really bad knock all of a sudden
Thread Starter
Joined: Feb 2007
Posts: 9,486
Likes: 67
From: Melbourne, Australia
really bad knock all of a sudden
Hi Guys,
ok so here is the deal:
last week i was crusing on the fwy in 5th... had to overtake so I dropped to 3rd and floored it... it wasn't the cleanest change, anyways i could hear knock - tap tap tap - so i backed off... logs confirmed i hit 7 -> 14 -> 22 knocksum ~4700rpm 24psi...
fast forward to today. I have JUST installed the turboxs downpipe and cat.. still have a stock catback...
so I got out todo some testing, not using my normal flat road, just some hilly stuff around my house:
here is the first log:
So I am thinking hrmm maybe the downpipe+cat is making me spool faster and hitting cells I normally wouldn't..
So I add some fuel and take some timing out - and redo..:
WTF - so I take some more timing out and add some MORE fuel:
anyone got any advice? this car has been tuned for 24psi in 4th gear and i never see knock higher than 3 doing that... (and thats only up top as well)
ok so here is the deal:
last week i was crusing on the fwy in 5th... had to overtake so I dropped to 3rd and floored it... it wasn't the cleanest change, anyways i could hear knock - tap tap tap - so i backed off... logs confirmed i hit 7 -> 14 -> 22 knocksum ~4700rpm 24psi...
fast forward to today. I have JUST installed the turboxs downpipe and cat.. still have a stock catback...
so I got out todo some testing, not using my normal flat road, just some hilly stuff around my house:
here is the first log:
Code:
sample RPM PSIG Timing Knock Load IPW TPS AFR 7383 2949 9.6 16 0 147 10.088 86.7 14.0 7384 2961 11.3 15 0 157 11.344 86.7 14.1 7385 3012 13.0 13 0 169 13.04 86.7 13.6 7386 3031 15.1 11 0 181 14.808 86.7 13.4 7387 3066 17.0 10 0 197 16.64 86.7 12.9 7388 3109 19.1 8 0 214 17.824 86.7 12.9 7389 3180 21.3 4 7 225 18.752 86.7 12.2 7390 3184 22.5 1 14 235 19.624 86.7 11.9 7391 3215 24.0 -5 28 243 20.512 86.7 11.4 7392 3258 24.7 -7 30 243 20.48 86.7 11.3 7393 3297 23.6 -4 28 222 15.568 86.7 11.1 7394 3227 6.5 10 28 118 1.28 86.7 10.0
So I add some fuel and take some timing out - and redo..:
Code:
sample RPM PSIG Timing Knock Load IPW TPS AFR 4967 2801 10.8 15 0 147 10.032 86.3 14.9 4968 2848 12.1 13 0 155 11.104 86.3 14.8 4969 2883 13.8 12 0 165 12.584 85.9 14.5 4970 2914 15.5 10 0 175 14.096 85.9 14.2 4971 2961 17.2 7 0 190 16.376 85.9 14.1 4972 3016 19.1 6 0 204 17.544 85.9 13.2 4973 3027 20.7 5 0 213 17.976 85.9 12.8 4974 3086 22.5 4 0 222 18.576 85.9 12.4 4975 3156 23.3 4 0 225 18.44 85.9 12.3 4976 3141 22.8 4 0 225 17.944 85.9 12.1 4977 3211 23.3 3 7 229 18.664 84.4 11.9 4978 3238 23.1 -2 14 233 18.56 84.4 11.1 4979 3316 22.8 -4 21 235 19.296 84.4 11.6 4980 3348 23.9 -5 25 239 19.776 84.4 11.6 4981 3383 24.0 -5 23 230 18.36 29.7 11.3 4982 3328 13.7 0 22 156 4.776 29.7 10.2
Code:
sample RPM PSIG Timing Knock Load IPW TPS AFR 1366 2660 10.4 14 0 152 10.4 86.7 14.5 1367 2699 11.5 13 0 158 11.2 86.7 14.3 1368 2738 12.6 11 0 166 12.1 86.7 14.3 1369 2746 14.0 9 0 173 13.3 86.7 14.0 1370 2777 15.5 7 0 183 14.5 86.7 13.3 1371 2820 16.9 5 0 195 16.3 86.7 12.9 1372 2859 18.4 3 0 209 17.4 86.7 12.4 1373 2914 19.8 2 0 217 18.4 86.7 12.2 1374 2883 21.7 -4 14 225 19.2 86.7 11.3 1375 2941 22.7 -16 17 232 19.8 86.7 11.4 1376 3027 23.2 -5 13 229 19.0 86.7 11.3 1377 3012 21.6 -4 13 194 14.1 86.7 11.5 1378 2793 1.9 25 13 92 1.3 16.8 10.8
Thread Starter
Joined: Feb 2007
Posts: 9,486
Likes: 67
From: Melbourne, Australia
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anything else is loose in the engine bay ? maybe some other vibration or loose items could be contributing to the knock but in your case, initially what i see is that afr could be a little lean but should not cause such high counts of knocks, timings looks fine. it could also be some bad quality fuel which i experienced before. try lowering a bit of boost for time being until it is rectified to be on the safe side. keep us updated with the plugs. are you still using stock ones or heat range 9 ? mine is still stock and so far things are alright for me except 2 or 3 counts of occasional knocks, i;ve been recently lowering & straightening my boost curve. will try to crack my brains and see if something pops up :P
