bigcountry25

07 4.2L 5 speed

I have a spark knock that I can't stop. I have no codes.

It doesn't matter if the truck was just started or drove for several hours it is the same. When I go up hills it spark knocks like crazy.

I have changed the plugs( tried motorcraft fine wire platiumand boush Platinum +4's, wires(motorcraft), air filter, and cleaned the mass air flow sensor fuel filter with no change. The plugs that are in it are the +4's

Is it possible with this being a 5 speed that the computer is not as sensitive as it would be for an automatic? It makes sense because a 5 speed will have different fuel to air mixtures due to the shifting and lugging if you shift too soon.

I am wondering if the knock sensors my be bad or going bad and the computer does not show it because it could be less sensitive than the automatic computer? If they are good then the computer should adjust the timing for the spark knock.

If you have other suggestion please post them.

Summers22

iTrader: (2)

You have no codes or no check engine light? I would scan it if you havent. Dont rely on the check engine light. Your theory that the knock sensors being bad may be good. But I doubt a manual pcm is "less sensitive" than a automatic pcm.

EBC-150

Out of curiosity, is your rig 4WD? If so try putting it in 4WD and going up the same hills. Sounds dumb...bear with me here. When I got my '05 it had 'spark knock' like crazy. I tried everything under the sun to make it better (fuel filter, cleaned injectors, plugs, knock sensors, cleaned TB and MAF, etc., etc.)- nothing helped. Finally when I got my Edge, I noticed that the ECM wasn't even trying to drop spark to compensate, so that got me to thinking that it wasn't detonation at all. Well one day I had to use 4WD to navigate a hill, and the knock disappeared. Turns out the vacuum check valves were bad and causing the IWE's to partially engage during low engine vacuum situations (i.e. going up hills). This sounds amazingly like spark knock- marbles in a can, card in a spoke, however you want to describe it. Hope this long story helps to eliminate your frustration...

lewissa81

EBC-150 makes a good point. The first time I heard my IWE'S partially engage, that was one of my first thoughts.
Also try running some fuel system cleaner. You may have carbon build up or some dirty injectors.
It's good that you're trying to solve this. If left, detonation can burn a hole in your piston or damage your rings and head gasket.

bigcountry25

My truck is a 2wd, I have tried several fuel system and injector cleaners from seafoam, berrymans B12 ect. no change at all.

lewissa81

Do you have access to a scanner that can read fuel trims? If you're running lean, then the mass airflow sensor may be malfunctioning.
Also, check out the exhaust manifold. An exhaust leak can sound very similar.

bigcountry25

I have scanned for fault codes and none where present.

I don't have a scan tool that will check the fuel trims.

Also I have checked for exhaust leaks and didn't find any.

Is there anything you can think of that could be the problem.

I would like to get this problem fixed but I have had 2 other fords that where like this just worse. I don't want to let this go until I have tried everything just like the rangers below.


I had two rangers both with a 2.3L (I think) four cylinder and both spark knocked like crazy, worse than any vehicle I have ever heard and the cause was never found and one went about 210,000 miles and the the other went over 325,000 miles before the motor gave out. One was a 5 speed and the other an automatic I had to rebuilt the automatic transmission 3 times it was an A4LD which explains it's self as far as problems and that was the truck that the motor last 210,000 miles.


Thanks!!!!!!!

lewissa81

Check out tsb 07-16-17

You can always switch to a higher octane fuel.

bigcountry25

I have ran several tanks of 93 octane 100% gas no ethanol added and still have the same of amount of spark knock.

I did check the fuel trims and they checked out fine both long and short term.