Topic: I am stumped; please help!

[sharpxmen]

the FPR is probably gone, but you can try the spring if you have an old one you don't care for that much. Can be the seat though in which case you can't do anything (which means it developed a ridge and it catches on, once releasing i lets out out more fuel and it repeats the cycle over and over). I might have a threaded one around (i need to look) but i remember it was not keeping pressure too well, i can probably find a spring somewhere also - can throw them in an envelope and mail them over if i can find them. Unfortunately i have no bodies left and the setup to make them is long gone so can't help you with that. could be a problem with the lengths too as i made them as pairs so not sure if it will work. I'll have a look in the garage tomorrow and let you know.

[jfrabat]

A friend of mine has a Hesco one he is not using, so I my just get that from him and throw it in there...  In the mean time, I am sticking with the stocker, as it seems to better hold the pressure (even if it's lower).

[sharpxmen]

ok, keep us posted

[jfrabat]

Took the Jeep to go fishing at the lake (better known as the Panama Canal), which is about 20~25 miles away from my home.  I did notice that, when cold (did it on 3 separate occasions, always close to where I had turned the Jeep on recently), the Jeep would seem to loose power (it felt like I was lifting my foot of the accelerator).  If I pressed the accelerator (all the way), the Jeep would "pop" (Backfire?  Pinging?).  The Jeep did throw codes, and they are as follow (read with my OBDI scanner):

52: Sustained rich air/fuel ratio condition detected in O2 sensor bank 1 position 1
21: Oxygen sensor bank 1 position 1 shorted to high voltage
24: Throttle position sensor input above maximum (this one is a fairly common one on my jeep when you go pedal to the metal)

Considering both the O2 sensor and the TPS are new, what do you think this is caused by?  Obviously, since it SHOULD be in open loop, it could be caused by the 19# injectors...  Once the Jeep warms up, it's running fine.  But I can smell the exhaust a bit rich (keep in mind I don't have a cat; got tired of clogging them, and I am guessing this could be the cause!).  So, any takers on how to improve this?

[sharpxmen]

did you reset the 'puter after replacing all that stuff? O2 might not get good contact in the connector as well.

on the tps check if your t/b butterfly goes beyond vertical, if it does you'll need to make sure it stops and not going beyond (which would be detrimental to the airflow), if that's not it then maybe it's a sensor ground going bad (which might explain the O2 issue also).

[jfrabat]

did you reset the 'puter after replacing all that stuff? O2 might not get good contact in the connector as well.

on the tps check if your t/b butterfly goes beyond vertical, if it does you'll need to make sure it stops and not going beyond (which would be detrimental to the airflow), if that's not it then maybe it's a sensor ground going bad (which might explain the O2 issue also).

I'll check the butterfly next weekend, though, as I don't have time tonight.  I did reset the ECU (with the scanner I have; not the manual way).  A bad ground would explain A LOT of things...  How do I check that? 

[sharpxmen]

I'll check the butterfly next weekend, though, as I don't have time tonight.  I did reset the ECU (with the scanner I have; not the manual way).  A bad ground would explain A LOT of things...  How do I check that? 

i think all the sensors (maybe except for the O2) have the ground black with a blue stripe. Measure with an ohmmeter from each sensor to the PCM sensor ground pin(s), I can look in the FSM for which ones are the PCM ground pins if you don't have a copy.

[dwtaylorpdx]

To reset the ECU, just disconnect the neg battery cable and turn the key
on for 5 to 10 minutes.. YJ ECU maintain memory from the battery.

When you restart make sure every single switchable electrical device is off.

Allow to idle for 5 minutes or so.. THen drive for 5 miles (I do a freeway run...)
It takes about 30 run start cycles for the ECU on mine to really get its act together.
I think Jeep claims 10... cant remember...

Dave

[jfrabat]

I reset it again with the reader, and it was still doing it.  But I noticed every time it was less, so I started doing what someone in this forum mentioned once, where you shut the Jeep off at stop lights, and it seems the ECU learned, because, at least for the last 2 days, it has been purring like a kitten, making me one HAPPY camper!!!   

