I have a 91 305TBI and I am getting terrible gas mileage. About 12-15mpg on premium gas. I also get smoke when I first crank it up in the morning. Only on the first start up though. Anyone know what may be wrong???

Any help would be greatly appreciated.

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http://formula305.cjb.net

 

Well, you could check your o2 sensor, if it's not reading right it could cause your engine to run rich, that would suck back the fuel quick, mine usually goes through less... sometimes.. but the smoke when you start it could be your valve seals.. mine do that too.. they don't seem to last long. Or for the worst your rings could be going bad.. but it depends on how it has been driven. hope this helps

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89 RS Camaro, LO3 305 TBI
Autometer Air/Fuel Ratio Guage
Cooling Fan Overide Switch
L69 Duel Snorkel Intake
Dynomax Ultra Flo SS Cat Back

 

Yeah, though the smoke thing might be valve seals, check your O2 sensor. That's a biggie.

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1992 Camaro RS (Auto) 5.0L TBI
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Performance mods
NOS (125 HP shot)
Dynomax cat-back exhaust
Hedman headers
K & N open element/ X-Stream lid
MSD 6A ignition
MSD 8.5mm plug wires
LT1 camshaft
Soon to be installed:
Edelbrock intake manifold
B & M 2400 RPM stall torque converter
Trans Go shift kit
World Products Torquer heads

Audio
Sony Xplod CDX-M610 head unit
Pioneer 2-way 4x6 front speakers
Pioneer 3-way 6x9 rear speakers
12 inch Pioneer VCCS PRO subwoofer
QLogic sealed box
Kicker ZR360 amplifier
Lightning Audio 1 farad capacitor

Other
Macewen White Faced Gauges/Shift overlay
A-pillar gauges (Phantom oil pressure, Air/Fuel)
180* thermostat
Window Tint

 

Take a look at the spray pattern from the injectors. It should be cone shaped and the same for both injectors. You could have a leaking injector. If you remove the electrical connector from one and it still runs the same, suspect a leaking injector. It should two-hole and stumble badly with one injector only firing, as only 4 cylinders are being fed. Then try the other injector by the same method. Does it start hard or smell of gas with the hood open?

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90 RS Convertible
Owner: Top-Down Solutions
(626)369-0040

http://www.sc3gfb.org/members/lonsal.html
http://www.taskerinc.com/gs3/profiles/Lon_profile.htm

 

There has never been any smell of gas. I do however, get the burnt oil smell from under the hood once I turn the car off. It's not really bad, but you can notice it. Thanks for all your help guys. I'll definately check the 02 sensor and those injectors.

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<A HREF="http://formula305.cjb.net" TARGET=_blank>http://formula305.cjb.net
</A>
1991 Formula 305TBI
3" Flowmasters
Hypertech Chip
3.42 Posi on the way

 

Hey Dan, I am glad to see ur using the TBI board to help u out. there is a lot of guys that know there stuff on here. I would also make a post in the Tech/General Engine section too for this. Vadar or someone over there might have some good advice too.

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Eric Natzke
91 Firebird 305 TBI
"It Ain't Stock"
http://members.aol.com/j007golden/91firebird.html
For info on certain parts or mods go to the site below
http://members.aol.com/j007golden/modeval.html