Lean and showing knock - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

southern0815 · 07-31-2016, 11:55 AM

Sr20det it's been running good until last night noticed my power fc showing it knocking under boost and running lean at idle and light throttle. It was idling at 13.8 now idles at 14.6-15. Anyone have this problem or know what tests to do before I just start doing useless tests? Also no sounds from engine or loss of power.

jedi03 · 07-31-2016, 05:20 PM

How do you have the pump wired?

southern0815 · 07-31-2016, 05:24 PM

It's wired as what factory was not sure what to call it it was good for the past 4 months until last night when I got on it.

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jedi03 · 08-01-2016, 07:25 AM

hard wire with a relay and see what it does...also do you have a walbro yet?

southern0815 · 08-01-2016, 07:26 AM

Yea it's a 255 but wouldn't it show a different fuel pressure if that was the issue?

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KAT-PWR · 08-01-2016, 08:12 AM

Quote:

Originally Posted by southern0815

Yea it's a 255 but wouldn't it show a different fuel pressure if that was the issue?

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Do you have a gauge in car?

Have you done ay maintenance to the car recently? Anything at all?

cotbu · 08-01-2016, 09:16 AM

Knock when there was no knock before or just a different amount of knock?
14.5/7.1 is stoichiometric, so let's say the tuner tuned it on the rich side 13.8.
So at 13.8 you had no knock while in boost?
What was the in boost afr?
(Then add fuel if it's missing or find where the extra air is coming from. Check the injectors, check sparkplug, do a boost leak test, will help find vacuum leaks as well. Check 02sensor check mafs and filter.)

What are the afr at 2500rpm any knock, what about full throttle afr? Have they changed as well or is there just knock present?
Have you done a tune up?
The information you provided with the afr, doesn't really suggest a problem other than you had a richer idle before.

Call your tuner, tell him you're knocking.
Try a better summer blend of high octane gasoline.

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*brndck* · 08-01-2016, 10:02 AM

start by inspecting all vacuum lines, and check for vacuum/boost leak

southern0815 · 08-01-2016, 10:06 AM

I'll check the afr for the Rpms when I get home. And check for any leaks when I get brake cleaner to spray. I have yet to hear any unusual noise just the power fc knock reading goes up.

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southern0815 · 08-01-2016, 02:44 PM

Thank you for the help but so so you know, I have no idea what it was it did it today, I stuck my hand to try and find the knock sensor tried to loosen it but too tight started up and everything is back to normal.

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jedi03 · 08-01-2016, 03:18 PM

rofl loose gremlins!

southern0815 · 08-01-2016, 03:30 PM

Yep that's what I was thinking

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07-31-2016, 11:55 AM	#1
southern0815 Join Date: Feb 2016 Location: florida Posts: 15 Trader Rating: (0) Feedback Score: 0 reviews	Lean and showing knock Sr20det it's been running good until last night noticed my power fc showing it knocking under boost and running lean at idle and light throttle. It was idling at 13.8 now idles at 14.6-15. Anyone have this problem or know what tests to do before I just start doing useless tests? Also no sounds from engine or loss of power.

08-01-2016, 09:16 AM	#7
cotbu Post Whore! Join Date: Sep 2005 Location: SWFL Age: 49 Posts: 3,318 Trader Rating: (3) Feedback Score: 3 reviews	Knock when there was no knock before or just a different amount of knock? 14.5/7.1 is stoichiometric, so let's say the tuner tuned it on the rich side 13.8. So at 13.8 you had no knock while in boost? What was the in boost afr? (Then add fuel if it's missing or find where the extra air is coming from. Check the injectors, check sparkplug, do a boost leak test, will help find vacuum leaks as well. Check 02sensor check mafs and filter.) What are the afr at 2500rpm any knock, what about full throttle afr? Have they changed as well or is there just knock present? Have you done a tune up? The information you provided with the afr, doesn't really suggest a problem other than you had a richer idle before. Call your tuner, tell him you're knocking. Try a better summer blend of high octane gasoline. Sent from my SM-N910T using Tapatalk __________________ LoverTechnologies "Half Broken Things!"

07-31-2016, 05:20 PM	#2
jedi03 Nissanaholic! Join Date: Jul 2008 Location: albuquerque Posts: 1,836 Trader Rating: (8) Feedback Score: 8 reviews	How do you have the pump wired?

07-31-2016, 05:24 PM	#3
southern0815 Join Date: Feb 2016 Location: florida Posts: 15 Trader Rating: (0) Feedback Score: 0 reviews	It's wired as what factory was not sure what to call it it was good for the past 4 months until last night when I got on it. Sent from my iPhone using Tapatalk

08-01-2016, 07:25 AM	#4
jedi03 Nissanaholic! Join Date: Jul 2008 Location: albuquerque Posts: 1,836 Trader Rating: (8) Feedback Score: 8 reviews	hard wire with a relay and see what it does...also do you have a walbro yet?

08-01-2016, 07:26 AM	#5
southern0815 Join Date: Feb 2016 Location: florida Posts: 15 Trader Rating: (0) Feedback Score: 0 reviews	Yea it's a 255 but wouldn't it show a different fuel pressure if that was the issue? Sent from my iPhone using Tapatalk

08-01-2016, 10:06 AM	#9
southern0815 Join Date: Feb 2016 Location: florida Posts: 15 Trader Rating: (0) Feedback Score: 0 reviews	I'll check the afr for the Rpms when I get home. And check for any leaks when I get brake cleaner to spray. I have yet to hear any unusual noise just the power fc knock reading goes up. Sent from my iPhone using Tapatalk

08-01-2016, 02:44 PM	#10
southern0815 Join Date: Feb 2016 Location: florida Posts: 15 Trader Rating: (0) Feedback Score: 0 reviews	Thank you for the help but so so you know, I have no idea what it was it did it today, I stuck my hand to try and find the knock sensor tried to loosen it but too tight started up and everything is back to normal. Sent from my iPhone using Tapatalk

08-01-2016, 03:18 PM	#11
jedi03 Nissanaholic! Join Date: Jul 2008 Location: albuquerque Posts: 1,836 Trader Rating: (8) Feedback Score: 8 reviews	rofl loose gremlins!

08-01-2016, 03:30 PM	#12
southern0815 Join Date: Feb 2016 Location: florida Posts: 15 Trader Rating: (0) Feedback Score: 0 reviews	Yep that's what I was thinking Sent from my iPhone using Tapatalk