[jfrabat]

It seems I counted my blessings way too soon...  The Jeep is at it AGAIN!  Same issue.  You are driving, and all of the sudden, it looses power (as if you unplugged the coil).  If you load it (give it gas while in gear), it will stall even more and then it will backfire (as if fuel is reaching the exhaust or something).  If you accelerate with the clutch in, sometimes it comes back to life, sometimes it doesn't.

The following items have been replaced (and are therefore no longer suspect):

From the fuel side:
1. Pump
2. Filter
3. FPR
4. Injectors

From the spoark side:
1. Coil (also relocated it to the firewall, so engine heat is not the issue either)
2. Wires
3. Rotor
4. Cap
5. Plugs

Computer side:
1. ECU (I have 2; it does it with both)
2. TPS (because of other issues)
3. IAC

I am thinking it could be the CAM position sensor that it is acting up, but other than that, I am out of ideas...

I will replace the following sensors (which I already have) just for good measure:
1. MAP sensor
2. Intake Temp Sensor
3. Thermostat
4. Oil Pressure Sensor

I am now trying to get the Crank Position Sensor locally; we'll see how that goes, but this issue is REALLY getting on my nerves!  Plus, I got a ride next month, and I need to Jeep to be running flawlessly, otherwise, no sense in going wheeling when I am going to have a hard time just driving down the road!

Any other ideas on what it could be?

[neale_rs]

The Crank Shaft Position Sensor might be the problem.  I friend with a 2.5 TJ had some similar problems recently and that is what it was.  The mechanic first suspected the O2 sensor but that didn't solve it.  No codes are showing up?

And both the dealership and a mechanic shop have told me you cannot distinguish between Cam shaft sensor and crank shaft sensor problems.  At one shop, they were good enough to try both and leave in and charge for only the one that solved the problem (this was in a Dodge Neon, not a Jeep).

[jfrabat]

The Crank Shaft Position Sensor might be the problem.  I friend with a 2.5 TJ had some similar problems recently and that is what it was.  The mechanic first suspected the O2 sensor but that didn't solve it.  No codes are showing up?

And both the dealership and a mechanic shop have told me you cannot distinguish between Cam shaft sensor and crank shaft sensor problems.  At one shop, they were good enough to try both and leave in and charge for only the one that solved the problem (this was in a Dodge Neon, not a Jeep).


Well, I plan on changing both, so if that is the issue, it should be solved.  Oh, and the O2 sensor was also replaced about a month ago or so...

[Jeffy]

I'm gonna say there's a bad/intermitant ground.

[jfrabat]

I'm gonna say there's a bad/intermitant ground.

OK, so WHERE would you look for the cause?  Because I am out of ideas by now...

[sharpxmen]

It seems I counted my blessings way too soon...  The Jeep is at it AGAIN!  Same issue.  You are driving, and all of the sudden, it looses power (as if you unplugged the coil).  If you load it (give it gas while in gear), it will stall even more and then it will backfire (as if fuel is reaching the exhaust or something).  If you accelerate with the clutch in, sometimes it comes back to life, sometimes it doesn't.

well, i had this issue with a vehicle way back when i started driving. I replaced the coil with a better one combined with a spark booster and after a little while i started to have an issue, turns out the spark was closing on the outside of the coil rather than thru the wire>distributor>plug and was misfiring, rev it up past a certain point it would come to life (probably when the spark booster was less efficient). I removed the booster and all was good - makes me think of your coil problems, i can't remember if you have a stock one or the 48kV one.

EDIT: could be MAP and x3 on crank sensor - might as well replace them since you put all the other new stuff in it. I think it's spark related but who knows.
Does it backfire out the intake at all (or whatever you call that)? if yes that's possibly too lean, so in that case could be MAP or an injector.
Does it do this at idle (like running in 3 cyl?)