93 Wrangler air\fuel problems

[nuke0070]

hello i have a 93 sahara yj. the engine was just rebuilt and heres the problems. First it has problems starting up not everytime but most of the time. it won't rev past 4000 rpm and it has no power and bad gas millage. i have replaced the spark plugs, the wires, the TPS, the fuel filter, i have check the fuel pressure the compression i have ran injector cleaner through it and i just can't figure it out. i would take it back to the shop that rebuilt it but they screwed me over so i don't trust them.

story behind that is my buddy blew a rod i took it to them they rebuilt it and it went out again. they told me it failed because of pre detonation but i always thought a new engine could have pre det but oh well so they charged me again to fix it and after a week of getting it back this is happning so any help would be great i am stumped.

	Throttle position sensor A throttle position sensor (TPS) is a sensor used to monitor the position of the throttle in an internal combustion engine. The sensor is usually located on the butterfly spindle so that it can directly monitor the position of the butterfly throttle valve. The sensor is usually a potentiometer and therefore provides a variable resistance dependent upon the position of the butterfly valve (and hence throttle position). The sensor signal is used by the Engine Control Unit (ECU) as an input to its control system. The ignition timing and fuel injection timing (and potentially other parameters) are altered depending upon the position of the throttle, and also depending on the rate of change of that position. For example, in fuel injected engines, in order to avoid stalling, extra fuel may be injected if the throttle is opened rapidly (mimicking the accelerator pump of carburetor systems).

[Craig]

Have all the plug wires in the correct firing order?

[mud4feet]

Might wanna check the o2 sensor(s)............when mine went bad (TJ), it wouldn't rev worth a crap, no power, and gas mileage was TERRIBLE. Just a thought.......nothing to do with the rebuild, but definitely effects performance.

[nuke0070]

yes the plugs are in the right fireing order and i just replaced the o2 sensor still nothing i am totally confused with this. I am out of things i can think of so any help would be nice

[TwistedCopper]

may be a clogged catalytic converter...

[nuke0070]

oh yeah i also unhooked the exhaust before the cat and still nothing

[Craig]

Are you getting any codes?, check engine light? If you can't figure it out, you could just pay the cash for some other shop to run a diagnostic on it.

[nuke0070]

i think thats the next step cause no check engine what kind of places do a good dio on vehicles?

[jfrabat]

You may want to check that (1) the engine is getting enough fuel (check fuel filter, do a fuel pressure test), and (2) that it is getting enough air (change air filter and check hoses, clean Throttle Body and intake manifold). If it neither, try reseting the computer; mine acted up a bit once.... Also, check the vacuum hoses for any leaks or disconected joints. Also had this problem on mine once.

Felipe