Can one of the list members here who owns a 1993 or 1994 XJ6 please pop the electrical connector off of one or two fuel injectors and using an ohm meter measure the resistance of the injector across the two pins inside the electrical connector of the injector?

The value should be either about 2.5 ohms or higher at approximately 13 ohms.

I am not sure my MY94 car has the correct injectors in it and I am trying to confirm which is correct from the factory.

Thanks

 

From memory I think the 94's have a green stripe on them

My car is parked up the block on the street so can't help with ohms sorry

Larry
Day19

 

The 4.0 AJ6 injectors can be distinguished by the color band.
The difference is the spray nozzle, so I would assume the coil resistance is not a good way to tell.
The 1990-1992 has a single nozzle and the GREEN band has TWIN nozzle.

TSBs are your friend.

 

I couldn't find a green band injector in my parts bin, but I have a white band D3156KA which measures 16.0 ohms and a red band D3165 that measures 15.9 ohms. These are the plate-type dual-orifice injectors for the N/A and S/C AJ16 mentioned in the TSB Bob provided. Other than fuel flow rate, I believe they are identical to the green-band D3155KA injectors used in the '93-94 cars with the AJ6.

I must have remembered incorrectly about the earlier injectors being high-impedance, because the 1993-94 Engine Management System Diagnostic Guide says the '90-'92 single-pintle injector coils measure approximately 2.5 ohms.

Cheers,

Don

 

I measured the resistance of the injectors in my MY94 and they were 2.5ohms, so low impedance.
The injectors out of my MY97 X300 car are high impedance injectors with a resistance reading of 12.5 - 13 (I forget the exact figures but they were certainly different than the AJ6 injectors I checked).

Low impedance injectors (2 - 4 ohms) are designed to be used with a peak-and-hold type of injector driver. This type of signal uses a two step current and requires resistors to prevent the higher current from frying the ECU. It uses a high initial current to open the injector quickly and then a lower secondary current to keep the injector opened for the rest of the pulse. Using a lower secondary current creates a weaker magnetic field, allowing the injector to close quickly. At the expense of a hotter operating temperature, the higher current gives low-z injectors their great response time, dynamic range and higher flow rates.

High impedance injectors are used with drivers that provide a saturation signal. A saturation signal is a constant low current supplied to the injector for the duration of the pulse, instead of the mid pulse current reduction that low impedance injectors use; increasing injector reliability by reducing the operating temperature. The downside is that this increases the latency of the injector, making them inconsistent in their dynamic range and fuel delivery.

Low impedance and high impedance injectors cannot be used interchangeably without modification of the injector drivers.

So I am trying to figure out without actually removing the fuel rail again if the injectors I have in my MY94 car are incorrect or not.
I guess I will see if I can see the reference number printed on the side edge of the injectors without removing them.

 

If you can see the Bosch part number (0 280 *** ***) on your injectors, you can look up their fuel flow rate and impedance here:

Stan Weiss Fuel Injector Fuel Flow Rate and Impedance Table

Another thing I forgot to mention: the original '93-'94 injectors are D3155KA and have a wide green band around the middle of their bodies. Some of the AJ16 supercharged injectors I have purchased, part D3165KA, have a narrow green band around their upper necks, so you can't just go by the color of the band - the placement and width also matters. But if you had the narrow green band injectors your engine would be flooded with fuel since their flow rate is 380 cc/min compared to 210 cc/min for the wide-green-band injectors.

Cheers,

Don

 

Thanks Don
Yeah, I know about the Stan Weiss fuel injector list.
I have used it a few times before when I was designing the fuel injection system for my Jensen Healey and when I wrote the advanced tech article on that design process.

 

Hey Don, That flow table is a great thing! I ordered a set if injectors for my 92 which set off my engine light. FF26, lean exhaust. They have no paint on them and the only number on them is the Bosch number which I was able to use to identify the new ones as wrong. Any chance of making it a sticky?