Intermittent knocking
 

I’m having a small knocking problem, not sure if I should be alarmed or freaking out.

I know there is different types of knocking but this one has me in between. When the truck knocks, it runs bad. When it stops, it runs normal. Lately when I go to start up for the first time in the day it’ll knock erratically and then stop. I’m not sure if it’s an internal issue or if it’s somewhere in the category with a spark knock? Could it be fuel related? Injectors? Pump? Let me know! I appreciate any input. Thanks everyone

Re: Intermittent knocking
 

Hard to give an answer without hearing it. What year is it? How many miles? Is there a CEL? Any stored or pending DTC's? Have you tried to run a higher octane fuel? Generally a pre-ignition knock happens worse under load when the engine is hot so its odd to happen only at startup. Are you sure its not a misfire or mixture issue just causing it to run rough and not actually a true knock situation?

Re: Intermittent knocking
 

It’s a 2002, 3.0 v6 and the body has about 305k miles. The motor only has about ~170k Miles on it. It does not have any codes, I’ve got a tuner on mine and that was the first thing I checked, no codes. It doesn’t only happen at start up, the first start of the day it’ll chatter then quit, after the motor is hot, it becomes pretty persistent. It’ll knock at high rpms like shifting out of first and second gear. I haven’t tried running a higher octane but I will try on my next fill up. I couldn’t give you a for sure answer on the mixture part, fumes from the tail pipe doesn’t really tell me anything, smells like any other. It’s a pretty distinguishable knock, pretty much like knocking on a 2x6 lol.

Re: Intermittent knocking
 

If it were me, id pull the plugs and use a borescope to examine the pistons for heavy carbon buildup. If you're the original owner of the truck have you been deligent with oil changes and pcv valve replacements? 170,000 miles is no spring chicken but if the engine was well maintained it shouldn't have enough buildup to cause knocking which is the main cause of knock in older engines. Next thing id do is look at where the ignition timing is at, you said you have a tuner, does you're tune involve advancing the timing beyond the stock parameters? The more the timing advances the higher the chance of knocking.

Re: Intermittent knocking
 

I’ll have to give it a look and see about that. I usually run some cleaners when I change oil, can of restore and occasionally a flush. I baby this truck to death. Just a pavement princess. But I’ve got the SCT X4, the only tuner that I could find that was compatible with a Ranger. But if I remember correctly when going through all of the “stock tunes” there was a spark degree option which I’m sure is to either advance or retard spark. But in that option I only saw negative values? Not sure if that’s normal, I didn’t flash anything to the truck I didn’t know what would happen to it, just took off the governor and increased the idle rpms and that’s it.

Re: Intermittent knocking
 

Actually just pulled two codes, P0413-secondary air injection system switching valve A circuit open, P3600 which doesn’t give me a definition.

Re: Intermittent knocking
 

Hmmmm thats.... Really weird. P0413 doesn't apply to your truck and P3600 doesn't exist.
Im getting very suspicious of this tuner.

Re: Intermittent knocking
 

I was thinking the same thing lol. Every now and then I’ll get a P000 which says “SAE reserves”. Super confusing. I’ve tried filling up with a higher octane but to no avail. I’ve also noticed that it seems like the knock gets worse as the motor warms up, it’s weird though, you can hear the knock pretty clearly but the truck runs smooth as a Cadillac. No shaking or anything, it’s starting to sound like something along the line of a piston knock to me but I could be wrong. I’m gonna run a can of sea foam through it to see if that’ll help but there’s no such thing as “a miracle in a can”. Are there any tests I can do to verify what the problem may be? Just don’t want to be taking shots in the dark here lol.

Re: Intermittent knocking
 

Well you could do a dry compression test. Usually you're looking for low numbers but in this case high numbers would indicate the piston and or combustion chambers are full of carbon. (Higher compression means more knock).

An oil pressure test wouldn't hurt to rule out mechanical damage and the noise coming from a lack of oil.

I'd also strongly suggest putting a scanner on it (not the one you have) and checking for codes, look at spark advance, fuel trims, and misfire monitors.

The other thing would be to use a mechanics stethoscope (or a screwdriver) to try and pinpoint the noise more specifically. Is it only around one cylinder? More from the top or louder through the oil pan? Ive seen instances where things can mimic the sound of a knock but be things like a broken flywheel bolt.

Hard to pin this issue down over the internet.

Re: Intermittent knocking
 

I’m gonna get this thing figured out this weekend and do whatever I got to do to get it fixed, it’s driving me nuckin futs. I just went out and bought one of those stethoscopes you mentioned and hopefully I can pinpoint the problem. A while back I pretty much rebuilt the motor, all new gaskets, lapped the valves, changed piston rings and cleaned everything from the inside out accordingly. I don’t know if it is something I done on my part or just something that wore out prematurely but I guess we’ll have to see. Once I get to the bottom of it and resolve the problem I’ll come back with a follow up post. I appreciate the help again Dirtman, I was stumped as to what it could be. If I come up with anymore questions I’ll ask ✊🏼