Low Z noise problems

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Re: Low Z noise problems

Postby B-lennium » Sun Dec 13, 2009 1:38 pm

I had a very irritating voltage spike, the voltage spiked to 17volt and to 6 volts, i could feel it in the car wile driving (same as a burn) (MSII msextra 2.10)

I did the injectordriver separate 12volt wire. this did't cure the problem.
then i tried the 220nf cap on the H1 position...

And away went my spiking!

I fixed it with a 12cent part!
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Re: Low Z noise problems

Postby BenGTT » Mon Dec 14, 2009 4:32 pm

B-lennium wrote:I had a very irritating voltage spike, the voltage spiked to 17volt and to 6 volts, i could feel it in the car wile driving (same as a burn) (MSII msextra 2.10)

I did the injectordriver separate 12volt wire. this did't cure the problem.
then i tried the 220nf cap on the H1 position...

And away went my spiking!

I fixed it with a 12cent part!



Hello, I did the same a few days ago since I have switch from high impedance injectors to low impedance.
I had noise and then starting to try 10nF, then 33nF, 100nF. With 100nF voltage was perfect but sometimes it was dropping to 7V but no peak anymore. Then I tryed a 330nF and this time it was the good one. incredibly stable.
I think it is one of the BEST solution for MS2 with low Z injectors.
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Re: Low Z noise problems

Postby Safir » Tue Dec 15, 2009 8:33 am

Just to be sure I'm getting this right, you're putting a small capacitor in place of the boot header on the V3 motherboard? are there any other moifications to be done first?

I have very low impedance injectors (~1.2ohm IIRC) and have voltage spikes like you describe, if this can smooth those out it would be great.
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Re: Low Z noise problems

Postby Peter Florance » Tue Dec 15, 2009 8:52 am

Safir wrote:Just to be sure I'm getting this right, you're putting a small capacitor in place of the boot header on the V3 motherboard? are there any other moifications to be done first?

I have very low impedance injectors (~1.2ohm IIRC) and have voltage spikes like you describe, if this can smooth those out it would be great.

I found 47uf 35v from center leg of Q3 to center leg of Q9 works well. Negative lead to Q3.

Also running alternating instead of simultaneous.
Peter Florance
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60-2 Wheel LS2 Coils, Low Z Inj
Check your grounds: http://www.msextra.com/doc/general/grounding.html
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Re: Low Z noise problems

Postby svocapri » Tue Jan 26, 2010 12:49 pm

I am having the low Z noise problems as well. So far I have done the flyback mod and ran the 12V middle leg back to the injector positive. Also I put a car audio noise filter on the power input going to the Megasquirt. My Innovate WBo2 is still having noise problems. I am wondering if I would do better to put the noise filter on the 12V lead to the injectors to help keep the noise from the flyback out of the rest of the system instead of just filtering the 12V to Megasquirt? Can anyone confirm that this is not a misconceived notion and might improve the noise to the Innovate? I am also curious about the capacitor on the boot header mod. How does this work?

Julian
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Re: Low Z noise problems

Postby ryniobl » Thu Jan 28, 2010 1:35 pm

Hello everybody It's my first post here :)

Here is my way to get rid of noises.
I made it in my 91 Accord with PnP MS2

1.connect pin28 DIRECTLY to batt positive pole (use relay).Don't connect anything else to this cable.
2.lift TIP125 middle legs and connect to IGN 12V
3.lift FQPF30N06 , IGN and IDLE drivers right legs ,connect them together outside of MS to the GND
4.connect sensors GNDs directly to 2nd leg of onboard MAP
5.WBo2 in my case LC1 CAN'T be connected to sensor GND.It injecting a lot of noises due to heater PWMing
6.now you can throw away all of those filters and capacitors.

log before mod

http://picasaweb.google.com/ryniobl77/Megasquirt#5431891152503591346

log after mod. notice BattV scaling 8)

http://picasaweb.google.com/ryniobl77/Megasquirt#5431891153352201522


Good luck
Hope you could understand my poor english

Richard
Last edited by ryniobl on Fri Jan 29, 2010 7:23 am, edited 2 times in total.
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Re: Low Z noise problems

Postby Black99rt » Thu Jan 28, 2010 6:11 pm

Do you have an LC-1 with a seperate sensor and heater ground? Is there noise on the sensor ground wire?
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Re: Low Z noise problems

Postby svocapri » Thu Jan 28, 2010 8:13 pm

I do have the LC1 with seperate heater and signal grounds. The manual specified to bond the two together and ground them in unison, which I did.
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Re: Low Z noise problems

Postby Philip Lochner » Thu Jan 28, 2010 10:34 pm

I've also had noise issues on my V12 Jag with LoZ injectors.

I also run the centre legs of TIP125s directly back to the injector 12V feed and have a 4.7uF cap in the bootloader position. This has made my PW remarkably stable.

If there is going to be a V3.1 or V4 board, this board should also allow for continuous barometric correction components.
Kind regards
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Re: Low Z noise problems

Postby ryniobl » Fri Jan 29, 2010 12:47 am

Black99rt wrote:Do you have an LC-1 with a seperate sensor and heater ground? Is there noise on the sensor ground wire?


