We've done all the basics; plugs, wires, cap/rotor, fuel filter, oxygen sensor, and replaced all vacuum lines. The idle improved slightly but still is rough. Only other issue besides the rough idle is it'll throw a CEL from hard acceleration and after letting off from cruising speed then flooring it. I was thinking possibly the crank position sensor and having the injectors checked but it's getting into the point where now we'd just be throwing parts at it. Any ideas? Also, does anyone know how to check codes from the CEL like where to install the jumper wire to get the light to flash the code?

8/17/2007 8:41:36 PM

clean all the carbon out of the throttle body with TB cleaner and a toothbrush

8/17/2007 9:14:45 PM

I'd damn near put money on the IAC. Remove throttle body and clean like said above but also clean the IAC out. If that doesn't work replace IAC. VERY common on 90's jeeps.

8/17/2007 9:51:40 PM

throttle body and map sensor both have been cleaned. sorry, forgot to mention that. he did that today actually.

8/17/2007 10:03:32 PM

still got money on IAC

8/17/2007 10:32:01 PM

iac

8/17/2007 11:20:35 PM

Diagnostic Codes

From the Chrysler FAQ

Start with the ignition off. Within five seconds, switch the key on,
off, on, off, on. (On is not start!)
The "check engine" light will flash. Count the flashes
Each code is a two digit code, so a (for example) 23 would be
FLASH FLASH FLASH FLASH FLASH
It will never flash more than 9 times, watch for pauses!
55 is end of codes, 33 is normal if you dont have air conditioning.
Please note that some codes are NOT included below, this
is not a complete listing, but it IS very close to complete.
88 Start of test (This only appears on DRBII, it's not blinked out)
11 No ignition reference signal detected during cranking (bad hall
effect)
OR timing belt skipped one or more teeth; or intermittent
loss of either camshaft or crankshaft position sensor
12 Memory Standby power lost (battery cable disconnected)
13* No change in MAP from start to run
14* MAP sensor circuit open or shorted; voltage too low
15 No speed/distance sensor signal
16* Loss of battery voltage detected with engine running
17 Engine stays cold too long (bad thermostat)
21 Oxygen sensor signal out of range, possibly shorted
22* Coolant sensor signal out of range (or disconnected to set timing)
23 Intake air temperature signal out of range
24* Throttle position circuit out of range
25 Automatic Idle Speed (AIS) motor driver circuit shorted
or target idle not reached, vacuum leak found
26 Peak injector circuit voltage has not been reached
27 Logic module fuel circuit internal problem
OR
27 TBI injector does not respond properly to control signal
31 Evaporator Purge solenoid circuit open or shorted OR
Evaparator solenoid circuit
32 EGR system failure OR
Power loss lamp open or shorted
33 Air conditioning clutch relay circuit open or shorted
34 Speed control vacuum or vent solenoid circuits open or shorted
35 Cooling fan relay circuit open or shorted
36 Wastegate control circuit open or shorted
37 Shift indicator light failure, 5-speed (blown bulb) OR
Park/neutral switch failure
OR
37 Torque converter unlock circuit open or shorted, A-413 4-speed auto
41* Alternator field control circuit open or shorted
42 Automatic shutdown relay circuit open or shorted
42 Fuel pump relay control circuit
42 Fuel level unit - no change over miles
OR
42 Z1 voltage missing when autoshutdown circuit energized (whatever
that means)
43 Peak primary coil current not achieved with max dwell time
OR
43 Cylinder misfire
43 Problem in power module to logic module interface
44 No FJ2 voltage present at logic board
OR
44 Logic module self-diagnostics indicate problem
OR
44 Battery temperature out of range (see Note #1!)
45 Turbo boost limit exceeded (engine was shut down by logic module)
46* Battery voltage too high during charging or charging system
voltage too low
47 Battery voltage too low and alternator output too low
51 Oxygen sensor stuck at lean position
OR
51 Internal logic module fault ('84 turbo only)
52 Oxygen sensor stuck at rich position
OR
52 Internal logic module fault ('84 turbo only)
53 Logic module internal problem
54 No sync pickup signal during engine rotation (turbo only)
OR
54 Internal logic module fault ('84 turbo only)
55 End of codes
61 "Baro" sensor open or shorted
62 EMR mileage cannot be stored in EEPROM
62 PCM failure SRI mile not stored
63 Controller cannot write to EEPROM
64 Catalytic converter efficiency failure
65 Power steering switch failure

* Activates Power Limited/Check Engine light.

