Injector Failure Signs?

[avijay]

What are some tell tale signs that your injectors / coils are going bad? I have a 91 and it surely doesn't feel right on acceleration and has a little bit of a shuttering on acceleration. I assume it's time to change the injectors, coils, plugs, wires, etc but just want to make sure I'm trouble shooting the right thing.

[Kevin]

well your car is a 91...so you can assume they're bad. when they first start going bad your car will start to run rich before it goes lean then you'll get a knock when the car is warm. you can also ohm them...12.5-15 ohms is what you want

my injectors are bad and while i'm in there in the spring i'm going to do air filter, injectors, wires and plugs

[tccrab]

Remember, there are 16 injectors, two separate systems that integrate on full acceleration.
The symptoms will differ depending on what combination of injectors are going bad and the condition of the "failure", i.e., injector stuck open, injector stuck closed, or simply an injector with bad spray pattern.
Lots of combos to think about.
A primary injector stuck closed or with a bad spray pattern will cause a lean condition with a rough idle and sympathetic dual mass flywheel knock.
A primary injector stuck open will cause a fuel rich condition and the spark plug will eventually carbon up and cause misfires.
Multiple bad primaries will cause rough idle, stumbling on regular (non-secondary) acceleration, dual mass flywheel knock, and if bad enough the ECM will set a SES light because the O2 sensors will read high or low depending on the condition.
Bad secondaries in a closed condition, i.e. fuel lean condition, will cause stumbling on secondary acceleration initiation and significant leaning of the engine at high rpm and O2 sensors reading high.
Bad secondaries in an open condition will cause stumbling on secondary initiation and smooth out as the airflow leans the a/f mixture to optimal.
Mix up the failures and all kinds of good things can happen.

My advice is to replace the fuel injectors, the spark plugs, and while you're underneath the plenum check the coils and replace as necessary.

Just my $0.02

TomC
'Crabs

[oricale]

Thats exactly what Im doing...AMMMOOUUNNGG.....other things!!!!;):rolleyes:

[tomtom72]

Use a spark tester, the inline kind to test for coil output or use a DVOM. Please resist the impulse to pull off plug wires while at idle as our Ignition brain boxes, aka the DIS module, doesn't react well at all to that treatment.

You can ohm out the coil + it's wire pair using the two plug ends of the wires, but if you have to go under the plenum the "while we're here" rule comes into play.

If a primary injector goes south from the alcohol in the fuel it will mimic a dead miss. The alcohol shorts the coil and no fuel to that cylinder. You'll get the Dual Mass rattle like Tom said. Also, if you have a scanner you can see the results of the lean mixture by looking at O2, BLM's and Integ numbers. Or, you can use your nose. If she's lean enough you can smell it....trust me! The miss will not go away. Also, it may not miss on cold start, as the coil heats uo the miss will become more pronounced. Also the plug(s) for those cylinders where the injector coils are bad will look like no gas is being delivered.

:cheers:
Tom

[carmine]

I Recomend RC Injectors And Jerrys Gaskets Carmine #357 Black Gray Stock

[Hib Halverson]

What are some tell tale signs that your injectors / coils are going bad? I have a 91 and it surely doesn't feel right on acceleration and has a little bit of a shuttering on acceleration. I assume it's time to change the injectors, coils, plugs, wires, etc but just want to make sure I'm trouble shooting the right thing.

You can remove all 16 and test their coils.
You also can have an injector specialist, like RC Engineering, test them for flow and spray pattern.

But, if your injectors are original, ie 20 years old, I'd just pull 'em out and replace them with RC Engineering units.

[ZR1Vette]

Are the RC injectors the ones that have to be modified by removing a small tab on the injector?? Or was that for Accel injectors?

Edit- added this pic showing the tab removal so can you ID that the injectors are RC or Accel from the pic?

http://i17.photobucket.com/albums/b79/MRBLU/ZR1injectorstabandtabremoved-1.jpg

[tomtom72]

Are the RC injectors the ones that have to be modified by removing a small tab on the injector?? Or was that for Accel injectors?

RC's are plug and play. I'm not 100% on the Accels, I think you have to do the grind to get our harness plugs to plug in to the coil terminal...not 100% sure though

:cheers:
Tom

[ZZZZZR1]

FIC have stainless steel injectors and look like OEM

http://fuelinjectorconnection.com/shop/

Speak with John. He also carries Jerry's gaskets, so you can get everything at once

We have installed many local Z's with these...

:cheers:

David

[Kevin]

David, is there a zr-1 net discount at fic?

[carmine]

Rc Discounts Zr-1 Members GreatProduct And Srevice Carmine#357 Black Gray Stock

[tomtom72]

Just to be above board on the various injectors. The RC and the FIC are the same Lucas based bodies. All the bodies are s/s. I do not know anything about the Accels though, but I believe they are also s/s.

:cheers:
Tom