1993 sidekick won't rev up

[budz]

hi all, newbie here. thanks for this site.

i am about to buy my friends sidekick which has been sitting in his garage for 8 mos now. he said the last time he was using it, engine idled roughly. i started the motor yesterday and it idled very very rough as if only two cylinders fired. then i tried to rev the motor but nothing happened even at full throttle opened. engine just idled rough (only about 300-400). it stays like that no matter what throttle opening i do.

fuel pump and fuel filters have been replaced. but i noticed that there is a big big crack and exhaust leak on the #4 exhaust manifold about an inch above the O2 sensor. could this be the problem? please help. thanks in advance.

[jtgh]

sure, big problem
no order but ide do #5 first, then 1 then 2.

#1 as always a full turn up. cap , rotor, wires and plugs. and fillters .

#2 do number two first. that crack will cause a hUGE rich condtion (oxy flood) and will foul out every set of plugs you put init.
for now unplug oxy sensor. at least the default value will be 14.7:1 to the ECU.
it is an 8 valve or 16valve engine, is the CEL lamp on key on,then off at idle .

#3 bad gas?
#4 fuel pressure test.
#5 compression test. ( heck any car if found sitting would get a compression test right of the bat so I know what IM up against , (small parts or new engine, why guess?)

cheers and welcome to the clan.

[budz]

thanks for the reply, it's the 16 valve motor.

the crack is on the exhaust manifold. will this also cause oxy flooding? pls pardon my ignorance. my guess also is that the oxy sensor sends signals the ecu to stop supplying fuel to avoid motor damage. is this possible?

tune up have been made (air,fuel filters replaced, new fuel pump installed).

i'll try to find out if i can pull out a manifold from a salvage yard and see what happens next. will keep you posted.

[jtgh]

yes,any leak there, will allow oxygen from the atmospher to leak into the exhaust.
(it pulses the exhaust ) and this hits the O2 sensor. the sensor they says the engine
is lean , way too lean, so as a result of that, the ECM throws max rich.
on some cars, it can go rich for 1 hour then lean for another hour , do the carbon
blanketing the O2 sensor, ( it's called O2 hell)
depends on year the ECU was made.


other than washing the rings with fuel and tad faster engine wear, the motor will be ok.
and you pocket book thinner due to horrible gas mileage.

some report 15mpg here. ( in the chevy blazer range, yah, really crappy)

this car will run much better with a tight exh. system (cat forward )

on a 93 look for leaks on the induction side too.
most will force engine lean. ( that bypass the MAF)

dont ask me what happens with both problems, my head will hurt.