Random Misfire Check Engine Light

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Jan 8, 2005 | 01:05 AM

#61

ez76

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From: bay area

Quote:

Originally Posted by dude

I'm no Computer Science guy, but if I recall Microprocessors and Electronics, I thought there were 8 bits in a byte, hence 19,200bits/sec would equal 2400 bytes/s?

I think he was measuring in CompUSA bytes.

Jan 8, 2005 | 05:57 AM

#62

ShapeGSX

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Quote:

Originally Posted by dude

I'm no Computer Science guy, but if I recall Microprocessors and Electronics, I thought there were 8 bits in a byte, hence 19,200bits/sec would equal 2400 bytes/s?

Depends on the connection. Open up hyper terminal and check out the properties when you tell it to use COM1 and hit configure. There are potentially parity bits along with each byte (probably not in this case). And there are always 1 or 2 stop bits that come along with every byte. So dividing by 10 is usually valid.

CompUSA bytes, eh?

You can't just stream bits along a cable without some sort of reference to tell the other computer where the byte starts.

Jan 8, 2005 | 06:13 AM

#63

ShapeGSX

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Quote:

Originally Posted by ez76

For those who care (what? nobody?), the XEDE serial link is 115.2kbps and each v3 log packet includes (up to) 29 distinct 16-bit values i.e. a max of 5800 payload bytes per second or about 46kbps when it's in v3 streaming log mode (no request/reply).

Aah, that makes more sense. There is always extra overhead, too. Add in the stop bit(s), too.

It was silly of me to think it was datalogging 8-bit values. While that would give enough resolution for some things, like O2 sensors, it wouldn't be enough to send RPM information.

Quote:

Not a lot of data but as you point out it's just one of many things the XEDE is doing at any given time. In addition to calculation, mapping, servicing requests from the DTE, etc., the XEDE is taking full resolution (relative to the noise floor) samples of analog inputs hundreds of times per second. Not too bad for a 15MHz processor when you consider that similar 286-class PC's of yesteryear had a hard time with anything more than a 9600 baud modem (and that was under DOS). Credit ChipTorque (or discredit IBM?) here.

Oh yeah, it is amazing what you can do with an embedded processor these days. I have a few Atmel 20 pin $2.50 8-bit RISC microprocessors that I've been playing around with recently. Completely self contained. Includes 2k of flash. No crystal needed. Just plug it in to power.

Contrast it with the 68HC12 I have, which is a freaking powerhouse.

Jan 8, 2005 | 09:03 AM

#64

raymerd

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From: Ft. Worth Texas

Quote:

Originally Posted by bbenavitz

This is certainly and interesting post, particularly when I have an Xede on order. One thing is certain, if I experience any "misfiring" with the Xede installed and not when it is uninstalled Vishnu will be sending me a refund.

I am not spending $900 to be a "test bed".

Vishnu will need to give me a "gaurantee" that the Xede will work as promised before I take delivery. Is this to much to ask?

I've got the XEDE and no misfires ... I had the problem (code and misfires) before I got my XEDE; the dealer tried to reflash .. the entire engine control system and a good bit of the electronics that were connected to it fried. They installed a new harness, ecu, the lot. Haven't had the code since, with or without the XEDE.

If you mod a vehicle, you are taking a risk. I for one firmly believe that the XEDE has improved the way my car runs to such a degree and with a reliability that is unmatched. My car runs better with the XEDE in than out (tried it).

I get the occassional cat flow, and I've had a CAS once, but I'm running 272i/272e cams and it coincided with a cat flow eff code, so I'm attributing both to a bit of overlap when the engine was cold.

Get the XEDE ... bar none, its the best choice out there.

-- dave