Back in the old days, if your car had a miss, you could pull a wire off each plug. When nothing changed, you found the bad cylinder. Can you do the same thing with fuel injectors? Also, if one is bad, should they all be replaced? I have a 91 coupe (L98) with 21k miles. Will anything else give me a bad hesitation on take off and a faint miss while cruising? Any help would be appreciated, I'd like to know a little something before I bring it in for service. Thanks...

 

what makes you think you have a bad injector?
inspect your ignition system first.
If your car has never had plug wires, change them, and go with high performance wires, your problem may be the spark is bleeding off through the plug wire insulation.
check the timing, make sure the connectors on the dist. cap are clean and clipped on securely. open the distributor cap, and look inside. wipe it out with a rag and contact cleaner, check the button in the middle, and check for carbon tracking. pull the spark plugs, check for cracked ceramic, proper gaps, carbon buildup, etc.
check for vacuum leaks, then check your oxygen sensor,
try checking for codes, injectors usually stick open, but some get plugged up.
if an injector is starting to get plugged up, add a can of Berryman's Chem Tool to the gas, and run it a little bit.
If the car has the original fuel filter, change it after the berryman's has been through the system.
You don't want to mess up a new filter.
If your car only has 21,000 miles, check all rubber vacuum hoses, and anything plastic that can deteriorate with time.
use a mirror, and a flashlight, look under the fuel injector plenum, check that the temp sensor connector is on securely.
after all that, if anything is amiss, you should find anything obvious.

 

In regaurds to an injector replacement.

Do a search on the forum for "Multec Injectors" its what is stock on your 91

 

unclip the injectors one at a time. same idear.

 

Unclipping a single injector does nothing - ECM will compensate and raise IAC counts to maintain idle.

If you want to isolate a cylinder, cut some 1/4 inch vacuum hose into one or two inch lengths and insert a piece between each plug wire and the distributor. Then touch the vacuum hose with a grounded test light to kill the cylinder while observing your tach. Any cylinder that doesn't have the same rpm drop as the others is the problem. Do the usual diagnostics from there - plug, wire, valve train, injector.

 

on my 88 f150, i have this test module that does a few different diagnostics. one of those is it raises the rpms, and cuts out one cylinder at reports which cylinder is bad. Also when it preforms the test, if when the cylinder cuts out, if the engine vibrates and loses rpms, you know that cylinder is good. does chevy have anything like this for the vette?

 

A sanning tool would be best. If you search the posts you could also check ohms of resistance for each injector. Check hot and cold.

My .02 - many posts told me my '91 with 69K had a bad injector. Yes, I replaced plugs that looked fine, wires that looked fine, cap and rotor which were fine. $1K later I replaced the injectors and it runs great. The hesitation during driving says to me it's fuel. My point - a scanning tool will pinpoint the problem. That's what my mechanic told me. Scanned and found the problem. It was worth the scanning money to me. Good luck. P.S. the injectors all go bad. I put Ford's in mine it runs great!