Stuck commanded AFR...ideas? - Pontiac Solstice Forum
 
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post #1 of 14 (permalink) Old 08-23-2019, 10:38 AM Thread Starter
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Stuck commanded AFR...ideas?

I think I'm onto something finally with the vibration. Haven't data logged in a while (since before the vibration). I've noticed that instead of commanding an AFR of 14.7, my car is commanding 13.79 (very rich!). And at DFCO its commanding 27.58 instead of 29.4. It gets super rich at 1k rpm (where my vibration is the worst) at a measured afr of 12.8. I haven't touched the tune....so any ideas as to what would would cause this? Wideband O2? Downstream O2? MAF? MAPs? It also commands 13.79 consistently during cold start. Its like its stuck at the 2 numbers. Now...the only time I haven't been with my cat was during the whole Belle Tire fiasco over a year ago. So I know nobody has changed the tune or done any OBDII stuff to it in over 3 years.

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post #2 of 14 (permalink) Old 08-23-2019, 11:19 AM
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Is your Engine Coolant Temperature reading correctly?

John
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post #3 of 14 (permalink) Old 08-23-2019, 12:06 PM Thread Starter
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Yes. I have no issue with that. My fan even comes on full at 198 like it was set for...

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Windrestrictor lighted door sills lighted in white
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ZZPerformance dyno tuned - 286HP, 317ft/lbs of torque at 23psi of boost.
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post #4 of 14 (permalink) Old 08-23-2019, 08:08 PM Thread Starter
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No ideas?????

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Solo Street Race exhaust
Fujita CAI
ASAP T2 stripes and badging
Windrestrictor V2 lighted in white
Windrestrictor lighted door sills lighted in white
DDM Works IC Piping
Undercar LEDs in white to match Windrestrictor

ZZPerformance dyno tuned - 286HP, 317ft/lbs of torque at 23psi of boost.
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post #5 of 14 (permalink) Old 08-29-2019, 05:27 PM Thread Starter
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Well...I'm throwing in the towel. I've asked for direction on what could be causing my commanded AFR to drop to 13.79 from 14.7 and my LTFT to be stuck at -8.79 and it's been crickets. I've asked which sensor(s) give the barometric ambient pressure outside...crickets. So car is going to dealership to be fixed next week.

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Windrestrictor V2 lighted in white
Windrestrictor lighted door sills lighted in white
DDM Works IC Piping
Undercar LEDs in white to match Windrestrictor

ZZPerformance dyno tuned - 286HP, 317ft/lbs of torque at 23psi of boost.
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post #6 of 14 (permalink) Old 08-29-2019, 08:06 PM
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There is no barometric sensor shown in the service manual, but a Google search found several references that said it is built into the LNF ECM.

John
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post #7 of 14 (permalink) Old 08-30-2019, 05:55 AM Thread Starter
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I appreciate the response John...I was afraid the ECM had the barometric pressure sensor. I did log again this morning and the barometric pressure did move. But not for quite a while and when it did, it jumped 0.14 in the log. So from 14.07 to 14.21. Thought that was a bit odd unless the car only checks every so many minutes apart. Weather is showing 29.9mmHG. When it moved, my commanded AFR did not...so that might just be a rabbit hole... I'm thinking about replacing the downstream O2 sensor. It appears to be very lazy. Sometimes not correcting itself for 15+ seconds to a richer state. So I'm thinking that both O2 sensors are "arguing". So the ECM is ignoring the values from the downstream and just commanding rich all the time. Even though the downstream is merely to show if you have a cat and if its functioning.

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Solo Street Race exhaust
Fujita CAI
ASAP T2 stripes and badging
Windrestrictor V2 lighted in white
Windrestrictor lighted door sills lighted in white
DDM Works IC Piping
Undercar LEDs in white to match Windrestrictor

ZZPerformance dyno tuned - 286HP, 317ft/lbs of torque at 23psi of boost.