LC1 heater GND i have connected to the chassis,and sensor GND to the main MS GND (not sensor GND).If you connect LC1 sensor GND to MS sensor GND ,turn IGN on and make datalog,you can see PWMing noises in TPSacc and MAPacc .
Richard
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Re: Low Z noise problems

Postby Black99rt » Sun Jan 31, 2010 4:12 pm

Thanks for the clarification, I'll make sure to do it the same way you have.
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Re: Low Z noise problems

Postby Perkele » Tue Feb 16, 2010 2:42 am

I'm plannig to make all the possible noise reductions just to be safe but I was wondring can there be any negative effects in this?
For starters I'm plannin to put 1uf caps paraller to D3 & D10 and the 4.7uf cap to bootloader. And I'm also curious how will the bootloader cap work as a filter for the 12V when it's connected between GND and PP5/KWP5 pin on the MS2 CPU?
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Re: Low Z noise problems

Postby Peter Florance » Tue Feb 16, 2010 5:07 am

I've been dyno tuning a TR8 this week (8 low z injectors)
The injector noise has been very low.

47uf 50v cap from center leg of TIP42C to TIP125
That's all I ever do for low Z injectors. I do a lot of jobs with 6 injectors. First V8.

I do above and provide plenty of ground wires.
Peter Florance
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81 BMW Euro 528i ESP Car
60-2 Wheel LS2 Coils, Low Z Inj
Check your grounds: http://www.msextra.com/doc/general/grounding.html
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Re: Low Z noise problems

Postby elaw » Wed Mar 17, 2010 6:05 am

Hey all, just thought I'd throw this out... this noise issue is definitely *not* limited to setups using low-Z injectors!

I'm using high-Z injectors and below you can see a log I made a while back... even though the battery V is on a fixed scale (10-16V) you can see it's very noisy. I put a cap in the boot jumper position on the V3 board and while I haven't had time to make another log, I can tell you the voltage is much more stable!

Edit: just to be clear, I do NOT know whether this noise is internal or external to the MS box (or both). Hopefully in the next few days I'll be able to go on a hunting expedition with a 'scope and answer that question.
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Re: Low Z noise problems

Postby Southcross » Fri Jun 18, 2010 11:00 am

I've been looking at doing this mod with my v3.57 board... I've got the usual noise and random "spikes"

but have some questions

In-Line Stereo Power Filter vs Soldered-on Capacitor?
With everything being surfacemount on the v3.57 board, is there a way to accomplish mounting an onboard Cap "filter" (for a not-so-technical electronics person... I bought the v3.57 to minimize the agony of trying to solder a whole board LOL)?
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Re: Low Z noise problems

Postby kubeq_sq » Sat Jul 03, 2010 8:42 am

hello, i have some other question about the low z inhjectors... i have read in the mextra manual,that if i use wasted spark i can't use low z injectyors... is it true??i would be very thankful for Your reply even though it isn't connected directly with the topic.

on the other hand i made the mods needed to have stable vbatt when using low z injectors and we will see, what i will get in the log when i connect my low z ijectors. just need to know if i can :)
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Re: Low Z noise problems

Postby decs » Sun Aug 01, 2010 9:39 am

i've set up 5 cars now with wasted spark and low z injectors. not being able to do so is certainly news to me.
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Re: Low Z noise problems

Postby svocapri » Wed Oct 13, 2010 9:51 am

Peter Florance wrote:
Safir wrote:Just to be sure I'm getting this right, you're putting a small capacitor in place of the boot header on the V3 motherboard? are there any other moifications to be done first?

I have very low impedance injectors (~1.2ohm IIRC) and have voltage spikes like you describe, if this can smooth those out it would be great.

I found 47uf 35v from center leg of Q3 to center leg of Q9 works well. Negative lead to Q3.

Also running alternating instead of simultaneous.


Since I have lifted the center leg of Q9 and Q12 to run to the injector 12V feed, if I use your mod, should I connect the 47uf capacitor between Q3 and Q9 or between Q3 and the now empty hole for Q9?

Julian
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Re: Low Z noise problems

Postby jsmcortina » Wed Oct 13, 2010 11:04 am

kubeq_sq wrote:i have read in the mextra manual,that if i use wasted spark i can't use low z injectyors... is it true??

I'd like to check into this.

Please give a link to the page and quote the text.

James
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Re: Low Z noise problems

Postby Peter Florance » Wed Oct 13, 2010 1:02 pm

svocapri wrote:
Peter Florance wrote:
Safir wrote:Just to be sure I'm getting this right, you're putting a small capacitor in place of the boot header on the V3 motherboard? are there any other moifications to be done first?

I have very low impedance injectors (~1.2ohm IIRC) and have voltage spikes like you describe, if this can smooth those out it would be great.

I found 47uf 35v from center leg of Q3 to center leg of Q9 works well. Negative lead to Q3.

Also running alternating instead of simultaneous.


Since I have lifted the center leg of Q9 and Q12 to run to the injector 12V feed, if I use your mod, should I connect the 47uf capacitor between Q3 and Q9 or between Q3 and the now empty hole for Q9?

Julian

good question. I'd say Q3 but I would want to try it each way
Peter Florance
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81 BMW Euro 528i ESP Car
60-2 Wheel LS2 Coils, Low Z Inj
Check your grounds: http://www.msextra.com/doc/general/grounding.html
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