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UNISA JECS pointed out that this connector is the end of the Knock Sensor sub-harness. The two wires on the back side of the sub-harness seen in the video
are Yellow and thin Black. That is, one is yellow and the other is black.
 

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I have ordered this KS sub-harness from wiringspecialties.com It appears to be the same connector as on the SR20DE. S13/S14 KA24DE Knock Sensor Harness - PRO SERIES
I'm questioning whether the cable in the wiringspecialties catalog photo is long enough.

The KS for an SR20DE is the same as that on a KA24DE. I cross-referenced these on Rock Auto.
* THIS HARNESS IS ONLY ABOUT 12" LONG. IT DOES NOT APPEAR TO BE QUITE LONG ENOUGH. *
 

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HEADS UP: THE SUB-HARNESS for a NISSAN KA24DE ENGINE I ORDERED FROM wiringspecialties.com IS ONLY 1 ft. LONG.
12 inches does not appear to be long enough to run from the KS to the harness plug-in next to the Idle Air Control Valve on the same side as the number 1 injector seen in the video. * NOT QUITE LONG ENOUGH *

The reason I have revived this thread is that my high port p10's ECU is flashing the Knock Sensor code 34 and MAF sensor code 12. I have tested both of these circuits and the sensors themselves.
I am still getting both codes at the ECU.

(I verified the voltage running to the injectors, Key ON Engine OFF:
12.19V, 12.15V, 12.15V and 12.14V
And No continuity to ground from each injector connector.)


As for the KNOCK SENSOR:

With ENGINE OFF, I removed the sensor and tested:
1.) the circuit from the ECU to battery ground ( NO continuity, infinite resistance )
2.) KS connector to battery ground ( NO continuity, infinite resistance )
3.) KS connector to terminal #27 on ECU connector ( YES continuity, 1.2 Ohms )
4.) The KS sensor is good, 566 or 569 Ohms.

With ENGINE RUNNING,
1.) KS connector to battery ground, 3.32V
2.) ECU Terminal 27 to battery ground, 2.04V
I made sure the connector was attached snugly onto the KS sensor.

After reattaching the KS sensor, I checked the ECU codes. This time, it flashed the MAF sensor code AND the KS sensor code. I am not sure which one would cause the other, or if one would necessarily cause the other.



The KS sub-harness wire is exposed about 10 inches back from the KS sensor. It appears to be silver-metal wire. The heat shrink sheath is hard and cracked open. Maybe this is the shielded ground wire? Not sure if this would be the reason for the KS Code 34.

QUESTIONS:

Someone who really knows their stuff says they always upgrade to a 2-pin connector, one that has two separate wires, (one signal, one ground).

1. Where should the second wire be grounded to?

2. Assuming part of the existing harness is bad, Which chunk of harness is to be replaced, from the KS connector to where on the harness? Or is just a new sub-harness what is necessary?
3. Where can I buy a sub-harness that is long enough to reach from the KS to the connection on the engine harness?


As for the MAF SENSOR:

The engine barely runs with both the KS and MAF codes in the ECU, so it was hard to test for voltage with the engine WARM and RUNNING, but I managed to keep the pedal down so I could test the wires.

With the KEY ON, ENGINE OFF:

I tested for voltage and continuity on that circuit.

Power supply voltage ----> 10V on both MAF sensor connector, term. B to Terminal 17 on ECU (My other Digital Multi Meter read 11.8V.)

Ground Circuit Continuity ----> YES, MAF sensor connector, term. C to Terminal 17 on ECU

Input Signal Circuit Continuity ----> YES, MAF sensor connector, term. D to Terminal 16 on ECU


With ENGINE RUNNING:

VOLTAGE:

Terminal slot A ---> 0.0V

Terminal B ---> 14.0V

Terminal C ---> 12.78V (Ground wire) After reading this post, I think I need to reground the MAF sensor. HowTo: - MAF reground (pics)

Terminal D ---> 12.11V


The FSM says (With ENGINE RUNNING) to probe Terminal A on the MAF connector and that voltage to ground should be 1.3 - 1.7V.

