Occaisional CEL after low rpm in parking lot and at streetlights - Diesel Forum

ZZRGuy · 03-03-2007, 02:28 AM

Anybody have any ideas as to why this would happen? I am gonna check for water the next time it happens. I am also going to check fuel pressure at idle tomorrow. That should be between 60-80, right? It only does this every once in a while and when it does it goes to idle. I was pulling out into rush hour traffic the last time it happened. One quick jab to the floor cured it but it was a tense moment with a concrete truck coming at me. Truck is a 1997 F-350, 5 speed, 4x4, stock mostly. All help appreciated. Thanks! Steve.

Tankota · 03-03-2007, 03:07 AM

Might have something to do with the low rpms not running the pump (fuel or hpop) enough to keep the pressure in the specs that the computer sees as normal...hence the CEL.
Just my guess. yah, fuel should be 60-80 at idle. HPOP = ?

Nit · 03-03-2007, 02:58 PM

only does it once and a while and RETURNS TO IDLE, thsi si your key, teh motor itself would never return to idle by itself, the only thing that would do that is teh throttle pedal assembly, it doesn't read and returns to idle only. so thats your problem. Slamming it to the floor moves the TPS enough to re-activate it.

**action4478** · 03-03-2007, 03:13 PM

[ QUOTE ]
Anybody have any ideas as to why this would happen? I am gonna check for water the next time it happens. I am also going to check fuel pressure at idle tomorrow. That should be between 60-80, right? It only does this every once in a while and when it does it goes to idle. I was pulling out into rush hour traffic the last time it happened. One quick jab to the floor cured it but it was a tense moment with a concrete truck coming at me. Truck is a 1997 F-350, 5 speed, 4x4, stock mostly. All help appreciated. Thanks! Steve.

[/ QUOTE ]Is this anything ?

No throttle response, engine idles only, DTC's P0220 or P0221; Vehicle jerks in parking lots, especially manual transmission:
Idle Validation Switch.
The IVS tells the PCM that the accelerator pedal has returned to the idle position. Even if the pedal is fully depressed, if the IVS remains off, the engine will only idle. Watching the IVS and AP data stream, the IVS should switch on below 1.41 volts according to Ford. Navistar spec is 0.2-0.3 volts above base AP voltage. If the PCM sees the Accelerator Pedal sensor voltage increase with out the IVS switching on, it may set a code. The IVS and AP sensor cannot be replaced without replacing the entire pedal assembly. If the IVS switches on at too high of a AP voltage, it can cause the truck to buck at low speeds as the IVS cycles on and off as the driver tries to control his speed. The only way to correct this is to first loosen and turn the AP sensor to reach the lowest possible voltage reading on the scan tool and retighten. Then bend the IVS stop to adjust the on/off point to 0.2-0.3 volts above the base AP voltage reading. Note: There have been cases of lack of throttle response and the above codes which were caused by the PCM not recognizing the IVS "on" signal. Replacing the PCM corrected the problem.

ZZRGuy · 03-03-2007, 05:19 PM

So the TPS is going bad? Or maybe just not getting a reading? Maybe I can adjust something in the assy. I guess I'll look in a couple days when it warms up, snowing now. Thanks though!

ZZRGuy · 03-03-2007, 05:37 PM

Rick, the truck runs great 99.99% of the time. No codes. Not jerky unless my boy is driving [img]/ubbthreads/images/graemlins/grin.gif[/img]. I will check voltages. Just a regular meter, right? Thanks! Steve.