ttopvincent

i am new to this site, and to the z28 world. so i dont know too much about these cars. i just bought a 94 t top z28 sunday, and the guy told me it has been sitting for years and not driven. the car starts, but runs really bad. its very slow, my 3.4 camaro will beat it if i raced them. now my question is, do you think maybe its old gas thats making it run like that? or do you think i need to do a tune up on the whole engine? i bought this car because i wanted something faster, not slower than my 3.4 camaro. any and all help will be greatly appreciated.

Injuneer

How many years was it sitting? And are you indicating you just started it up using the old gas that was in the tank?

I'd clean the entire fuel system for starters, with a new filter, machine-cleaned injectors, drain the tank and flush the entire system. Check the fuel pressure regulator for fuel in the vacuum compensation line.

Have you changed the other fluids and applicable filters - engine oil/filter, coolant, trans lube, rear axle lube, air filter, PCV valve?

Then check the fuel pressure, and scan it for codes. Examine the plug wires and spark plugs. Be sure to check the wire ends and terminals for corrosion. Check the harness connector for the Optispark distributor for corrosion.

Check all vacuum lines and possible sources of vacuum leaks.

ttopvincent

i didnt start it. the guy i bought it from started it to show me that it runs, and it does, but it runs super rough. if i punch it from a dead stop all it does is rev up a bit and take off very slowly. i already took the old gas out, and put new gas in with a fuel injector cleaner. now this weekend im going to change the plugs and wires, crossing my fingers that this will work and the car will run ten times better. as far as changing other fluids i already did the oil. transmission is fine. like i said im new to these engines so idk where the pcv valve is at. could that be a major problem if plugged?

mrmint69

As already stated, change the fuel filter, check the air filter, check the opti harness for corossion and all hoses for cracks. Did you find out how long it sat for? I would just change the plugs and see how good the plug wires appear. The opti could be shot from sitting so long and can you put the mileage on here. Can you tell me how much you paid for the car also? Thanks

ttopvincent

i bought the car for $1200.00 and the windshield stickers say 2007. so its been sitting since then. where is the opti harness? i bought plugs, wires and a fuel filter which i will be installing this weekend.

Injuneer

There is a short harness piece that runs from the bracket on the passenger side of the intake manifold.....

http://shbox.com/1/evap_sol.jpg

..... to the Optispark distributor on the front of the engine, under the water pump. The harness plugs into a short tower on the passenger side of the Opti, facing upwards at about 10:00 o'clock when viewed from the front of the car. The connector tower is by the "3" in this photo.

http://shbox.com/1/opti_cyl.jpg

All links courtesy of Shoebox. You need to bookmark his website..... the best source of LT1 information on the Internet.

4th Gen LT1 F-Body Tech Aids

ttopvincent

alright cool. thanks alot. imma look into this in the morning

ttopvincent

got a new update. i changed the plugs and wires, and the car is running alot better, but there is still no power. if i stomp on it from a dead stop it just barely starts going and sounds loud like i am going fast, but really im not.

mrmint69

Sounds like your heading in the right direction. Have you done the other things mentioned? I have a feeling they will solve most or all your problems. A plugged cat, fuel filter, bad fuel pump or bad opti could be your problem.

ttopvincent

I'm thinking a bad opti. I changed the fuel filter, took the cat off so its running straight headers right now, I'm thinking it could be a bad Egr or I need to clean the iac.

mrmint69

Those should not cause the issues you say and a lot of things will throw a code if they occur.

Injuneer

Do you mean the engine revs up (RPM increases) but the car doesn't move? Is it an automatic (slipping trans) or manual (slipping clutch) trans?

mrmint69

Does it idle like a healthy running engine and rev up smooth with a little gas? What about out driving at a steady speed, does it seem to have a miss or run rough? How many miles on the car and is it an automatic? You might have something like bad 02 sensors and opti like mentioned, that are bad because of high miles and should be replaced because there life span might be up. Trying to think of things to do that isn't just throwing money, but might need replacing because of the cars age and mileage.

ttopvincent

the car has 107,XXX miles on it. if i give it gas from a dead stop it moves, but there is no power to put me in the seat like my v6 camaro does. it ran fine the other day when i started it. it has a auto tranny, but its been rebuilt so i know thats not the problem. the problem lies in the engine. im going to look at the egr, iac, and the opti this weekend.

mrmint69

I would check the opti harness first. Amazing how many people found this to be there problem.