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[Techmaven]

Got myself a cheap 86 2wd 5 speed with 2.3....horrid on gas and VERY slow...55mph top speed. Search feature here yields vague results...HELP!!!

 

[SenorNoob]

Howdy and welcome to TRS.

There are many things that could cause your problems. I'm gonna assume fuel injected.

Tires too big for the gear ratio.
Bad sensor. (O2, MAP ...)
Bad state of tune-up. (Plugs, wires, distributor cap rotary button, clogged air filter ...)
Leaky fuel injector.
Stuck wide open EGR valve.
Timing is off.
Electrical or mechanical failure of some kind.


Those are just some of the possibilities that immediately come to mind.

We can narrow it down but it means checking many things.
First off: Do you have any check engine codes?

How To Read the Codes

Code Definitions

 

[jhammel85]

Sounds like it needs a good "going over". Start with a tune up and making sure the carb is tuned right. Then go from there...If it has bigger tires than stock (check your door for the original size) then it can throw off your speedo / miles to make you think you're getting worse MPG than you are.

 

[Techmaven]

Did cap,rotor, plugs and wires...air filter too...timing reads 20btdc at idle...tires are stock 195/75r14. It's 2.3 F.I.

Engine won't rev over about 3k..just lays down like it has a rev limiter. Very little power regardless of throttle position. smells of gas/over-rich.

Old plugs had no wear and were tan on one side/black on the other. no check engine light. runs worst when cold..slight improvement when warmed up.

 

[cammeddrz]

Welcome from Utah

 

[SenorNoob]

It's possible to have codes without a check engine light.

If you have no codes though then something is wrong that the computer can't recognize as wrong. Pretty common one is the ECT sensor. There is a guide to checking it here: ECT Sensor Test

Another likely suspect is: ACT Sensor

There are more tests you might want to do there as well.