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View Full Version : '84 'Vette - terrible gas mileage & CEL



craig0ry
03-28-04, 09:21 PM
Hi guys, according to my gauge, I'm averaging about 8 or 9 mpg, and every now and then after the car has been on for about 20 minutes, it throws a CEL at me. It runs smooth as silk, I have no problems except this terrible gas mileage and sporadic CEL. Just curious if you have any suggestions, I'm thinking a new air filter, o2 sensor, plugs + wires should help a long ways, but would any of those things set off the CEL?

Ken
03-28-04, 09:45 PM
CEL?? :confused

craig0ry
03-28-04, 10:04 PM
CEL?? :confused
Check Engine Light, sir :)

Ken
03-28-04, 10:19 PM
Okay, I understand now. The world's just too damn full of acronyms! :L

As for your problem; changing the air filter wouldn't be a bad idea if you think it's old and dirty (If it's an aftermarket oiled filter, you can clean it and re-oil it.) The oxygen sensor can be checked with a scanner if you'd like to eliminate that possibility first before spending money needlessly.

Plugs and wires would fall into the routine maintenance category; it's said that plug wires require a recommended change every three to four years, no matter how they look on the outside. ;)

The EGR could also be, and it probably is, the culprit here. It could be sticking; you should see a Code 32 if you plug a scanner in, or use a paper clip to pull the codes.

jim coulter
03-28-04, 10:36 PM
Before I would start throwing money at it, "hoping"to find the right thing wrong, I would retrieve the trouble code from the computer. You would have to take a small jumper wire to ground the diagnostic terminal (B)and ground terminal (A) in the ALCL plug located under the dash, below the instrument panel (about where your right leg would be driving) With the ignition on, engine "not" running you should get a code 12(one flash followed by two flashes). It will do this three time, and then will flash a trouble code if there is one stored in the computer. Since your check engine light comes on, you should have something stored. If you go to your local parts store, you can get a Haynes or Chilton manual that is very helpful with you car. It also tells you what each code is. Post you code and I'll look to see what the book says it is. Hope this helps.

craig0ry
03-29-04, 01:19 AM
I actually picked up a Haynes today, I am not sure what they are called in the world of GM but I was looking for what Toyota owners commonly call the "big green book", or dealership shop manual. I couldn't find one, so I picked up the Haynes.

I will check what code it is throwing, and I'll report back with my results. Thanks for all your help guys!

As far as the EGR, I have only owned this car since Tuesday and I have yet to truly familiarize myself with it's workings - can I simply clean out this EGR to remove the buildup, or is it more likely an internal valve is stuck or something?

BTW, what year and model Camaro had this engine, just so I can start looking at junkyards? I inquired at the stealership for some parts, for what they are asking they may as well give you some vaseline when you enter the parts department.

Have a good one,
-Craig

craig0ry
03-29-04, 11:22 AM
Something I just thought of - if the car was run on 87 octane for years and years, and I'm the first person to put 93 octane in it... would it still be running a timing map from the old octane? Should I find and pull the fuse for the ECU and see if it resets and "learns" for the higher octane? Thanks!

jim coulter
03-29-04, 08:14 PM
Not sure what a timing map is, but wouldn't think that running higher octane fuel would require resetting the computer.