These codes cover multiple years and engines (2.2l, 2.5l, 3.0l).
NOTE #1. The power module has an air-cooled resistor which is
used to sense the incoming air temperature. This information is fed
to the logic module and is used to control the duty cycle of the
field current in the alternator. This code applies ONLY to
alternators whose voltage is computer regulated. The battery voltage
is sensed by the logic module -- there is an internal takeoff from
the wire feeding the NVRAM keep-alive power circuit which is fed to
a voltage comparator. So...if you lose the feed to keep RAM
information stored when the engine's off, you also lose battery voltage
sensing.

-- Bohdan Bodnar

8/17/2007 11:25:18 PM

have you checked the compression for major issues?

8/18/2007 7:39:12 AM

He needs to check the obvious first.. like the CEL light that is blaring in his face.

8/18/2007 11:23:59 AM

Quote :

"We've done all the basics; plugs, wires, cap/rotor, fuel filter, oxygen sensor, and replaced all vacuum lines"

don't think a compression check is too far out there after all that stuff

8/18/2007 12:20:45 PM

I didn't say it was way out there.. but still, checking the code is easier and quicker than a compression test and will (hopefully) give him more info than he got out of throwing parts at it

8/18/2007 12:25:46 PM

uh yeah why would you start replacing shit when you haven't checked the code?

8/19/2007 12:18:50 PM

because all that shit needed to be replaced anyway.

8/19/2007 3:27:29 PM

checked the code yet?

8/19/2007 9:37:15 PM

i dont really know this guy but its actually right. the most advanced knowledge ive scene on this board in about 2 years . bump on that..
[quote]Diagnostic Codes

From the Chrysler FAQ

Start with the ignition off. Within five seconds, switch the key on,
off, on, off, on. (On is not start!)
The "check engine" light will flash. Count the flashes
Each code is a two digit code, so a (for example) 23 would be
FLASH FLASH FLASH FLASH FLASH
It will never flash more than 9 times, watch for pauses!
55 is end of codes, 33 is normal if you dont have air conditioning.
Please note that some codes are NOT included below, this
is not a complete listing, but it IS very close to complete.
88 Start of test (This only appears on DRBII, it's not blinked out)
11 No ignition reference signal detected during cranking (bad hall
effect)
OR timing belt skipped one or more teeth; or intermittent
loss of either camshaft or crankshaft position sensor
12 Memory Standby power lost (battery cable disconnected)
13* No change in MAP from start to run
14* MAP sensor circuit open or shorted; voltage too low
15 No speed/distance sensor signal
16* Loss of battery voltage detected with engine running
17 Engine stays cold too long (bad thermostat)
21 Oxygen sensor signal out of range, possibly shorted
22* Coolant sensor signal out of range (or disconnected to set timing)
23 Intake air temperature signal out of range
24* Throttle position circuit out of range
25 Automatic Idle Speed (AIS) motor driver circuit shorted
or target idle not reached, vacuum leak found
26 Peak injector circuit voltage has not been reached
27 Logic module fuel circuit internal problem
OR
27 TBI injector does not respond properly to control signal
31 Evaporator Purge solenoid circuit open or shorted OR
Evaparator solenoid circuit
32 EGR system failure OR
Power loss lamp open or shorted
33 Air conditioning clutch relay circuit open or shorted
34 Speed control vacuum or vent solenoid circuits open or shorted
35 Cooling fan relay circuit open or shorted
36 Wastegate control circuit open or shorted
37 Shift indicator light failure, 5-speed (blown bulb) OR
Park/neutral switch failure
OR
37 Torque converter unlock circuit open or shorted, A-413 4-speed auto
41* Alternator field control circuit open or shorted
42 Automatic shutdown relay circuit open or shorted
42 Fuel pump relay control circuit
42 Fuel level unit - no change over miles
OR
42 Z1 voltage missing when autoshutdown circuit energized (whatever
that means)
43 Peak primary coil current not achieved with max dwell time
OR
43 Cylinder misfire
43 Problem in power module to logic module interface
44 No FJ2 voltage present at logic board
OR
44 Logic module self-diagnostics indicate problem
OR
44 Battery temperature out of range (see Note #1!)
45 Turbo boost limit exceeded (engine was shut down by logic module)
46* Battery voltage too high during charging or charging system
voltage too low
47 Battery voltage too low and alternator output too low
51 Oxygen sensor stuck at lean position
OR
51 Internal logic module fault ('84 turbo only)
52 Oxygen sensor stuck at rich position
OR
52 Internal logic module fault ('84 turbo only)
53 Logic module internal problem
54 No sync pickup signal during engine rotation (turbo only)
OR
54 Internal logic module fault ('84 turbo only)
55 End of codes
61 "Baro" sensor open or shorted
62 EMR mileage cannot be stored in EEPROM
62 PCM failure SRI mile not stored
63 Controller cannot write to EEPROM
64 Catalytic converter efficiency failure
65 Power steering switch failure

