Idles too low and dies

[blkgolfer1]

2010 Ram 1500 5.7 L Hemi that stalls at red lights but only after the truck has warmed up some. When it's initially turned on it seems fine until it has been running for a few minutes. It idles at 700rpm until warm and then when it's in Drive and come to a stop it drops to 500 or lower and most of the time it stalls.

 

[Bigskyroadglide]

Issue is not idle, something else. 500 to 550 is factory warm idle.

I'd check intake manifold bolts, (9 ft lbs or 108 inch lbs) torque specs for potential vaccum leak , IAT sensor on the air intake tube or look for codes. Maybe clean TB.

If you have a tuner you could up the idle but you need a tuner.

 

[blkgolfer1]

It's funny but I was thinking the same thing about the intake manifold!! Shortly after I purchased the truck I had new lifters put in because of a misfire and I maybe should've re-torqued the intake manifold and didn't. I will update after I do that.

 

[blkgolfer1]

I checked all the intake bolts and got a small amount of movement on them but I haven't driven yet.

 

[Ken226]

I checked all the intake bolts and got a small amount of movement on them but I haven't driven yet.

I checked my intake manifold screws a few weeks ago on my truck, and on my wife's Durango. Both 5.7 Hemis.

On both, ALL of the screws were loose. Like, really really loose. Some could be threaded out with my fingers.

Those suckers gotta be checked occasionally.

 

[62Blazer]

As stated above, I believe 500 RPM is the normal idle range. If that is true, turning up the idle would just be a band-aid fix and you need to fix what is actually wrong.
You can do a visual check and make sure everything is tight. Intake manifold and would also check for exhaust manifold leaks (snapped studs). Other things that need checked, but would require a scan tool capable of reading live data....even a lower-mid level scan tool can have this capability so not like you need a fancy one.
- what do the O2 sensors read? Meaning is it running rich or lean?
if they are saying the engine is running either rich or lean that can point you in the right direction
I have seen a faulty O2 sensor give an incorrect reading....it said the air/fuel ratio was correct but it really wasn't
- IAT (intake air temperature) sensor
- IAC (idle air control) valve

The explanation as to why the truck may run fine when first started and cold and then start running poor when warmed up. During the initial startup the engines are running in open loop, meaning they are running on preset parameters (fuel ratio, etc...) programmed into the ECM and NOT based on what the sensors are stating. Once warmed up the engine goes into closed loop mode which means the sensors are adjusting the engine parameters. The main one is probably the O2 sensors as they need to be warmed up some before getting good numbers. Once in closed loop the ECM depends on the readings from the O2 sensors to adjuat and optimize the running of the engine. In general, if the engine runs fine when cold and then starts running poorly when warmed up there is a sensor issue somewhere that is either not working or giving a bad signal.

 

[1999 White C5 Coupe]

2010 Ram 1500 5.7 L Hemi that stalls at red lights but only after the truck has warmed up some. When it's initially turned on it seems fine until it has been running for a few minutes. It idles at 700rpm until warm and then when it's in Drive and come to a stop it drops to 500 or lower and most of the time it stalls.

Sounds like a dirty throttle body bore. If the issue isn’t cured by tightening the intake manifold bolts, clean the inside of the bore with spray throttle body cleaner.

When cold, the compute increases the idle speed. When warm, it returns to the set or learned position and idle.

If the bore and/or throttle body blade is dirty, it will not flow enough air at idle (such as stopped with the vehicle in drive), causing the stall or a rough idle.

While checking it - check the engine air filter too.

 

[blkgolfer1]

Thank you! I will clean the throttle body tomorrow and I put a new filter on already. I will update tomorrow!

 

[Wild one]

Thank you! I will clean the throttle body tomorrow and I put a new filter on already. I will update tomorrow!

If you decide to remove the throttle body to clean it,disconnect the negative battery post first,then do a key on / pedal to the floor and back up with-in 10 seconds / key off / open and close drivers door throttle body relearn .Do not start the truck,just go to key on position.Use legit throttle body/air intake cleaner,and don't use anything harsh or abrasive like steel wool /SOS pads to clean the throttle body

 

[rayrmjet]

I have the same problem on my 2013, and my engine lean's out causing the throttle plate to close down from 13 degrees to 12 and the engine dies. If I leave the air conditioner running then it keeps idling most of the time due to higher rpm at idle

 

[Dean2]

blkgolfer1

www.ramforum.com

So BK - what did the fix turn out to be???? You promised to report back but haven't been back on for almost a year.

 

[Ken226]

blkgolfer1

www.ramforum.com

So BK - what did the fix turn out to be???? You promised to report back but haven't been back on for almost a year.

Twice, actually. But as is so typical, no follow up.

I will update after I do that.

will update tomorrow!

 

[Jeepwalker]

Sounds like a dirty throttle body bore.

That's what I was going to suggest too. Had it happen on a few vehicles. It's maintenance which it easy to overlook and put off.

Have you had it checked for codes BTW?

I'd also check for vacuum leaks. Esp given its age, and work was done to it. Spray ether here and there in various 'bursts' around the top of the engine as it's running. If the engine smooths out then it might be getting sucked into a cracked/damaged vacuum line, and there you've found it.

Check PCV valve/hose/grommet also for cracks or damage.

Come back and let us know what did the trick so we can all be a little smarter.

 

[Old Sarge]

Low trans fluid will cause that too

 

[Jeepwalker]

In addition to the throttle bore cleaning, someone mentioned cleaning behind the IAC solenoid with carb cleaner, and that's another great suggestion. That can certainly affect idle.

Check codes for anything related to throttle position sensor ...and/or ignition, misfires, etc. Might be worth checking the spark plugs at some point soon if they've been in there a good while. Look for 'traces' on the coil stems, color/condition of the tips.

Those are all good basic maintenance steps ...plus the items everyone else has suggested so far incl intake leaks (since a 'mechanic' did the work).

 

[Ken226]

In addition to the throttle bore cleaning, someone mentioned cleaning behind the IAC solenoid with carb cleaner, and that's another great suggestion. That can certainly affect idle.

When the fly by wire throttle system came out, 2003'ish i think, the IAC solenoid became obsolete and is no longer used. I could be wrong about the exact year though, but it's been a long time.



With a fly by wire throttle system, an IAC solenoid would serve no purpose, since the PCM can control the idle speed by varying the throttle blade and injector pulsewidth, directly, as needed.


On the older throttle cable setup, the PCM controlled idle speed by opening/closing the IAC solenoid to add/remove air, and varying the injector pulsewidth to control fuel.