I'm having an issue with the truck not staying idle after cold start up. The truck will turn over and start right away (not even 2 second crank) but immediately dies. The throttle will not work at low RPM. When I start the truck, it will instantly rev high, the revs will drop low, it will try to compensate and rev high again, then it will immediately die.


If the RPMs are under under 2.5k, the truck will immediately stall and die. When I attempt to use the throttle under that RPM, it will not work. No matter how much I depress it, the engine will instantly cut and stall out. It will not attempt to deliver fuel. The only way I can get the truck started is if I rev the engine high and hold it. I need to hold the truck at 2.5k+ RPM for atleast 30 seconds. It generally takes me about 5 tries to finally get it running (mainly due to the throttle immediately cutting out and I have to 'catch' and hold it.) After that, there is no sign or issue. The truck will start immediately back up after it's been running for a couple minutes.

CEL: MAP sensor (0069?) -- Sensor is spotless. Harness looks fine.

I replaced the injectors, both batteries, and the alternator this summer. It doesn't sound to be any these either as the truck sounds extremely healthy and immediately turns over.

 

Have you inspected the EBP tube to make sure it isn't clogged? Any way to check fuel pressure?

 

Yessir, EBP tube was cleaned. I just noticed a flaw in what I originally typed.. The code IS P0069 - MAP / Baro sensor.. Not the EBP sensor. doh.. When I went to check the MAP sensor, it was spotless. Didn't need cleaned at all (unless that means something else is plugged up fubar'ed..). The intake manifold connection was not plugged either.

I have a diagnostic/stats reader, but I can't get fuel pressure off of it. The weather has been absolute garbage here so I haven't had a chance to check the fuel filters and FICM.

I can't really replicate this either, it just seems to happen after it sits for 2 days. It seems to be computer or fuel related since when it first fails, the truck will spike RPMs, drop, spikeup again, then instantly die. When it does spike, it almost sounds like some belt or a hydraulic (Kind of like an old powersteering pump in negative degree weather). When I try to turn over the engine again, this sound doesn't occur, it's just initially. From the second try onwards, the throttle doesn't engage unless it's caught when the truck is initially turned over and held at 2.5k. If the RPMs drop under this mark, the truck will decrease RPMs and die within 1-2 seconds (throttle is non-responsive during this time).

So it kind of seems at startup: A fuel pump isn't working at lower RPMs, fuel is clogged somewhere, maybe perhaps air in the lines, or the computer is dieing off under this (Less current at lower rpm?). I'm not sure why this would only occur if the truck has been sitting for 2+ days and not just overnight. Typically if trucks sitting for multiple days it would have trouble turning over, but the truck turns over just fine, no rough idle or anything.

 

Here are a couple of links to help diagnose. I would start with monitoring, ICP, IPR Duty Cycle, bat Voltage, FICM Main Power & RPM's during startup.

Diesel Diagnostic information for Powerstroke 6.0, 7.3, IDI 7.3 and 6.9 L, by Oregon Fuel Injection

http://oregonfuelinjection.com/pdf/f...diagnostic.pdf

 

I would suspect a damaged IPR screen or clogged IPR outlet. It's common to have IPR issues after the upper portion of the engine has been torn down due to foreign objects getting into the system. Even lint from paper towels has been known to affect the IPR.

 

FWIW - This is going to probably sound stupid. With the key off depress and release the gas pedal about 50 times at a fairly quick pace then start. You might have a dirty or dead sector in the gas pedal. Not sure an engine code would be set for this particular fault. I do this on all of my vehicles a couple of times each year and they seem to respond better.

Ed

 

My scanner only readers IPR Duty Cycle as a percentage, any idea what I'm supposed to be looking for? ICP is running 1v+ which should translate to 750+ PSI from information I've found. I still need to test the FICM, however.

 

750 psi at idle? That indicates that the system has gone into limp mode due to the inability to read the ICP sensor output.

 

IPR duty cycle is measured in %, so you are seeing the correct parameter. On a warm engine (norm operating temp) she should be 22-24%.

Is your ICP voltage consistently steady at 1 volt or does it fluctuate? what are you using for a scanner?