There are 4 slots on the connector (A-B-C-D) but ONLY 3 wires that attach to it (B-Orange, C-White, D-Orange).

QUESTION: Given there is no wire running to Terminal slot A on the MAF sensor connector, What exactly am I probing for when I probe Terminal A per the FSM's instructions? (Is there actually a wire that would deliver the 1.3 - 1.7V, Where would the 1.3 - 1.7V come from?)
 

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This has been so long ago for me kinda hard to jump in here and recall but all I know is I fixed man 240's Sentra's and G20's with this issue by following what I had posted on here a few pages back I will stress the importance of figuring this out each and everytime was depinning the pin in these instructions this can't be ignored very important step, you should know all the shielded sensor cable ground share a common lug so if one of them goes rouge it will inject voltage into the shielded ground and cause all kinda of problems hence why the depining is crucial or you will chase your tail for a long time


Below is quoted from me "UNISA JECS"

Before doing any of teh below check the component itself by checking the resistance of teh knock sesnor, a good knock sensor reads 560 Mega Ohms thats 560,000,000 ohms

Now you can proceed!

Well I fixed my knock sensor error code problem.

After spending many hours actually days on this **** I finally fixed the problem and the ECU now gives me a code 55 ......

Heres are the diagnosis steps I performed:

1. Disconnect ECM harness connector from ECM.
2. Disconnect KS subharness connector from KS.
3. Check harness continuity between terminal (B) and ECM terminal (27).

Im my case continuity did exist (so good to go right? NOPE) im still getting a code 34 and my knock sesnor is good to go.

Next I pluged everything back together like it should be then:

Step:
1) With a DMM, one probe to ground other back probing pin 27 (Knock Sensor) with KOER and KOEO.

Results = 0.013v (no good) FSM states you should see aprox. 2.5v at idle and or KOEO.

2) I disconnect ECM harness connector from ECM and de-pin, pin 27 from harness connector alltogether.
3) I re-attach the ECM harness connector to the ECM with pin 27 detached from connector.
4) With my DMM I ground one probe and the other to pin 27 and I get 5v, so the ECU is good to go.

So next step:
1) Taking a jumper wire to pin 27 and reconnecting the original (white) KS wire to the jumper wire I instantly lose the 5v (so im thinking why what is causing this to happen (a short to ground etc etc)
2) I take the same jumper wire and disconnect the original (white) KS wire from it and get about 3ft of regular 16 gauge wire and run it directly to the knock sensor subharness terminal (B).
3) I take measurements back at the ECM with my DMM one probe to ground other to pin 27 and I get 2.5v (good to go finally
4) So now I clear the codes and start the car run it for a few seconds and shut it off.
5) Check codes for any errors and all is good (code 55 finally)

If some of you are wondering why I didn't get 5volts when I rewired, its becasue the KS itself is a 0.560M-Ohm resistor and it reduces the voltage down to approx. ~2.5v.

My code 34 was instantanious means I could clear the codes and get code 55, start the car for 1 second then turn it off and check teh codes and I have a code 34, thats becasue it basically had no voltage present of pin 27.
 

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Screenshot_2020-12-03 Knock Sensor Junk .png
 

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Thanks for explaining this again. I will see about removing the "gate" on the ECU connector and de-pinning Terminal 27. To be sure, testing the resistance of a Knock sensor, one touches probe 1 to left male terminal and probe 2 to right male terminal on the Knock Sensor itself, right? I did this and got 566, 569MOhms and am under the impression that my method of testing resistance was correct.
  • Could please you confirm this method of testing resistance on the KS? I've read of folks running one probe to battery ground and the other probe to one of the KS's terminals. (Not 100% sure which method is correct.)
  • Also, when you run the 3ft. of plain, 16 gauge wire from the ECU to the KS, does the lack of a ground wire effect the signal wire in any way,or does it not need a ground wire?
  • Is the KS connector attached to the KS at this point? ---> [QUOTE 2) I take the same jumper wire and disconnect the original (white) KS wire from it and get about 3ft of regular 16 gauge wire and run it directly to the knock sensor sub-harness terminal (B). QUOTE]
 

