Hard Sputter
 

I can drive my truck 40 plus miles up on top a mountain and it drives fine. When I come home on the same roads about half way home I get these hard sputters. Real hard. It is like something choked it out. I only get a few of these and then it quits. The rest of the way home it is fine. I really think it is when I have a light throttle cruising and never when I am giving it throttle to accelerate. Any ideas? I was thinking IAC or Throttle control valve. The truck does have one of those stupid K&N filters on it. I made sure the connections are all tight and cleaned it a few times to make sure nothing was getting in.
Any ideas are greatly Appreciated.
1997 Dodge Dakota 5.2 Auto.

IAC shouldn't play a role if you have your foot on the gas. Coming home, are you driving downhill, hence, less pressure on the go-pedal? If so, I would look real hard at the TPS.

Nothing when going down hill. Just on flat ground cruising. But light throttle.

Test the TPS, just for giggles. Make sure things are good and warm when you test it. Use an analog meter (one with a gauge, with a needle), the digital meters don't react fast enough, and are erratic to begin with, so, testing with one is basically pointless.

Sorry I don't even know how to use one. I can get one today but where do I put the leads?

What is the elevation change from the mountain on down?

I recall a thread last year about a fella in hawaii having a similar issue coming down the mountain, I recall it was something about pressurization because if he loosened the gas cap the issues went away.

Well I guess I should have said sometimes it does and sometimes it doesn't. Because it will do it also if I go to town 18 Miles and on the way back it will do it. AS for the Mountain it is 10,500 feet and where it sputters it is usually around 4800 feet. But when I go into town it is mostly around 4400-4800 feet.

Red lead from the meter goes to the 'signal' wire that goes back to the PCM, (I think it's the center wire, assuming a three pin connector) black lead just goes to a good ground. You will have to poke the red lead into the wire enough to get good contact though..... so, have some electrical tape handy to seal it back up as well.

With the leads in the correct spots, have a friend turn the ignition "on", (don't start the motor) and SLOWLY press the gas pedal down, all the way to the floor. Meter should be set on the lowest voltage range it has. (5 or 10 volts will be fine) Meter should start out at less than one volt with the throttle close, and SMOOTHLY increase to greater than 3.5 volts at wide open throttle. If it bounces around, AT ALL, it's bad, and needs to be replace. Run the test several times, engine warm, if possible..... See what ya get.

HeyYou, thanks for the info. I will pick up a meter tomorrow when I take the wife to work. Just so you know,I only use the truck on occasion and only drive it at most 80 miles round trip.

I would say your MAP sensor is the problem with or plus a dirty throttle body clean the throttle body first if still a problem look at the MAP sensor.

First let me say I am sorry it took this long to get back to you. I bought the Analog Multi meter. I was busy Ice fishing all winter and never needed the truck. SO I tested this multiple time and can only get 2.8 Volts at best. It didn't jump around and was smooth with the throttle. I also tested the MAP sensor and it tested out at just over 5 volts each time WIth wire connect middle pin and unconnected 3rd pin . Both read the same. So I guess it is good.
Question is the TPS only measures the 2.8. WOuld you say it is bad? Thanks for any help.

Is the 2.8 volts on the supply wire, or the signal return wire?

It is the Center Wire like you told me to use.

If you are only getting 2.8 volts at wide open throttle, thats bad. :)

I will change it out and hope that is what caused the sputtering. I took it for a drive the other day to pick up another small boat and it sputtered 11 times in the first 5 miles. TOtal of 25 miles and it never sputtered after those first 5 miles.

OK went for a ride of about 20 miles and not a single sputter. Pulled into my drive way and the check engine light came on. Po300 po301,302,303,304,305,306,307 and 308. WHat the heck. That means every cyclinder is misfiring. The truck ran pretty good and I never felt any misfire. Now what?

One more note to ad. I remember this happened last year and I forgot about it. It is that the Volt meter would drop down and then go back up. As in the Gauge on the dash, I thought I was going to have to change out the alternator but after messing with it I found it was a wire that once moved the volts would go back up. Either a fraid wire or loose connection I guess. Never looked into it much. But anyway it did this again on my trip and back.

OK went out and tested battery. It was 12,58 then I was looking at that wire that last year would make the Volt meter to go back up and my truck is under a carport with little light. I saw sparks or something lighting up inside the alternator. I moved the wire 3 times and every time I saw the sparks/Lighting up whatever. If it isn't one thing after another with this.

When it rains it pours repairs come in groups always in old autos.

Just wanted to say Thanks to you HeyYou!

Ok so I needed to take my Grandson some furniture today. The truck started sputtering again. Back to the drawing board. Throttle body was cleaned, TPS changed, Alternator does have a problem and will be checked or replaced tomorrow.