racinghonda

I know, I know another noise thread. But let me explain. I have been getting a faint rattling noise from the engine bay whenever I have part throttle on (10-20% throttle) and didn't think anything of it because I had full compression and everytime I pull out my magnetic sump plug, it comes out clean. Also sent the oil to a lab and it came back ok.

In preparation for a track day I put the car on the dyno and *shock* it was a good 15HP at the wheels down on the last time I was on, the car is making the same power as a stock H22A

My tuner then put a pressure guage on the intake system to check if it was a clogged filter but he recorded virtually no pressure drop. AFR was normal, the dyno plot looked just like my previous best result, just that the curve was lower. A bit down at the top. My tuner thinks I might have a blocked Cat.

I go the track day and it ran faultlessly all day (did 30 laps, 3.4km track). In the last session I noticed that the rattling was louder as I was pulling onto the track and slowly built up speed. I did my best time in the last session, engine worked normally. I also had to drive 200 miles home. No problem.

But now I have this loud rattle/knocking noise. But it only happens on a light throttle. It is not RPM dependant, seems to be throttle opening dependant. I replaced my fly wheel and clutch after the track day too but noise was there before and after. It sounds like it is coming from the intake side of the engine bay. It will rattle no matter the rpm, as long as I have the throttle open slightly. If I shut the throttle the noise goes away instantly.

My optimistic guess is that the cat has really broken and when I open the throttle slightly the broken part bounces around the cat violently due to the pulses/gasses. But when I open the throttle more the gas pressure holds the broken piece in place.

I rechecked the compression and it is unchanged from my previous 5 test (over 3 yrs), 210PSI across all cyls. I pulled the magnetic sump plug and there is no metal on it.

So, is it the cat? Or could it be the engine?

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I you no longer go for a gap that exist, you're no longer a racing driver" Ayrton Senna.

 

D_Ludesions

sounds like the cat

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Sash

"When you start down the slippery slope of actually adding HP to your engine, it is like trying crack for the first time. The added rush feels awesome, but soon enough you will get used to that dosage, and the amount must be upped. " - author unknown

racinghonda

Could it be a loose valve lifter lock nut? Would explain the loss of power if a valve isn't opening fully. But then wouldn't it rattle all the time?

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I you no longer go for a gap that exist, you're no longer a racing driver" Ayrton Senna.

racinghonda

Well, I have replaced the cat, the noise is still there. Had 2 mechanics listen to it and they say that it's not a bearing noise. They thought it might have been the valves, so I did a valve clearance inspection and they were all within spec. I had a look at the valve train and couldn't see anything wrong, no scoring on the cams etc.

Engine pulls normally still, I have Vtec etc. Now I am really stumped.

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I you no longer go for a gap that exist, you're no longer a racing driver" Ayrton Senna.

racinghonda

Well, I got my oil test results back and it was worse fear realised. A stuffed bottom end.

http://www.racinghonda.com/pictures/...lTest_0508.pdf

Getting a low kay JDM H22A installed in the next couple of weeks.

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I you no longer go for a gap that exist, you're no longer a racing driver" Ayrton Senna.

natemanas

Well looks like a recurring issue is the bearrings and thrust washers..
I hope thats not too terrible to fix.. I'm still learning..

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I used to be different, Now I'm the same.