So i go to start up my 318 96 ram sport this morning and it didn't wana start (seemed to me like the battery was going dead or something) I think nothing of it...

I continue to head to the bank to cash a check and the truck shuts off about a mile down the road... no warning other than it didnt wanna start up right away as usual. I go to start it now and 60% of the time it wont stay running in park unless my foots on the gas. other times it will.. But when i go to put it in drive and go (if my foots not on the gas while doing so) it cuts off...

I got a diagnostic computer yesterday at walmart for $100(CanOBD2 3100) heres the only trouble code it comes up with.

Emission status light is yellow- indicating there is a possible emissions problem

PO456
"Evaporative Emission"
System leak detected
(very small leak .025)

'Catalyst Monitor' light blinking
'Oxygen Sensor Monitor' light blinking
'Oxygen Sensor Heater Monitor' light blinking

What would you do if this were your truck? Im tring to learn about vehicles more and more, but i swing a hammer not a wrench (im not a mechanic)

These codes etc. lead me to believe that i need to change the 02 or oxygen sensor and see what happens.

I cant afford a mechanic at the moment as i've been laid off since november of 09

Whats your advice?

 

Could be loose or bad gas cap read this
http://www.obd-codes.com/p0456

Dave

 

put a new gas cap on... It didn't change anything.

 

Sounds like a bad/dead battery to me. The PCM don't work right if the voltage is to low. Throw a charger on it and see if that helps. Or you could take the battery to a parts store and have it tested.

ETA if the battery turns out to be bad, get the alternator tested too.

 

yeah it really sounds like the battery thing.

Happened to me many times so i can usually spot this a mile away.

For me it was never the alt. i usualy was stupid and left a light on or something then jumped it the next day, and while it would start it also would perform exactly how yours is.

New battery and it was fine.

 

battery and alternator turned out fine, volt meter is above normal... Put a nickle in the throttle (taped it there so when i hit the gas it doesn't fall out) that way it idles slightly higher than it was (right around 1000 RPMs) this allowed me to get out of the cab and the truck will at this point continue to run (a temp. fix if you will)

I've driven it a few miles with the nickles help and haven't had any issues with stalling out.

Next thing i'm going to try is slowly inspect the vacume lines (now that i can check them without the truck stalling out) around the front of the engine bay on the drivers side (not sure where yet) theres a very slight hiss. I'm going to lightly spray the vacume lines with carb. cleaner... When the RPMs spike while im doing this it should be near the vacume leak then wether its a pin hole in a vacume line or a crack in one of the fittings I'll have to change out that piece (hopefully this will turn out successful)

 

can't pin point the vacuum leak, its still very noticable. Sounts like a faint windshield wiper motor

 

a mechanic suggested i change the IAC module on the back of the throttle body (did that, and took the nickle out) ran like a champ... I left it running about 45 minutes. Turned it off and can back to it several hours later (i've been jumping it so much tinkering with it tring to figure out the problem) seems as though i killed the battery. I jumped it again to tinker with it alittle more and it was back to the same old acting up (had to put the nickle back in the throttle)

***Picked up a new die hard platinum battery from sears today, and continued tring to locate the vacuum leak (no luck yet) I scheduled for it to go to the mechanic next week.

Anyone have anymore suggestions before i start paying a mechanic per hour?

Thanks for all the suggestions and advice guys, I really appriciate it.
~Tim

 

keep in mind that a weak battery screws up the electronic signals on these trucks.

i agree that IAC is most likely culprit.

its also a good idea to reset the pcm following any part replacement, to ensure that the pcm is not still trying to adjust for the old one. reset pcm by disconnecting negative battery cable and turning on headlights for 30 seconds. this drains the memory in the pcm.

^i'd reset pcm first

idle is controlled by both the IAC and the TPS. if you can afford to throw parts at it, then replace the TPS also. about $40-50. if it doesn't fix it, keep your old parts as spares. they come in handy for troubleshooting.

i doubt that your small evap leak p0456 is your problem.
it sounds like your post cat 02 sensor is bad. i'd replace it, although i doubt this is your immediate idle problem either.

 

The O2 wouldn't affect a cold idle startup/shutdown as the truck is in open loop and ignores that sensor.

Did you take the throttle body off the truck and clean it out (esp. The IAC port) before you put the new IAC in?

You can test the TPS with a voltmeter: Set voltmeter for hundredths of a volt. Place black lead in a ground source. Back probe the middle wire of the TPS with the red lead. At Key On, Engine Off, note the starting voltage, it should be .30-.80Volts. Swing the throttle open slowly, and watch the voltmeter for large skips in voltages. If the voltage increases slowly and evenly the TPS is good.

Here are all the vac lines I can think of:

One line runs under the battery toward the front of the TB, this is the cruise control line.

The brake booster is a thick tube that runs from the Big cylinder on the Drivers side firewall to the intake manifold.

The PCV tube is a big thick tube the runs from a valve cover to the intake manifold and can leak vacuum if it's cracked

The "Accessory tree" is a bunch of small vac tubes on the passenger side intake manifold that have 2 vac check valves in them. Those tubes are hard plastic and can crack easily if they are bent too far. The check valves are the widest points on the tree branches and ccan be checked by pulling them and blowing thru them. Air should go one way, but not the other. Reinstall them so that the air flow is toward the intake manifold.

The MAP sensor has a small rubber tube underneath it that can sometimes crack and cause a leak you have to take the sensor off to check it. It's the sensor on the front of the Throttle Body.

The larger tube that goes in right next to the MAP sensor is the evap system return line, and it can leak air causing a vac leak. Check for cracks, it snakes down the intake manifold, back by the firewall, and then back up to the front of the truck. You can repair a crack by cutting that line and stuffing the 2 cut ends into the appropriate sized rubber vacuum tube.

The tube that comes off the air hat and into a valve cover is not a vac tube, don't worry about it.