I am getting 15 mpg now, I thought I used to get more.

Any ideas on what could be the problem? I have headers, a gutted cat, and a cat back, open air element. I have had the car for 18k miles and have never changed the spark plugs. I looked at them, they seemed alright buit a little brown stain on the white head of it.

Also my IAT sensor is bad I think because it throws codes now and then when on the highway. I was going to replace it, but you think that would effect mileage?

------------------
89 camaro 305 tbi, flomaster 3 chamber cat back, gutted cat, Edlebrock TES Headers, Exhaust cutout, Edlebrock open element, and a 160 degree T-stat. 2 kicker comp 12"'s, polk for the rest. Phoenix gold xs2300 to subs, kicker impulse 404XI to 4 speakers, pioneer DEH- P7000R head unit, and finally a 12 disc changer. Full leather interior from http://www.MrMikes.com (its nice)

 

Your foot is too heavy

------------------
*1989 RS
*Red, Daytona Turbo fiberglass hood, chrome 16x8 IROC wheels
*355 CID
*TPI ported plenum, SLp siamesed runners, Edelbrock high flow intake
*Edelbrock TES Headers (getting SLP 1 3/4 this summer)
*Richmond 3.73
Modded 700-R4, 2800 stall converter
NO recent time slips.

 

no these last 10 gallons Ive been very grandma like. off of every stoplight the other cars have been passing me ive been going so slow and I got about 16 mpg.

 

[double post]

[This message has been edited by Jza (edited May 10, 2001).]

 

Is your TCC locking up? That's worth about 3mpg.. Unless you have a 5-speed... :\

 

I dont know when my tc locks up, I know nothing aobut tc lockup

 

My gas mileage went down to about 15 MPG one time so I changed spark plugs, wires, dist. cap and nothing helped, then I changed the O2 senser and that fixed the problem, the next tank of gas my mileage was back to 20 MPG.

------------------
92 Camaro RS 5.0 5-Speed
14" Open Air Cleaner
3.08 Posi-trac
Edelbrock TBI Intake
Crane cam
Ported & polished stock heads 3 angle valve job
HyperTech Chip
SLP Headers (Ceramic Coated)
UltraFlo cat-back exhaust

74 Dodge Dart Sport 360 (11.2 1/4 mile)

2000 Dodge 1500 Ram Sport

 

What code is coming up? You might want to check out your 02 sensor readings so see if it's running rich or not. Alos pull a plug and look at it, black = rich, white = lean (probably not going to be).

------------------
, Jon (350 TBI!)
91 Red My website

 

One thing that you might try is replacing your PCV valve. And if you're running a 160 degree stat without a low temp stat chip, that will cause your torque converter to not lock up as soon, thus limiting gas milage. I also run a 160 stat with Hypertech's Thermomaster chip and I get the best gas milage with 87 octane gas. I think that the lower engine temps from the low temp stat don't allow the premium gas to burn as efficiently as the 87 will.

 

the car manual says to use premium gas so Ive always been usimg that. I put in a new O2 sensor and a new IAT sensor(mine was broken) and now it seems to be doing a LOT better. I have driven 125 miles already in the city and According to my fuel gauge I still have 3/4 of a tank left. I know these gauages are not even close to accurate, but I think I will easily get 260 miles off this tank.

Also I plan on gettign a new chip from fastchip.com that is designed for cars wtih a 160 t-stat. Will this cause my TC not to lock up as early?

------------------
89 camaro 305 tbi, flomaster 3 chamber cat back, gutted cat, Edlebrock TES Headers, Exhaust cutout, Edlebrock open element, and a 160 degree T-stat. 2 kicker comp 12"'s, polk for the rest. Phoenix gold xs2300 to subs, kicker impulse 404XI to 4 speakers, pioneer DEH- P7000R head unit, and finally a 12 disc changer. Full leather interior from http://www.MrMikes.com (its nice)

 

to me, bad mileage means tuneup time. or at least a checkup.

 

15 - 17 mpg is about right if you do alot of stop-and-go driving....regardless of how heavy your foot is. These engines can drink gas with a straw. Replacing the o2 sensor was probably the trick. Try taking it out on the highway for an hour or two and check your mileage then. If its better than 25mpg, then you are ok.

------------------
92 Camaro RS, LO3, 5-spd, T-tops

Performance:
K&N Open Air Filter, Edelbrock performer TBI intake, Fastchip Prom, Timing +4 degrees, Centerforce clutch, Xact 8mm wires, SLP 1 3/4" Headers (coated), Flowmaster Catback Exhaust, Z28 Grille w/aftmkt fog lamps
Electronics:
Alpine 8030 Alarm System, Valentine One Radar Detector (How did I ever drive without one?), Pioneer DEH 7450 Head Unit w/6-pack CD changer, Pioneer DEQ 7600 Sound Processor, 2 Kenwood KAC-846 Amps powering 2 12" Pro Red subs, 2 Pioneer 6x9 and 2 MTX 4x6 speakers.
NEXT UP: TBI mods, 3.42 gears w/Torsen posi

 

chageing your chip to a to one that is supposed to run with a low temp stat will make you TC lock up sooner witch is what you want.

 

Low temp stats will cause premature wear of the piston skirts (never mind bearings and rings) unless the engine had a low-temp stat from the fresh build. No need for them.


EDIT: BTW, I run a 195 high-flow in my TBI 350, runs about 185-190 all the time. The 180deg high-flow actually ran a little too cool and below 180 for me. Radiator cools too well???

[This message has been edited by FastBroker (edited May 16, 2001).]