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Autotap giving bad (spiking) data

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Old 04-02-2004, 05:15 PM
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Default Autotap giving bad (spiking) data

I have a bi-directional autotap cable (non-usb) and it's pretty much always given me bad data. Not every parameter does this but a lot of them will spike the data every couple of seconds... for example the KR or LTFT's will go from a normal value to something outrageous (like +50) for one frame of data and then drop back... it'll happen every couple of seconds and makes analyzing the data and looking at graphs VERY difficult. I've sent it back to the manufacturer several times and they've never found anything wrong with it. Strange thing though, when using the EFILIVE demo that lets me log 5 seconds of data I NEVER EVER get a spike in the data... even recording like 50 5 second samples in a row... Yes I've downloaded the latest ATAP version... (this has happened for at least 3 revisions) and it's never gone away... Anybody have any ideas or have this happen before???? Thanks!

'01 GMC Sierra C3
6.0 AWD
Old 04-04-2004, 08:00 PM
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i just bought atap resently and mine does the exact same thing. it will iether spike up or down. my buddy has efi live and his has no problems. i also tried logging with efi live on mine for 5 sec. and no problems. the other thing i am very dissapointed with is how slow atap is. my buddys efi live can record like 20 things at once. with atap anything over 3 is to many. anything over three is like playing a good video game with a shitty video card.
Old 04-04-2004, 08:03 PM
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i guess you get what ya pay for. The V2 interfaces and the new usb ones are supposively faster too.
Old 04-04-2004, 08:17 PM
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my buddys efi live is serial so evidently the bottle neck is not at the serial. i thing its just the software.
Old 04-05-2004, 12:13 AM
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Yup, mine is the V2 serial interface and I've noticed I get about 3-4 times the refresh rate out of EFI live using the same cable than I do with atap... And EFI live never spikes... crappy software...

Originally Posted by 500plus
my buddys efi live is serial so evidently the bottle neck is not at the serial. i thing its just the software.
Old 04-05-2004, 02:44 AM
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The bottleneck is neither in the PC, nor the the cable nor the the software.
The major factor that determines how fast you can log data is the scan mode that is used. There are basically three different ways to scan data from an OBD II PCM.

1. One PID at a time which is supported on ALL OBDII vehicles. So scan tools that support multiple manufacturers and vehicles will usually use that method. It is the slowest method. EFILive can be configured to use this scan mode so that it can scan non-LS1 vehicles.

2. Up to 6 PIDs at a time. This method is supported on *most* OBDII vehicles but may be implemented differently by different manufacturer's. It is obviously about 6 times faster than the first method. EFILive fully supports this scan mode.

3. Up to 24 PIDs at a time. This method is supported by the LS1 PCM and is the fastest way to log data from that PCM. EFILive fully supports this scan mode.

So it's not really fair to compare cables, PC's and software because it is the scanning method that determines the data logging speed.

Regards
Paul
Old 04-05-2004, 11:36 AM
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Well how can you say it's not fair to compare software when it's the software that controls the scanning method? I can find no way in autotap to alter the method that it scans... if you can point me in the right direction I would be eternally greatfull...

Originally Posted by EFIliveV5
The bottleneck is neither in the PC, nor the the cable nor the the software.
The major factor that determines how fast you can log data is the scan mode that is used. There are basically three different ways to scan data from an OBD II PCM.

1. One PID at a time which is supported on ALL OBDII vehicles. So scan tools that support multiple manufacturers and vehicles will usually use that method. It is the slowest method. EFILive can be configured to use this scan mode so that it can scan non-LS1 vehicles.

2. Up to 6 PIDs at a time. This method is supported on *most* OBDII vehicles but may be implemented differently by different manufacturer's. It is obviously about 6 times faster than the first method. EFILive fully supports this scan mode.

3. Up to 24 PIDs at a time. This method is supported by the LS1 PCM and is the fastest way to log data from that PCM. EFILive fully supports this scan mode.

So it's not really fair to compare cables, PC's and software because it is the scanning method that determines the data logging speed.

Regards
Paul
Old 04-05-2004, 03:36 PM
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in autotap if i click or move the mouse alot on the screen i can get all kinda spikes in data... now efilive does not do this. what are the spec of the computer your running this on?
Old 04-05-2004, 03:36 PM
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Originally Posted by EskimoPie
Well how can you say it's not fair to compare software when it's the software that controls the scanning method? I can find no way in autotap to alter the method that it scans... if you can point me in the right direction I would be eternally greatfull...
Sorry for the confusion.
Technically you're right, the scan mode and hence the scan speed is determined by the software. What I actually meant was the "speed of execution" of the PC/software itself is not the bottle neck. So it is not really fair to make comparisons about which software "runs faster".

There is no way (that I know of) to change the scan method in AutoTap.

Regards
Paul
Old 04-05-2004, 08:35 PM
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so your telling me to get efilive. thanks paul.
you said there is a way to get evilive to work on other vehicles.
very interested
Old 04-05-2004, 08:51 PM
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Originally Posted by 500plus
so your telling me to get efilive. thanks paul.
you said there is a way to get evilive to work on other vehicles.
very interested
EFILive will work as a generic scanner on all GM OBDII (SAE J1850 VPW) vehicles. (There are a few GM OBD II vehicles that use the KW2000 protocol, to which EFILive will not connect)

As a generic scanner (on non-LS1/LS6 vehicles) EFILive only has access to generic PIDs and the EPA information.

The parts of EFILive that are specific to LS1/LS6 are:
- enhanced PIDs
- bi-directional controls
- high speed data.

GM may have implemented the high speed data on other models - I don't know.

Regards
Paul
Old 04-06-2004, 09:09 PM
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any way to get ford, chrysler, import?
Old 04-06-2004, 09:53 PM
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Originally Posted by 500plus
any way to get ford, chrysler, import?
No, you'll need to buy AutoTap for that.
Regards
Paul




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