'96 Dakota Stalling

[Fleetmon]

My '96 Dodge Dakota 5.2L is stalling. It ran perfectly the other day, parked it, and the next morning started right up but will stall when you let off the accelerator. It runs great; just won't idle. I drove it all day yesterday and like I said, it runs great but will stall out each time you come to a stop.....RPM's drop to normal idle speed (around 750 or so) and then just dies off. It doesn't act like it loses spark and it fires right back up. It did rain pretty hard the other day and I was hoping maybe something was just wet but that doesn't appear to be the case. I looked things over in the engine compartment today and all looks normal...wiggled a few wiring harnesses (particularly the one near the ac receiver tank since that particular one seems to be an issue from what I've read) but it made no difference.

I keep this truck at work so taking it home is expensive gas-wise and time-consuming. Any ideas folks?

Thanks in advance for any ideas!

 

[eljefino]

Auto shutdown relay? Swap it with another with same # on it, like the horn relay.

I'd also check all the battery cables and grounds particularly the quick connect about a foot down the positive cable from the battery.

Actually while at it the whole fusebox can be suspect.

Potentially the battery is a flaky participant and the alternator won't carry things at idle RPM.

 

[javacontour]

EGR stuck open?
IAC?

 

[chestand]

Two suggestions:

1. Take the intake tube off the throttle body and, using a throttle body cleaner, clean the butterfly and the inside of the TB.
2. Remove the idle air control valve and do basically the same thing.

It's been my experience that those two things are responsible for a lot of idling issues.

 

[VNTS]

Check the [censored] codes. Do the key dance.

How many miles on it?

Could be dirty or tired IAC, bad TPS, MAP etc

 

[Fleetmon]

The alternator is new (charging around 14) and battery is good. It doesn't appear to be an electrical failure. I played around with it a bit this morning...turning on/off headlights, ac, and etc seemed to have zero affect on the symptoms.

I don't think the EGR is stuck since it's running extremely well although when I hold the accelerator steady at 1k RPM's the engine is loping around 200 RPM's....a continuos "lope"....almost like the roll of a Detroit Diesel 2-stroke with an out-of-adjustment buffer.

The IAC is a good possiblity since it seems like it wants to idle but the engine speed drops too low and it dies. Doesn't act like it's running out of fuel or spark just acts like its running too slowly to maintain an idle. Running up through the gears, it runs smooth and plenty of power.

Thanks so far for the suggestions....I may get a chance later this afternoon to take a look at it. As you're aware, it's tough to look at something in a parking lot and raising a hood attracts the attention of the TSA so I'll need to go offsite somewhere probably..

Edit - no codes and approx 115k miles.

 

[meep]

IAC would be the very first place I look. If it's original it's probably caked with crud. may have also failed as a result of old age. I've never gotten into one on a 5.2. The '93 jeep I had, (the closest I owned in that era that I worked on), was very simple to get out and clean.

Vacuum leaks could also cause this if they are overwhelming the vehicle's ability to maintain a good mixture at idle. check the big lines.

good luck!

 

[The_Eric]

Idle air control...

 

[440Magnum]

Dirty or clogged automatic idle speed valve. IIRC the inlet for the AIS is tucked sorta between the two main venturis, can't remember if its in front or in back. Flooding the whole area around it with EFI cleaner will usually free it up and flush the gunk out- best of you have a helper to keep the engine running while you're doing it. Spray in the AIS until it nearly stalls, let it recover, repeat. That also "exercises" the AIS while its full of cleaner.

Always worked for me when my folks had a 5.2 and a 5.9.

 

[eljefino]

Now I'm gonna bet on the TPS. The truck needs to see it's at zero throttle angle to want to idle. If TPS > 1% it leaves the idle speed controller alone. The clue (to me) is the surge, where it's trying to set the idle then ignoring it.

If it's a self calibrating TPS like many GMs when you restart it, the computer takes the new flaky reading as "zero" and the cycle renews.

Here's how you test your ISC motor: Take off the air cleaner and whatever else you need to to see the throttle body and the hole where the air bypass goes. Run it and put your finger over the air bypass. It should still run but at about 350 RPM. Jack up the base idle screw (on the main throttle blade(s) ) if it stalls. Now, release your finger and it should rev up to 1500 RPM then settle to a proper idle.

Also check for vacuum at the MAP sensor. IIRC they put these on the end of a bunch of vacuum spaghetti on the firewall. Any leaks anywhere in the system can mess up the MAP. Should be ~21 inches at idle.

 

[Fleetmon]

All good stuff and I appreciate it.

The surge occurs when I hold the pedal to maintain 1k RPM.....any lower RPM, then it will balk and stall; meaning the lope dips lower when I try to maintain 800 RPM with the pedal and stalls. It's not a violent stall and just sort of dies off.

I won't have a chance now to look at it until tomorrow and may decide to drive it home tomorrow evening to look at it.

FWIW this is port injection not throttle body.

 

[Doog]

Replace your throttle position sensor and check the IAC valve. You may have to replace both. But put in a new TPS and then disconnect the neg terminal on the battery to allow the IAC to reset to default.

 

[mattd]

definitely IAC/TPS related.

 

[Fleetmon]

I'll pick up both parts and replace them due to age....it returned to normal yesterday and is idling fine.

Thanks for all the advise folks!

 

[tailwhip]

Any luck with the stalling? These are notorious for leaking intake plate gaskets. First thing I'd do is remove the air cleaner from the throttle body. Then crawl up there with a good flashlight, open the throttle blade fully and look at the bottom of the inside of the intake. Usually if it has a blown gasket you will see oil laying in there, if so you need to remove the intake and reseal the bottom cover. Also make sure the throttle bore is very clean. Good time to look at the distributor seal for leaks.

 

[Fleetmon]

I didn't get a chance to run it home this weekend but it's still idling fine now....I think I'll pick up a TPS and IAC and replace them just for good measure.

As stated, it runs great and now that it's idling on its own, is back to normal....runs like new (and I know since I've owned it since new!).