05 NB MS2 VVtunner lost tach under load at 3-4K RPM

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05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby SIMS Customs » Wed Jul 18, 2018 1:58 pm

Hi everyone I'm a DIYer building a drift car 90 RX-7 FC with a 05 miata NB BP engine. I've got the thing idling and driving decent with the base maps found on DIYautotune besides the fuel map needing some work I still got it pretty close.

Problem#1: Here's the problem I'm currently experiencing. When I apply the throttle 40% or more I get what looks like a lost of sync. at 3000 to 4000 rpm at 130+ kpa. The RPM drops to 0 for a split sec. and the ignition timing follows causing it to act as a rev limiter. I've monitored this on logs and on composite logs. I have attached some pictures of the logs showing the problem occurring.
extra tooth (2).png
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lostsync.png
lostsync.png (16.02 KiB) Viewed 1358 times


Problem#2: I keep having problems with the FET injector drivers not closing all the way. When this happens my AFR goes full rich and I found I've bin able to pin point this problem using a NODE light. The node light will light up slightly and STAY ON when the ecu is powered on and engine is not started yet. I think this could be related to an install error. If there's any special instructions on how to install them please point me in the right direction because I've changed 4 of these so far and instead of getting the 25 Cent ones, I used the 3$ ones for the last one I cnanged and still just went on me last night at the same time Problem 1 happened. So the problems could be related. The last 2 FET failed this way and both on Cylinider 1 wich is INJ 1.

Here's my whole setup:
-Stock BP VVT engine from 05 miata
-Toyota corolla COP
-RC 550cc high impedance injectors
-custom made turbo kit set at 15 psi with t3 turbo (all made in my shop)
-DIY MS-2 (built by me) -JBperf dual vr board v2.1 with 1k pull up resistors from 5 volt for both CKP and CMP inputs
-JBperf 4 channel ign/inj driver board v1.1 with built in logic level ignition coil driver circuits
-DIYautotue VVTunner VVT controller I have it wired exactly as per the instructions with shielded wires for the signals and vvt pin 9 wired to the ms2 pin 1 (not sure about that ground??). The sensors are wired as passthrough and output trigger set as passthrough. (I've read this caused some similar problems for certain setups??)
resized.jpg
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Please help me get this sorted out so I can start shredding throu my stack of half worn tires.
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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby SIMS Customs » Wed Jul 18, 2018 2:13 pm

This involves problem 2, I was just reading of a similar problem on this forum and I think I've put too much heat in them when I installed them, I heated both the pad and the FET driver tab. I will swap out the failed FET. I'm not a pro at this or nothing but here's how I think I should do it from what I understand. Preheat the pad with soddering iron then place the FET in place and heat the pad only and apply soder for each 3 pads per FET?


An other question I'm looking for an answer to is What is the recomended jumper wire size I should use to install a board like the 4 channel driver?
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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby jbelanger » Wed Jul 18, 2018 9:30 pm

Your composite log shows that you have one extra tooth on your crank signal. That's likely to be noise so you should make sure you use shielded wiring and route it as far away from high current source as possible (coils, ignition wires, injector wires,...).

Which FET drivers are you using? And you should definitely try to heat up only the pad as much as possible and you should see the solder being wicked up under the tab. One thing that does help a lot is to use a solder flux (from a flux pen, for example) and apply flux to the pad and the tab. I use a water soluble flux because that's less messy but you need to clean it out with warm/hot water because it is slightly conductive and corrosive.

And I solder the 2 legs first to make sure the transistor is solid and well positioned then I solder the tab by heating the pad with the solder iron and applying a bit a solder to the pad and continue to heat the pad until the solder goes under the tab (I add more solder as needed). You need to position the transistor such that you can access the pad with your soldering tip without touching the tab (touching it a bit is not an issue) and you want to move your soldering tip around to heat the whole pad.

And you can use quite small wires to connect the board to the main ECU board; 28 gauge is sufficient. But that depends on the wire length and you also want to make sure there is not too much vibration especially near the solder joint; using zip ties and gluing the wire to the board near the solder joint are good ideas.

Jean
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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby SIMS Customs » Wed Jul 18, 2018 10:50 pm

Thank you Jean for the reply.

Thanks for the tips on how to soder the transistors.
The transistors I am using are the ones found on this page.
https://www.mouser.ca/ProductDetail/stm ... cycode=CAD

I currently have the cam and crank signals shielded and grounded from the sensors to the vvtunner box and also from the vvtunner box to the ms2 that's right next to it. I currently have all the ecu related wires going to the engine bundled in one bundle, the starter and alternator are in an other bundle and they all go throu the same hole in the fire wall. Your saying I have to separate my cam/crank signal wires from the rest of the wires and route them so they don't come close any other wires?
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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby jbelanger » Thu Jul 19, 2018 2:00 am

Those transistors have characteristics that fit this application. So the issue might be how they were soldered.

