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Sniper EFI AFR issues #2951361
08/07/21 12:39 PM
08/07/21 12:39 PM
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Michigan
MarkZ Offline OP
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Does this look like a faulty O2 sensor to you guys? Damn reading is all over the place. Wiring is free of any sources of EMI/RFI. Even disconnected the alternator belt just as a sanity test. When the temp comes up to 160 and closed loop learning starts I can't keep it running unless my foot is in it.

Edit: forum resizes the image so it's hard to read. Yellow is AFR and green is RPM.

afr.PNG
Last edited by MarkZ; 08/07/21 12:40 PM.

1987 Fifth Avenue - 512/518/D60
Re: Sniper EFI AFR issues [Re: MarkZ] #2951364
08/07/21 12:56 PM
08/07/21 12:56 PM
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what does the exhaust look/smell like?
should burn your eyes based on that graph if I read it right. looks like it is going over 36.

Re: Sniper EFI AFR issues [Re: MarkZ] #2951382
08/07/21 02:03 PM
08/07/21 02:03 PM
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Tulsa, Oklahoma
340Cuda Offline
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Closed exhaust or open header?

Re: Sniper EFI AFR issues [Re: 340Cuda] #2951402
08/07/21 03:01 PM
08/07/21 03:01 PM
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MarkZ Offline OP
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Yeah, it burns the eyes. This is through closed exhaust.

Just trying to get it back up and running. Had to send to unit out for repair due to a failed injector driver. Holley stated they also replaced the ECU. Tune was blanked and it wouldn't load any of the saved tunes off of the SD card. Might be because the firmware is newer than tune saves, dunno. Ran the initial setup again and figured I would let it self learn again.


1987 Fifth Avenue - 512/518/D60
Re: Sniper EFI AFR issues [Re: MarkZ] #2951418
08/07/21 03:29 PM
08/07/21 03:29 PM
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I would be calling to ask about why it won't load saved tunes.

is it same o2 sensor as before, or new one with the repaired kit?

I don't know about that setup, mine periodically asks for recalibration.
if it was the old one with fuel dumping into the system, it might be over saturated and you need to pull it out into fresh air and let it heat up and have it recheck 0.

Re: Sniper EFI AFR issues [Re: MarkZ] #2951428
08/07/21 04:18 PM
08/07/21 04:18 PM
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Take a look at some other sensors to see if you can find what the root cause is. Is the MAP signal fluctuating and calling for lots of fuel? Look at the fuel flow sensor to see if it is fluctuating like that also.

Start the engine up and have someone look down the throttle bores to see if one injector is stuck open or something else is weird like that.

Re: Sniper EFI AFR issues [Re: AndyF] #2951455
08/07/21 06:47 PM
08/07/21 06:47 PM
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MarkZ Offline OP
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I pulled the o2 sensor out earlier today and let it read fresh air while looking at the handheld. All over the place.

All of the other sensors show normal readings.

Last edited by MarkZ; 08/07/21 06:48 PM.

1987 Fifth Avenue - 512/518/D60
Re: Sniper EFI AFR issues [Re: MarkZ] #2951500
08/07/21 08:57 PM
08/07/21 08:57 PM
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Benton, IL.
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Change your 'smoothing' and sampling interval settings. That will clear your graph up a lot.


Master, again and still
Re: Sniper EFI AFR issues [Re: MarkZ] #2951503
08/07/21 09:01 PM
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Yeah looks like the sensor has gone bad on you. In fresh air it should just be full lean. I think there is a pass car sensor you can get rather than buying the Holley sensor but I don't recall the application. The info is probably on the Sniper forum. I think it was a VW application but I'm not sure.

Last edited by AndyF; 08/07/21 09:03 PM.
Re: Sniper EFI AFR issues [Re: AndyF] #2952841
08/11/21 03:37 PM
08/11/21 03:37 PM
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MarkZ Offline OP
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Originally Posted by AndyF
Yeah looks like the sensor has gone bad on you. In fresh air it should just be full lean. I think there is a pass car sensor you can get rather than buying the Holley sensor but I don't recall the application. The info is probably on the Sniper forum. I think it was a VW application but I'm not sure.


