2 Starting Problems
Fleet Mechanic
Joined: Feb 2007
Posts: 1,652
Likes: 79
From: Mooresville, NC
Thanks for the quick response - I went out a few min ago and messed around with it some - more info below.
So I've been driving the truck this morning so it is hot. I experimented some more with the second problem.
The hot engine will start, run for a fraction of a second and die.
If I goose the gas at just the right time while it is running, I can occasionally get it to recover and run.
If it dies, the ONLY way to get it to start is to hold the throttle most if not all the way open and crank it for 2-3 seconds - it will eventually begin to start to fire and then I let off the gas and it starts.
5.0l / 302
Just did - 33 PSI at idle, will jump to 37 and dip to 30 as the engine is revved but always comes back to 33. Does this on either tank (2 tanks with 2 pumps)
I pulled the codes
KOEO - 334
Continuous - 334
Running - 116, 334, 225
334 is an EGR
116 is temp high/low - as far as I could tell the engine was at operating temp during the testing
225 is knock not sensed
225 got me to thinking - so I went and took a hammer and tapped on the back of the head and an exhaust stud to see if the RPM dropped and they never would (not sure if this trick works on this engine or not)
I doubt the EGR valve would cause this kind of problem but could the temp or knock sensor failures do it?
RP
So I've been driving the truck this morning so it is hot. I experimented some more with the second problem.
The hot engine will start, run for a fraction of a second and die.
If I goose the gas at just the right time while it is running, I can occasionally get it to recover and run.
If it dies, the ONLY way to get it to start is to hold the throttle most if not all the way open and crank it for 2-3 seconds - it will eventually begin to start to fire and then I let off the gas and it starts.
5.0l / 302
Just did - 33 PSI at idle, will jump to 37 and dip to 30 as the engine is revved but always comes back to 33. Does this on either tank (2 tanks with 2 pumps)
I pulled the codes
KOEO - 334
Continuous - 334
Running - 116, 334, 225
334 is an EGR
116 is temp high/low - as far as I could tell the engine was at operating temp during the testing
225 is knock not sensed
225 got me to thinking - so I went and took a hammer and tapped on the back of the head and an exhaust stud to see if the RPM dropped and they never would (not sure if this trick works on this engine or not)
I doubt the EGR valve would cause this kind of problem but could the temp or knock sensor failures do it?
RP
Both sensors, if bad, would produce some of the exact symptoms you've described.
Thread Starter
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Senior User
Joined: Jul 2005
Posts: 139
Likes: 1
From: Warrenton, VA
Quick update - so I got a few minutes to work on this today and discovered the knock sensor was an easy fix. Apparently when I re-assembled and installed the engine after the rebuild I forgot to attach the sensor to the wiring harness (Dooht!). Connected it up, re-ran self test, code 225 is now gone.
One other observation - when troubleshooting the ECT sensor, I had forgotten to connect it back up and I discovered that with the ECT disconnected, neither of the problems occurred. When I connect the ECT, both starting problems came back.
So it is off to get a new ECT.
I am glad the knock sensor was an easy fix - not only is that thing hard to get to, but when I rebuilt the engine I replaced all the electrical sensors. It ticks me off that the ECT only lasted 18k miles but it was really grinding my gears that 2 sensors would crap out so soon.
Regardless - THANKS FOR THE HELP EVERYONE!
RP
One other observation - when troubleshooting the ECT sensor, I had forgotten to connect it back up and I discovered that with the ECT disconnected, neither of the problems occurred. When I connect the ECT, both starting problems came back.
So it is off to get a new ECT.
I am glad the knock sensor was an easy fix - not only is that thing hard to get to, but when I rebuilt the engine I replaced all the electrical sensors. It ticks me off that the ECT only lasted 18k miles but it was really grinding my gears that 2 sensors would crap out so soon.
Regardless - THANKS FOR THE HELP EVERYONE!
RP
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