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Discussion Starter #1
I'm experiencing an extremely unusual amount of knock on my NA 3000, and cannot figure out why.

Car is 94 VR-4, with 94 VR-4 Harness, and Chromed V2 PNP for a 94 car, with TT Rom
NA Swap
275CC High Impedance Injectors (Resistor deleted)
10.8:1 Compression
3SX Adjustable Cam Gears
Long Tube Headers
TT Upper Plenum
Pump 93 W/ 15% Ethonal
Logging on Evo Scan 2.9

I'm experiencing a ton of knock, mostly in mid range RPMs. I'm seeing 15-20 counts of knock tapering off to <10 as RPMS increase if I keep my foot in it, I've added fuel and pulled timing considerably, so much that now I am just running what is basically a California Spec SL Timing and Fuel Map for both high and low octane, and running as rich as 10.8AFRs from 5,500+ RPM to redline, and 18-24* of Timing

but I'm also seeing alot of knock during light to mild load situations, just cruising say up hill in 5th gear at 2500-3,000rpms (about 60-65mph) Knock often starts to build, even though I'm only using 30% Throttle

If I roll into it in 3rd gear from 5500rpm or higher, it will carry all the way to 8,000RPM with less than 2 counts of knock, often zero, as soon as I upshift, I will get a huge spike in knock, as much as mid 20's and it will taper off slowly if I keep my foot it.

I have Throttle Tip in Timing Reducer set at 7*
Accel Enrich is set at 9.0

On my old NA Setup I struggled to make the car experience knock of any kind. I was running 12.4:1 AFR's with 30* of Timing at Redline on the same Pump 93, Throttle Tip in was 1*, and Accel Enrich was set way lean to like 18.0:1, and the car was about the same compression... The car was extremely happy like this... So my only thought it is that something must be wrong somewhere that I cannot find.

I'm almost wondering if its my new ChromedECU, The CEL on Knock function isn't always working, even though EVOscan shows tons of knock. unless something is wrong with EVOScan or I am using the wrong knock display? I also does not look like the ECU is actually pulling any timing or adding a ton of fuel even when I'm showing 20+ Counts mid pull.

All Thoughts are appreciated...
 

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First thing I'd do is determine if it's actually picking up knock, or manufacturing it in software somewhere... Plug in a spare sensor, jumper the housing to ground, and insulate it from any noise or vibration source. if it still registers knock counts then, it isn't real...

If it is real, I'd look for a single lean cylinder... Possibly a bad injector. There's also the possibility you just got a crap sensor that's going nuts for no real reason.
 

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SDSU Alumnus
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What is the condition of the shielded ground? Also, have you ruled out phantom/false knock? One easy test is running race fuel (for those reading that are unaware)

-sent from my Galaxy Note 9
 

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Discussion Starter #4
Race
First thing I'd do is determine if it's actually picking up knock, or manufacturing it in software somewhere... Plug in a spare sensor, jumper the housing to ground, and insulate it from any noise or vibration source. if it still registers knock counts then, it isn't real...

If it is real, I'd look for a single lean cylinder... Possibly a bad injector. There's also the possibility you just got a crap sensor that's going nuts for no real reason.
Not a bad idea, and yeah probably next weekend I will swap the sensor

What is the condition of the shielded ground? Also, have you ruled out phantom/false knock? One easy test is running race fuel (for those reading that are unaware)

-sent from my Galaxy Note 9

One of the next steps I was thinking to take, unfortunately the nearest gas station with 110 at the pump was 40 minutes away and it was too late for me to get out there last night.
 

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+1 for the race gas test and injectors. I had really bad knock that i could not figure out (though on a TT) and i finally put in race gas to confirm it was fuel related and the knock went away. Pulled the injectors to have them flow tested and cleaned, and the spray pattern on 2 was characterized as "dripping" while the others were "poor" at best. Some were also flowing as little as ~250 cc and they were 550cc injectors. They had about 100k miles on them. Before the injector cleaning, no amount of adding fuel on pump 91 would make the knock go away, even down to 10.0 AFRs.

If the knock goes away on race gas that should basically confirm it is real knock and it is likely fuel related.
 

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1G Foglights b!tches
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+another for race gas. You all tree'd me
 

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Is it a converted sohc ecu? I’ve seen tons of knock sensor related issues with the converted ecu’s.
 

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So what oe ecu did he convert? Either 98/99 Dohc 3s, or a few different sohc boards are used. The sohc boards are the ones I’ve seen have issues with the knock circuit, it has to be added.
 

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Discussion Starter #10
I thought with the Plug and Play ECU's they were his own new boards that he made/Had made, not Mitsubishi ones. They definitely do not look like any OEM Mitsubishi ECU I've ever seen inside.
 

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I have a like new OEM knock sensor. I switched to a Bosch flat response if you're in need of one hit me up.
 

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Discussion Starter #12
For the most part figured out my problem. I'm just an idiot per usual... After i spent the money on a bunch of random parts to throw at the car of course..

The car ran fine before trans swap so I gave that fact too much credit to not be related to my problem.

Found one of my cam gears slipped, tossed a couple extra inch lbs on all the bolts for all 4 gears
CAS lockdown nut was left loose, so cas went way out of adjustment. Which made me realize the Timing Degrees I see in the log do not change based on where the CAS is set - So spent some time with the Timing Light, and set it correctly.
also was having some idle issues, swapped to a spare throttle body with a FIAV Bypass plate installed - that fixed that.

Car runs great again - feels like it picked up a solid 20hp all through the rev range, leaned it back out to the low 12's without issue up top.

still getting a spike in knock when blipping the throttle hard, but only 5-8 counts and now it drops to zero almost instantly where before it would be 20+ counts and slowly fade.

pulling vaccum at the top of the rev range so time to upgrade to my big boy manifold and throttle body I think.
 

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1G Foglights b!tches
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Might be wise to drop the pan to check bearings after bearing on it with lots of knock.


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