Question : How far off can the ohms be on fuel injectors?

[DukenukemX]

My 90 Beretta V6 has a problem with stalling recently and I found two injectors that were different then the rest. A 7.6 ohm and 10.6 injector. So I ordered rebuilt injectors from Rockauto and got a 13 and a 10.6 injector. It will start and run for 30 minutes but does stall a couple of time. Though it would start back up with a few more attempts, as opposed to never.

Rockauto agreed to replaced the 10.6 ohm injector, but how far off can an injector be? I'm assumed that my injectors need to be around 12-12.5 ohms?

[AleroB888]

My 90 Beretta V6 has a problem with stalling recently and I found two injectors that were different then the rest. A 7.6 ohm and 10.6 injector. So I ordered rebuilt injectors from Rockauto and got a 13 and a 10.6 injector. It will start and run for 30 minutes but does stall a couple of time. Though it would start back up with a few more attempts, as opposed to never.

Rockauto agreed to replaced the 10.6 ohm injector, but how far off can an injector be? I'm assumed that my injectors need to be around 12-12.5 ohms?

Injectors I have of the same type do not vary much at all from unit to unit, although they do vary between different brands and styles. for example:

GTP 36 lb --13.0
RC Engineering 35 lb --16.3
Trailblazer 28 lb -- 12.6
1999 Alero stock -- 12.6

(Allowing for the accuracy of the Fluke meter, and 0.4-0.8 ohm in the test leads.)

The units within each set were very close when I checked them.

[DukenukemX]

Most of my injectors registered around 12.6 ohms. The one 13 was installed to replace the 7.6, which allows me to run the car. Before I had to have the car towed when it stalled on the highway. Once I let the car cool down I started it again and stalled within 10 minutes, and wouldn't start up again. At least now it takes 30 minutes to stall and the car will start back up with 2 - 3 cranks.

From what I'm hearing is that 10.6 is too far off? Since the injectors get worse when they're hot, I might just try testing the ohms in the wire harness when the engine is hot. I think they need to be 4-5 ohms for each set.

[DukenukemX]

I tested the hardness to the injectors and got two sets of readings. One is 4.6 ohms and one is 4.2 ohms. Then I let the car run for about 45 minutes and tested the hardness again. One was 4.6 and the other was 3.3. So something is certainly getting worse as it gets hot. It could be that one 10.6 ohm injector, but I wouldn't know unless it's hot. I could try removing the plenum while it's hot, but I'll likely burn myself trying to do it.

Would a heat gun aimed at each injector be a good idea to see which injector is getting worse as it warms up? Removed safely from the car of course.

[1988GTU]

I tested the hardness to the injectors and got two sets of readings. One is 4.6 ohms and one is 4.2 ohms. Then I let the car run for about 45 minutes and tested the hardness again. One was 4.6 and the other was 3.3. So something is certainly getting worse as it gets hot. It could be that one 10.6 ohm injector, but I wouldn't know unless it's hot. I could try removing the plenum while it's hot, but I'll likely burn myself trying to do it.

Would a heat gun aimed at each injector be a good idea to see which injector is getting worse as it warms up? Removed safely from the car of course.

I'd look for the ground points. They over time can get shoddy and cause your issues. Also, check the crank position sensor out. If its not reading accurately, itll cause intermediate problems.

[Superdave]

10.6 is too far off, they should all be around 12 ohms cold.

3 in parallel on the harness should be 4 ohms (or close to that).

The only way to perform a heat test on them is to let them generate their own heat, i used to do this when i was servicing injectors but you have to limit the current or you can damage them. I used a nice benchtop adjustable power supply. a 12 ohm injector usually drops to around 11 once the injector warms up.

[DukenukemX]

10.6 is too far off, they should all be around 12 ohms cold.

3 in parallel on the harness should be 4 ohms (or close to that).

The only way to perform a heat test on them is to let them generate their own heat, i used to do this when i was servicing injectors but you have to limit the current or you can damage them. I used a nice benchtop adjustable power supply. a 12 ohm injector usually drops to around 11 once the injector warms up.

I don't have access to that kind of equipment. At best I could try to hook it up to the car battery and put a resistor in between. I might try avoiding to start the car again and just wait for the replacement injector, and then I'll switch out the 10.6.

[DukenukemX]

Just to give an update I tried to heat up the three injectors that dropped in ohms when the engine gets hot and got interesting results.

Before heating with heat gun.
10.6 ohms
12.8 ohms
12.6 ohms

Afterwards.
10.4 ohms
4 ohms
9 ohms

I don't know what to do anymore except buy 3 new injectors. I thought the 10.6 was bad but it stayed at 10.4 after heating. The other two injectors dropped massively.

[Superdave]

That's pretty bad... lol


I'd save yourself some cash, just go to the junk yard with a few tools and a multimeter and pick through them till you find a set that's all at 12-13 ohms cold.

Use a 9V battery and some wire to make sure they click when power is applied and you should be set.