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New here. Other sites are full of part throwers so looking for a knowledgeable community. 99 dakota 3.9 magnum. Started with an intermittent low idle/stall. Lose power bog down to 400-600 rpms and eventually die. Pop in neutral shut it off, and fires right back up and drives a few miles, only to do it again. I got a code for bank1 02 sensor and TPS. I threw a TPS at it, and no luck.

Next a buddy told me he had the same problem with his jeep, so I went to the salvage yard an picked up an IAC. It seemed to help, the CEL went away but it bogged down and stalled a few miles later.

So I had an extra Walbro intank lying around and a few people threw out weak fuel pump. So today I go to start the truck and it fires up to 400rpms and immediately dies. Did this 3 times and I figured the fuel pump may have been right and it finally died. So I spent the day putting the walbro pump in. The pump is working but now the truck wont idle. If I give it gas it winds up, but as soon as I take my foot off the gas it immediately dies.

What in the world is going on? Any help would be awesome. Thanks.
 

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New here. Other sites are full of part throwers so looking for a knowledgeable community. 99 dakota 3.9 magnum.
On the sequential port fuel injector Dakotas, you need to add 4 more tools to your tool box,
OBDII code reader,aftermarket fuel pressure guage and a Digital voltmeter, and a Haynes manual for the year of your truck, so you can test a bit before you swap parts. It might save you a lot of expense and repair time, if you do the diagnosis first.

Started with an intermittent low idle/stall. Lose power bog down to 400-600 rpms and eventually die. Pop in neutral shut it off, and fires right back up and drives a few miles, only to do it again. I got a code for bank1 02 sensor and TPS. I threw a TPS at it, and no luck.
O2 sensor is probably bad if you are getting a code for it. I just had both of mine replaced on my '98 magnum V8, because I got the code.
No problem with it stalling though, because the PCM will ignore a bad 02 sensor and just revert to "open loop" mode on the sensor, but your gas mileage will go down slightly because it wil run at the default (14.7 to 1) air to fuel ratio.

As far as the TPS, you should measure the o/p with a digital voltmeter while on the vehicle. With the vehicle harness connector still on the TPS, remove the air hose at the throttle body, turn on the ignition..BUT do not start!
Probe the DVM between the MIDDLE WIRE on the TPSsensor and a suitable good ground for the DVM and operate the
throttle by hand. The sensor if good will read 0.5v closed throttle and INCREASE up to 3.75 or 4.5 volts fully open.
That's all there is to these. If you get that reading, (voltage range) it's good and you don't need to replace it.

Next a buddy told me he had the same problem with his jeep, so I went to the salvage yard an picked up an IAC. It seemed to help, the CEL went away but it bogged down and stalled a few miles later.
The IAC is a idle rpm motor..not a sensor. Usually it just needs to be cleaned and inside around the throttle plate area.

So I had an extra Walbro intank lying around and a few people threw out weak fuel pump. So today I go to start the truck and it fires up to 400rpms and immediately dies. Did this 3 times and I figured the fuel pump may have been right and it finally died. So I spent the day putting the walbro pump in. The pump is working but now the truck wont idle. If I give it gas it winds up, but as soon as I take my foot off the gas it immediately dies.
You should have checked the fuel pressure first with a fuel pressure guage.
If you are getting 45psi when the fuel pump is running, and the pressure in the fuel rail doesn't go down below 35psi for at least an hour with guage still hooked up and the ignition shut off, the pump and the fuel pressure regulator pressure valve (in the fuel pump module) are working fine.

To check the fuel pump pressure, just hook up the guage to the test port on the fuel rail and turn the ignition on, but DON'T start it.

If the pump and pressure regulator are good, the fuel rail will pressurize within 1 second, with pressure at 45psi.
If you are getting good fuel pressure at the fuel rail test port, then you have to look elsewhere.

Stalling and dieing on these dakotas, can also be attributed to the camshaft or crankshaft sensors.
These are semi-conductor hall effect (magnetic) sensors and have been known to cause intermittent stalling
problems, and don't always give you a code, then fire right up. Unfortunately there is no way of testing
these to determine if they are the culprits, so I do carry a spare camshaft sensor with me in the truck..in
case I need to replace it.
 

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I am having a problem with stalling and revving as well. I have replaced the TPS, IACV, spark plugs, battery, and removed and cleaned the TB. Would it be a good idead to replace the cam sensor?
 

