Stalling at stop in gear
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Stalling at stop in gear
Ok guys, I have a 2001 F250 V10. It idles around 1k and when stopped at stop lights or when put in reverse it stalls. I have replaced IAC, fuel filter, tranny filter, oil filter, plugs, coil boots, tranny fluid, oil, air filter, and PVC along with the PVC hose. I'm totally stumped. It doesn't stall if I do a rolling stop.
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Too many possibilities to guess the right answer.
Do you have any diagnostic trouble codes? What do the fuel trim numbers look like. What is the IAC percentage at idle. What are the MAF numbers.
If you don't know the answers to these questions, you have been replacing a lot of parts without reason.
Guess yourself to bankruptcy by replacing parts or troubleshoot properly and repair your truck. Of course, the choice is yours.
Do you have any diagnostic trouble codes? What do the fuel trim numbers look like. What is the IAC percentage at idle. What are the MAF numbers.
If you don't know the answers to these questions, you have been replacing a lot of parts without reason.
Guess yourself to bankruptcy by replacing parts or troubleshoot properly and repair your truck. Of course, the choice is yours.
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The p0720 is an output speed sensor code. If the voltages and signal on the sensor are OK, you need to replace the sensor.
23% on the IAC at idle is too low. Something is causing the PCM to command the IAC to close or there is a problem with the IAC connection or wiring to it. Could be vacuum leaking somewhere. Common cause is the brake booster or hose leaking vacuum. Another common cause is PCV hose. Any major vacuum leak will cause the PCM to command the IAC to close.
The IAC, with the engine warmed up (closed loop), should be reading about 35 to 40 % at idle. At 23% it is basically fully closed. A bad connection or broken wire on the IAC circuit would cause this. Try holding you foot on the accelerator, just a little, when you stop. If that keeps it from dying, focus on the IAC connector/wiring and look for vacuum leaks.
23% on the IAC at idle is too low. Something is causing the PCM to command the IAC to close or there is a problem with the IAC connection or wiring to it. Could be vacuum leaking somewhere. Common cause is the brake booster or hose leaking vacuum. Another common cause is PCV hose. Any major vacuum leak will cause the PCM to command the IAC to close.
The IAC, with the engine warmed up (closed loop), should be reading about 35 to 40 % at idle. At 23% it is basically fully closed. A bad connection or broken wire on the IAC circuit would cause this. Try holding you foot on the accelerator, just a little, when you stop. If that keeps it from dying, focus on the IAC connector/wiring and look for vacuum leaks.
Frmr Ford Trans Engr
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Before replacing the sensor I recommend doing a little bit of diagnostics. Check the wiring from the PCM to the sensor for open circuits, short to ground, or short to power. If the wiring checks out, then replace the sensor.
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So you're saying if the sensor is good, he needs to replace the sensor?
Frmr Ford Trans Engr
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Ok so I read the scanner wrong. I don't know what the percentage is. I read the temp % on accident. It only dies when in gear with foot on the brake. Engine light comes on and the O/D light flashes. I do believe one of my O2 sensors is bad because it isn't reading any voltage.
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Well, that symptom still matches IAC closing at idle with brake booster vacuum leak. (NOT an IAC problem, but a brake booster problem). If the brake booster has a bad leak (happens when pressing the brake), that causes the IAC to close at idle and the engine dies. This is just a guess without further testing. One quick test that you can do is to pinch off or disconnect and plug the hose going to the brake booster, then, at idle, press the brake and see if the engine dies. If it doesn't, you need a brake booster. If it dies anyway, then more testing is needed. A good scanner should help in getting a direction to locating the problem. The dead 02 is a problem as well as the other symptoms.
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Ok, I unplugged the air hose that goes from the throttle body to the booster and the idle becomes irratic, and the pedal is hard but the truck does not die. I pushed the e-brake in and put in gear and after 10-15 seconds the truck died. I did read somewhere that a faulty alternator may be the culprit. The truck does need a new battery.
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Well, that is not exactly the test that I wanted you to do, but it is probably sufficient to eliminate the vacuum leak/IAC issue. I remember on another car with your symptom where the fuel pump and the brake lights shared a common ground. The ground was loose and when the brake pedal was pressed, the fuel pump voltage dropped, due to the bad ground and extra current draw, and caused a stall. I would like to see more scan data. i.e. Freeze Frame data to see what the conditions were at the time any codes were stored. Also, can you post ALL dtcs that you are seeing? Note: A bad alternator and or battery could cause the same problem if the voltage is dropping too low while idling and adding loads, like brake lights.
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Thanks for posting the readings. Nothing on there really jumps out at me. The 02 sensor numbers don't mean much on a still frame. You have to look at them live, preferably graphed, to see what is really going on. What was the trouble code that was set? You might want to see what the battery voltage reads at idle, and at idle with the brake pedal pressed.
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FIXED for now
Sry for the delay. I think I found the problem. I waited so long just to make sure it was the problem. I read somewhere that to unplug the alternator pigtails to see if the problem persists. We'll it didn't. No issues. I almost drained the batteries doin this. But after looking closer at the pigtails, I noticed that they both had a lot of currosion on them so they were not making good contact. I cleaned them up as well as I could and plugged them back in. Well the truck has not stalled since then.
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