Last edited by The_Ghost; 08-30-2019 at 07:25 AM.
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post #8 of 14 (permalink) Old 08-30-2019, 06:20 AM
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I think that the BARO sensor is only there to provide a sanity check for the boost sensor, and maybe the MAP sensor, since there is a check done when you power the car and when you crank. If the sensors are not within acceptable limits a DTC will be set. Mine seems to be either 14.07 or 14.21.

I have been trying to find the reading for the pressure part of the TMAP sensor that is between the CAC and the throttle body, but can find it in the available inputs on my DashDAQ. I have gotten just about curious enough to get the Tech2 out and see what it knows.

What does your intake air temperature read?

John
Lexington, KY
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post #9 of 14 (permalink) Old 08-30-2019, 07:24 AM Thread Starter
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Intake temps are pretty close to accurate. There is variation, usually a bit warmer, but not drastic. After the barometer jumped to 14.21, commanded AFR seemed to move around a bit more. But it still commands rich. Guess since yours is showing 14.07 or 14.21, like mine...I'll look at other things.

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Fujita CAI
ASAP T2 stripes and badging
Windrestrictor V2 lighted in white
Windrestrictor lighted door sills lighted in white
DDM Works IC Piping
Undercar LEDs in white to match Windrestrictor

ZZPerformance dyno tuned - 286HP, 317ft/lbs of torque at 23psi of boost.
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post #10 of 14 (permalink) Old 09-03-2019, 08:06 PM
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OK, this is odd.

As I stated above, the boost sensor doesn't show up in the service manual wiring diagrams, even though it is referenced in several of the DTC descriptions. I finally got around to plugging the Tech2 in to look for it and found something I don't understand. The boost sensor is listed, but has a (*) where there should be a value.

I hope someone with a scanner will have a look at their car to see if they have the same thing.
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John
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post #11 of 14 (permalink) Old 09-04-2019, 06:21 PM Thread Starter
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I appreciate it John... I'm still struggling with why the car is commanding a rich afr. I put new o-rings on the MAP and it calmed the vibration down a little bit, but it's still there too. Going to test the emissions solenoid tomorrow...

____________________________________________

Solo Street Race exhaust
Fujita CAI
ASAP T2 stripes and badging
Windrestrictor V2 lighted in white
Windrestrictor lighted door sills lighted in white
DDM Works IC Piping
Undercar LEDs in white to match Windrestrictor

ZZPerformance dyno tuned - 286HP, 317ft/lbs of torque at 23psi of boost.
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post #12 of 14 (permalink) Old 09-05-2019, 02:15 PM Thread Starter
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Hey John...dumb question. What are the high and low values of both of your O2 sensors (upstream and downstream)?

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Solo Street Race exhaust
Fujita CAI
ASAP T2 stripes and badging
Windrestrictor V2 lighted in white
Windrestrictor lighted door sills lighted in white
DDM Works IC Piping
Undercar LEDs in white to match Windrestrictor

ZZPerformance dyno tuned - 286HP, 317ft/lbs of torque at 23psi of boost.
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post #13 of 14 (permalink) Old 09-05-2019, 05:55 PM Thread Starter
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Here's my "vibration" video....I let off the gas at 0:16 and it smooths out for the rest of the video...


____________________________________________

Solo Street Race exhaust
Fujita CAI
ASAP T2 stripes and badging
Windrestrictor V2 lighted in white
Windrestrictor lighted door sills lighted in white
DDM Works IC Piping
Undercar LEDs in white to match Windrestrictor

ZZPerformance dyno tuned - 286HP, 317ft/lbs of torque at 23psi of boost.
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post #14 of 14 (permalink) Old 09-05-2019, 07:19 PM
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Quote:
Originally Posted by The_Ghost View Post
Hey John...dumb question. What are the high and low values of both of your O2 sensors (upstream and downstream)?
I drove the NA today, so the readings I got are after idling for a few minutes and not completely warmed up.
ECT is 87C.
Sensor 1 reads 1.006 Lambda
Sensor 2 reads 645 mV

As a side note, I did find the reading for the boost pressure sensor. It is on the Induction Data page, and not the Engine Data page.
I'm not sure why the sensor would sometimes be listed but without a value, and I'm not sure why it isn't part of the OBD data. Oh well.

John
Lexington, KY
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