unburned fuel?
 

Grandma had her brakes on on the on-ramp, and when she saw that there were no cars in our time zone, she decided to go (gotta' love it:eek:). I held the ramp to go around, then she put her pedal to the wood. Then I put mine ALL THE WAY DOWN, and when I checked the rear view, I had left a black gas cloud.

No oil, fortunately, but all that black is botherin' me. Do I need plugs? New ignition coil? Can't be wires, the tune is great. In fact, mileage is at 27.6 mpg's (that's not a highway re-set; it's overall mileage).

Anybody else's LT1 burn like this???

RE: unburned fuel?
 

What's your fuel delivery system? Carb, TBI? You're running rich.
If it were your plugs, she'd miss. Bad coil, weak on power. Just my opinion , don't cha know. :)

RE: unburned fuel?
 

It's the LT1 - just a little higher-po tuned port injection.

It DUMPS rich, when I dropped the hammer (or rubber mallet:D), but it's gettin' over 27 mpg's. I don't see how you can get them mpg's and a rich burn out of the same motor.[sm=smiley25.gif]

RE: unburned fuel?
 

Sorry, I'm puzzled on this one. [&:]
Is this a new prob?
With that kind of mileage, it just doesn't compute with me. :eek:
With all the sensors and such, it could be a really simple fix.
Personally, I'd call on mech259 for this one. ;)

RE: unburned fuel?
 

That happens to my vette as well when I have to lay off the gas and then hit it. No big deal according to 2 vette shops around town I have talked to. As long as it doesn't happen all the time whenyou accelerate heavily. I guess it just means like you orignally said your running rich and lots of unburned fuel out the back. As far as your mpg goes I got 29 mpg on the way to Kansas and still run rich from time to time. Better to run rich than lean though!:)

RE: unburned fuel?
 

was up, my 93 does the same thing when i nail it. still get 26mpg from it,charged vette said it right. my cats are burned out for awhile,so the idle is alittle rough[can't even tell really without smellin it] but it sounds great and runs hard.

RE: unburned fuel?
 

well cwb allow me to futher you vette and automotive education, lean is hot, fast and dangerous, rich is cold, slow and safe, so how do you think you can make your engine last the longest???well the perfect mixture is 14.68 part air to 1 part fuel which isideal, your engine rounds it to 14.7:1.The fact is your ecm reads a lot of air going in fast, well what is it to do? you ask... put a lot of fuel in and calculate it to the best mix it can for safety and power but the lt1 like many engines isnt perfect, some of the gas doesnt get burned there for the black smoke you see , you are also clearing carbon build up in you intake and exhaust system out.

RE: unburned fuel?
 

YUP. I never thought of that. That's exactly what passed. Especially since Ihardly drive it, and even rarerpedal down.I'm shamed.

And to think I used to pedal down on carbeurated cars when parking it, to leave the unburned fuel in there and solve carbon deposits.

Methinks I'm gettin old.

Good call.

RE: unburned fuel?
 

lol well I have learned a lot of great things from you here like headlight gear replacement;) which im about to try to perform in the comming weeks:eek:and countless other things you have showed all of us on this forum:D

RE: unburned fuel?
 

Yeah thanks. I think that shiver guy knows the first c4 headlight design better. He posted a good link somewhere on that one there.

I got the new gear today from corvette america. Gonna' put it in tomorrow AM.