How do U check the injectors woth a VOM? What values are U looking for? Is it possible to have the correct values andd the injectors clogged up?

 

You unplug the connector, and measure across the injector.

Should be 16-18 ohms.

yes, you can have good reading...and a clogged injector.

To take it a step further, you'll need a fuel pressure gauge and an injector tester..which cycles the injectors while you monitor fuel pressure drop.

 

Thanks for the info. I have done several searches about this but haven't quite found the answers to my questions.

ANY additional info or "tricks" to doing this from anybody would be appreciated!

 

Doing the flow test on the injectors? You'll need to:
Connect FP Gauge
Connect the tester to an injector
Cycle the pump on and off a few times so you have max pressure on the gauge. Write this down.
Fire the injector, you should be able to select how many times and for how long (on the high end ones) but you might just have to select how many times to fire it.
Once the 'cycle" is complete, note the new reading.

Move to the next injector and start over by cycling the fuel pump again to max pressure.

Once you have done all eight injectors, compare the pressure drop to each. I forget the "spec" it's in my manual somewhere, but most likely the instructions with the tester will have them.

 

I am not familar with a "injector tester". Where would I find one?

I have access to a OTC 4000 scanner, but I just got it--borrowed for a couple weeks. Is this of any value for this test procedure. or would it give me similar info that I have not yet learned about yet?

 

Actron makes one...I think mid america corvette used to sell'em as well, not sure what brand.

The scan tool won't do this, I'm pretty sure.

The scan tool will tell you what the ECM is seeing.

What exactly is your problem?

 

Rough idle--if it was a non computer car, I would say it has a low speed miss and/or surging, dies often while idling. idle speed is now set higher so it won't die, but problem is still present

Recently replaced:
Dist
coil
MAF
fuel filter

Problem was present before replacing above, but now is magnified after replacing above!


Tps--reset according to a Vader article/post
IAC-- " " " " " "

Took car down to the shop on the corner,--hooked up OTC 4000 scanner (same kind I have on a loan from a friend)--PROBLEM WENT AWAY WHILE SCANNER WAS HOOKED IN "DATA STREAM MODE"-- unhooked it and problem came back a minute later. He said was showing bad TPS CIRCUIT. Replaced TPS and IAC and cleaned and reset--no change!

I remember reading a thread with a similar problem , but have done several searches to find it again, and can't find it. Does anyone remember this thread and /or shed any light on this? HELP!

 

Best bet would be to now post a new thread, you'll get better response.

I'd look into what the OTC does while in DataStream..it may be sending the IAC to a fixed value, etc.

I don't think the OTC can do anything to mask over an injector problem.

Did you test drive it with the OTC hooked up? If so, did the car perform better? If it did, I'd almost be 99.9% sure, it's not an injector problem.

 

No, I did not drive it while it was hooked up.

It runs great under power/load--as strong as it ever was--just won't idle right--runs like a low speed miss/surging--but that could be the low speed miss (symptom) making it seem like it is surging. I might add that I just bought the car a couple months ago with most of the mods listed below already done--when I first had it, it started first time every time and was very clean, crisp idle, but this started and has been getting progressively worse--then got real bad agter replaced dist, coil MAF.

Could it be a timing problem?

 

FYI - Depending on the injectors you used, acceptable resistance can be as low as 11.8 ohms. Secondarily, injector operating coil resistance has nothing to do with the injector flow rate nor the spray pattern whatsoever. Only a failed injector coil will affect flow (no flow - duh!).

Short of a rudimentary power balance test with the injectors, your only option may be to remove them for flow testing.

This, of course, is all assuming that you have verified good compression in all holes.

 

Vader,
Thanks for the info. Any thoughts on what might be causing the overall problem here.

 

i kinda had the same problem but what i found out was that my 1st and 3rd injectors were bad and i had replaced everything you can think of as far as being electric. so i found out my problem when i went to my college school and had some assistance from my professor. so the conclusion was that my injectors were bad, i replaced them and my problem was gone. by the way i had rough idling like my rpms were going low and regular, low and regular. i hope this helps..

 

Yeah, I think i read your thread. I am beginning to think it is either an injector problem or a non computer problem, since it really got bad when we replaced the dist, soil and maf. OTC scanner on it yesterday-- no codes, and what values I know to check seem good. I just found out that the guy who did the Dist did not replace cap--going to do that today/tomorrow.