This is my first post. I Own a 92 LT1 bone stock. I have worked on my previous high performance car a lot (80 V6 to 327V8 conversion Chevy Monza boasting approx 350 HP) but now I've moved up in the world to this great new technology called "FUEL INJECTION" So I apologize beforehand if I seem unedumacated.

Anyway, here's my problem:

I have been having sluggish performance with some backfiring (basically, popping noises escpecially when down shifting) So I thought I needed a tune up. I haven't brought my car anywhere yet because I don't want to have to pay some dealership $85 just to tell me what might be wrong with it. (not that it might be the right diagnosis anyway)

I only have 54,000 miles on it and the Chevy dealership is saying it's most likely a bad injector because they say the car has too few miles on it to be the wire, cap&rotor, plugs, or optispark.

I called D&M Corvette in Downers Grove Il and they say it might be the optispark causing my problem. But they can't look at it for 2 more weeks ARRGGH!

1.) If the issue is the optispark I'd like to diagnose this myself and even fix it if I could. Does anyone have some tips for diagnosing this?

2.) If it is a bad injector, what is the amount of time it might take me to replace them? (let's consider me novice-to-intermediate at this point with experience with a Chilton's total care book.)

I apologize for rambling. It's my first post...I'm excited!! :crazy:

 

From what I have read, it sounds like the optispark.

One way to test the injectors is to hook up a fuel pressure guage to the schrader valve (please do this on a cool motor, as there will be some leakage).
Turn on the key and let the pump pressurize the fuel rails.

Note the reading. Turn off the key and go have lunch. Come back and check the pressure. If you have lost pressure, you probably have a leaky injector.

If it is the opti, I suggest taking it somewhere to have it done and smile when you write the check. I just finished doing mine, and it is just plain evil. :cuss

 

Coool! I have no idea how to do what you just said with the shrader valve and everything, but I'll do what I can to figure it out.

Is it entirely possible that the injector might not be leaky, but might be bad? Whatever bad may mean. The Dealership meantioned Ohm'ing them. :confused:

 

Injectors can fail because the electrical coils within develope shorts in the windinngs and becuase of buildup in the fluid passages that restricts flow or causes leaking.

Measure the resistance of each to see if all are about the same value to see if the electricals are OK. Send them to Rich at Cruzin Performance to be rebuilt if any are leaking; the symptom of leaking injectors is hard starting when the engine is warm.

 

Ok.

The engine does run fine except for the occational WOT bog and backfiring and starts in the first second of cranking when the engine is hot or cold. With that in mind i'm leaning towards optispark problems considering the past couple suggestions.

Thanks for the explanation though!

 

The first thing you should do is get yourself a set of Helms Shop Manuals. Plan on $100 unless you can find some here (C4 Parts for sale) cheaper. They are invaluable.

I just did an opti replacement on my 92. You have to remove the serpentine belt, the radiator hoses, disconnect the heater hoses from the waterpump, remove the waterpump (note there are 6 bolts holding the waterpump, one is kinda tucked behind the alternator pulley but can be gotten to with a bit of patience), then you have to remove the front balancer. On these engines, the harmonic balancer/pulley unbolts from the hub which is pressed onto the crank. You may not have to remove the hub, I did because I wanted to replace my timing chain cover crank seal. If you decide to remove the hub to do that...let me know and I'll walk you through it.

After you've done the above, the optispark is right there, held on by three bolts and is easy to remove and replace. There are a couple of tricks, so if you do this, re-post and you'll get lots of help.

at 54,000 miles, it may very well be the optispark. However, mine lasted 102,000 and I only replaced it to head off any problems, it was still working fine. If I were you, I'd check the condition of my wires and plugs. if you have to replace them, that's another story...but can be done by your average guy.

Let us know if we can help

 

The Schrader valve is a pressure fitting on one of your fuel lines at the back of the engine. You need a fuel guage meant to be attached to it.

If you aren't sure what you are doing, I wouldn't mess with it. You can start a nice fire messing with pressurized fuel. :eek:

 

I've been fixing cars my whole life, like I said in my first message I have more experience with carburated engines. Just cause I say I don't know how to do it, doesn't mean I can't learn...

...but thanks for the vote of confidence. :flag

 

An obvious question, any codes? ..... That will give you a direction to go rather than throwing parts at it....just my $.02 worth. :lol:

 

No codes, everything checks out fine by the computer. Though, I haven't checked since end of last summer when I started noticing the problem. I guess I should check one more time.

 

Just a quick question to emoson. I heard tell of '94 (sealed and cheeper) optis fitting on a '92 with some mods. Comments?