[jonno_racing]

Hey guys i am picking up a TBI kit for my current build
it will be going on a g16a carbi..
few questions from people in the know..
what fuel pressure do they run? ruffly? full efi style?
where would i get a Wiring diagram/pin out for the ecu? google is shooting blanks on this one...
how much better fuel economy would i expect?
i am going tbi for more reliability and the ability to run on big angles!
Phil

[Fatzook]

EFI pressure. There is still a fuel regulator IIRC.
There aren't many wires. Besides that, if you open the ECU case, there should be labels on the printed circuit. If not, I could probably use my mates factory TBI as a template for you.
No increase in economy at all. NONE.
You will definately notice the difference on side angles!

[Rhinoman]

Vitara TBI? I have manuals here.

http://www.rhinoman.org

You want section 6E of the Vit FSM. I also have some Swift info. The Vit TBI ECU doesn't have any usable markings on the PCB - you only get those on Denso ECUs.

[Fatzook]

Rhinoman wrote:

The Vit TBI ECU doesn't have any usable markings on the PCB - you only get those on Denso ECUs.

Good to know

[droverdave]

Fatzook wrote:

No increase in economy at all. NONE.

why not?

[Fatzook]

Because it just doesn't. Its a single point injection system, not multi point. Think of a carby with one injector in it.

Its a crude, yet effective way to remove the reliability issues that come with carbies. ( no fuel bowl means no flooding on side angles etc)

If you want marginally better economy, skip over the 8v motors, straight to the MPFI 16v.

[droverdave]

Have you tried them back to back? (not having a go, just interested)

Im not convinced that it wont help, electronic fuel metering and spark i reckon will always be more efficient than the carby.

[Fatzook]

Yes. My mate Charlie has the TBI vitara motor in his sierra now. It returns the same figures as his G16a motor did in the same car. Ofcoarse we are working on .5L/100km accuracy, but at the end of the day, that still proves the difference to be negligable enough to not bother mentioning it.

Power is almost identicle, but torque feels better with the TBI.

My TBI sierra was brilliant. Even though it was less powerfull that the later 16v motor, I found it to be super reliable, and very nice to drive. Twas a great motor.

[droverdave]

Fair enough.

I was considering adapting a throttle body injection to my g13a and running an aftermarket computer. (megasquirt).

Sounds like it might be a feasible idea still.

[jonno_racing]

Thanks for the help/imput guys

Fatzook wrote:

My TBI sierra was brilliant. Even though it was less powerfull that the later 16v motor, I found it to be super reliable, and very nice to drive. Twas a great motor.

The exact reason i am going tbi
i have had a sierra laying on a bank that wouldn't start due to huge lean, and had to back it out on the starter motor, not a great experience and not even possible with my new set up (3speed auto). also had a zook that wouldn't start below 0' and yes that does happen here a fair bit in winter.
i am picking up my TBI kit in a few weeks when i am in qld. then all the fun can start! i cant see it being a huge issue to wire etc, has to be simpler than a gti or g16b, just wondering as pinouts for the ecu are very scares

Phil

[JrZook]

IIRC that TBI unit your looking at has the complete loom for a vit still attached to it. Should help with the wiring etc.

[jonno_racing]

Sure does! and i now have the ECU pin out! Big thanks to Rhinoman for that one! should be nice and simple to fit in!

[Rhinoman]

droverdave wrote:

Fair enough.
I was considering adapting a throttle body injection to my g13a and running an aftermarket computer. (megasquirt).
Sounds like it might be a feasible idea still.

MS isn't great for a TBI as it doesn't have a proper driver for a low impedance injector.

[want33s]

TBI.... been there, done that...... It's way way way overrated...
Sell it to someone who thinks it fully sick and get a 16V mpfi.

[jonno_racing]

No....

[jonno_racing]

So this has popped up again for me..
Can anyone tell me if I need a fizzy from the tbi setup or does the computer run from a earth signal on the dizzy for engine speed? (like a mk1 gti)

[want33s]

When I did TBI on a g13 I used the original sierra dissy.

[jonno_racing]

Thought as much!
All good. Should be a simple afternoon job!

[jdk81]

It took Josh (31zook) a little while.
Have you asked him?

[Rhinoman]

You need the Vit dizzy, it uses a different sensor and the ECU takes care of timing.

[johnmath]

I did a TBI conversion on a G13A and got >40% in fuel economy - from ~8 kpl when I bought it, up to 13.3 with the TBI on a long run of mixed high speed and off road. See: viewtopic.php?f=5&t=41393

[JrZook]

Rhinoman wrote:

You need the Vit dizzy, it uses a different sensor and the ECU takes care of timing.

Cant you just use the VR sensor in the sierra dizzy and omit the coil driver.

[Rhinoman]

If you just use the VR sensor then you will be driving a negative voltage into the input. You will also get a lot of unwanted timing advance from it, the HE sensor interface triggers at around 2.5V. Its a long time since I measured a VR sensor so I can't say if you will get enough voltage at low speeds, its certainly not going to have a proper termination impedance.

[Hybrid]

Just a couple of notes as I run G16A TBI on a megasquirt

1. I get better economy with the 1.6 TBI than I ever did with the 1.3 carby. Less than 10 liters per 100. The thing is though it runs a wideband o2 sensor so fuel can be dialed right in. Stock would run a narrowband.

2. I'm running the low impedance injector straight off the megasquirt without a flyback board and have never had any issues. It's obviously handling the transient voltage spikes ok.

3. I'm running a VT in tank pump with the standard reg doing all the work setting the pressure. I do have suspicions though that the return line size should be upgraded.

[JrZook]

Rhinoman wrote:

If you just use the VR sensor then you will be driving a negative voltage into the input. You will also get a lot of unwanted timing advance from it, the HE sensor interface triggers at around 2.5V. Its a long time since I measured a VR sensor so I can't say if you will get enough voltage at low speeds, its certainly not going to have a proper termination impedance.

Ah righteo I see your concern. Virtually all the TBI setups Ive seen round here run factory VR so for these, the sierra dizzy with a VR should work fine

[droverdave]

When i was playing with my G13a VR sensor on the Haltech, I had it running and driving fine, but i was having trouble starting it, especially when cold. (i was just running the haltech on the spark, kept the carby for fuel). Changing the starting ignition advance did not appear to have any effect on it. I'm fairly sure it was the VR sensor giving me troubles at cranking rpms, I would have loved to check it on a CRO, but never got around to it and abandoned the project and threw the distributor back in.

So I dunno if the oem ecu has some additional filters in them to help at low rpms (stab in the dark, i no electronics nut). Or alternatively perhaps 4 pulses per engine cycle (G13a VR/dizzy) is not enough at cranking rpms.

[JrZook]

droverdave wrote:

So I dunno if the oem ecu has some additional filters in them to help at low rpms (stab in the dark, i no electronics nut). Or alternatively perhaps 4 pulses per engine cycle (G13a VR/dizzy) is not enough at cranking rpms.

The OE Denso VR filtering/conditioning circuit in the early vits work very well. I replicated the circuit for my ECU project and got reliable triggers from a 4 tooth pickup at ~100rpm