Saturated to Peak Hold Injector Conversion

[Mikes95RT]

I really don't care about the injector impedence if the maps are fubared with the NA ECU in the first place. My concern was to run a TT ECU with a NA ATX controller.You can build a custom harness with all of the wires that send the signal between the NA ECU and NA ATX controller. I had built this harness pin for pin and knew where every wire plugged in to the TT ECU. So now if you follow you would have been able to run the TTECU and harness with this new harness attached and it would have controlled the ATX computer also. Well after 1.5 solid weeks of tracing wires, pulling them from their harness and marking them, I got to 3 wires that had no place to go on the TT ECU. They were all shift related so after talking with Frank at Kormex and Steve at 3SX along with Brian at GTpro I was given the same answer. Well maybe it will work just fine without those wires connected and maybe it won't. Well no shit! So I just pulled the ATX and installed the 5spd. It would be nice to run the TT ECU and the ATX.

[Import Power]

http://www.3si.org/forum/showthread.php?p=2165191

DONE

http://importpoweronline.com/ipw-web...y/resistorpack

[92es]

so no one has figured out if the TT ECU will work on my NA ATX? (at least its got 222hp )

[TooFast4Radar]

Originally Posted by 92es

so no one has figured out if the TT ECU will work on my NA ATX? (at least its got 222hp )

The 1G Turbo DSM transmissions are similar to the N/A 3S transmissions. I believe the 3S version was a just a bit beefier. It might be possible to get a 1G DSM TCU (Transmission control unit) and use it as a piggy-back. Food for thought? Even though I don't have an ATX I will try to look into this more fairly soon.

[cbatters]

Originally Posted by Imp Pwr Online

Without the resistor pack you can not swap in larger low impedance peak hold inj.

Saturated Injectors (NA high impedence) can be used in Peak Hold (TT) systems, but not the other way around. So if you want to use the better (larger) injector you must do this conversion.

Quick question regarding Peak/Hold

Are you 100% sure TT uses Peak / Hold drive for the injectors. I always thought the injectors were low impedance injectors with a series resistor but driven in saturation mode - not peak/hold where the ECU modulates the current.

I'll toss a scope on one of my injectors to confirm. If the ECU pulls the injector to ground for the entire duration of the injector period, it is being driven in saturaion mode not peak/hold.



Clint

[stevep]

Originally Posted by cbatters

Are you 100% sure TT uses Peak / Hold drive for the injectors. I always thought the injectors were low impedance injectors with a series resistor but driven in saturation mode - not peak/hold where the ECU modulates the current.

I'll toss a scope on one of my injectors to confirm. If the ECU pulls the injector to ground for the entire duration of the injector period, it is being driven in saturaion mode not peak/hold.

Clint

I'm pretty sure the ECU uses a saturation driver with the current limiting resistor rather than actually having peak and hold drivers. Jeff L. seems to confirm this http://www.stealth316.com/2-fuelinjection.htm

Evey time I looked at this thread I cringed at the references to low impedance injectors as peak and hold but it's a very common mistake and didn't seem worth mentioning.

[cbatters]

Originally Posted by stevep

I'm pretty sure the ECU uses a saturation driver with the current limiting resistor rather than actually having peak and hold drivers. Jeff L. seems to confirm this http://www.stealth316.com/2-fuelinjection.htm

Evey time I looked at this thread I cringed at the references to low impedance injectors as peak and hold but it's a very common mistake and didn't seem worth mentioning.

The reason for my post was that when I first saw the thread, I thought someone had come up with a piggyback Peak/Hold injecor drive circuit for TT but was disappointed that this was really a NA -> TT ECU upgrade thread.

Haven't seen any hard data but my theory is that a Peak/Hold would provide more precise injector timing.


Clint

[Jeff Lucius]

Originally Posted by Imp Pwr Online

Simply put both NA and TT ECUs put out the same inj signal. On the NA it just goes directly to the Inj. On the TT that signal just gets put thru the resistor pack first then to the inj.

Well not exactly.

1. The ECU does not put out any "signal" to the fuel injectors. It quite simply grounds a circuit for a prescribed length of time (in milliseconds). For the TT injectors, that circuit happens to include an external resistor, with a total resistance in that circuit of about 9.5 ohms. The NT injectors supply their own extra resistance (no external resistor) for a total resistance in the circuit of about 13.8 ohms. In both cases, resistance in the wiring and connectors has been ignored. The main consequence of this difference in circuit resistance is the amount of current (amps) in each circuit. Bringing us to item 2.

2. Because the amps are higher in the TT circuit, and because the TT injectors are designed to act faster, the ECM decreases the duration of the pulse (that is, the amount of time the current is applied or the circuit is grounded) to compensate for the faster solenoid response. The ECM for NT injectors knows to use a slightly longer pulse duration. This is most evident if monitoring IPW on TT vs NT engines.

So, if the ECU is not changed (TT into a NT car after switching to TT injectors) then the ECU will be using a longer IPW than it should. An AFC should be able to compensate for this.

[Kadius]

Kinda bringing this thread back...can a TT ECU be used with a single turbo setup?

[<T>]

I'm bringing this back up as well:

For an NA staying NA looking to upgrade the injectors, a TT ecu is pointless, correct?

And all that is needed in this case is the TT injectors and a resistor pack along with an AFC, right?

IPO, you think you might start selling kits for conversions?