I'm stumped...
11-22-2014, 01:45 PM
#1
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I'm stumped...
1993 f150 5.0 4x4
Symptoms: when at an idle, and only after reaching full operating temp, if you go more than 50% throttle there is a hesitation and puff of black smoke out of the exhaust.
Parts thrown at it: fuel filter, EGR block off, ECT sensor, IAT sensor.
I've checked timing, it's good 10* w/ spout out, fuel pressure is good with both tanks, no surge in pressure with sharp throttle application. Only code that pulls is for the EGR.
Other than the slight hesitation it runs great... No rough idle, good MPG(13-15), cruises good.
What say you???
Symptoms: when at an idle, and only after reaching full operating temp, if you go more than 50% throttle there is a hesitation and puff of black smoke out of the exhaust.
Parts thrown at it: fuel filter, EGR block off, ECT sensor, IAT sensor.
I've checked timing, it's good 10* w/ spout out, fuel pressure is good with both tanks, no surge in pressure with sharp throttle application. Only code that pulls is for the EGR.
Other than the slight hesitation it runs great... No rough idle, good MPG(13-15), cruises good.
What say you???
12-02-2014, 12:22 PM
#3
Just because you've blocked off the EGR valve doesn't mean that you've rendered it inoperable. The computer still commands the EGR valve open and expects it to. It will lean out the injectors a bit and play with the timing. And when you get the symptoms is exactly how the EGR system works; only after the engine warms up and only at part throttle.