I've been battling this problem for over a year now and am getting frustrated with it. Once or twice a week when I pull up to a traffic light, my idle drops right down and stalls. It seemed to start happening after I had my transmission rebuilt, but I'm not convinced it's related. Even if it doesn't stall, the idle tends to be rough while sitting in gear. if I shift to neutral, the idle seems to be stable at around 750. The idle will drop below 500 and feel like its going to stall. I've done several things to it over the last year. Cleaned throttle body, cleaned MAF sensor, New plugs/coils, new IAC, fuel filter, cleaned K&N air filter, checked all vacuum lines.

Also, while pulling my boat, it pings pretty badly uphill...I have tried other gas and didn't notice an improvement. I have a code reader, but there are no codes. One shop suggested maybe the MAF sensor...it was giving him what he thought to be a slightly low reading. Air flow seems to be changing as it should if I view the live data on my code reader.

The only other thing I notice is, it seems to run great if i disconnect the battery for a while and reconnect. I assume its resetting the computer to default settings. After time, it starts running rougher and rougher.

Please help end this frustration. Thanks in advance

 

Pinging is either running excessively lean or excessive combustion chamber deposits.

 

They all do that when there's a problem. There really isn't a default setting, per-say.

The low idle, then stall. They do that when the transmission is low on fluid. You should check that properly. A 20 mile warm up and you may have to go thru the gears pausing each time w/foot on the brake before checking. Look that procedure up top be sure. I could, but so can you. Could also be that your Trans range sensor is slightly misaligned.

Could be a partially plugged converter.

Those K&N's for two valve intake set ups engine are bad news as they screw with the MAF and DO NOT filter properly. This is just for the Two valve intake box/MAF set ups. The 3 valves are different, I'm not as familiar with. However, I would never trust K&N systems from what I've seen in the past.

Check fuel pressures and delivery as this CAN cause this issue.

I'd suggest purchasing a cheap reader or scanner, -since they can be had cheap. Harbor freight for the cheapest or purchase a low end Actron as it is all you need to retrieve DTC's. Why? Always scan before a battery disconnect as CEL illumination doesn't occur 100% of the time. I've scanned many without a CEL and found O2 DTC's, EGR DTC's, etc...

 

BTW- you could have multiple problems for what your describing. Definitely check your EGR system and valve operation. That's close to the top as far as suspect.

 

Your thread title, - "rough idle/stall"

Then you mention pinging, low idle stalls...

Yea, -That's a sticky EGR valve or bad EVR solenoid IMO. Hard to find a sticky one unless they lock up somewhere within the valve. That may never happen.

To troubleshoot:

It's a non-serviceable part. The way you can determine this problem yourself is to catch it while its acting up @ idle.

The engine Idle in park should be VERY smooth and steady between 700-750 rpms. Meaning, idle might be 730 rpms and it WON'T fluctuate. Wherever warm idle rests, the rpm needle should NOT move or fluctuate, not even a little and this is between 700-750 rpms.


Quickly remove the green vac line from the valve.

Does idle smooth out ? Yes ? EVR is bad. No ? Tap the valve with a wrench. Any difference ? No ? Work the valve yourself while at idle by attaching a hose to the valve and applying vacuum. Either use a vac tool or suck on hose as if drinking a milkshake. Do this until engine just about stalls, then stop. Do this a few times as your working the valve and may exhibit changes in idle once through.

 

I recently cleaned MAF again, cleaned air filter and worked the EGR by applying vacuum to it repeatedly. I haven't had the truck stall on me since, although i still get a bit of a rough idle periodically. I've also noticed that it seems to idle better when it's still cold. I was all set to just replace the EGR valve, but then I got a code finally. P0136. Could this 02 sensor be the culprit? My understanding is that sensor 2 really is only used to monitor that catalytic converter and isn't used to adjust fuel/air ratio. Is that correct? I guess I'll replace the sensor and see what happens. If I still get the rough idle occasionally I'll replace the EGR. Thanks for your help

 

http://www.obd-codes.com/p0136

 

I have the same exact truck and motor with the same exact problem .. well I did.

I've been poking around google and found this thread, I know it's old, and I don't know if you fixed your problem yet (don't see that you reported that you did) so heck with it, I will add

My truck stalled at idle, intermittently, and would ping towing my trailer going up hill.

Ended up being 2 vac leaks both coming of the PCV valve. GAH! I've dealt with this problem for well over a year and finally FINALLY fixed it.

Coming off the PCV valve there are 2 elbows that need to be looked at, one right off the T fitting and one if you follow the pipe to the back side of the intake.

Maybe this will help someone? I hope. Those elbows turn to gummy junk and develop huge cracks causing many problems. Vac leaks are BAD news but EASY fixes.

 

hello im new to the site. but im not here to blab. i have a 99 f-150 4x4 with the 5.4 v8 my problelem is that three months ago my truck started rough idling now its rpms are low still rough idles but jumps from 600rpm to 900rpms then drops to 400rpms then stalls out no codes are showing up and there is no loss of power under load or a ping for that matter i took it to three ford shops and ive gotten three different answers. one said idle control valve the second said distributor cap and the third said injectors. and there is no check engine light. I've fixed all vacum leaks and excust leaks. i have no clue what it could be some please help me here

 

The one that said IAC was probably correct. Replace the IAC. order it from rock auto and its easy to install. You dont have a distributor and most likely if an injector failed you would get a code. IAC get one.

 

will that fix my problem?

 

Maybe.

The shop that said distributor cap doesn't know what they are talking about.

If you think the injectors are dirty, put a bottle of Techron in the gas.

 

thank you. and i do put techron in it. i put that in it when it first started rough idling. it made it worse

 

How many miles are on the spark plugs and what brand are they?

 

Doing nothing wont for sure! Theres a good chance it will. Your driving a 14 soon to be 15 year old truck. IAC's wear out. its a maintenace deal no mater what. I replaced mine along time ago and it wasnt even acting up..