Spark Knock in my Harley F150
 

Hey Guys. :-wink I normally hang out in the 67-72 truck section but I'm having trouble with my 2003 Harley F150. It has Diablo programer,s/c power pulleys,12# boost,throttle body,C&L air duct,and Cold air intake. These have all been in it for years. Nothing changed except maybe the gas here in Phoenix Arizona. It does seem to be better with Chevron.
Driving home from work it is normal at first. After maybe about 10 miles it starts spark knocking under load up a grade. The farther I drive it, it spark knocks easier. By the time I get home 30 miles from work it will spark knock even on a level city road if I lug it in overdrive and accelerate like passing a car. The funny thing is that if I stop and get gas it reverts back to normal on the drive home. No codes in PCM. I had a tech here at the Ford dealer I work for read my PCM. It says everything normal and the knock sensors are working. Any Ideas?

sounds like you maxed out the MAF and burnt at least one plug...


so start with the plugs gapped for the additional boost, and if the issue persists, then swap out the COPS



and time for a MAf upgrade and a TUNE

Just swap out the COPs?? Don't even test them?? That's one expensive swap to do without confirming they are faulty. Besides, bad coils won't give spark knock. Spark knock (Detonation) happens when the compressed air/fuel mixture in the cylinder ignites from heat BEFORE the spark plug fires. Therefore it couldn't be a COP. It can destroy a normal motor quickly let alone a S/C motor. You most likely are having a lean condition, or too low octane fuel. Check for gaskets leaks all around the S/C and intake. Pretty much anything after the MAF sensor including vacuum hoses. I've read about the S/C'ed 5.4s having a vacuum line leak at an elbow behind everything out of sight.

Oops old thread. My bad.

Actualy I'm glad you did. I never did figure out what the problem is/was. I had the plugs changed which helped but was still there. Now that it is cooler temperture around here it is a lot better. A couple times recently at a stop light it started to stumble like the gas tank was empty. Putting it in neutral and reving it a littlle cleared it. I figured I need a new programmer. A vacuum leak as you suggested is possible I suppose. What is your O now?

Well gentleman now the air temp is back up so is my detonation. The problem may be I had the engine's thermostat changed a bit before this problem started. I had the aftermarket 160 taken out while the cooling system was flushed and a factory one installed. I figured either way the engine would reach the same running temp. What is your opinions? What brand stat and from whom do you guys buy yours?

is your intercooler pump working??

I had thought about that at one time and then forgot. Thanks for chiming in and reminding me. :-X22Will check it out.

Hey guys I'd like to re-vive this thread since I never resolved the issue. Pump is working. Still no check engine light so no codes. The Service Dept here is no help since I have all the aftermarket stuff on it. Last time the plugs were changed 4 of them were fried. Pinhead didn't tell me which 4. Recently one of my Wholesale customers told me he thinks I got 4 "lazy" injectors. I went "things that make you say HMMMM". I know spark knock and fried plugs mean Too Lean. I kept wanting to blame knock sensor,Diablo, etc. Hadn't considered the fuel source. This makes sense ,kinda (lazy?), to me. So gentlemen, I'm asking your opinions. I am at work and don't have the time in between answering Wholesale Parts phones to use the search engine above or I would and research it myself. Thanks in advance.

I am new to Lightnings but maybe a crank or cam sensor?

Thanks for your reply Chief. :-X22I'll add that to the list.

I'm leaning towards intake gasket leak, POSSIBLY a partially clogged fuel rail on one side. My only idea to try and figure out what cylinders are freaking out, is to get a temp gun and measure the exhaust manifold temps right by the cylinder ports. Do this right after it's freaking out bad. Hotter temps on certain cylinders will tell you which ones to look at.

Thanks for the reply OffRoader. I'll tell my Service Dept that one also. Like your sig. I've said that for years about warehouse help and drivers.

I found this,

The oil treatment on K&N-type low-restriction filters has been known to collect on the wires of the MAF sensor, causing a malfunction.

You might try Seafoam How to use SeaFoam to clean your Engine - The RIGHT way! which is safe and won't harm anything. I probably would just use it in the fuel where it works all the time. All this is assuming that carbon is actually the problem. It could also be a fault in the engine controls by allowing too much spark advance. In the old days we would get out the timing light and check the timing and adjust it at the distributor. I guess now they have to hook it up and do a diagnostic. Dealers and other shops now also do injection cleaning which is probably a good idea since you're having a severe problem.

Premium fuel is good for this on a temporary basis because it reduces 'ping' and also has more cleaners. I would keep using it and put in a can of Sea-Foam with each fill of 15 gallons or more.
If it doesn't get any better in the first few weeks, you probably should have the diagnostic done to see if there are any control or sensor problems. Most engines have a 'knock sensor' that could go bad and fail to send the signal to retard timing to prevent knock.

Thanks Stephen. I am a Ford Parts Man at a ford dealer. I've had it in our Service Dept. At 1st they didn't even want to look at it with the programmer,pulleys,etc on it. I forced the issue and told them to at least scan the PCM. Which they did. Everything looks normal to a scanner. Knock and all sensors working. I can feel the PCM is pulling back on the timing when it starts to spark knock. Less power and less vacuum on my vac/boost gauge. So I know I got my foot deeper into it until I hear the spark knock. Hopefully with next paycheck I can afford to have our shop pull the spark plugs and see which 4 are prolly fried again. This set has been in there a while. Once I see which 4 they are I'll figure out what they have in common. I've tried various fuel system cleaners but I like your seafoam idea. I suggest people use it on the Bumpside board rather often.