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The reason for the depining of the ECU at pin 27 was to isolate the circuit which was in fact broken thus the KS signal wire was being compromised because it now had a direct path to ground through the shielded spiral cable stranded braid AKA the shielded ground wire which also shares a common ground lug between all sensors TPS, MAF, KS, essentially all the sensors that use a shielded spiral over the conductor, this is what was causing a short to ground and was very damn tricky to figure out and you won't find it unless you depin 27 and then run a temporary jump from pin 27 at the ECU to the KS sensor directly, this was how I fixed the circuit, I later then ran a shielded proper cable just as it were OEM again but I took the strands from the new shielded cable I ran it to the appropriate ground lug were all the TPS, MAF and KS originally went

I went as far as tearing down an entire engine harness to see up close how all these wires ran an split

Test the knock sensor directly at the knock sensor

The shielded cable only connect to ground at one side of the cable via a junction lug near the (but it runs the whole lenght of the signal wire to protect it along its path, it does terminate a lil before the KS sesnor itself and that is why the subharness general only has a single signal wire and its not stranded for a short length of the subharness) ECU but it does not connect directly to any of the ECU pins, this shielded cable sole purpose if to protect the signal of the conductor wire it is spiraled around such as EMI or what not and run it to ground and keep it out of the sensitive signal conductor inside.
 

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When testing the resistance of a Knock sensor, one touches probe 1 to left male terminal and probe 2 to right male terminal on the Knock Sensor itself, right? I did this and got 566 or 569MOhms and am under the impression that my method of testing resistance was correct.
  • Could please you confirm this method of testing resistance on the KS? I've read of folks running one probe to battery ground and the other probe to one of the KS's terminals. (Not 100% sure which method is correct.)
  • Is the KS connector attached to the KS at this point? --->
    I take the same jumper wire and disconnect the original (white) KS wire from it and get about 3ft of regular 16 gauge wire and run it directly to the knock sensor sub-harness terminal (B).

it does terminate a lil before the KS sesnor itself and that is why the subharness general only has a single signal wire and its not stranded for a short length of the subharness
So it (The Ground wire that becomes a spiral weave shield down on the KS sub-harness) grounds to a lug just before the ECU, but on the other end it becomes a spiral weave of shield wires.
  • What happens at the end of these spiral shield wires, DO they connect to anything at that end of the KS sub-harness, down by the Knock Sensor? (I see one wire, the signal wire, that attaches to the KS connector. Is the ground shield wire weave NOT connected to the KS connector somehow?

A side note: I am also getting the MAF code 12, and the idle is very very low, and eventually the engine stalls. This quote was interesting ---->
because it now had a direct path to ground through the shielded spiral cable stranded braid AKA the shielded ground wire which also shares a common ground lug between all sensors TPS, MAF, KS, essentially all the sensors that use a shielded spiral over the conductor
 

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The spiral shield for all intended purpose covers 95% of the cables overall length it terminate into air at the knock sensor end and the opposite end that nears the ECU is split and daisy chains up with a bunch of other shielded spiral cable
 

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This is pretty cool video showing you the importance of and why only one end is grounded to prevent a ground loop

 

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Thanks for that video.
What is the proper way to test a knock sensor's resistance?
Whey you say you take a jumper wire to pin 27 once you have de-pinned the wire and re-attached the ECU connector to the ECU, How are you able to attach that jumper wire to Pin 27 on the ECU?
1) Taking a jumper wire to pin 27 and reconnecting the original (white) KS wire to the jumper wire I instantly lose the 5v (so im thinking why what is causing this to happen (a short to ground etc etc)
 

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With a multi-meter and generally 1 prob to the center of the knock sensor ring were the bolt goes through and probably the left side pin but do both and your lookig for 56kohms IIRC but you should use the FSM for refference on everything i talked about

