89 IROC--350/700R4--TPIS mini ram--SVO 24# injectors ( see additional specs in sig.)

I think I have a clogged injector?

I have done several searches and reading for about 4 or 5 hours, but can't seem to find the info I am looking for.

I know about checking the resistance--which I have done and that all seems good--within specs.

How do U check to see if an injector is clogged or partially clogged?

All of the plugs look ok--light brown--except #2 + #6.

I can go through and ground each plug wire and there is an appreciable drop in idle speed and rougher idle except for #2 cylinder. There does not seem to be much difference when #2 is grounded. Checked compression on the 6 easy plugs to get at (1-3-5-7-2-4) and #2 is acceptable--within 5% of all the rest of them.

By the looks of the plug, #6 is obviously pumping some oil, but that cylinder seems strong when grounding it.

Any help would be appreciated!

THANKS,
Craig

P.S. is there a tech artcle/thread that explains the basics of injector testing? Not on how they work--read a couple of very informative articles on here about that--but of how to check to see if they are working correctly both the electronics and/or actual fuel delivery?

 

The injector balance check would spot a plugged injector if you did it with the fuel rail & injectors up off the engine. You could also do a "simple" flow check on them by pulling the fuel rails & injectors up off of the engine and using a graduated container under the injector apply 12 volts (with the fuel system pressurized) to each one for the same amount of time (NO MORE THAN 1 SECOND or you could burn them up). Then measure the amount of gas each injector squirted out...if any injector measures much less than the others...it should be replaced.
Keep in mind that this is a crude method and probably would only spot a severely clogged injector.

 

double post

 

there are 2 ways i use to check injectors.
the first test is not always conclusive, sometimes an injector can check good but still have a problem.
the first is a pressure drop test, using a fuel pressure gage hooked to the pressure test port & an electronic fuel injector tester to trigger the injectors 1 at a time.
with everything hooked up & no fuel leaks the system is pressured up by turning the key on but not starting the motor for each injector, take a note of what the pressure gage is reading & then hit the trigger button on the injector tester & make a note on where the fuel pressure dropped to. you do each injector like this. if 1 has notably less pressure drop than the others it has a problem.
don't trigger any of the injectors more than 2 times without starting the engine.

this way takes longer & is more work but is much more accurate
pull up the injector rail & pressure up the system & using the injector tester trigger each injector & watch it's spray pattern, the fuel pressure has to be the same for each injector. run through the spray pattern test again but instead of watching the spray pattern use something such as a syringe that is marked off & catch the fuel & make a note of the volume from each injector.

if you don't have access to an injector tester, you can swap the injector from the weak/miss firing cylinder to a known good firing cylinder, if the miss follows the injector, its bad.
put a shop towel under the injector being tested to catch the fuel from it, & of course, no smoking, open flames, or sparks of any kind when doing this.

**edit** Morley types faster than i do, lol