I've got an 84 EA-81 1.8L MPFI turbo engine. My manual shows a dropping resistor that the injectors connect to. I need: either a service-able dropping resistor, or the resistance (and wattage) so I can put something together to run the injectors without frying them. Thanks, Bob

You need a new manual not a resistor.

Your car does not use one.

Thanks Naru!!

To set the record straight: My injectors did require resistors. 10 ohms 25 watts does the job (don't know if this is factory specs but it works fine in my application).

I like it when someone is wrong, and gets corrected

 

It is good to know you got it sorted. I did not think the dropping resistors came in until the EA82 went four plug ecu !

 

The dropping resistor you used went on the constant positive power supply side, and switched the earth side vua the ECU ??

Good catch! I am building 2 of these engines (EA81T) right now and at least 1 will use the stock harness and ECU. I didn't even know this critical detail. Thank you.

Subwat, on 03 Jan 2015 - 22:05, said:

Subwat, on 03 Jan 2015 - 22:05, said:

To set the record straight: My injectors did require resistors. 10 ohms 25 watts does the job (don't know if this is factory specs but it works fine in my application).

 

How did you determine that?

The factory does not use dropping resistors on the EA-81T.

 

What IS your application exactly?

Edited January 4, 201511 yr by naru

I like it when someone is wrong, and gets corrected

 

It is good to know you got it sorted. I did not think the dropping resistors came in until the EA82 went four plug ecu !

 

The dropping resistor you used went on the constant positive power supply side, and switched the earth side vua the ECU ??

 

Then you will like this.

The factory does not use dropping resistors on the EA-81T

Good catch! I am building 2 of these engines (EA81T) right now and at least 1 will use the stock harness and ECU. I didn't even know this critical detail. Thank you.

 

You still don`t.

The factory does not use dropping resistors on the EA-81T

I have rebuilt my EA-81T engine wiring harness in recent months.I`m driving it now.

Ok Gang, Here's what's going on.

 

There are 2 types of injectors (any car) high impedance (Hi Z) or low impedance (Lo Z). Hi Z injectors will measure about 12 to 16 ohms, Lo Z injectors measure about 2.5 ohms or less. Measure this with your ohm meter. Hi Z injectors don't need resistors, Lo Z need resistors or a circuit called peak and hold (full current to open injector, then less current to hold it open).

 

My injectors are Lo Z (2.4 ohms) and needed 10 ohms to limit the current. The resistors go on the power (plus) side and the ECU switches the ground. If you fire more than one injector at a time, you need one resistor for each of the injectors that fire together. I believe the EA-81T was bank fire and fired the injectors in pairs. I'm running sequential fire (each injector separate).

 

I don't know what the factory was doing at any particular year or model, but my injectors are Lo Z. I bought the engine used (it was complete) but I never saw the car it came from (engine might have been pulled from a car in Japan). I never saw the wiring harness or computer and couldn't locate a computer for the engine. I built a computer from a kit (MegaSquirt) and I drive this engine daily (it's in a 65 Fiat). i'm still working on getting the best tune for the engine.

Cool,How about a photo of this radical Fiat.

850?

Edited January 4, 201511 yr by naru

1100 D Station Wagon I posted a description and some photos at "Member's Rides". Post title: Subwat