I used a spare ECU pin I removed from a spare harness with a couple of inches of wire attached to it for using a jumping and an easy way to make contact with the pin
 

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Ahh, ok. I had been probing both prongs inside the KS's plug. I got 564K Ohms.
  • Is this not an accurate way to test for Resistance?
  • Where can I get a Jumper wire like the one you used to bridge from ECU Terminal 27 to your 3ft. section of 16 gauge wire? I don't have a spare ECU or a spare ECU connector.
  • How do you know that there are supposed to be 5V running from the ECU to the KS? (2.5V when the KS is unplugged) Is this stated in the FSM?
I am getting MORE THAN 2.5 volts testing from Terminal 27 to Ground. I get 3.32V, with no change in voltage, regardless of whether or not the KS is plugged in.
I have a brand new, spare KS that has 560 Ohms of resistance. The existing KS has 564K Ohms.


Currently, when I check the ECU for codes, BOTH the MAF sensor code (12) AND Knock Sensor (34) codes flash in the ECU.
To reset the ECU, I turn the screw clockwise and immediately turn it back counterclockwise. If I turn it clockwise again, pause for a few seconds, and then turn it back counterclockwise, only the MAF sensor code flashes.
Apparently, I can clear the KS code (34) and am left with just the MAF code flashing; however, the KS code comes back, instantaneously, upon restarting the engine.
I am wondering if the MAF code is CAUSING the Knock Sensor code. (You noted earlier that their ground wires, along with the TPS's, ground to a common lug.)

Here are today's results:
(There is continuity between Terminal 27 and Knock Sensor connector.)
KS CONNECTOR ATTACHED to KS
Engine RUNNING:
  • Terminal 27 to Chassis Ground-------> 3.32V
  • Terminal 27 to Battery Ground--------> 3.31V
Key ON, ENGINE OFF:
  • Terminal 27 to Chassis Ground --------> 3.32V
  • Terminal 27 to Battery Ground ---------> 3.32V
KS CONNECTOR DISCONNECTED from KS
Engine RUNNING:
  • Terminal 27 to Chassis Ground --------> 3.32V
  • Terminal 27 to Battery Ground ---------> 3.31V
Key ON, ENGINE OFF:
  • Terminal 27 to Chassis Ground --------> 3.32V
  • Terminal 27 to Battery Ground ---------> 3.32V
KS CONNECTOR STILL DISCONNECTED from KS:
Engine RUNNING:
  • KS connector to Chassis Ground ------> 3.32V
  • KS connector to Battery Ground -------> 3.31V
  • KS connector to Terminal 27 ------------> 0V
  • Resistance, KS Connector to Terminal 27 ---> .7 Ohms
Key ON, ENGINE OFF:
  • KS connector to Chassis Ground -------> 3.32V
  • KS connector to Battery Ground --------> 3.32V
  • KS connector to Terminal 27 -------------> 0V
  • Resistance, KS connector to Terminal 27 ---> .6 Ohms
 

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With a multi-meter and generally 1 prob to the center of the knock sensor ring were the bolt goes through and probably the left side pin but do both and your lookig for 56kohms IIRC but you should use the FSM for refference on everything i talked about

I used a spare ECU pin I removed from a spare harness with a couple of inches of wire attached to it for using a jumping and an easy way to make contact with the pin
Is the spare jumper wire you used like either of these? -----> Alligator Clip to Breadboard Jumper Wire Dupont Cable 20cm Male Female US Stock | eBay
Or did you actually remove the ECU pin that the connector attaches to, and not just the female connector that would slip over the male pin on the ECU?
I am confused because you said you de-pinned Terminal 27, but you showed how to remove the WIRE from that terminal using the special tool you fabricated.
I have the idea that you removed the WIRE from the connector, reconnected the ECU connector to the ECU, and then inserted a jumper wire with a female end that slips onto the male PIN still attached to the ECU, in order to attach the 3ft. section of wire to the opposite end of the jumper wire. Do I have the correct idea?
 

