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Dodgerench
Dodgerench, ASE Certified Technician
Category: Dodge
Satisfied Customers: 3399
Experience:  30+ years Dodge/Chrysler exp., ASE Master with L1 certification. Driveability/ combustion specialist
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99 durango: wont cold start..runs fine..new intake gasket,tune-..iac

Customer Question

99 durango-won't cold start,holding pedal down allows start,but no idle unless kept at 1000 or higher.After 5 to 7 mins. of trying engine eventually starts and runs fine for rest of day. new batt,new intake gasket,tune-up, cleaned IAC motor&fuel presure
Submitted: 8 years ago.
Category: Dodge
Expert:  Dodgerench replied 8 years ago.

HiCustomer welcome to Just Answer!.

 

Do you ever see a CHECK ENGINE lamp illumination while driving?

Have you had the engine scanned for codes by chance?

Did a low or dead battery just precede the onset of this problem?

 

Talk in a few,

Ed

Customer: replied 8 years ago.
COLD START PROBLEM OCCURED 2 DAYS AFTER REPLACING INTAKE MAN. GASKET. NO CODES FOUND . HAD THE EXACT SAME PROBLEM BACK IN JULY BUT UNDER A HOT START[ AFTER RUNNING AN HOUR OR TWO]. i DISCOVERED BY CHECKING WITH A VOM THAT BAT. VOLTAGE DROPPED BELOW 12 VOLTS DURING CRANKING CAUSING ECM TO RESET. NEW BATTERY SOLVED THIS PROBLEM
Expert:  Dodgerench replied 8 years ago.
Thanks.
That's a significant discovery you made. Low system voltage allows the PCM (engine controller) to lose its idle air control motor step count. When this calibration is lost, it makes it tough for the PCM to control engine idle with any real certainty.

It may have happened to you again, but for different reasons this time. We'll see.

I'd like to know if the IAC motor has any life left in it first. They're an electro-mechanical unit, using a worm drive within the body of the unit to extend and retract the pintle that I'm sure you're familiar with. If the IAC fails to follow a PCM command for any reason, the step count will be lost, either incrementally or all at once.

Let's try another relearn procedure to see if idle control is restored immediately. Disconnect the battery for about 30 seconds, reconnect and then just roll the key on.

Don't crank the engine immediately, as this is the time when the PCM is attempting a relearn. Give it five seconds, then hit the key. If it starts, flares, then settles down (an improvement), you may need a new IAC motor. Time will tell as the PCM either holds the step count and idle remains strong, or it slips back to where you were.

There is also a software update to improve IAC step count retention for your PCM, but it may already have that software... hard telling.

Give this a try first and let me know how it goes. It may only be the first step, so there's no need to click the accept button just yet.

Talk in a bit,
Ed
Customer: replied 8 years ago.
Just did what you recomended,and she started fine,not muchof a flare but car was already driven to wrk. Temp was much colder on morns. of no start,been warmer since and started fine, When no start occurs again would repeating the relearn procedure you last described tell us anything if she immediatly starts.
Expert:  Dodgerench replied 8 years ago.

Sounds good, j. If there's anything I have... it's time. Let's get it right.

 

Talk later,

Ed

Customer: replied 8 years ago.

Started first time this morning,no flare, dropped to normal idle ,temp above 40 degrees.

I DROVE LESS THAN A MILE AND ENGINE DIED ,FIRST TIME THIS HAPPENED ,DIDN'T HAVE WRENCH TO DISCONECT BATT TO SEE IF LAST SUGESTION MATTERED[IAC MOTOR RELEARN] CAR STARTED AFTER A FEW MINUTES AND RAN FINE.

Expert:  Dodgerench replied 8 years ago.

That sounds like a different problem, j! I'm not liking the sound of that... what you've been dealing with so far has always been a "nuisance"-type stall, right? One where the engine will always restart, but won't hold an idle?

 

Ed

Customer: replied 8 years ago.

YES, ENGINE WOULD RESTART JUST NO IDLE, WHAT HAPPENED THIS MORNING WAS A FIRST,EVEN 8 MONTHS AGO WHEN THE RESTART PROBLEM OCCURED UNDER HOT RESTART[new batt.] SHE NEVER STALLED, ONCE RUNNING. FYI- WHEN NOT IDLEING, IF I RESTART IN NEUTRAL AND IMMEDIATLY DROP INTO DRIVE AND PULL AWAY PROBLEM SEEMS TO CLEAR UP INSTANTLY.

Expert:  Dodgerench replied 8 years ago.

Did you happen to notice a NO BUS alert in the odometer while it was a no-start?

 

Ed

Customer: replied 8 years ago.
NEVER SAW NO BUSS ALERT,I'VE BEEN TOLD TO LOOK FOR THIS ALREADY,
Expert:  Dodgerench replied 8 years ago.

Do you have a CHECK ENGINE lamp illumination now since the stalling event?

Customer: replied 7 years ago.
NO
Expert:  Dodgerench replied 7 years ago.

It's way early to say you've got a PCM failure in the works, but it's not out of the question, j. If you have a 5.9 engine with the 56040147A# XXXXX a hot engine stall like what you'd seen isn't at all unusual. If it's the PCM, it's gonna do it again, so you might as well give it every opportunity while you're home and safe. Start the engine and let it idle with the A/C on for a half hour or so with the hood down. Let it get good and hot underhood and see what happens.

 

Most problems that cause a stall like what you had will leave a code behind and the CHECK ENGINE lamp would be on afterward. But if the PCM takes a short nap, it wakes up with no realization anything ever happened except that it's lost its internal memory... all adaptives and any stored codes will be lost.

 

So what I'd recommend at this point is to set a code of your own choosing to turn the light on, get the engine to stall and see if the light disappears after the engine wakes back up. It's like putting bait in a trap to see if it's still there after the door shuts.

 

As much as I hate to say it, your idle problem may be related to what you're seeing now. I see an awful lot of these PCMs with P0505 codes set, which turns out to be an internal IAC circuit failure.

 

Let me know what you find.

Ed