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Last seen: 3 years 3 months ago
Joined: 08/26/2015 - 16:36
Injection issues using TBi

Hi y'all,

Im using the FIC 8 on a single-point (throttlebody) injection driven engine.
I have converted this engine to forced induction. I wanted to use the boost-control solenoid, so that's why I went with the FIC 8 (instead of 6).

There are two problems that come to light after wiring up the fic:

  1. Leaning out on load, caused by erratic injector-driving
  2. Irregular RPM signal.

1.: Injector issue:

For wiring the injector, I have used INJ 1 IN and INJ 1 OUT wires to intercept one of the injector wires coming from the ECU. The choice in wiring was a bit difficult, because both wires off the injector go into the ECU (as opposed to just one signal wire from ECU to injector, plus one wire to 12v+ from the injector).
Apart from that; the injector did respond well to changes in the fuel-table, when increasing trim; I would get richer A/F and vice versa.
But the strangest thing happens when I press the accelator fully: it starts revving to max RPM like normal; but then leans out and stays on 3.5kRPM with a very lean (>18:1) mixture. Same thing happens on the freeway: no greater speeds than 50mph can be achieved because it will start leaning out very badly. I have to go way back on the throttle to compensate until I have almost no power to accelerate any further.

Here is a YouTube link of a oscilloscope probing the injector's two wires: https://youtu.be/j6LayEZaekM

I have swapped the following bits in search for a probable cause: injector, FPR, fuel pump, new fuel filter, distributor. Nothing made any difference.

When I bypass the FIC, injector-wise (so connect the injector like stock, on stock ECU), the problem is gone and it runs like stock.
I have probed a identical car (bone-stock) and I get exactly the same oscilloscope-readings as with my current situation. YouTube link: https://youtu.be/ZndYtO5XjX4

You can see that there is an additional pulse right behind the primary pulse when things go south. The secondary pulse is so short that I don't believe this will actually open the injector.
Apart from that; this pulse is not generated by the stock ECU when the FIC is bypassed... So what causes this additional pulse? It definitely is the source of leaning out (not delivering the right amount of fuel in the right way).

I have also played around with the injector time delay, but this didn't do anything for this problem.

Anyone has any thoughts on this issue?

2.: RPM (crank) signal

For getting a crank signal, I used the 4 CRK MAG wires to intercept two wires coming from a pickup in the distributor:

This pickup has 4 lobes creating a signal like this: YouTube link: https://youtu.be/fRcsT4sGhcw

Unfortunatly I'm not sure if this is the correct way to wire this type of crank signal. Apart from that; I do get a fluctuating (and sometimes even spikey) RPM measurement out of this signal... As you can see: the white line in the middle lane. This was at steady throttle, constant speed:

There is a fluctuation of at least 400rpm between steps. And the big spike you see is 5180rpm in between two measurements of 3583 and 3377rpm...

Anyone know a solution to this? Change wiring, add resistor, find different crank signal (don't know where I should get it from...)

I'm not sure if this has anything to do with the CRK MAG wires, but the altering of ignition timing in the FIC is actually working. And really precise also.


I hope anyone can help me out here.


Thanks a lot in advance!

Last seen: 3 years 3 months ago
Joined: 08/26/2015 - 16:36
It's a G13B (or G13BA) 1.3l 8

It's a G13B (or G13BA) 1.3l 8 valve single cam engine from Suzuki

And all testing was done without the turbo mounted

Also bypassed crack signal; injection problem still persists...