Surging idle & stall at lights with (seemingly phantom) no oil pressure warning

[Adieu]

2012 Gator with the same 5.4 Triton

ran down a battery in accessory mode and needed a jump last night.


After it started, it would stay in 3500-4000rpm at highway speeds even with all the power draws off, so i thought OK, battery is kaput and it's trying&failing to rejuice it.. was going to walmart for tires anyhow, had em swap in a battery

NOW, rpms at speed are OK at ~1500... but MAJOR hesitation to start rolling, stalls out at long stoplights, idle surges around but surges low (200-400 ish), and when it stalls out it shows the "oil warning" icon and NO oil pressure (albeit if it's like the expy's, then that gauge is a fakeometer?)


First thought: walmart drained my oil by mistake

Popped hood, checked oil level, all OK.

Restarted, went home, stalled out once more and almost stalled a couple times again....


WTH????

 

[Adieu]

PS originally planned to flush & change oil and do plugs this weekend anyway. Should I just do that and see if it goes away?

Other ideas?




PPS ****no**** check engine light

 

[Adieu]

And now.... it stopped doing that???

Clatterred like a diesel for a few seconds then evened out..

Idles OK temperature OK

HOWEVER.... fuel level suddenly dropped from 100 to E to 32 to E???


Note: when battery died, fuel level was shown as a "false zero", and then crept back up

STILL NO CODES, STORED PENDING CURRENT OR OTHERWISE

 

[GaryH2]

Did you check the battery connections and cables (including the grounds) ? All good there?



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[Adieu]

Can that make idle jump around?

 

[coolzzy]

Yah, if they VCTs are not getting correct juice to actuate it will clatter and have rough idle and mess with the timing. Either that or you lost a cam phaser and it's just pure coincidence it happened at the same time as the battery. I'd disconnect the battery for an hour. Then reconnect and make sure the terminals are tight. Start truck and let it idle for a few minutes(if it will), then drive it easy for a few miles to relearn shift patterns and sensor readings.

How many miles on it?

 

[99WhiteC5Coupe]

I believe the inside of your throttle body is dirty, including the edge of the butterfly valve. When the battery terminals were disconnected, the system defaulted to the factory preset idle.

However, since the inside of the throttle body is dirty, there is reduced airflow at idle - causing the system to try to learn and reset the correct idle. Whe you release the throttle pedal, the valve closes and there is not enough airflow past the butterfly valve blade.

As the throttle body become dirty inside over time, the system can compensate for the reduced airflow. But at battery disconnect, it erases the learned setting and defaults.

Clean the inside of the throttle body with spray throttle body cleaner. I suspect that will smooth out your idle and the fluctuations.

 

[benyl]

I believe the inside of your throttle body is dirty, including the edge of the butterfly valve. When the battery terminals were disconnected, the system defaulted to the factory preset idle.

However, since the inside of the throttle body is dirty, there is reduced airflow at idle - causing the system to try to learn and reset the correct idle. Whe you release the throttle pedal, the valve closes and there is not enough airflow past the butterfly valve blade.

As the throttle body become dirty inside over time, the system can compensate for the reduced airflow. But at battery disconnect, it erases the learned setting and defaults.

Clean the inside of the throttle body with spray throttle body cleaner. I suspect that will smooth out your idle and the fluctuations.

Interesting.

I have 2010 F150 and since I changed the battery I’ve been experiencing the high idle and stalling after a bit on the highway. Very much like what is described in the OP.

The oil light is due to the stall, nothing to do with pressure or oil levels. All engines will have the same oil light when there is a stall.

Is there a way to see if the throttle body is dirty? What do I take apart? Searching the F150 forums, it was suggested that it could be a fuse or the TPS. I like your explanation more as pushing he the slightly during the crappy idle smooths things out. I don’t think it is the TPS and I’ve checked the fuses.


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[99WhiteC5Coupe]

Interesting.

I have 2010 F150 and since I changed the battery I’ve been experiencing the high idle and stalling after a bit on the highway. Very much like what is described in the OP.

The oil light is due to the stall, nothing to do with pressure or oil levels. All engines will have the same oil light when there is a stall.

Is there a way to see if the throttle body is dirty? What do I take apart? Searching the F150 forums, it was suggested that it could be a fuse or the TPS. I like your explanation more as pushing he the slightly during the crappy idle smooths things out. I don’t think it is the TPS and I’ve checked the fuses.


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Remove the intake hose and look inside the throttle body opening. A clean throttle body bore and butterfly valve will be shiny and bright silver. Chances are, your inside will be black and “gummed up”.

If you have a “throttle by wire” throttle body, do NOT move the butterfly valve with your finger or tool while the engine is off. If you throttle body is operated by a cable, you can move the throttle body connector (where the cable connects) to open the valve wider (with engine off and cool).

Spray the inside of the throttle body (engine cool and off) with throttle body cleaner. Do NOT use spray carburetor cleaner as it can damage the oxycgen sensor. Put rags under the throttle body to catch the dirty runoff. Use caution as the cleaner is flammable and so will be the rags.

I own a 2015 Expediton Limited 4x4.

 

[Adieu]

Hmm. That actually makes sense.


And explains why it ran progeessively better and gained a bunch of MPGs - it was learning..

Hmm and DO we have throttle by wire on 5.4 tritons?