SIMS Customs

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.

EDIT:
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??)

Please help me get this sorted out so I can start shredding throu my stack of half worn tires.

ungluedflyer

I can't say I'm an expert at all, but I just fought a very similar issue with sync loss and I had to physically adjust my trim pots on the megasquirt pcb itself. Seeing as yours is an MS2 I can't say we have identical issues but my thread might be of help to you
https://www.miataturbo.net/megasquir...6/#post1492457

And another one here that has some more knowledgeable people going into details on why sync loss happens:
https://www.miataturbo.net/megasquir...nc-loss-91089/

ungluedflyer

If you aren't sure about this I'd rip out the VVT Tuner at first just to verify that isn't the problem. I vaguely remember that thread you're talking about.

SIMS Customs

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 have 2 injector driver transistors that are stuck open for sure. I found testing them with a noid makes it easy to test for stuck transistors.

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. So I have 4 transistors left on hand and I will try changing them and installing them properly. Hopfully this is the last time I replace them. I also change the oil after every time this happened because the engine gets flooded bad.

SIMS Customs

UPDATE
I just finished testing the 4 injector outputs with a Noid and test mode in tuner studio. And found that output A and C are still functioning as they should. The last one I replaced was output A and I soldered it as per Jean B. instructions. Output B and D are stuck to ground so injectors would stay on as long as there's power to the MS. From looking at all my logs where I had an injector transistor fail. They all failed at higher load/higher open time over 13 ms. I will keep bench testing with a noid with longer injection duration.

What should the highest duration be for injection time? I'm using high impedance 550 CC injectors.

I will go ahead and replace the 2 failed transistors as per Jean B instructions and hopfully I can put this chapter to bed and start burning some tires!!

SIMS Customs

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

SIMS Customs

So after fixing the vvtunner map I havnt experienced any lost of sync like I had. But I am still experiencing failed injector output transistors every time I went into heavy load. 10+ psi boost. I reinstalled the drivers properly and tested them with the original miata injectors attached to the harness instead of the rc550 high impedance injectors in the engine. I used test mode in tuner studio and put the circuits throu all sorts of loads from 400 rpm to 6000 rpm and 5 ms to 25 ms. and the transistors held up no problem. I attached the harness back on the rc 550 cc in the engine and started the car, let it warm up, afr are not too far off, and then went for a ride and drove nice with lots of power and then I did a wot run and at 4500 rpms it goes full rich, I let off and it stays rich so I shut it down and towed it back to my shop to test the outputs with the noid light and found 3 transistors stuck to ground. keeping injectors open as soon as power is on. anyone ever experience this?

Reverant

iTrader: (10)

This behavior is completely consistent with using low impedance injectors. Please measure the resistance across the two pins of these injectors.