My 2.8 mpfi (1988) injectors' resistance is supposed to be 12.6 ohms max. Only one of mine is 12.6, all the others around 13(!) The ohmmeter zeroes out ok. Looking for a steady miss which I've ruled out the cause to be ignition, and was expecting to find one injector with resistance out of range...not almost ALL of 'em. What does that resistance actually mean in terms of performance, and how much life they have left in them, etc.
Don't feel to anal about the exact resistance reading. I think you are OK if they are all about the same at 13 ohms. If one injector read 2 ohms or zero ohms, that would be a problem
Interesting point: the book's specified range of resistance for an injector is probably simply intended to mean that a 'normal' one (or a new one) would have resistance measuring from 11.8 to 12.6--rather than that if it isn't within that range it's junk (which I guess this proves).
Meanwhile, however, other components have a similarly small "window" of ohms or voltage it must test at--and, failing that, the component IS junk. Noam sayin'? :-)
You are failing to take into consideration the tolerance and accuracy of your meter. Get some 1% resistors from RS and double check your meter..
I wondered about that myself, since all injectors were close to each other but slightly out of range. I touched the probes together to see if it zeroes out, which it did, but that doesn't address the total accuracy. Should a person get several resistors of different ratings? like 1 ohm, and .1 ohm, etc.
Or you could use the 0 (That's zero) adjust...this will calibrate your meter according to the probes wires resistance...
"Woody" a écrit dans le message de news: rzZOe.1052$ snipped-for-privacy@newssvr22.news.prodigy.net...
Touching the probes will zero it but won't address the accuracy of the meter itself. I would try to find some 1% or better resistors to check calibration. Is it an analog or digital meter? Analog meters will change over time as well as with temperature and humidity. All of this is ok but I don't believe the resistance at 3% is out far enough to cause a problem. Have you checked valve adjustment, compression....
I recently put new heads on it about probably 8000 miles ago, new plugs & wires, ECM has been replaced prior to that. I have a donor car which I robbed the ign module off of, but never swapped out the modules although I did take a coil pack and swap it for the cylinder which didn't seem to make as much difference in rpms when I took that plugwire off, miss persisted. Haven't checked injector harness for pulses as I'm having to do this between other stuff. If one of the injectors isn't getting voltage, what is the likely cause of that?
Today I got a chance to test all injectors for input voltage from harness, also applied voltage to each injector, all ok. I discovered EGR was stuck solid, replaced it, still runs the same. But this got me wondering: The non-functioning EGR should've set a code--obviously hasn't been working for awhile. How does the ECM determine the EGR isn't doing its job--by the 02 sensor? Also, shouldn't the 02 sensor voltage be out of range if a cyl isn't firing but getting fuel? Even if you're getting tired of me... Think of it (your replies) as information for the masses. ;-)
O2 sensor and MAP sensor.
Not always.
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