It is probably not a big issue to have the wires bundled as you mention or go through the same hole. However, if it is relatively easy to use a temporary setup where you isolate the cam and crank signal wires it would be a good thing to try. But I suspect that this would be quite an undertaking. My main worry was more inside the engine bay an if the signal wires go near the high tension ignition wires or the coils or other high current devices (any electrical motor).

Another question I have is what type of sensor are these? You mention pull up resistors so I assume they are both Hall sensors. So do you have the power, signal and ground for each sensor in a shielded cable? And how is this connected to the dual VR board exactly?

Jean
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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby SIMS Customs » Thu Jul 19, 2018 5:54 pm

That's great I'm using the proper transistors. I'll be more careful to how I solder them on the board from now on.

As for the cam and crank signal I believe they are Hall effect and there is one located on the valve cover reading 3 teeth off the cam. there are 2 tooth tight together and I believe those are for the VVT. The other sensor reads a 4 tooth wheel behind the cank pulley. I confirm the gap between the sensor and tooth is correct. Each sensor has its own +12 volt wire, ground and signal wire. I used shielded wires that have 2 wires inside the shield so I used one for the ground and one for the signal, the voltage wire is just a regular stranded automotive wire probably 18 gauge. The sensors are wired to the VVTunner box I got from DIYautotune just like in the following diagram.
VVTWIRING DIA.png
VVTWIRING DIA.png (85.7 KiB) Viewed 1338 times

VVTPINOUT.png
VVTPINOUT.png (35.48 KiB) Viewed 1338 times



There are no high tension ignition wires as its COP, for electrical motors there's only the rad fans that are approximately 8" away and wired separately. There are solenoids like the VVT valve and the idle valve that share the same wiring harness, the coils and injectors also share the same harness but as far as the sensors being to close to actual injectors and coils I find unlikely because the Toyota coils are a popular mod on this engine and a lot of people have successfully installed them. I will pull the cam/crank wires out of the bundle of wires and will rout them to avoid other wires as much as possible.
Could it be one of the coils is going bad and causing some noise? I will test the coils and see if i can determine if one of them is faulty.

As for how I have the signal wired to the dual VR board. I have it wired as follows:
Cam signal
from VVtunner pin 1 to DB37 pin 5/spr 3
to Dual VR board VR1+ with 1k resistor pull up from 5 volt from proto
for the output its Dual VR board Out1 to JS10

Crank signal
from VVTunner pin 2 to DB37 pin 24/tach in
to Dual VR board VR2+ with 1k resistor pull up from 5 volt from proto
for the output its Dual VR board Out2 to TSEL

The rest is wired as per you instructions just a ground and 5 volt from proto. I have the dual vr board is soldered on a 8 pin header I made on the proto area of my V3.0 board with the provided pins.

engine2.jpg
engine2.jpg (1.91 MiB) Viewed 1338 times
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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby jbelanger » Thu Jul 19, 2018 6:15 pm

I'll go through your post in more details later but there is one thing I thought about that could be an issue. Are you using resistor sparkplugs? If not, you absolutely need to change that because that will cause noise and the type of issue you're seeing.

Jean
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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby SIMS Customs » Thu Jul 19, 2018 7:50 pm

I just checked my plugs and I'm currently running BKR5E-11. They have a resistance of 5000 ohms. But my budy made me realize that these are too hot for my application. He recommends I get some BKR7E. Are those what you call a Resistor spark plug
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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby jbelanger » Thu Jul 19, 2018 8:13 pm

Yes 5000 Ohm resistance is a resistor type sparkplug and what you want. Usually the "R" in the name means resistor. And running the correct temperature range cannot hurt.

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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby SIMS Customs » Fri Jul 20, 2018 10:49 am

Looking at spark plugs I found some that are 10K ohms that fit my application. Maybe I should give those a try?
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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby SIMS Customs » Sat Jul 21, 2018 11:18 pm

Thanks for the replys. I'm not using any of the original tach input circuits on the V3.0 board. I'm using the Dual VR board by JBperf so there's no pots to adjust.
I think my noise problem was partly because I didn't clean my boards after sodering and everything was full of dirty resin. I cleaned everything really good and I also realized I had the wrong plugs for my power level. I had NGK BKR5E and switched them to BKR7E. An other thing I did is richened up my fuel map at wot.

So after doing these changes I went for a run on my back road dyno last night and the car drove nice and pulled nice even at 50% throttle with no more sync lost. But then I tried a WOT pull and as soon as I let off the throttle the AFR went flat to full rich and a few sec. later i'm o the side of the road with a flooded engine. I found testing the injector outputs with a noid makes it easy to test for stuck transistors. So I tested all 4 outputs tonight and found that output A and C still function as they should. The last one I replaced was the output A transistor and I soldered it as per Jean's instructions he posted up above.

