Do a 60k tune up first, all below assumes you did, spark parts, filters. dah?
first off the engine EFI runs a map sensor, (called speed density system)
so that means if the engine can pump air (compression tests PASS)
the MAP see that, air flow (calcs) and matches air with proper fuel.
1990 is a vary bad year, it has the horrid, Renix french pos EFI system. (owned 2, can taLK days on this ecu FROM H3LL)
but there is no CEL lamp, nor any scan tool , that will work here.
(unless you can find a working DRB tool, ) NO FLASH CODES !!!
above poster never seen RENIX, so.. .answers wrong. ITS OK.
1993 this changed (Chrysler) and started OBD1 ECU which we can scan easy. (innova 3140)
all this means is you must be smarter than the average bear.
are you>? got tools, meters. and all that? you will need it.
and a FSM book or login to alldata.com like we do.
if compression test pass, and vacuum at 19" idle and gunned throttle drops low fast and if you release throttle it goes why high fast 25inches>? and goes to 19inchs again, the engine is ok and cat not melted, all that in 5min work (vacuum tests) and vacuum not bouncing? 1 glance, no its steady vavcuum.
so I wave my magic wand, go, gee engine is ok.
i then check fuel pressure use a REAL gage.
it idle and throttle gunned. for spec pressures.
if all that pans out> whats next? well EFI is next,.
i check the MAP sensor voltage at 3 points.
key on, idle and gunned. for spec, readings. if not map is bad. or just clogged.
check all the other sensor by hand is next. and ill not attempt do post what ever mech ,knows here, "basics"
a volt meter , you can check them, ECT, IAT, etc.
my wild guess low fuel pressure. (BASE ON OK 1 MILE)
or FPR stuck wide open' (bad fuel pump reg)
or a bad wire to fuel pump, such that pump does not receive full 12vdc power.
here is map readings, ill post this because many books fail to show it.
http://www.fixkick.com/sensors/my-map.html#Jeep
if input to map is good, but output wrong, the map is DOA.
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i got more, if the power loss is violent (called misfire) that is spark failing or flooding, if the power lost from engine is smooth as silk, like dragging a 1000lb dead weight, that is bogging and is loss of fueling. (weak) see? we cant drive and and see that fact in 1sec.flat. so must list 50 thiings, not only that we cant see the dash lights or the head lights dim. either. or the engine banging away.
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Fuel filter, plugs, air cleaner, plugged catalytic converter, poor fuel pump. Odds are its one of those.
x2, not tuned up, low fuel pressure.
but if fate wins, its 50 things, wrong, odds only works if , LUCKY
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Fuel delivery system. last time serviced? Fuel filter, Fuel pump, Fuel pump relay, Fuel pick up in tank may be plugged. Fuel pressure regulator not keeping fuel pressure high enough for fuel injectors. ECU problem. Any error codes? You will probably need a service repair manual to learn how to read codes.
Do you think hooking a scan tool up to the jeep can diagnose this? I've only had the jeep for 4 weeks and this just started happening two days ago. I can even get off of my street with out needing to turn around
As far as I know there was only a code reader in the engine bay with sort of an sos with number of red light flashes for a series of code numbers Ie 1-2-3. Thats why you need Service manual and learn how. Try this http://www.manualslib.com/
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SOURCE: 1999 Jeep wrangler runs rough
Check the gas, could be water in it or drive the car with a fuel
pressure tester connected to it and watch to see if you lose pressure.
Normal pressure while driving is about 30 to 40 psi
SOURCE: 1991 jeep wrangler sahara shifting promblems
Your clutch is not disengaging. If it a hydrolic clutch chk. the fluid in resavor, Or slave cyl. for the clutch is bad, Or it has got air in it and needs to be bleed. This is a clutch problem, nothing wrong with trans. If its a manual clutch linkage its an ajustment thing. My best guess if its hydrolic slave cyl. went bad, or resavor is out of fluid.
SOURCE: backfiring and loss of power
'till you do some in depth testing of all systems, I'd place equal weight on every possibility. Make sure you cover the basics like fuel filter etc before getting crazy with it though. Also check cap. rotor, coil and wires. Idle cylinder pressure is different than that encountered when driving. This additional pressure will cause ignition spark to seek a better easier ground,(not the spark plugs where it should be going) causing missing under load.After checking , if you haven't found anything, its time to begin testing fuel pump pressures, modules and controls.
good luck
SOURCE: 5th. Gear
Sounds like you may have bent a shift fork or your cluster gear has some missing teeth on it now. I would venture to say that is it a bent shift fork. This will require the transmission be removed to gain access to inspect and repair.
SOURCE: 1990 Wrangler yj 5 speed manual transmission -
The clutchless shifting doesn't help your cause any. Has the fluid been changed yet? Start with fresh fluid and go from there.
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