PLX SM-AFR Serial upgrade

[JezzaB]

Top job mate! Looks great and once youve gone serial you will never go back!

Well done

Jez

[vxleather]

I finally got around to having a go at it myself.






Very happy with the way it turned out but when i tested it in pass through mode (not even going to attempt BBL at this stage) i noticed some AFR spikes down to AFR 10 and up to 17.5.





I found a thread on a similar problem during BBL but not sure if anyone really got to the bottom of it. I'll check all my connections and try to get another log this week.

Any help would be appreciated.

Cheers.

Make sure you are using the latest upgrades... some of the pre versions had a issue with the time it takes to read... eg 40msec to 10ms...

[CV8IIM6]

I've had a bit more time to look properly at the log with the voltage spikes in it and to play around with my DM-100.

Firstly in the log i can see regular spikes (21 in a 12 minute log) to AFR's of 12.5 17.5 and 10 which just isn't plausible.

I decided to set up the DM-100 to display a warning when ever measured AFR is less than 10.1 I then went driving with the V2 not even connected. It was disappointing to see the warning displayed on a reasonably regular basis confirming an issue with the PLX SM-AFR not the V2 or software.

So I'm wondering if i have a poor earth, if the unit was faulty, if my modifications have damaged a component, if my converter chip is faulty etc.etc.

I'll run a new earth, check my connections inside the unit and have a look at the analog output to start with.

expensive experiment at this stage.

[Shupe]

I've had a bit more time to look properly at the log with the voltage spikes in it and to play around with my DM-100.

Firstly in the log i can see regular spikes (21 in a 12 minute log) to AFR's of 12.5 17.5 and 10 which just isn't plausible.

I decided to set up the DM-100 to display a warning when ever measured AFR is less than 10.1 I then went driving with the V2 not even connected. It was disappointing to see the warning displayed on a reasonably regular basis confirming an issue with the PLX SM-AFR not the V2 or software.

So I'm wondering if i have a poor earth, if the unit was faulty, if my modifications have damaged a component, if my converter chip is faulty etc.etc.

I'll run a new earth, check my connections inside the unit and have a look at the analog output to start with.

expensive experiment at this stage.

I too have noticed these spikes on my modified SM-AFR. I remember the DM5 gauge also has these spikes. Betting the spikes on the display correlate with the spikes on the serial output.

[CV8IIM6]

Has anyone else noticed strange variations with their SM-AFR?

I'm far from having this issue resolved and considering buying another unit, but i have little faith in the product as it's been suggested that this may be a processing issue in all SM-AFR's.

I have had no help from "PLX Support" who despite being told that:

1. I removed the chip and returned the SM-AFR to it's original condition (ie. no MAX 3232 chip and no V2 connected).
2. Powered the unit from a completely independent power supply with nothing else connected to it (ie known good/clean power and earth, no interference).
3. Tested the unit with the engine and ignition completely OFF (ie. no interference).
4. Logged the analog output and found that while it doesn't display the spikes, it is on average 0.2 AFR leaner than the DM-100 gauge.
5. Still notice frequent, random AFR spikes to 10, 12.5 or 17.5 on the DM-100 gauge.

PLX Support Replied by saying "The digital spikes you're seeing may be coming from a poor power supply source or ignition noise"

I thought i had done a pretty good job of ruling those things out and was expecting the PLX electronics engineers to suggest replacing a particular capacitor or filter on the circuit board perhaps?

Anyway, enough of my red wine induced rant. if someone can assure me it IS possible to get accurate results from a modified SM-AFR i'll buy another one and keep trying. if many others have similar problems i'll look at other options.

[JezzaB]

I never experienced any of those problems with my SM-AFR when analog or digital but I just dont like I had to mod the crap out of it to get RS232 etc..

But I like my TechEdge 2J1 (www.wbo2.com) better. Ive tested it against quite a few very expensive Autronics etc and its always been within .1 AFR and I only have to use a gender bender on it. RS232 stardard and an Aussie company. For a low cost unit its very good.

Jez

[ntae]

If you want i can send you my spare SM AFR for you to test your set up

[Tre-Cool]

I just ordered myself 8 max3232 boards from the US last night and allready have 10 gender benders from my local computer shop.

Paid $10us for the rs232 boards and $3.50 for the male to male gender benders. this way i can plug the efilive cable straight in.

i have my 2 plx's to mod and more than likely a couple of mates as well.

question: what did you guys use to cut through the alloy for the rs232 plug?

[JezzaB]

I just ordered myself 8 max3232 boards from the US last night and allready have 10 gender benders from my local computer shop.

Paid $10us for the rs232 boards and $3.50 for the male to male gender benders. this way i can plug the efilive cable straight in.

i have my 2 plx's to mod and more than likely a couple of mates as well.

question: what did you guys use to cut through the alloy for the rs232 plug?

I scored. Then use a small drill bit and then filed it to size. Dremel would have done the trick but im out of bits.

Jez

[CV8IIM6]

If you want i can send you my spare SM AFR for you to test your set up

Mate, that would be fantastic. I'll send you a PM.

question: what did you guys use to cut through the alloy for the rs232 plug?

I drilled about a 7mm hole and then used a small triangular file.