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I am having a problem with stalling and revving as well. I have replaced the TPS, IACV, spark plugs, battery, and removed and cleaned the TB. Would it be a good idead to replace the cam sensor?
So you have replaced the TPS and IAC?

In order to give a more informed decision on whether you need to replace
the cam sensor, we need some more information on your stalling and
revving symptom.

1. When does it stall...what gear are you in?
2. When does it rev up? what gear are you in?
 

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The majority of the time it stalls in drive or reverse. It revs in park or neutral. The stalling usually occurs when coming to a stop after backing up or driving forward. If it doesnt stall it will idle around 300 to 400 rpms and hesitates when taking off.
 

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The majority of the time it stalls in drive or reverse. It revs in park or neutral. The stalling usually occurs when coming to a stop after backing up or driving forward. If it doesnt stall it will idle around 300 to 400 rpms and hesitates when taking off.
Normal idle for a auto transmission is 600rpm. The idle may be a bit higher when the engine is cold because the ECT (Engine Coolant Temperature) sensor is telling the PCM that the engine/transmission hasn't warmed up to normal operating temperature. The PCM will adjust the IAC to provide basically what is equivalent to the old carburetor fast idle cams on the
throttle linkage.

Once the engine comes up to the proper temperature, the PCM will adjust the idle air setting (the air passage in the throttle body that is used when the throttle plates are in the CLOSED position..ie: foot off the gas pedal) , with the IAC.

If it's stalling coming to stop, the TPS sensor may not be providing the correct voltage feedback of the throttle plate position to the PCM, so the IAC is not being set correctly and ,the idle will drop down, and it will stall.

The TPS sensor should ALWAYS be checked out with a DVM (digital voltmeter before replacing and replacing it on the throttle shaft requires some understanding of how it works. You can put it on 180 degrees out on the throttle shaft and it will still screw on, but it WILL NOT work correctly.

Check the TPS sensor out by:

1. Remove the air cleaner so that you have access to the throttle plates
and can see them.

2. Use a DVM on the 10volt DC scale.
Black (ground) of the dvm to engine ground, and BACK PROBE the red lead of the dvm
THROUGH the insulation on the MIDDLE wire, with the TPS sensor still bolted on the throttle body, and plugged in.

3. Turn on the key..DO NOT START!

4. With the meter on the middle wire of the TPS sensor, move the throttle plates smoothly (via the throttle linkage) by hand, from fully CLOSED to fully OPEN, while watching the reading on the meter.

Readings should be: 0.5volts with throttle CLOSED

anywhere from 3.8volts to 4.5volts with throttle FULLY OPEN.

If you got those readings, TPS is good. If not, either it's installed incorrectly, (180 degrees out on the throttle shaf>
or the replacement TPS has a problem.

Usually, the PCM will give you a check engine error code if it is way out of range.
 

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I did the test. Here are my readings. 1.34 volts with the throttle closed, 3.82 fully open. Thanks for all your help. Whats my next step.
 

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I did the test. Here are my readings. 1.34 volts with the throttle closed, 3.82 fully open. Thanks for all your help. Whats my next step.
The throttle closed position reading doesn't appear to be right.

Yours is only providing a voltage spread of 2.18 volts when it should be a voltage spread of 3.30 volts..that's over 1 volt
difference in the reading at IDLE!

Typically on a known good TPS sensor, with the throttle plates closed AT IDLE, you should see a reading of around 0.50volts, with a smooth transition in voltage up to 3.80V when the throttle plate fully open.

The TPS data goes to the PCM which determines the IAC stepper motor setting for setting up the idle rpm.

If the PCM cannot determine a "idle signal" from the TPS, it will go for a "no load" setting in adjusting the IAC, so there appears to be some conflict between the two in your case.

Where is your old TPS sensor?

If you still have it, temporarily hook it up to the 3 pin plug, but don't engage it on the throttle shaft.
Turn the ignition on, back probe the center wire again and see what reading you get from the old sensor at idle.

It needs to be closer to 0.50volts AT IDLE (throttle plates closed).
 

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I don't have the old TPS. I replaced it due to a check engine light. The truck was bucking and surging then the light came on. I scanned it and got code P0121. This is when i should have tested it, but didnt know i should. I never thought about it until now but I didnt have the stalling issue I am having now before I installed the new TPS. Should I get a new one or have I possibly installed it wrong. The CEL turned off when I put the new TPS in. Is there anything else I can do?
 

