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Closed loop poor performance. Open loop fine.

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Old 11-05-2018, 10:57 PM
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Default Closed loop poor performance. Open loop fine.

2012 CTS-V no mentionable mods. CAI.

Noticed some sluggish performance a few weeks ago. Turned out the CAI had came loose from the TB. So it was pulling air outside the filter. Fixed that, but still had poor performance.

Did a few test drives but my tech couldn’t find any unusual values on the snap on. O2’s seemed to be okay, jumping around like they should. Fuel trim was a bit lean but nothing serious. However he noticed performance was only sluggish in closed loop. Open loop it pulls just fine.

By by poor performance I mean low rpm wot it just accelerates poor. Unless - it’s in open loop. Which doesn’t always happen. I’m unsure on what condition it’s supposed to happen. So here’s what I’ve changed so far :

new zl1 lid. Suspected maybe the brick was leaking. It wasn’t. Oh well.

New plugs -
new maf - acdelco
new wires
new knock sensors
new o2’s upstream and downstream NTK
new temp sensor in the lid

car has a few misfires on all cylinders - but nothing persistent. I’m talking like 2 maximum 4 randomly on random cylinders. No cel.

65K miles

any ideas, pointers ? Could it be the tps or the tb ? The cats?
Old 11-06-2018, 06:06 AM
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I would suspect a vacuum leak.
Old 11-06-2018, 06:25 AM
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Would that explain the P219A check engine light that just started showing up ?
Old 11-06-2018, 06:51 AM
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WOT is always open loop. However if your fuel trims are excessively lean before you enter WOT it will add that much fuel to your open loop commanded fuel.
Old 11-09-2018, 07:15 AM
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Originally Posted by Keith Thomas
Would that explain the P219A check engine light that just started showing up ?
In that case; It is possible for you to have an exhaust leak in bank1, making the sensor read lean and making bank 1 rich. Just an idea. When you are in open loop you're just operating on VE or MAF, trims stop.
Old 11-09-2018, 07:21 AM
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I don’t know what’s going on now.
I get
P015B
P015D

P219A
P219B

now. I wonder if this batch of o2 sensors is just ****. I didn’t get any CEL before I changed them. However I bought new ones (NTK) to remedy the closed loop poor performance problem.

Now i got new sensors - Problem Stil persists. But new CELs

i looged some sensor data (timing retard, o2 voltage o2 % st fuel trim, lt fuel trim and intake manifold pressure). It’s to big to upload as it’s a screen recording about 12 minutes long.
anybody have some baseline numbers what it should look like ?
no mods besides the CAI and ZL1 lid

thanks for any help
Old 11-09-2018, 07:31 AM
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What are your fuel trims for bank 1 and 2
Old 11-09-2018, 01:34 PM
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Could only send a small 10 second video
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