all, recently picked up an 87 V6 firebird (dad/sons project) and am chasing down a rough running problem. was testing the injectors yesterday and had a couple of questions. i got consistent 15.9 ohm readings for all the injectors cold -- is this normal? haynes manual says 11-14 ohms is the spec.

also, pulled the fuel rail and tested the spray patterns one by one. all "pulsed" fuel when cranking the engine, but the pattern of the spray was pretty narrow and the volume of fuel didn't look like much. does this seem right? if not, is there a DIY process to clean the injectors to improve the pattern and volume? they don't look serviceable. or is there another way to test the full spray pattern and volume (other than cranking the engine)?

fyi, i capped the cold start outlet at the fuel rail for the test, and was thinking that perhaps the cold start valve provides most of the fuel at startup and the injectors don't add much?

many thanks in advance for any help.

 

The injectors don't appear to spray much because they are "batch fired". Batch fired injectors are pulsed every Distributer pulse signal, which on a V6, is 3 per crank revolution. So you can see, the injector fires several times for each 1 intake valve opening, so all the fuel needed for one cylinder is not sprayed in one shot. The cold start injector gets its power from the "crank" position of the ignition switch, so once you release it to the "run" position, it stops spraying.

 

16 ohms is good, If the resistance was low (<10 ohms) that would be a problem.

If you don't need to drive the car, send the injectors off to Rich at http://cruzinperformance.com/ for cleaning, includes flow testing and new o-rings. Or do what I did, bought a junkyard set and had them cleaned and then swapped 'em out when I got them back.

You might want to start a post on the V6 board about your problem, a lot of the V6 guys don't read this board very often since it is mostly V8 posts.