I know of one way to test for a failing injector on my V6, and that is to hold a long screwdriver against it while the car is running, but I couldn't hear the clicking I was supposed to hear (the solenoid activating/deactivating). How else do I test the injectors to see if they are firing? I know that the sound coming out of the tailpipe should be a constant whatever it is, and mine has little pauses in it like something isn't firing or getting gas, and the engine tends to hesitate a little during braking and at stop signs and lights. Heck, I have to practically break the tires loose at the stop to keep it running. I have all new vac lines and such, and am not looking to do a complete tuneup at this time. Also, which injectors have the worst tendency to die first?

 

You can do an Ohm test on them. Take digital volt meter and go across the terminals on the injector, you should get a reading of 11 to 14 ohms. if the injector is busted electricaly, this will tell you.

 

Sounds good. Now I have a reason to tear the upper plenum off the engine again besides to paint it...

 

You don't need to tear the top off... only if you want to.

The book way to check the injectors requires an injector tester and a fuel pressure gauge. The injector tester is set up to pulse a single injector for a certain amount of time. What you'd do is watch the fuel pressure gauge and record the pressure drop. Then you repeat this for the other injectors. All should fall within a certain percentage of the other values (like a compression test).

Since I'm Mr. Bargain, the injector tester can be found at a blowout price by going to http://www.sunpro.com , and clicking on the garage sale link, and then going under Test & Tune, and getting the CP7819 injector tester. You can't beat that price at all!! But you'll need to buy a fuel pressure tester at your local parts store, they're usually $40. Make sure you get one meant for "port fuel injection" and not the cheaper carbureted one, or a throttle-body injection one. Port injection gauge will have high pressure markings- up to 80 or 100 PSI, and will have the Shraeder valve adapter on the end.

And think about http://www.cruzinperformance.com for cleaning up those injectors. I had Rich J service a spare set of mine- WOW what an improvement!!

 

Also, how much would missing the plasit tips on injectors #2 & 4 compromise performance? I'm missing the plastic, but the o-rings are still there.

 

I did my fuel pressure test with the car running under hard acceleration and differents conditions (presure tester attached to windshield + a long fuel hose + hood not completely closed + a lot of care).

It's possible a injector test under the same conditions/test system?


Thanks

Denis V.

 

I've been told the plastic caps are just there as extra dirt protection, and that it's okay to run without 'em.

Not sure if you can test out a single injector that way; the pressure gauge would be showing pressure at the rail, and the ecm would be energizing all the injectors. It might work if you had readings at certain rpm's with "good" injectors, and then the same readings with "possible bad" injectors... but I don't think you could find a problem with 1 injector just by driving.

 

BTW, while were in this general area, attached to the injector harness, there is a blue plug that looks just like the ones used on the injectors, and a two-wire weatherpack. What do they do? They are located just under the TB underneath of the fuel lines as they come across the front of the intake manifold.

 

I believe the blue plug is the cold start sensor solenoid.

 

I didn't know they had a sensor for that, but it makes sense to me. Could the weatherpack be the CTS, or am I thinking in the wrong place for that?

 

Two sensors in that area; CTS and cold start switch.