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I am a bit confused.
You said in post #146 Sep 29, 2014:
"Just strip a long piece of plain copper wire and shove it through pin 27 to make contact or you can simple cut the wire and solder it back after if you cant depin it. For testing you can uses regular wire it doesn't have to be shielded."

  • What do you mean by Take the copper wire and shove it through pin 27 to make contact? Are you saying that at this point the wire at Terminal 27 has been removed from the ECU's connector, but the PIN 27 on the ECU is still in place?
  • Are you trying to make contact with the PIN 27 at this point, or has it been removed from the ECU at this point?

This is the only way in my mind that one would be able to shove anything through and make contact with something on the ECU that would deliver voltage.

  • What type of RG-58A/U cable is the sort used for the Knock Sensor harness/ wire, STRANDED COPPER conductor wire OR SOLID, BARE COPPER conductor wire? I looked at you post #165 and referenced the UL 1533 cable drawing. I see that the conductor is stranded copper wire, not a solid, bare conductor wire.
Is it RG-58 A/U cable or is it UL 1533 cable??
Have a look ----->
 

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Hey UNISA,
I am trying to make sense of your instructions from post #164.
  • ----> 2) I disconnect ECM harness connector from ECM and de-pin, pin 27 from harness connector alltogether. (You said "I disconnect . . . pin 27 . . . alltogether." DID YOU SIMPLY REMOVE THE WIRE FROM THE CONNECTOR? OR THE PIN FROM THE ECU TOO?? IF YOU REMOVED THE ACTUAL PIN TOO, HOW DID YOU MANAGE TO DETTACH IT FROM THE ECU??

  • 3) I re-attach the ECM harness connector to the ECM with pin 27 detached from connector. (NO WIRE and NO PIN, OR IS THE #27 PIN STILL ATTACHED TO THE ECU??)

  • 4) With my DMM I ground one probe and the other to pin 27 and I get 5v, so the ECU is good to go. (THIS SOUNDS LIKE PIN #27 IS STILL IN PLACE ON THE ECU??)
Do you have instructions on how to remove the wire and the pin using your special allen wrench tool? Never mind. I found a helpful video ----> VIDEO: Start watching at 6:17 min.
I used a straight test probe like the one seen here. ------> Test Probe Set
 

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..............
Hi UNISA,
Today, I de-wired Terminal 27 on the ECU connector.
The hard pins are attached (soldered) to the ECU, so I could not remove the pin.
I inserted a new, Test wire into slot 27 on the ECU connector and fastened the connector to the ECU.
When testing, I kept one test lead on the end of the TEST WIRE and touched the other lead to Ground, Fuel Injection Harness connector, and KS connector. (Something is telling me this was not the correct way to test the KS circuit, having substituted the TEST WIRE for the stock KS wire at the ECU but not connecting directly to the KS connector.)

With the Test wire in place, I reset the ECU and performed the Self Diagnosis again, and the Knock Sensor code 34 no longer flashed. But I think this was simply because I did not start the engine after I reset the ECU.
I tested for voltage at ECU Term. 27 in order to verify the amount the ECU would be sending to the KS if the Code 34 had never appeared in the ECU.
This amount was 3.32V, not 5.12V.
(However, I did see the 5.12V number recently while testing the voltage delivered to the distributor, which was interesting.)

Previous to substituting a TEST WIRE for the stock Knock Sensor wire at Terminal 27:
TESTING from ECU Terminal 27 to Knock Sensor connector:
  • (ECU connector DISCONNECTED) ----> Continuity , 1.2 Ohms
  • (ECU connector FASTENED) ----> Continuity, .4 Ohms (ENGINE OFF), .6 Ohms (KOEO), .7 Ohms (KOER)
  • (ECU connector FASTENED) -----> 0.0V

