin with engine running as suggested. Middle I get a solid 5 on violet/white and 1.7 on green/red when idling. No voltage on black/blue. This is going back to negative battery terminal for negative. When I rev the engine up the map voltage on green/red actually goes down. From .2 to 1.2 somewhere under hard acceleration. Does this mean I have a bad MAP sensor?
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individualizedrepair
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Dec 22, 2013, 7:08 PM
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Re: 1993 dodge dakota acceleration problems
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The map sensor common voltage comes from the pcm so if i am getting 5v to the common on the map sensor that means the pcm is feeding the map sensor properly correct?
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Discretesignals
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Dec 23, 2013, 5:40 AM
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Re: 1993 dodge dakota acceleration problems
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The voltage on the signal wire should go up as manifold vacuum goes down. With the key on engine off the voltage from the MAP should be around 4 volts on the signal. The PCM supplies 5 volts to power the sensor. The PCM also sends 5 volts down the signal wire.
Connect a vacuum gauge to manifold vacuum and monitor engine vacuum while monitoring the MAP sensor voltage. You'll understand the correlation. If your vacuum gauge shows low vacuum under hard acceleration, but the MAP's voltage goes down instead of up, I'd say something is up with the MAP sensor. What was the voltage on the ground wire? It has to be less than or equal to 0.1 volts. That will tell you if the MAP sensor has a good ground.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Dec 23, 2013, 5:41 AM)
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individualizedrepair
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Dec 23, 2013, 6:57 AM
Post #11 of 54
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Re: 1993 dodge dakota acceleration problems
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I do not have a vacuum gauge but under hard acceleration the voltage does go down. I understand the corralation now that you explained it. Should i chrck input to signal wire from map sensor or should it be good since common is at 5v? Ground wire has 0.0 volts so the ground should be good. Map sensor is pretty cheap so you think this could possibly bethe issue?
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Tom Greenleaf
Ultimate Carjunky
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Dec 23, 2013, 7:19 AM
Post #12 of 54
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Re: 1993 dodge dakota acceleration problems
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Get a vacuum gauge - still good info with the things. Handy as all get out is this type.........
Pumps to make vacuum for testing and reads vacuum both. Not expensive and should come with a "T" so if inline to actual vacuum the item is still operating you are just watching what it gets - cool tool,
T
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individualizedrepair
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Dec 23, 2013, 8:27 AM
Post #13 of 54
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Re: 1993 dodge dakota acceleration problems
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Ill grab one and let yoy know what i come up with thankd
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individualizedrepair
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Dec 23, 2013, 4:27 PM
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Re: 1993 dodge dakota acceleration problems
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i'm looking for a vacuum gauge similar to what you showed me and I am having a hard time finding one. Any suggestions on where to get one at? Voltage at high rpm about 4000rpm is 1.0v to map sensor so I am either not getting enough vacuum or the sensor is bad...
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individualizedrepair
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Dec 23, 2013, 5:39 PM
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Re: 1993 dodge dakota acceleration problems
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Ok thanks, I'll pick one up!
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individualizedrepair
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Dec 26, 2013, 4:14 PM
Post #17 of 54
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Re: 1993 dodge dakota acceleration problems
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Ok got a vacuum gauge for testing. I get about .5 to 1 hg during idle and when rpm's go up the vacuum goes up. I get about 19 hg at 4000 rpm. My voltage from map sensor at 4000rpm is around 1v usually. I get about 1.7v from the map sensor with engine idling. Does this mean the map sensor is bad and should be replaced? Remember I was getting error code 14 which is map sensor voltage high/low also...
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Hammer Time
Ultimate Carjunky
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Dec 26, 2013, 4:23 PM
Post #18 of 54
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Re: 1993 dodge dakota acceleration problems
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You have to be reading that from the wrong place. You should have your highest reading at idle.
A healthy engine shouls be seeing 16-18" at idle and as you slowly increase the RPMs you shouldn't drop more that an inch or two at 2000RPM.
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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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individualizedrepair
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Dec 26, 2013, 4:36 PM
Post #19 of 54
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Re: 1993 dodge dakota acceleration problems
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I am reading it from the only vacuum hose going to the throttle body, is this the right place or where should I be reading it from?
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Hammer Time
Ultimate Carjunky
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Dec 26, 2013, 4:39 PM
Post #20 of 54
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Re: 1993 dodge dakota acceleration problems
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You have to be reading from behind the throttle plate to get full manifold vacuum. It sound like you are reading in front of the throttle plate and you won't get a reading there until the throttle is opened.
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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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individualizedrepair
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Dec 26, 2013, 4:46 PM
Post #21 of 54
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Re: 1993 dodge dakota acceleration problems
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busted a t fitting, going to get a replacement, ill let you know and thank you for the help
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Discretesignals
Ultimate Carjunky
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Dec 26, 2013, 4:47 PM
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Re: 1993 dodge dakota acceleration problems
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Should correspond like this with the voltage signal from your MAP sensor.
Remember that at 4000rpm you will probably see high vacuum readings if you slowly bring the rpm to that or hold that rpm in park. The engine isn't under any load in park. If you snap the throttle in park or you have the vehicle in gear and you accelerate, you will see a drop in vacuum.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Dec 26, 2013, 4:49 PM)
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individualizedrepair
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Dec 26, 2013, 4:54 PM
Post #23 of 54
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Re: 1993 dodge dakota acceleration problems
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ok, reading from back of throttle body. get 16hg when idling and 18hg when at 2000rpm. Not sure why the vacuum is going up?
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individualizedrepair
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Dec 26, 2013, 4:59 PM
Post #24 of 54
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Re: 1993 dodge dakota acceleration problems
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so it would seem like my vacuum readings are operating correctly under normal parked conditions then? I do not get any jumping or anything else with it and the map sensor code 14 was thrown from the vehicle. Just trying to figure out if the map sensor is bad or not I suppose.
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Discretesignals
Ultimate Carjunky
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Dec 26, 2013, 5:14 PM
Post #25 of 54
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Re: 1993 dodge dakota acceleration problems
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Did you get a hand held vacuum pump/gauge like in the picture above or just a gauge?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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