Found an 88 IROC with 58k original miles that I couldn't pass up. Has the 5.7 and all the extras. Has a real strong gas smell after driving the car and is getting, at least what I think, horrible gas mileage. The engine is clean and strong. I am planning on tuning the car up to the best of my ability, but I am limited on automotive knowledge. No leaks that I can detect either. Would anyone have any pointers or suggestions, not even relating to the gas mileage question, that you think I should take in account or be aware of? I would truely appreciate any tips/advice!!

sounds like ur running real rich. 11 is horrible unless you have a lead foot. do the 88s have O2 sensors? if so it could be that. in any case you need a tune. Also make sure you dont have a hole in the tank. My 69 w/ a 350 gets 16 w/o overdrive.

Has a real strong gas smell after driving the car and is getting, at least what I think, horrible gas mileage. Strong gas smell?
From the engine compartment? As if raw gas is being pumped onto the engine/ground? Might have a leaky injector(s). Look for evidence of raw gas leaking externally while engine is running anywhere the fuel rails are.

Also, underneath the car, are fuel lines and a fuel filter. Other sources of leaks, they are located on driver side.

From the tailpipes? As said, could be O2 sensor needs replacing. However, if overfueling, engine would run ragged, as if the choke was closed. Check to make sure the coolant sensor is plugged in. It is located underneath the thermostat housing, the item the upper radiator hose attaches to on the engine. It will be a two-wire connector.

Gas mileage should be, I think, 15-20 mpg, depending upon amount of pedal depressing.

Welcome to the Club! Be sure to turn out the light and close the frig door when you leave.

That car is a 'speed density' system guys....o2 could be telling the car 'more fuel' but, need to make sure the choke is opening fully after warm up. choke is prone to stick in these cars after sitting for awhile...

Granted, he has a Speed Density system. I described his problem as if the choke plate was closed.

I guess I did forget to say his engine does not have a choke plate, hence the mention of the coolant sensor. This device tells the ECM how cold/warm the engine is and adjusts fuel mixture accordingly. If a bad sensor, open circuitry in the harness, or bad ECM stage for the sensor, then the ECM will give max fuel, regardless if MAF or Speed Density.

I'm figuring he may have a leak somewhere if he smells raw fuel. If his eyes burn while standing at the rear, then engine is overfueling. But, if over fueling, engine would run erratic, or barely run at all.

That car is a 'speed density' system guys....

Would one of you explain to me what a 'speed density' system is? And would this be a good time to mention that my temp gauge doesn't work either? I assume that the temp sensor is bad and needs to be replaced (when I can find it on the engine.....). I have bought the Haynes manual but haven't had the time to dig into it yet. Honestly, I didn't really know where to start! Also, the gas smell isn't strong enough to burn my eyes (yet) but it is very strong.

Here's an article from Car Craft that tells about "speed density" engine mgmt systems.
http://www.carcraft.com/techarticles/electronic_fuel_injection/

According to the article DjD provided (thank you for that), the 'speed density' measurement system was used on all TPI systems from 90' - 92'. It states that the 'Mass Air Flow' measurement system was used on 85' - 89' TPI years. So wouldn't I have a Mass Air Flow sensor on my 88' instead of the Speed Density?

And (you just have to love us newbies!!!:D) the dealership salesman told me that they replaced the 'throttle body' when they got the car, said it idled really rough. It looks to me like a different air intake duct was put on as well. I say this because written on the side of it with a yellow marker it says "5.7 t.p.i. corvette". Hmmmmmm, am I getting in over my head????

I guess I need to tell you all that I know about the car. Dealership that I bought the car from did an inspection on the car and it came back needing new tires and exhaust. They (dealership) threw on the cheapest tires they had and put a SINGLE cat-back exhaust. They also told me that they replaced the throttle because it idled rough. The temperature gauge doesn't work on the dash either. That's basically all I know about what is wrong/has been done to the car.

The car drives strong. The engine hesitates when I step into it and there is a slight kick when the car shifts into second gear. I honestly haven't driven it too much because I know the car probably needs some good maintenance performed on it. I will try and take some picture of the car and post them out here to help show what the dealership "replaced".

You'll probably want to spend some time searching through the tech articles and forums over at www.thirdgen.org .

http://www.thirdgen.org/technical-articles

I saw articles on the IAC (Idle Air Control) and O2 sensor that may be relevant.

Also, you may have to check the thermostat. Some folks install a cooler (160 degree) thermostat to keep engine temp down and trick the sensors and ECM (Electronic Control Module) into staying closed loop and running rich for a little more performance.

It states that the 'Mass Air Flow' measurement system was used on 85' - 89' TPI years. So wouldn't I have a Mass Air Flow sensor on my 88' instead of the Speed Density? Yes, you would have a MAF system. A sensor, round in shape between the air horn mounted above the radiator and the large, 3 inch diameter, hose connecting to the front of the throttle body and this sensor has a connector going to it.

Make sure there is not a hole in the intake hose between the sensor and throttle body, however slight hole might be. This MAF (Mas Air Flow) semsor measures the amount of air entering the engine and helps, along with other sensors, to adjust the fuel volume delivered by the injectors. If a hole is present, then air is 'bypassing', and an incorrect volume of fuel is being injected into the engine because the MAF sensor is giving the wrong info.

Temperature gauge not working may mean there is no coolant or not enough, along with a broken sending unit for othe gauge, broken gauge, broken wire on the sending unit, or a fuse blown if other gauges don't work.

As said by Eric, a cooler thermostat may be used to 'cheat' the ECM in delivering more fuel for more performance reasons.

Read the Haynes manual several times and compare pictures to what is in frony of you.