Personally I would've replace both at the same time. If it were MPFI where you had 4, 6, or 8 injectors then sure I would've just replaced the one, because the difference is diluted over a larger number of injectors. But when there's only 2 injectors and each is carrying 50% of the fuel demand, then slight differences between them can make a difference.

 

Looks like one of "they" has responded and is very willing to spend your money for you.

It's not like each injector only feeds 1 bank of cylinders. While I remember paying about 90 dollars per injector, I think rockauto now has some unknown name for under 40 dollars. If that is the case i would buy 2 new ones, but I have at least 50 k miles with mismatched injectors, and drive around with a backup.

I think a failed injector on an MPFI engine would be worse for the engine than on a TBI. You might drive hundreds of miles on an MPFI with 7 cylinders where as when a TBI injector fails you know instantly something is wrong.

Mine was stumbling and surging ridiculously.

 

Sounds to me like you just gave 5 reasons why "they" were correct!

 

You guys are funny!

Well I got the new injector in on the right bank (connector #2), sealed things up on the throttle body, fired her up.....BAM....Not even a squirt on the new injector AND my check engine light came on. It's Code 27.
Then I swapped the injectors around to verify the new injector even worked. It works great.

Both the new and old injector work fine on the left bank (connector #1) but neither injector works on connector #2.

So I was doing a tad of research and looks like they are both controlled by the ECM and also may have a fusible link for each fuel injector connector.....Is that correct?

So if that's the case...there is constant power to the injectors with the key in the run/on position and the ECM provides ground control signals for the injectors to fire off?


I was tracking down the fusible links and found them all jammed behind the brake booster. Things got late for me this evening and it was hard to see in there.

So again just to reiterate....
Each fuel injector connector has a fusible link correct?



Damn, I was soo close to driving this baby again.

 

http://minimopar.knizefamily.net/ecu/smec-1988-tbi.html

I have been looking in my '89 factory service manual. On the engine computer, the 60 pin connector


It indicates that pin 32(gy/wt*) is injector control 1, that pin 33 (Violet/Yellow*) is injector control 2.

This is different than the above link which says for an '88.

I have not found anything(yet) that says there is a fusible link for each injector. It did say the ASD relay controls the power feed to the injectors{z1 dark green/black], so the ecm must provide the switched ground.

Also look closely at the connectors that slide over the injector pins, and re bend them to make sure they grab the pin tightly.

I think you must start looking closer at the wiring leading from injector to ECM. There is also some other info you might want to check out on that site.


edit: There are 2 separate circuit boards in the ECM's of our vintage. Thus the 14 pin connector and the 60 pin connector.

On my '89 the FSM states
On the 14 wire connector, it says pin 9(18 awg white) and pin 10(18 awg tan) are the drivers for the injectors.
It says pin 33 joins to pin 8 on the 14 pin connector (20 awg yellow)
It says pin 32 joins to pin 5 on the 14 pin connector ( grey/ white)

My wiring diagram for this circuit does not indicate the presence of fusible links on this circuit.

Since the '88 pin readout does not indicate separate fuel injector drivers, one might think the one wire drives both injectors. At some point this wire must split to feed both injectors.
If you cannot find a broken, suspect wire/ connection:
Perhaps you could run a new wire from pin 9. Or just bridge the 2 wires within the connector.

to each injector.

 

Ok looking at the site and info LandYacht.....

SMEC controls for the injectors are

SMEC-Connector #2 (14 Pin Connector) Pin 9 controls Injector #1
SMEC-Connector #2 (14 Pin Connector) Pin 10 controls injector #2

Looks like the connectors have a constant ground (Dark Green w/tracer) that are spliced into Z1....chassis ground I believe

So I just went out and checked the 4 pin connector that sits close to the throttle body that subsequently splits into the two separate injector controls.

Pins 1 and 4 should have Z1-Chassis ground.........Both pins have a solid ground

Now Pin 2 and 3 are from the SMEC. I'm not sure what the operating voltage for the injectors is but it must be less that 1 volt as I hooked up a voltmeter and both pins 2 and 3 are giving a low voltage upon cranking the engine.....I don't think a voltmeter while accurately read the pulses as they are probably too rapid for the display to even change but they do show some low voltage coming off both pins

It's 11pm out here on the west coast so I didnt bother checking the injector connectors through the 4 pin connector. I'll recheck tomorrow the contacts for injector cover #2 and buzz em through into the 4 pin connector. Just doesn't make sense that such a low voltage would damage the 18gauge wiring

Now I can't verify what the operating voltage for these injectors is so for now it's speculation

Thanks for the tip otherwise I'd be tracking down fusible links like a mad man

 

I just followed the Z1 in my '89 fsm.
It also connects to the (-) side of the coil
Asd relay
fuel injector 1 and 2
heated 02 sensor
pin 10 in the 14 pin connector.

I think the problem might lie close to the connector itself on the injector. See if a little wire wiggling and an ohm meter shows any poor connections between the injector 4 wire connector, and the 2 tabs which touch the pins on thebad injector itself.

Since removing and replacing the injectors is the common link to it working normally, thinking it was fixed, only to return, seems like the weak link might be in that area.

Are you getting any engine codes related to the 02 sensor or asd relay?

The ECM get's it's ground from a wire at the coil's base on the intake manifold. Make sure that, and any other ground cannot be the issue. Also unhook the connectors at the ecm and look for water or corrosion.

 

The voltage would either be 5,8, 9 or 12 volts, and a digital meter could never respond quick enough to show you the pulses on the injectors.
On the 60 pin connector:
Pin 13 says 5 volt supply
Pin 52 (orange) says 8 volt input. In another section of the FSM it says 9 volt input??

On the 14 pin connector:
pin one is 8 volt output

 

Nope, the two injector common wires come off the ASD relay and are +12v. The two control wires from the SMEC provide a negative pulse to the injectors.

 

First you had this:
Now you have this:
That's two completely opposite results for the same test. This happens when the person doing the testing isn't being careful, or when there are multiple problems going on. So you might want to start looking closely at your electrical connections, or possible at a bad SMEC.