AnthraciteTypeS

Here’s the rundown of a problem Ive been stuck with for the last 3+ years..

Bought my 03 AT cls 4 years ago. Was doing some wot runs on the highway one night (again, yrs ago) and I don’t know what happened, but the motor didn’t like it.. pretty sure it wasn’t an overrev because obviously there’s a limiter. Car developed a loud knock from the top end and threw a cel. Scanned it and it came back as a random misfire on every cylinder. Come to find out I had broken a rocker arm on one of the heads. This is obviously what was causing the knocking. Got it replaced along with a valve adjustment as the car was due for one anyway. Car ran fine, smooth idle, no cel, etc (so I thought). Here’s where the problem starts. The car was 110% FINE in every aspect until you bring it over 5500-6000rpm’s (basically into vtec). It then makes a weird grinding? noise is the best way to explain it from the affected head, has a serious loss in power, cel flashes and again throws a misfire code which when cleared, is fine until you bring the motor up to those rpms again. No compression loss, no gas mileage decrease, no noises otherwise, etc. The person that replaced the rocker arm assumed I had a very slightly bent valve that wasn’t showing any loss in compression and this was my problem. I just let it go for 3 years and didn’t beat on the car because it was my daily driver and I was too lazy/didn’t want to invest the money into fixing the problem because 99% of the time as I said as long as I didn’t beat on the car..it was fine. FAST FORWARD 2 months ago.. the auto tranny blows (who knew??), I had been planning a 6mt swap for a while and finally had all the necessary pieces to complete the swap, which I did. The heads on the 6mt motor were bad though, so I sent the auto heads to a local machine shop recommended by my friend to find out what the story is with them. They disassemble both heads, do a valve job, grind the seats, clean them, charge me $300 and tell me they didn’t find ANYTHING wrong and there are no bent valves in the head. Fine. I buy all new gaskets, valve seals, etc and put the heads on and am having……now excuse my language here: THE SAME FUCKING PROBLEM to a tee (now with the 6mt and a different bottom end which rules that out as the problem). Naturally I called the machine shop, explained the situation, and they basically told me to get bent and there’s nothing wrong with them. Next week a local who is supposed to be really good with J’s is taking a look. Does anyone have any idea what the hell might be causing this? I’m starting to think it’s something in the vtec assembly.. I could try and get a video but I really don’t wanna beat on her with this problem with fear of damaging something further. Thanks for reading and thanks for any ideas you hardcore J guys can offer, I just need to get this fixed!

typeR

my car did exactly this when my cat fouled ! easy way to see is un bolt exhaust from cat and go WOT if she flies its the cat which BTW is covered under warranty like 8yr 100K something like that if your not covered go with a hi flo from excelerate

richardparker

iTrader: (7)

Do you have pictures of the rocker ?
What about the cam lobe from the problem rocker ?
Were the lost motion assembly's easy to move ?
I would like to see the cam

AnthraciteTypeS

I don't have pictures of the rocker or cam and not sure which rocker it was

NSXNEXT

iTrader: (2)

Yeah sounds like a camshaft related issue. When the car hits vtec it switches to alternate lobes on the camshaft and changes the cam's timing. Maybe have the camshaft swapped out with a known good one.

typeR

change over is at 4800 if it were vtec engagement issues itd be happening there ...5500 is however one of the fail ssafe rpms like limp/park/neutral fuel cut ... consider looking at the cat for giggles

AnthraciteTypeS

It's not the cat. I can rule it out because the car was running awesome with the 6 spd heads until I accidentally misshifted and bent a ton of valves the 2nd day the car was done, this is the reason I said the heads were bad in my original post, they weren't really bad.. I just destroyed them lol. The problem is 100% in these auto heads..just don't know where!

civicdrivr

iTrader: (9)

Just want to verify:

-You over-reved when you had the auto tranny?
-You swapped the block but kept your old auto heads (that were rebuilt)?

typeR

https://acurazine.com/forums/showthr...ght=CAT&page=2

typeR

can any of this be the sensor variation of the auto heads and 6mt

AnthraciteTypeS

Morgan, to verify.. I swapped the entire 6mt longblock in. Bent valves the 2nd day it was done due to a mis shift. Sent my auto heads to the machine shop to be inspected so I wouldn't have any downtime. Swapped the front cam sensor from the 6 spd head to the auto head and installed my old AUTO heads. Having the same problem now as I had all along with the auto heads.

typeR

arent the cam gears different from the 6mt to auto ?

