Hot start/knocking problems
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Hot start/knocking problems
99 f250ld 5.4. I have a problem when starting the truck when hot, and also a pinging problem, although I'm not sure if they are related.
When starting my truck cold, it starts fine though i think it takes a couple more cranks than it should. If I turn the truck off when hot and start it within 5 minutes or so, it starts fine. If I wait more than that it will not start unless I cycle the key off and on a couple of times. If I turn the truck off and the temp gauge gets close to the C it will start just fine. It has done this for the last 60k miles, since i bought the truck.
As far as the knocking goes, I run 93 gas in it, and that eliminates most of the knock. But if i run anything less than that, it will knock, especially when accelerating and with the a/c on.
replaced the spark plugs and 6 of the 8 coils (motorcraft) 15k miles ago. I replace the fuel filter every 10k. Not sure if the 2 problems are related but any insight as to where to start looking would be great.
When starting my truck cold, it starts fine though i think it takes a couple more cranks than it should. If I turn the truck off when hot and start it within 5 minutes or so, it starts fine. If I wait more than that it will not start unless I cycle the key off and on a couple of times. If I turn the truck off and the temp gauge gets close to the C it will start just fine. It has done this for the last 60k miles, since i bought the truck.
As far as the knocking goes, I run 93 gas in it, and that eliminates most of the knock. But if i run anything less than that, it will knock, especially when accelerating and with the a/c on.
replaced the spark plugs and 6 of the 8 coils (motorcraft) 15k miles ago. I replace the fuel filter every 10k. Not sure if the 2 problems are related but any insight as to where to start looking would be great.
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Spark knock or pinging can be the results of fuel pressure to low.
This means the mix can go a bit lean but codes should eventually show up for this.
A leaking EGR can also be the cause.
I would test fuel pressure and service the EGR by cleaning the vacuum regulator that opens it. It may be sticking open just a bit.
If this happens the ignition timing advances a bit and could be the cause of the pinging. Try removing the hose to the EGR as a test to see If the pinging goes away.
Also carbon deposits in the combustion chambers can be a source of uncontrolled spark knock.
A look at the fuel tables might show a lean condition, what the ignition timing is doing etc. as leads on the problem.
You would do this with a good Scanner looking at the live data.
Good luck.
This means the mix can go a bit lean but codes should eventually show up for this.
A leaking EGR can also be the cause.
I would test fuel pressure and service the EGR by cleaning the vacuum regulator that opens it. It may be sticking open just a bit.
If this happens the ignition timing advances a bit and could be the cause of the pinging. Try removing the hose to the EGR as a test to see If the pinging goes away.
Also carbon deposits in the combustion chambers can be a source of uncontrolled spark knock.
A look at the fuel tables might show a lean condition, what the ignition timing is doing etc. as leads on the problem.
You would do this with a good Scanner looking at the live data.
Good luck.
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