Spark kncok

[182Ranger]

Can anyone tell me what may cause a spark knock? I'm running out of ideas of what it could be. I was told a bad oxygen sensor or a bad EGR valve. Any other thoughts?

 

[Epixstar]

bad gas, wrong fuel pressure, timing off, any codes? When do you get the spark knock?

 

[Big Jim M]

???

Can anyone tell me what may cause a spark knock? I'm running out of ideas of what it could be. I was told a bad oxygen sensor or a bad EGR valve. Any other thoughts?

Spark knock can be caused by high compression ratio... (carbon buildup in the chamber).
OR increased timing. Advanced too much will cause pre-ignition.
OR lean mixture. Flame travels faster in a lean mixture and increases the pressure too quickly.

A small vac leak is common on these engines which may cause a lean condition.
Big JIm

 

[182Ranger]

I was getting a code for oxygen sensor, so I replaced it, but I'm still getting the knock. It seems to do it worst when working hard, going up hill. Even if I step on it trying to accelerate fast, it will knock. The timing cannot be adjusted on these engines, so I've been told. It is a '99 3.0 liter.

 

[Epixstar]

check your fuel pressure first. If you dont have a tester harbor frights sell them for around 20 bucks. it should be around 30-40 while running. What kind of o2 did you put in ive heard horror stories about the universal ones before. Good luck

 

[182Ranger]

How would fuel pressure make it knock? I thought knock was the fuel burning unevenly. I got the oxygen sensor straight from Ford, so it is a direct replacement.

 

[182Ranger]

For Big Jim M:
Where is the vacuum leak that you are talking about located?

 

[Big Jim M]

Possibly

For Big Jim M:
Where is the vacuum leak that you are talking about located?

Could be anywhere there is a vacuum. From the air cleaner to the heads. Could be a vac hose cracked.. could be a vac 90* elbow that has a crack in it... could be under the IAC.. there are many places that are known to encourage a leak.
The fpr can cause a knock if the pressure to the engine is too low. The computer doesn't KNOW the pressure is low and assumes full pressure so it allows the amount of fuel full pressure.. Which in turn is a mixture that is too lean and makes a knock.
Big JIm

 

[Hahnsb2]

Probably carbon build up, likely from babying it.. Seafoam it and you'll probably be surprised.

 

[McCormack]

Pinging is common to the Ranger 3.0 engine, and they ping because Ford runs a tad too much ignition timing from the factory. A couple of ways to deal with the problem is to do the intake manifold hot water bypass mod and install a 180* T-stat. If those items don't work then you can either run premium gasoline, or else buy a tuner and retard your timing a couple of degrees.

 

[Froggmann]

If your truck is Flex Fuel, run several tanks of E-85 through it, if you have access to it. E-85 does wonders for cleaning the fuel system and the overall running condition.

If E-85 isn't an option, I'd recommend Seafoam, 180* T-stat and some injection cleaner.

 

[kimcrwbr1]

Did you reset the computer when you changed the sensor. You can try disconnecting the battery for 1/2 hour or so to reset the values and then run the engine for a complete warmup after you erase the memory and run the codes again while it is still hot. It could be the computer has not adjusted to the new sensor.

 

[182Ranger]

I'll check my vaccum lines, that sounds like it could be an answer. Makes sense anyways. I didn't bother resetting the computer, the engine light was on, and turned out to be the oxygen sensor. I cleared the code, then changed it. Hasn't come on since. Thanks for the help, I just didn't want to waste time and money on it, and the problem turn out to be something stupid.

 

[oldfordman]

Some things to check on pinging Ranger 3.0 engines. The 3.0 Vulcan Flex-fuel engine is very prone to pinging. They are set up to run on up to 85% ethanol, so they have more advance, a bit more compression, and the chambers tend to carbon up.
•Buy a service manual
•Check for vacuum leaks. Hoses, and the intake manifold gaskets.
•Sea foam the engine. Be careful- feed it in too fast and you can seriously damage the engine. Go in through the vacuum port just behind the idle solenoid. Get a friend to keep revs at about 1500, feed in just enough to make it run rough. Suck in about 2/3 can, shut it down and let it sit about 20 minutes. Start it up, feed in the rest of the can, hook the vacuum line back up and go for a hard drive. It will smoke like hell, if you have sensitive neighbors, do it out on a back road someplace.
•Check the EGR valve, make sure it is operating smoothly. You can apply a little vacuum to the EGR valve, it should open easily and the engine will almost stall.
•Check the metal EGR tube- mine had a huge split in it. Check the 2 pieces of silicon tubing that go from the EGR tube to the DPFE sensor, they sometimes get plugged. Do not use vacuum tubing, this is high temperature stuff. Find a dealer that buys it bulk, the individual tubes from Ford are stupid expensive.
•The old DPFE sensors have a habit of going bad. It measures the flow through the EGR tube by pressure drop through an orifice. Check the input and output voltage. I forget what it should be, it’s in the manual.
•By-pass the hot water going through the intake manifold. Sometimes helps.
•Run colder spark plugs. Original factory plugs were a #AGSF32 (not sure of the letters), later they went to #22, some people have gone down to #12. I am currently running AR-93, Autolite racing, 2 steps colder than stock.
•I know this will cause some arguments, but after all the above, my truck still pings a bit on some brands of 87 octane, does not on others. If I am not sure of a particular brand, I just put in the 89. Ten cents a gallon is a lot cheaper than engine parts. I do not get hung up on running 87 octane just because "the manual says ...". I run whatever works best in my vehicles. 6 vehicles with well over 200,000 miles tells me I'm doing something right.

 

[182Ranger]

That's some good stuff you got, there, Old Ford man. Thanks. I tried using a MAF sensor off another Ranger 3.0, but it still has some knock, also I ran some combustion chamber cleaner. What is a DPFE sensor? When you say to apply a little vacuum to the EGR, what do you mean by this? Thanks.