Author Topic: low o2s  (Read 108 times)

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Offline shmed

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low o2s
« on: August 05 2017, 06:13:02 PM »
what could be. the cause of low o2 readings at idle. like in the 100.  range?   new. sensor
an the Wideband to read 17.9. then shut off?


new motor roller cam roller lifters.   tt5.7 chip.  50 lb injs   stock mass meter

Offline Steve Wood

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Re: low o2s
« Reply #1 on: August 05 2017, 06:37:42 PM »
sounds like a big air leak somewhere. 
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Offline Scoobum

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Re: low o2s
« Reply #2 on: August 05 2017, 08:07:07 PM »
Only thing outta whack is your IAC count at 40. Should be 10-20. I'm Scooby Doo asking questions on the other board. You in Toronto? I'm retired...and can drop by.
109 STD Bore Short Block-Balanced Rotating Assembly
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Offline Scoobum

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Re: low o2s
« Reply #3 on: August 05 2017, 08:19:08 PM »
Just what I've noticed swapping 02 sensors. Once the engine comes up to temp...it'll take a couple of minutes for everything to learn. What I do is watch the 02's on the laptop via the graph.
109 STD Bore Short Block-Balanced Rotating Assembly
Stock Crank
Stock Pistons
Stock Rods
Stock Timing Chain/Gears
212/212 Flat Tappet Cam
8445 Race Ported Big Valve Heads
Stock Rockers
5.7 TT 110 Race Chip
Built 2004R
AC 16930
6262 JB

6.72 at 104.67-1.58-25 PSI

Offline shmed

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Re: low o2s
« Reply #4 on: August 05 2017, 08:41:03 PM »
Thanks for the info brad.    id love for you to check out this wreck...
but I'm about 3-4 hours west of Toronto.
So what I. did was block off the exhaust an the intake    put about 5 psi compressed air into the intake track an started soap testing everything ..
when I was about to give up I heard a hiss , so.  I see someone installed an aluminum ear block off plate.   that thing was singing...   offf that. pos came on went a. crude piece of 1/8 steel plate I quickly ground up.   a little silicone,  an fired it up. not up. to par but o2s are in the 600 area. an the Wideband 14ish,


thanks again. Steve an Brad
Dave


Offline Scoobum

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Re: low o2s
« Reply #5 on: August 05 2017, 08:48:12 PM »
What town/city are you in?
109 STD Bore Short Block-Balanced Rotating Assembly
Stock Crank
Stock Pistons
Stock Rods
Stock Timing Chain/Gears
212/212 Flat Tappet Cam
8445 Race Ported Big Valve Heads
Stock Rockers
5.7 TT 110 Race Chip
Built 2004R
AC 16930
6262 JB

6.72 at 104.67-1.58-25 PSI

Offline Steve Wood

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Re: low o2s
« Reply #6 on: August 05 2017, 09:45:49 PM »
That egr plate has burn a lot of us
Steve Wood

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A lot of broken parts does not make you a racer; it makes you a slow learner.

Online good2win22

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Re: low o2s
« Reply #7 on: August 05 2017, 10:37:01 PM »
EGR block off has gotten me twice.  Once on a friends car and then on my barn motor. Then again, I always get gotten
Jason

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Offline Scoobum

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Re: low o2s
« Reply #8 on: August 06 2017, 07:53:42 AM »
I believe this Champion intake I got from my ATR buddy is filled...but I put a fancy ass Turbo 6 cover over it and sealed it as tight as a nuns...well... you know.
109 STD Bore Short Block-Balanced Rotating Assembly
Stock Crank
Stock Pistons
Stock Rods
Stock Timing Chain/Gears
212/212 Flat Tappet Cam
8445 Race Ported Big Valve Heads
Stock Rockers
5.7 TT 110 Race Chip
Built 2004R
AC 16930
6262 JB

6.72 at 104.67-1.58-25 PSI

Offline earlbrown

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Re: low o2s
« Reply #9 on: August 06 2017, 01:41:00 PM »
Brass pipe plugs for me.   There's no way I was going to attempt to use that damn plate. There's just too much leverage against the screw for that thing to work troublefree.
'87 GN - 4.2L SFI Turbocharged innercooled V6 - Chrome valve covers - supra pump - 14" K&N - 52mm throttlebody - rocker shaft supports -  1/2 intake spacer - TB coolant bypass - 3" ATR exhaust tip - Alum intake pipe - NOS timing cover - chip - relocated charcoal canister - CR42's - stock


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