IROCmonkey

I am wondering what kind of MPG you all are getting out of your TPI's I have a 91 305 TPI in an 85 IROC with a Hypertech Thermomaster chipset, last I filled up I am getting 11.4 MPG in the city. Motor only has 20k miles on it and I used to get around 13...tune up time.

tpi_roc

20mpg with very light timing (worse for fuel mileage) and running a bit rich (you know what that means) and highway mode disabled.

Engine is in the sig.

IROCmonkey

Is that highway milage or stop and go in traffic.

If its city, man I am getting robbed....of course I am what you would call an "aggressive" driver

89Irocz23

Damn thats bad man. I get over 20. I usaully get like 21-23, but I take it easy most of the time unless im racing someone. Highway is around 27. Also I have a custom chip. Im not sure what I will get when I get this lt1 intake swap done, but hopefully it doesnt change much.

Firebird90V6

AHH if i only got 11 or 13 mpg id park the thing. Im currently getting 19 in the city and 24 on Eway in a 85 305TPI. Id check over your fuel system

tpi_roc

That was 20 highway

Z_Ghost

I get 19 to 20 city and 35 to 36 HWY. This is on my Z

91TA

11MPG is way off. I can get around 22/27 with my 91 305 and I have 60k on my car. Something is wrong.

gmgod

I drove my car on a 10 hour round trip this weekend and got 25 mpg with passing several cars and cruising at 80 mph a good amount of time.

IROCmonkey

well I am gonna throw some plugs in it and a new O2 sensor. plus go to synthetic oil. I recently replaced the fuel filter. BTW I live in FL so I do run the air 24/7. Any suggestions?

87transam5.7tpi

I get about 24-26 on the highway.

Duke901

In my stock 85, my 305 tpi gets like anywhere from 8 to 10 mpg in the city not sure about highway, what the heck could be doing that, it has a newer tune up on it and it dont seem like its running rich. Could some of the injectors be bad or maybe a fuel filter. Please help us with are bad MPG.
THANKS

P.S I dont have any smog on the car would that be causing bad gas mileage.

DSaylor

I don't have any smog neither, and I get around 20 in the city if I don't beat on it too much, and 29-30 on the highway.

I always keep my car in top tune though.

IROCmonkey

hmm ok so it looks like I should be getting between 15 and 20 MPG in the city?!?! Well considering I have an *ahem* heavy foot and run my air all the time, I'll be aiming at the low side and shoot for 15. Any obvious stuff to do, besides the plugs, o2 sensor? My air filters are clean, just looked at them recently...I run 8mm wires and a stock coil. Suggestions please!

2QUIK6

I get about 13-15 mpg with my TPI in my truck! Components listed in my sig, and its definitely not in tune. You should be easily getting more than that in a lighter and more aero-dynamic car.
O2 sensors and plugs would be the first place to look. If you have a scan tool handy, hook it up and check the O2 readings for being rich (higher than .800 mV most of the time) or low O2 Cross-counts (should cycle from 0-255 in less than 90 seconds, if not, then O2 is lazy and needs replacing)
Also, be sure your getting fire to all cyclinders and not running on 1 or 2 less cyclinders.

IROCmonkey

Thanks quik..I don't have a scan tool..but if you're getting that much I should get at least that much, even though I have an 85 with a more primitive computer.

I have all 8 cylinders running, smooth at all idles and plenty of power. Exhaust does smell rich at times though.

SMURFN' Z28

iTrader: (2)

dude you just said it.
the lead foot and the AC... that is the answer right there.

noway anybody would get close to 20 mpg while beating on the car on a regular basis (in a V8 TPI car)

TransAm87

i was getting 13-15 in my car untill i put that "gum-out" in a take of gas and now im 16.5-17.2 around town and probably 20 highway with now smog or ac, new O2 sensor and plugs,i dont know...
Aj

Drkhrse89

iTrader: (1)

With air on and going 80 I can get 30 mpg on the highway but that is with some prom tuning. I agree with SMURFN' on the fact that you said it you are driving with air on and stomping the gas. Although 11 still seems a little low dont expect to get 20 in the city with AC on high. I would say 15 would be closer and that is staying off the pedal. I can get 15 with air and kinda hot rodding around.

Duke901

Heck i get 11 with no air and not having my foot in it, so what could be the problem. Could something be out of tune, it seems like the car runs alright.

IROCmonkey

Yeah 14 or 15 is what I used to get and what I will shoot for...I will try a few things and see how it turns out.

This motor is or was at any rate literally brand new... GM motor that still had the factory oil in it. Now has 20k miles on it.

I am gonna try putting in plugs (bosch plats...damn parts store was out of em last time!) New o2 sensor, and try cleaning the IAC. hmmmm what should I use to clean off the IAC? If that doesnt work, I'll put an EGR valve on there.

Beast5spdGTA

I get about 13-14 mpg city/lead foot big time(150-160 per tank). Last highway was 22-25 mpg at 75+ ave. on a 750 mile trip(270-300+ per tank). I also got 20-22 mpg highway loaded up like 600+lbs of baggage 1400 mile trip.

107,000 mile 305 saimese TPI, crane 2032 cam, 51 psi fuel pressure, SLP chip, 3.42 gears, 5 speed, headers, '89 MAF car with check engine light going on and off randomly(probably MAF problem, but maybe TPS code as well.)

rezinn

35mpg? no way! You can't accurately measure mileage on only one trip, you need to do it over a couple weeks or more to be precise.