I have a built evo 8. What are the symptoms of Rod knock? When I drive on low loads the car starts jerking and making taping noises. I have a Built 2.0LR motor, 1450 FIC injectors, AEM Series 2, Making 550hp on pump gas (30) psi, ETS 6262 setup. My motor has 3k miles on it.

Basically the noise started a few months ago. On cold start-ups there is a very loud tapping sound coming from the motor until it warms up. It didn't cause any issues until recently when I was driving it normally, and under low throttle it started jerking. Every time I gave it gas, it jerked. Almost like a intercooler piping popped off. I pulled and checked plugs(looks normal), checked compression (180 all across all 4), checked lifters and head(looks good). I did notice that cylinder 1(far left) had oil in it.

Please help? Any ideas people? I dont want to pull the oil pan just yet. What can I try to check for?

 

Its been my experience that a rod knock is just a noise... Its never effected my drivability til it wasn't knocking anymore lol... Its a lil hard to pull a solid guess out from what you describe... But a couple things would be... Carbon build up do to blowby oils being burnt... Do a pretty serious decarbonizing fuel system cleaning... Pull the plugs again and lower the gap by about .002 to ensure you are blowing out the spark... I hope those help... Might even wanna try an oil additive like lucas or slick 50 or maybe a higher quality oil... But thats not likelyto help anything just more piece of mind

 

Try taking a long screwdriver and place the tip on the block where the cylinders are, stick your ear on the end of it and listen for sounds. If the tapping is down in the block, then you may have rod knock. If the tapping is up top, then a lifter or an ignition problem with the wires or plugs.
In the cases I have seen it, rod knock usually gets worse or louder when the engine is revved.

I had some ticking in my car when I went to Kelford 272's so I replaced them with the GSC zero-tick lifters and the problem went away. I made sure I bled them thoroughly. It was easy diagnose because I had just changed the cams.

Good luck.

 

The screw driver trick is something i have to try... Sounds legit... I prefer my electronic stethoscope but i know the average guy doesnt keep one layingaround

 

I am going to try that. I could probably burrow a sethoscope from my mechanic friend. I just don't want to pull the motor and send it all the way to the engine builder($450 one way) if I don't need to. I have been having low fuel pressure problems. I hope it's not related?

 

An electronic stethescope would be nice to have, but I won't buy one because I may use it like once or twice. The screwdriver trick is also used to diagnose faulty/sticking fuel injectors. Works like a champ.

I have also heard people using the diy knock ear muffs to listen to things in the block. Essentially its piece of metal that attaches to the block in the areas being monitored and it amplifies the noises for you to diagnose ignition knock, in this case rod knock.

As for the jerking though, how much timing are you running in the low load ignition map? When I was tuning for the cams, I had to add a lot of timing down low to keep idle up and when I added too much timing the car would become jerky at low load and rpms. After finding a good happy medium the jerking is less but does happen occassionally when cruising in first gear at slow neighborhood speeds.

If I had to guess, since the sound goes away after it warms up, I think its your lifters need to be bled. Sux though because you will have to pull the cams out again unless you risk the screwdriving prying method. When you say you checked the lifters, what did you do to check them? I think the only way is to actually push each one with your finger and make sure it compresses and decompreses fully and easily... Is there another way to check them?

 

The problem was realized by me when the jerking started. To my knowledge rod knock should have nothing to do with the jerking. Right?

As for the lifters. I physically pushed down on each of them with my finger to see if it had pressure. Changing them shouldn't be a problem. I don't mind taking off the cams and whatnot. I also bought a new tool which allows me to change lifters without removing anything. And I am dying to use it.

I heard people say that it may be a bad tensioner which causes the timing to jump a tooth or so. So I just finished putting my car to tdc and all the marks lined up perfectly.

Also, I should mention that this problem happens when my fuel pressure drops to 20psi. It's tuned to 39psi at idle. 9 degrees of timing at wot. 30psi pump gas 92octane. I am using the buschur double pumpers.

Could this be related to low fuel pressure?

 

Yes, fix the fuel pressure issue first. Low fuel pressure can cause the fuel not to atomize correctly when injected and cause a fuel knock or tapping sound.

 

Oil pressure gauge would be nice, if a rod is going out you will notice a drop in pressure across the board, normally about 10psi at all speeds and the tap.

 

The oil pressure guage would be great. But if I had low oil pressure, don't you think my oil light would be on or flashing from time to time? And why is there oil on top of that cylinder(1) only?

 

rod knocking from my experience is when you rev it mor than 1000rmp it starts to hear a knocking noise ..not really jerking but a loud knocking noise..it happen to me but in a good way at least my whole block and head is fully built.

 

My head and block is fully built also. But that doesn't mean anything. It could still break.

 

I didn't mean it that way, what I ment was in my orginal block it ate a rod bearing so it had a knocking noise..so i than replace my stock motor with a brand new built motor..so i guess what i what iam trying say its a blessing and a curse at the same time lol

 

I know what you ment. I am just pulling your chain.

 

from the sounds of it with your fuel pressure low the knock sound might be just that, fuel knock. might not be, but the low pressure is a problem for sure. get that fixed first and see what that fixes

Or Your sound and the car driving badly may not be the same problem. if the sound goes away when the car warms up its because the oil is to tick to get to where it needs to be to protect that part while cold. I have the same issues on my 2g right now. its really loud but in a min when the oil gets warm then it goes away. Yours should more like lifter tick to me but look at where the sound is coming from.

still fix the fuel pressure first though as it could be all your problems