So seems like the noise causing the lost of sync is gone but I'm still frying transistors. I was told its easy to put too much heat into them and to only heat up the pad when soddering them wich is not what I did originaly. So I have 4 transistors left on hand and I will change the 2 failed transistors and installing them properly this time. I also change the oil after every time this happened because the engine gets flooded bad.
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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby SIMS Customs » Sat Jul 21, 2018 11:41 pm

Oh yeah...I almost forgot one detail that probrably made all the difference with the noise. The VVT map rpm axis was messed up, the rpm bins stopped at 4000 rpm and all the bins from there on were at 0. So I fixed the VVTuner map and I bet that was the real problem.
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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby SIMS Customs » Sun Jul 22, 2018 1:43 am

Perhaps I have bin so worried about getting too much heat in the injector output transistors that I didn't fully solder the big tab to the board. The following picture shows evidence that B(2) wasn't fully soldered. I will clean the board real good and solder them properly as you described and try that.

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20180722_014733.jpg
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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby SIMS Customs » Mon Jul 23, 2018 9:22 pm

So I replaced 3 of the transistors 1, 2 and 3 because these were the only ones I had left. I soldered them with flux for soldering boards and seen the solder wick under the transistors. pretty confident I did it right this time. Then I started the car, idled very well, got it warmed up, then drove down the road and shifted in 1, 2nd...ran really nice, afr were really not far off then I hit the throttle and did a nice smooth pull to 4600 rpm, waste gate blew open. I let off the throttle and its full rich, shut it down right away. Then I pulled it back in the shop and tested the outputs again and 1, 2 and 3 are stuck making the injectors wide open. So then I opend the ms2 back up and I checked the resistors to make sure maybe I had the wrong ones in there. So R5 to R8 are 1K ohms and R9 to R12 measure at 55K ohms measured on the board. So I checked the bag of resistors that contains extras of the 100k resistors and the bag is clearly marked 100k. and they all measure at 100k. the colors also match up. Could resistors get damaged or is there something in the board reducing the resistance?
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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby jbelanger » Mon Jul 23, 2018 11:28 pm

Measuring resistors while they are in a circuit is meaningless. At 55k, I assume they are correct.

As for the drivers, there are two things I can think of that could burn drivers quickly like that. First, are the injectors really high impedance? Measure the resistance and they should be above 10 Ohms each. Low impedance injectors (less than about 6 Ohms) could draw a high current and that would also create a very high flyback energy; this could easily burn drivers. The second thing is the grounding: do you have all 3 ground wires connected to the DB15 connector and are those ground wires going to a good car ground?

With the drivers you said you use and the way you soldered them, there should not be an issue driving one injector per driver.

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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby SIMS Customs » Tue Jul 24, 2018 9:17 am

I can confirm all the injectors measure at 13 ohms.
For the grounds I will check them when I get in ny shop tonight.

There is one more point I forgot to mention in my previous post. After reinstalling the transistors I bench tested them witg the MS2 connected in the car. I disconnected the harness from the high impedence RC 550 cc injectors and connected the mazda factory injectors to each output and in test mode I tested each injector/output at different RPM and different PW up to 25 ms and 6000 rpms. The injectors were not in a fuel rail or had no fuel running throu them during the test. I was trying to put a load on the drivers to see if they would hold up. They held up fine. then coonected the harness back on the engines injectors and they ran good until i went WOT.

So could it be my injectors on the engine are no good? Could they be doing something under high load that meeses up my outputs? they all measure at 13 ohms but I dont know muchelse about testing injectors.
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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby jbelanger » Tue Jul 24, 2018 3:38 pm

I must say I'm a bit stumped; I'm curious to see what you see with the grounds. The injectors might be ok but the may have inductance characteristics that create more extreme flyback conditions which the drivers do not like. Changing injectors would be a good test if you can do it.

Having said that there is also a possibility that the board has been affected by replacing the drivers many times. It could affect resistance between the injector and the driver and between the driver and ground. It could also affect heat transfer between the driver and the board and between the board and air.

One thing you may want to do is to post on the msextra forum. There is very little traffic here so you don't get many views but you will get many over there; you might get some feedback from others.

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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby SIMS Customs » Tue Jul 24, 2018 5:18 pm

So I just confirmed what I did for the 3 ground pins from the DB15 of the 4 channel board and I have the 3 ground pins soldered to each a 20 gauge wire and the 3 wires attach to one single 20 gauge wire and the wire goes to a good chassis ground. My gut feeling tells me that's probably not good enough. do you think this is the problem?
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Re: 05 NB MS2 VVtunner lost tach under load at 3-4K RPM

Postby jbelanger » Tue Jul 24, 2018 5:36 pm

I would prefer to see all 3 wires go all the way to ground or, as a second choice, to have a larger gauge for the single wire. But what you have should still be acceptable.

One thing that could make a difference with the ground wiring is how you fire the injectors. Are you using sequential injection or something else? Even though the average current will remain the same, sequential injection will minimize the largest current seen while using simultaneous untimed injection will maximize it. In the latter case, your wiring might be an issue.

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