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I don't have the old TPS. I replaced it due to a check engine light. The truck was bucking and surging then the light came on. I scanned it and got code P0121. This is when i should have tested it, but didnt know i should. I never thought about it until now but I didnt have the stalling issue I am having now before I installed the new TPS. Should I get a new one or have I possibly installed it wrong. The CEL turned off when I put the new TPS in. Is there anything else I can do?
Rule #1, never throw out the old sensor until you are sure the new one is working correctly.

:D I had a brand new defective TPS sensor that I installed and it was worse than the OEM and my truck died on me at
idle. I put the old one back on and it's working fine with it. I got the the defective one replaced as a spare now.

P-0121 Means TPS signal does not correlate to MAP sensor.

The MAP sensor is Manifold Absolute Pressure sensor. It monitors intake manifold pressure and absolute barometric pressure . The PCM uses this input to adjust the engine load and fuel mixture accordingly.

So in your case, not having the original TPS sensor, it is difficult to tell NOW which sensor was causing the P0121 problem..the TPS or the MAP.

However, about the only thing you can do now to determine whether the TPS you put on is defective or INSTALLED INCORRECTLY..(out 180 degrees on it's tang)

1. remove the sensor from the throttle body, so that it is relaxed under it's own internal spring tension and it should return to "closed" position.

2. With the sensor plugged in and ignition key ON (BUT DO NOT START THE TRUCK!).
BACK PROBE AND MEASURE THE CENTER LEAD OF THIS SENSOR.
If it is good and perhaps only installed incorrectly (happens), the sensor should read about 0.5volts (about half a volt).
IF it doesn't , the sensor either was defective to begin with or is now defective!

Note, when installing these, ensure that the sensor body is tilted slightly (towards the rad), so that the tang of the sensor which is spring loaded, fits it onto the throttle shaft, then rotate the body of the sensor towards the windshield so that the screw holes in the sensor line up with the two holes in the throttle body. Tighten up the screws.

Before starting the truck, check out the sensor o/p reading with a voltmeter from closed throttle to fully open, with the ignition on but NOT RUNNING. You want to verify that it is installed correctly and has the proper range for the PCM
depending on throttle plate position.

If you don't get a smooth voltage reading from 0.5volts (closed) up to 3.80 volts f(throttle fully open)..
then either the sensor is STILL installed incorrectly, or you really have got a defective one.
 

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I took the TPS off. My readings with the ignition on showed 4.62.

I reinstalled it the way that was posted. When I did this I could see the throttle moving when I turned it toward the windshield.

I put the screws in and attempted another test. The sensor "popped" and the throttle returned to its original position.

I got the same reading of 4.62 again with no reading moving the throttle.

The truck will still crank and run with the same symptoms. I'm guessing I need a new TPS?
 

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After last nights episode, I am getting codes p0122, p0123, and p0505.
I think the PCM on your truck is getting a wee bit annoyed with your sensor.
P0122 TPS sensor low voltage
P0123 TPS sensor high voltage
P0505 Idle Control system MALFUNCTION.

Here is a link to all the Chrysler Pxxx error codes. (save this link for
future reference. )
http://www.allpar.com/fix/computer-codes.html


From these codes, the PCM is just not satisfied with the o/p from your
replacement sensor. That is why I mentioned, during trouble shooting idle problems
UNLESS codes SPECIFICALLY related to the TPS sensor are flagged by the PCM,
you should never to throw away the old one, until you are sure the new one is working properly..
Because a replacement sensor that is "wacko" can drive you "wacko" . :D

I had to return an aftermarket TPS for that reason. I put the old one back in the meantime to keep
driving, and my truck is still working properly with the old one to this day.
Mine had transmission up-shifting issue. In my case, it was a different sensor on the auto transmission that
was responsible for the delayed shifting problem. Eventually it finally produced a code from the PCM
that indentified it as the culprit.
I should have check my TPS first with a voltmeter and eliminated as suspect, rather than replace it.


Here's what my Dakota Haynes manual has to say about the TPS:

"When installing the TPS, align the socket (the plastic thingy) locating
tangs on the TPS with the throttle shaft.

Ignition on but not started.
With the throttle fully CLOSED (the voltage should read between
0.35v and 0.90 volts. Gradually open the throttle, the voltage
reading should go up SMOOTHLY as you move the throttle linkage
to 4.50 volts at wide open throttle.

If the test results are incorrect..REPLACE THE TPS.
 

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TPS has been replaced. The new one checked out on the voltmeter. My truck hasn't run this good since I got it. Carverman, I can't thank you enough. If there is anything I can ever help you with please let me know.
 
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