With KOEOFF, ECU connector fastened, TEST WIRE IN PLACE:
  • ECU Terminal 27 connector (attached) to Chassis Ground-------> 3.32V
This tells me that the ECU is sending 3.32V (not 5.12V) through the wire attached at ECU Terminal 27.
3.32V were also present during the same test using the original wiring.
  • ECU Terminal 27 to Fuel Injection Harness (F.I.H.) which the knock sensor sub-harness plugs into ------> 3.32V
  • ECU Terminal 27 to KS connector (KS detached) -------> 0.0V
With Key OFF, ECU connector fastened, TEST WIRE IN PLACE:
  • Fuel Injection Harness connector to Chassis Ground ---> YES Continuity, 2.6 Ohms
  • Knock Sensor connector to Ground --------> NO Continuity, Infinite Resistance
  • Knock Sensor Sub-harness, end to end -------> YES Continuity, 14.6 Ohms
  • ECU Terminal 27 to KS Connector -------> NO Continuity, INFINITE Resistance
  • ECU Terminal 27 to F.I.H. connector -----> NO Continuity, INFINITE Resistance
This "NO Continuity, INFINITE RESISTANCE " was due to the incomplete circuit between the ECU and the original KS wire, which has been detached from the ECU.

With Key OFF, ECU connector DISCONNECTED, TEST WIRE IN PLACE:
  • ECU Terminal 27 to KS Connector -------> NO Continuity, INFINITE Resistance
  • ECU Terminal 27 to F.I.H. connector -----> NO Continuity, INFINITE Resistance
I am thinking the Knock Sensor sub-harness is bad, due to the higher resistance (14.6 Ohms) on it from end to end and due to the lack of voltage (from ECU Term. 27) present at the KS connector, despite 3.32V having been detected at the point just before the KS sub-harness connection, at the Fuel Injection harness. Also, the ECU was sending 3.32V from Terminal 27 (as tested to Ground), but none of it was detected at the KS connector, despite the ECU connector being fastened.

What do you make of this? Did I fail to carry out any necessary test?
 

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UNISA,
So next step:
1) Taking a jumper wire to pin 27 and reconnecting the original (white) KS wire to the jumper wire I instantly lose the 5v (so im thinking why what is causing this to happen (a short to ground etc etc)
2) I take the same jumper wire and disconnect the original (white) KS wire from it and get about 3ft of regular 16 gauge wire and run it directly to the knock sensor subharness terminal (B).
3) I take measurements back at the ECM with my DMM one probe to ground other to pin 27 and I get 2.5v (good to go finally
4) So now I clear the codes and start the car run it for a few seconds and shut it off.
5) Check codes for any errors and all is good (code 55 finally)
Here, in STEP 2, when you said you ran 3ft. of plain wire directly to the Knock Sensor Harness connector and then took measurements, DID YOU NOT RECONNECT THE KS CONNECTOR TO THE KNOCK SENSOR BEFORE YOU STARTED THE CAR FOR A FEW SECONDS??
HOW IS IT THAT YOU DID NOT GET CODE 34 WITH THE KNOCK SENSOR DETACHED FROM ITS CONNECTOR??


I ran the test wire from ECU Terminal 27 to Terminal B on the KS connector (which is no longer connected to the KS at this point), reset the ECU, performed the SELF-DIAGNOSIS, and the KS code 34 flashes along with the MAF code 12.
 

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I switched out the ECU with a known good one, and the good one shows 5.11V at the Terminal 27 ECU (probing Term. 27 and chassis ground). The other ECU was showing 3.32V at Terminal 27. My current KS sub-harness wire is kinked and the shielding ground wire is exposed. I have a new one on the way. I will switch it out and see if I get 5.11 V. at the KS connector.
 

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It tends to happen where the injector harness splits and runs down the intake runner on high port motors. I'm not sure howLow port harness is routed, but the wire will be swelled up in the spot where the short is.
I have a highport and recently replaced the KS subharness. The KS is good. I think its resistance was about 556 Ohms. The KS code 34 is the only code the computer is generating.
Where exactly does the injector harness split and run down the intake runner? What is "the intake runner"?
 
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