AnthraciteTypeS

Yes, the gear was also swapped. Forgot to add that

civicdrivr

iTrader: (9)

Ok, so you over-revved with the new engine - gotcha.

Are you 100% sure it is timed correctly?

AnthraciteTypeS

Yes 100% timed correctly. It's something in the head, I just dont know what The more I'm thinking about it..it could be a worn lobe from what I've been reading

StreetKA

iTrader: (8)

PM me i have my heads for sale i will let them go cheap... i could even meet you half way. you're in CT right ? it must be related to that rocker that broke maybe there is other one that is messed up...

i said that too not long time ago :P

A418t81

iTrader: (1)

Sounds to me like it's a VTEC issue. The ECU knows when vtec is supposed to engage and it enriches the fueling to compensate for that. If the system doesn't engage, then it actually runs really rich and will cause the engine to misfire and break up. Sounds like what is happening, probably just on one head too. I would make sure your engagement pins are all there, and moveable, or that there isn't cam damage. Also the oil passages that actuate the engagement pins can become clogged. Pretty much all of this requires the head off to inspect though. If you can trace it to the particular head with the issues, it honestly may just be cheaper and less headache to buy another used one for a couple hundred bucks and be done with it.

typeR

vtec engagement is at 4800 rpms things like low oil level will actually cause fuel cut to occur at the vtec change over point however park neutral limp has a 5500 rpm trigger it does not sound vtec related unless he is off on the what rpm this starts

fuzzy02CLS

iTrader: (2)

Easy... Fix the 6mt heads & put them on there. Obviously if the car ran fine with the 6mt heads & you put the auto heads back on & the problem comes back it's the auto heads that are a problem somewhere.

AnthraciteTypeS

Obviously, don't you think I know that? Not so "easy" because I don't have a few hundred MORE to fix the 6mt heads. I just shelled out 300 to have the autos looked at, reground, and cleaned. Id like to be able to leave them on the bottom end and fix the problem at hand...

A418t81

iTrader: (1)

Yes, I am well aware of when the vtec engagement is. The fact is, that the VE of the engine falls off hard as it continues to rev up towards 6 grand on the small cam lobe. As the VE falls off, the AFRs continue to fatten because the ECU is tuned for the VE of the engine on the hot cam lobe. Around 6k is where I would expect the mixture to become rich enough that he starts having misfires.

My brother and I had Evos at the same time. We both had cams. During his cam install, he accidentally knocked one of the lifters off the hydraulic lash adjuster which basically made that intake valve inoperable. The car had a bad misfire around 5800 rpm that we couldn't make go away. Looking at the plugs, it was obvious which cylinder it was, and no amount of decreasing the gap fixed the issue. We ended up pulling the valve cover, and there was the problem. That cylinder was only getting 1 intake valve open, which in turn caused the fuel mixture, especially high up the the rpm range, to be WAY to rich since it was in essence only receiving about half of it's normal air flow...which caused bad misfiring. Opening one valve down low in the rpm range doesn't affect anything because the valve is open long enough that most of the required flow can enter through one...it's in the higher rpm range that multi-valve arrangements shine.

I suspect something similar is going on with the valve actuation in one of his heads. Either the vtec mechanism is screwed up on a cylinder, or the valve actuation itself (the lifter or the like) is to blame.

Also, just because the cylinder head shop said everything was Ok, doesn't mean it necessarily is. Most of those guys are idiots from painful personal and close friend experiences.

AnthraciteTypeS

Agreed, definitely let them have it on the phone.. nothing much a can do though. Shitty situation

typeR

http://www.streetfire.net/video/sorr...een_173657.htm

in this video just before the 1-2 you can here a mini fuel cut... on my car i would loose about a quart a month of oil it was easy for me to tell when i was low because at 4800 ish it would actually fuel cut and if it got low enough it would cut multiple times just like if reving to 5500 in park .. worse if turning a corner for obvious rreasons ... however my car did very much what your describing and got increasingly worse when my cat fouled ... id like to see you consider unbolting the exhaust in front of the cat and just run the car with those two pipes seperated from eachother just to rule it our ... or do what i did first ...try a known good ECU , nope not it , try coil packs nope not it ,new plugs nope not it , fuel pressure test ,nope , leak down nope ...someone here suggests foulded cat try unbolt ...BINGO ! just saying


BTW i hear a metalic maybe sorta grinding sound before hand and leading upto ...it was peices of my cat rattling around until the flow got enough to pull them in to the melted deformed substrate causing more restriction at which point the car would go no furthure and dash board lights up