I think I may have an injector problem so I am going to check them. How many ohms should they be reading at? It is a 350 TPI motor. Thanks.

 

X84,

Be careful about using the injector solenoid coil resistance as a diagnostic tool. It basically is only a go/no-go test for the solenoid coils, and says absolutely nothing about the flows, spray patterns, and propagation delays of the individual injectors. It won't tell you if they are opening or leaking. It only determines the resistance of the operating coil, and that really doesn't mean much.

But, since you asked, the acceptable range for a Bosch injector is 12-18 ohms. Typical values are 16 ohms, and the injectors are probably losing insulation if the resistance is much below 12 ohms. Injectors at the low resistance limits might still operate, but might not be electrically as "healthy" as they once were. Again, this says very little about the injectors' performance, and those injectors might last another twenty years with low resistance.

If you suspect you have an injector that is completely dead (not operating) you might be able to determine that with an ohmmeter. If you suspect a flow imbalance, sticky pintle, or spray pattern degrading, you are wasting your time with an ohmmeter.

I had a set of Bosch injectors that were all at a perfect 16 ohms, but one of them flowed 38% less than the specification, another was 16% off. I might also have had one that was completely stuck open and it could have read the same resistance.

Since the solenoid only operates the pintle needle core by magnetic attraction (Henry's Law), trying to gauge the performance of the injector by reading the resistance is futile. (OOPS, wrong sci-fi!)


------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader

[This message has been edited by Vader (edited June 15, 2001).]

 

The Ford motorsport injectors in the 24lb-hr flavor test a little lower (14.1-14.3 ohms) than the bosch's @ 22lbs/hr. (15.9-16.3)

These are observed tests, like prev mentioned these resistances actually change during use, sometimes becoming an open CKT when warm (a hard diag problem to say the least) but any variance, like one inj standing out from the crowd, should be seriously ditched.

The lower the resistance, the more power they draw. The more power they draw, the harder on the injector drivers (in ECM) they are. I would stay at least over 13.5 ohms.

If they pass the ohm test, hook them up in the fuel rails and rig up some fittings somehow to supply regulated 40psi or whatever, w/o blowing the fpr off its seat and drip some soapy water on the ends to check for bubbles. This is what disqualified my test! Dirty or not I changed them...


-----------------
'88 Camaro RS 2.8L
'88 Formula 350 (Too many mods to list...)

[This message has been edited by JoelOl75 (edited June 16, 2001).]