B7tribz

I have a 1991 C4, have asked this question before but I have much different info. The battery light is coming on, it's old and was sitting a long time when I got it, and even after a charge won't hold any. After fixing the radiator tank, new cap tank and heater hose, I took it for a spin. The car is running rough at low RPM's and even stalling out. Even at higher RPM's I don't think its running to its full potential. Anyways I was told it could be the alternator trying to charge the battery and its taking away from the motor, but I don't think it would cause this much power loss, what do I check next? Spark Plugs/Wires? I'm having a local mechanic look at it because my scan tool doesn't fit on the DLC in the corvette. Also put in a fuel treatment(dry gas), and also an injector cleaner, so it isn't moisture in the tank. Cheers

B7tribz

Can't believe I forgot to mention but it is automatic, so no it's not my driving, and unfortunatley I can't give it gas at stop lights or signs

GKK

Change the battery if you haven't already done so...

Then, do a complete tune up.

Cliff Harris

Do a minimum idle adjustment:

http://forums.corvetteforum.com/1570563689-post1.html

Does the battery voltage get up to around 14 volts when driving? If not the alternator could be bad. It's fairly common for the voltage to drop at idle when the alternator is barely functional, but the voltage should go up when you go over about 1500 RPM.

Paul Workman

Pre-93 injectors were not alcohol resistant, and as non-alcohol fuel disappear across over the country, pre-93 injectors will suffer, and the symptoms you're reporting are very similar to how mine acted (twice) when injectors went south due to alcohol "poisoning".

Once the low voltage question is satisfied, if the problem persists, you'd want to check/replace your plugs (the easy thing). With the plug condition being satisfactory, I'd want to get it up to operating temp and then "ohm out" the injectors.

They will normally all read within about a 1 - 1.5 ohm window - centering at about 12.5 ohms or 14 ohms, depending. But if an injector resistance falls out of that normal range, say falls to 10 ohms, that injector is hurting and on the way out. Buy the time it gets to 7-8 ohms it is in serious trouble and consequently will be starving the motor of fuel. Worse, left un-treated, there is a risk of burning a valve...ask me how I know! (So far, a weak injector has resulted in a burned valve in my LT5 AND my Ford F150 truck.)

The L98 is a "batch fired" injection system, so if one injector is bad, I would for sure recommend Changing them all. (I Had a problem in my 90 with alcohol contaminated injectors failing, and the dealer "fixed" it by replacing them with "new old stock" (NOS) which after a couple years were already crapping out. Next change out was on MY dime (new stainless injectors, immune to alcohol). Jon at FIC (board sponsor) can fix you up with a new set of stainless steel units that are immune to the alcohol now present in fuels.)

Hope this helps. Good luck!