* Activates Power Limited/Check Engine light.

These codes cover multiple years and engines (2.2l, 2.5l, 3.0l).
NOTE #1. The power module has an air-cooled resistor which is
used to sense the incoming air temperature. This information is fed
to the logic module and is used to control the duty cycle of the
field current in the alternator. This code applies ONLY to
alternators whose voltage is computer regulated. The battery voltage
is sensed by the logic module -- there is an internal takeoff from
the wire feeding the NVRAM keep-alive power circuit which is fed to
a voltage comparator. So...if you lose the feed to keep RAM
information stored when the engine's off, you also lose battery voltage
sensing.

-- Bohdan Bodnar

8/20/2007 4:07:08 AM

oh yeah, it's throwing a code 44 which doesn't make sense to me unless those codes aren't for a jeep.

8/22/2007 2:22:11 PM

um, i GUESS that could be the problem. the batt. temp sensor has effect on the alternator. i guess it could be outputting a low voltage at idle, causing problems?

those aren't neccessarily jeep codes. they're generic chrysler codes. they are correct for a lot of motors, but not all.

i would look to the IAC also. don't bother cleaning it, waste of time for most.

[Edited on August 22, 2007 at 2:28 PM. Reason : .]

8/22/2007 2:26:37 PM

http://www.jeephorizons.com/tech/yj_codes.html

8/22/2007 2:32:51 PM

WTF is a battery temp sensor? I guess that is obvious, but where is it located?

[Edited on August 22, 2007 at 2:39 PM. Reason : p]

8/22/2007 2:38:46 PM

bring it by Jeepman's house sometime, i could take a look at it for you, probably a sensor issue

8/22/2007 2:42:31 PM

^^it's located under the battery. its function is to adjust alternator output depending on the temp. i.e., if it's cold it bumps it up a little, if it's warm it lowers it some.

it doesn't have complete control, but it does have the ability to drop voltage enough to cause problems. especially if you have an older/weak battery.

8/22/2007 3:02:41 PM

Oh weird. I guess I just never noticed that shit on any of my cars. Good to know.

8/22/2007 3:12:41 PM

my car was idling rough one time and it ended up being that i used diesel instead of gas, you might want to check your fuel

8/22/2007 4:35:28 PM

Quote :

"um, i GUESS that could be the problem. the batt. temp sensor has effect on the alternator. i guess it could be outputting a low voltage at idle, causing problems? "

hmmm, i can see how that could be the problem then since when it's at idle, the idle is rough and acts as if the engine is lugging.

8/22/2007 7:55:46 PM

ive never seen a jeep with a regular idle.

8/22/2007 10:59:12 PM

^^^^^^^^^Cleaned the IAC on my buddy's 91ish XJ and it solved the problem without replacement.

^That's because you've never seen mah stroker

8/23/2007 10:47:39 PM

yeah, well a blind squirrel finds an acorn every once in a while too.

8/23/2007 11:06:27 PM

as easy as it is to do though, it's worth the shot. I do agree that most of the time replacement is a much better option.

8/23/2007 11:11:08 PM