1990 Q45 Injector Help

[yiannitQ45]

had the injector analysis code "51" after reading the self diagnosing computer. Did the test of checking the ohms all except bank 4 had a consistent reading. Bank 4 read 0, what should i do next/check for? Any good feedback is appreciated!!!

[Q451990]

Continuity isn't enough. You want cold and hot accurate ohm readings. 12.xx ohms cold is in spec. - anything much above 14 is a sure sign that injector is on it's way out. The typical failure mode is rising resistance until they go to zero ohms.

Heath

[goody90q45]

......Bank 4 read 0, what should i do next/check for? Any good feedback is appreciated!!!

Since it will cost more than the car is worth to pay to have it done it's time to familiarize yourself with the top end of the engine because you will soon be having to remove the plenum to replace injectors. Q45.org is an excellent source that will summarize everything you need to know about your Q. Read every section of Tech Help before you start wrenching on anything. I'm partial to this thread for removing the plenum.

zerothread?id=367568

[yiannitQ45]

thanks all for the responses, mike to make it more clear i meant the readings at cold were consistent within each other, and also i believe from what you said if injector 4 reads 0 ohms it is time to be replaced?

[goody90q45]

Correct. Unless you have a corroded wire in the injector harness (no continuity from plug to injector) then #4 FI is dead and the plenum has to come off to replace it.

[Q45tech]

The exact resistance readings are a function of the quality and cost of the device used to measure resistance. Most common handheld devices are accurate within <5% [12.8 x0.05= +- 0.64 ohms or 12.2>13.4] depending on internal battery [usually a 9 volt] condition and ambient temperature.

Zero resistance is an impossibility except at absolute zero! Now 000.1 ohm is a possibility with test leads shorted together.

The reason the FSM shows 12-14 ohms is to consider the test equipment and operator errors. But a brand new injector will read 12.8 ohms at 77F with accurate enough test equipment.

Every single one will be exactly the same since the size and number of turns of copper wire are identical in manufacture inside the injector.

Obviously an internal failure of the crimp connections can change the resistance.