Tephra,
I hate to say this, but you need to hope its the relay with all your might. If not, it might be a ring. My friend's car did this, and his symptoms were very similar to Boostd4's Evo X. There is a whole thread dedicated to Boostd4's car here, I think you've actually posted in it and might remember it well. https://www.evolutionm.net/forums/ev...ower-loss.html
My friend's car did not hammer a spark plug closed, but it knocked audibly and he ended up trading it in after we tried everything to isolate it. We too thought it might be an installed part, and returned everything to stock. I finally had to go to a lesser than stock map to quiet the knocking to less than 5 counts, running heaps of fuel, low timing, and minimal boost. Before that, once he would spool and get going, it would hit 18+ counts and fall over and die powerwise. I drove it, and it felt very unnatural, like I was not in the throttle at all when the knock came on (before immediately lifting).
While these incidents were isolated before, they are becoming more and more common. It has me rethinking longterm ownership of the X and wanting to get back in an Evo IX. Please keep us updated.
Edit: As mentioned, some cars have it worse. They will close a plug, show visible piston damage with a borescope, and the very worst ones experience catastrophic engine failure. If its not the relay, start investigating the short block.
I hate to say this, but you need to hope its the relay with all your might. If not, it might be a ring. My friend's car did this, and his symptoms were very similar to Boostd4's Evo X. There is a whole thread dedicated to Boostd4's car here, I think you've actually posted in it and might remember it well. https://www.evolutionm.net/forums/ev...ower-loss.html
My friend's car did not hammer a spark plug closed, but it knocked audibly and he ended up trading it in after we tried everything to isolate it. We too thought it might be an installed part, and returned everything to stock. I finally had to go to a lesser than stock map to quiet the knocking to less than 5 counts, running heaps of fuel, low timing, and minimal boost. Before that, once he would spool and get going, it would hit 18+ counts and fall over and die powerwise. I drove it, and it felt very unnatural, like I was not in the throttle at all when the knock came on (before immediately lifting).
While these incidents were isolated before, they are becoming more and more common. It has me rethinking longterm ownership of the X and wanting to get back in an Evo IX. Please keep us updated.
Edit: As mentioned, some cars have it worse. They will close a plug, show visible piston damage with a borescope, and the very worst ones experience catastrophic engine failure. If its not the relay, start investigating the short block.
Last edited by Noize; Jan 30, 2010 at 07:24 AM.
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Joined: Jan 2010
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From: on the street
i think my evo x knock too guys, the car had been tuned properly making 350whp at 24psi, it drive pretty good for about couple months thou. When iam on 4th gear one day, i floor it, i see 24psi but there 's some weird noise on the engine near redlined. Sound like something vibrate on the engine bay. I check for loose under the hood, nothing is loose.
Is this all been on one tank of fuel? I had a similar situation, after cutting boost way back throwing a ton of fuel at i could only get to about 6 counts. I was at a half tank went and filled up and threw in a can of the Lucas octane booster ( I know most are snake oils but I had to try something) cruised around for fifteen twenty miles, next log no knock. Now I'm working back to my old map.
Since you have the sensor isolated, is there any chance of a bad load of fuel? Did you use a different station?
With my friend's car, it was catless, and we put in some 6 gallons of 110 octane. If there was a bad fuel question, this would cure it immediately and take the knock away. If there is some internal breakage, the knock would remain.
Let us know what else you find out.