spark knock
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spark knock
Hello I have a 98 f150 4.6 with 175000 miles on it, I have developed a spark knock, with no codes. I have tried c foam thinking it might be the fuel injectors being dirty bet that didn't help so what do you think could be the cause?
Lead Driver
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Ask yourself what is spark knock.
What could be the causes?
Injectors would be a long way from causing it because a code would be set for a Lean condition.
Spark knock, Pinging, pre ignition and special conditions caued by malfunction are all variations of the same sound you hear with intensity and when it occurs..
A light marble in a can sound is not spark knock but the first stage called Pinging.
Under heavy throttle and high load, a very loud knock is the second stage after pinging.
Pre ignition is yet another type caused by cylinder hot spots you may not even hear depending on the conditions.
Which one of these fits what you hear then we get into the causes.
Under acceleration and light loading, wider throttle popenings, in OD at light throttle etc.
Good luck.
What could be the causes?
Injectors would be a long way from causing it because a code would be set for a Lean condition.
Spark knock, Pinging, pre ignition and special conditions caued by malfunction are all variations of the same sound you hear with intensity and when it occurs..
A light marble in a can sound is not spark knock but the first stage called Pinging.
Under heavy throttle and high load, a very loud knock is the second stage after pinging.
Pre ignition is yet another type caused by cylinder hot spots you may not even hear depending on the conditions.
Which one of these fits what you hear then we get into the causes.
Under acceleration and light loading, wider throttle popenings, in OD at light throttle etc.
Good luck.
Lead Driver
Joined: Sep 2006
Posts: 7,907
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My suspicion is your hearing Pinging from excessive ignition advance.
This can be from the EGR valve passing exhaust gas when it's supposed to be closed during acceleration.
Check the EVR for leaking vacuum to the EGR first.
Take the solenoid off, clean the filter under the round cap and be sure the solenoid is free operating by using cleaner.
The EGR itself could be leaking, but not likely.
Another way to check for excessive timing is with a Scanner looking at it as you drive under those conditions.
Good luck.
This can be from the EGR valve passing exhaust gas when it's supposed to be closed during acceleration.
Check the EVR for leaking vacuum to the EGR first.
Take the solenoid off, clean the filter under the round cap and be sure the solenoid is free operating by using cleaner.
The EGR itself could be leaking, but not likely.
Another way to check for excessive timing is with a Scanner looking at it as you drive under those conditions.
Good luck.
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Thanks Bluegrass what is the EVR I know what the EGR is. I do notice when I move my climate control **** my engine changes rpm could that be a sign of a vacuum leak. Thanks for your help. Where might the EVR be located?
Lead Driver
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The climate control reaction could be a sign of a vacuum leak.
Usually you might hear the leak but not always.
The EVR is the solenoid that gates intake manifold to the EGR to open it.
This solenoid is operated by the computer at the time it is supposed to function.
To find it, follow the vacuum line from the EGR back to the EVR.
The EVR should be found right on the top side, driver side.
It has a round cap, an electrical plug and 2 vacuum lines attached vis a rubber fitting.
One line goes to the intake for vacuum, the other goes to the EGR.
Make sure it is clean inside aand the filter under the round cap is removed and cleaned.
Good luck.
Usually you might hear the leak but not always.
The EVR is the solenoid that gates intake manifold to the EGR to open it.
This solenoid is operated by the computer at the time it is supposed to function.
To find it, follow the vacuum line from the EGR back to the EVR.
The EVR should be found right on the top side, driver side.
It has a round cap, an electrical plug and 2 vacuum lines attached vis a rubber fitting.
One line goes to the intake for vacuum, the other goes to the EGR.
Make sure it is clean inside aand the filter under the round cap is removed and cleaned.
Good luck.
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Bluegrass there's a thing on the fire wall that says Evap service port with a white vacuum line going to a black thing looks like its on the side of the throttle body it has a black cap that one has a green vacuum line going to the EGR the one on the fire wall looks like it has a dieaphram behind were the wires plug in the one with the green line coming off of it looks the same but has no diephram
Lead Driver
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That one is the EVR.
To clean it properly take it off.
The filter in under the round cap.
You have to persuade it off over the clip areas. It is donut shaped and filters air coming in after the solenoid closes so air in will allow the EGR to close fast.
It's the third port you normally don't know about until this is pointed out.
Good luck.
To clean it properly take it off.
The filter in under the round cap.
You have to persuade it off over the clip areas. It is donut shaped and filters air coming in after the solenoid closes so air in will allow the EGR to close fast.
It's the third port you normally don't know about until this is pointed out.
Good luck.
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