I found an o2 sensor at the chain store what looked exactly the same with the same plug. It was $60 cheaper, but the guys on the Holley forum were adamant that the Holley branded one had to be used. Something about it being calibrated by Holley. In the end I just ordered a new one from Summit. The AFR stopped jumping around after plugging it in and when I smothered it in a brake clean soaked rag the reading went gradually down without spiking. Finally took the car out last night and got gas. Everything seems to be good now. Thanks again.


1987 Fifth Avenue - 512/518/D60
Re: Sniper EFI AFR issues [Re: MarkZ] #2952885
08/11/21 05:27 PM
08/11/21 05:27 PM
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If you want to experiment with the passenger car O2 sensor you could. Plug it in and see how the car runs. Take some careful data logs with each O2 sensor and see if there is any difference. I kind of doubt that Holley plays around with the calibration since they would most likely want to use off the shelf stuff but I'm not positive one way or the other.

Re: Sniper EFI AFR issues [Re: AndyF] #2952957
08/11/21 08:12 PM
08/11/21 08:12 PM
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MarkZ Offline OP
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Originally Posted by AndyF
If you want to experiment with the passenger car O2 sensor you could. Plug it in and see how the car runs. Take some careful data logs with each O2 sensor and see if there is any difference. I kind of doubt that Holley plays around with the calibration since they would most likely want to use off the shelf stuff but I'm not positive one way or the other.


This is it: https://www.oreillyauto.com/detail/c/bosch-direct-fit/bosch-direct-fit-oxygen-sensor/b02d/17212

Lists for diesels though. Don't know if that matters.


1987 Fifth Avenue - 512/518/D60
Re: Sniper EFI AFR issues [Re: AndyF] #2952970
08/11/21 08:34 PM
08/11/21 08:34 PM
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Originally Posted by AndyF
If you want to experiment with the passenger car O2 sensor you could. Plug it in and see how the car runs. Take some careful data logs with each O2 sensor and see if there is any difference. I kind of doubt that Holley plays around with the calibration since they would most likely want to use off the shelf stuff but I'm not positive one way or the other.

I would agree.
I doubt they can change the calibration of a sensor but they may have one made specifically for them by the same MFR. that may look the same. One would have to have a source inside holley or their supplier to confirm. Or the ability to test both while recording any differences. twocents

Re: Sniper EFI AFR issues [Re: TJP] #2953022
08/11/21 10:54 PM
08/11/21 10:54 PM
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CSK Offline
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The Holley Sniper uses the cheaper parts store VW sensor, the HP & other efi use a calibrated by Holley sensor


1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim
2020 T/A 392 Stock 11.79 @ 114.5

Re: Sniper EFI AFR issues [Re: CSK] #2953039
08/12/21 02:40 AM
08/12/21 02:40 AM
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Graz, Austria
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Originally Posted by csk
The Holley Sniper uses the cheaper parts store VW sensor, the HP & other efi use a calibrated by Holley sensor


The Sniper uses the newer 4.9 sensor whereas the HP, Dominator, Terminator use the older 4.2 sensor - maybe the newer sensor simply does not need a Holley calibration to work as expected? I assume the Terminator X would use the same sensor as the Sniper since it also uses the 4.9 sensor.

Re: Sniper EFI AFR issues [Re: DGS] #2953047
08/12/21 06:55 AM
08/12/21 06:55 AM
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https://www.oreillyauto.com/detail/c/bosch-direct-fit/bosch-direct-fit-oxygen-sensor/b02d/17212

If that is an significantly improved design wide band Oxygen Sensor
does anyone sell an add on meter to connect to it
so that it can be used “stand alone” extra gauge below the dash board gauges
and not as a part of an EFI kit?

$65 seems very reasonable.

Re: Sniper EFI AFR issues [Re: DGS] #2953087
08/12/21 10:44 AM
08/12/21 10:44 AM
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Originally Posted by DGS
Originally Posted by csk
The Holley Sniper uses the cheaper parts store VW sensor, the HP & other efi use a calibrated by Holley sensor


The Sniper uses the newer 4.9 sensor whereas the HP, Dominator, Terminator use the older 4.2 sensor - maybe the newer sensor simply does not need a Holley calibration to work as expected? I assume the Terminator X would use the same sensor as the Sniper since it also uses the 4.9 sensor.


The 1st sniper used the 4.2, I guess they updated, the HP does not use a 4.2, it is a Holley specific plug & calibrated, I use the Holley NTK sensor on my HP efi


1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim
2020 T/A 392 Stock 11.79 @ 114.5







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