Topic: I am stumped; please help!

[neale_rs]

Hopefully that will solve the problems.

[jfrabat]

OK, list of parts that have been replaced and are no longer in question as the source of this never ending problem:

From the fuel side:
Fuel sending unit (includes pump)
Fuel Filter
Fuel injectors
Fuel Pressure Regulator
Replaced some cracked fuel hoses (at the filter and at the tank)
Charcoal canister
FPR

Ignition:
Rotor
Cap
Wires
Coil
Plugs

Computer:
ECU (I had another one as a backup)
TPS (was faulty anyway)
IAC (had some idle issues)
CPS
Cam Position Sensor
IAT
MAP
Oil Pressure Sensor (was also acting up)
ASD Relay
O2 Sensor

I also checked the plug on the ECU, and there is no corrosion whatsoever.  There is also no cat on my Jeep, so it's not the cat.  Air filter was recently cleaned out (along with the whole TB) and oiled (Fram AirHog).

When it fails, I get a code 52 (Sustained rich air/fuel ratio condition detected in O2 sensor bank 1 position 1), which leads me to believe that the problem is on the ignition side.  Besides, if I give it gas while it's acting up, it starts detonating heavily (kind of like a backfire, but I think it is the unburnt fuel hitting the exhaust manifold).

Today, I sent the Jeep to an Electromechanic shop to have the electrical side looked at, as I am out of ideas by now...  Only things left that I have not checked is engine harness and Ignition Switch (but considering it sputters, and everything else continues to work, even the stereo, I doubt it is the ignition switch).

Felipe

[neale_rs]

Maybe it is the O2 sensor.  I have known of some problems here locally when they don't put in exactly the right one.

[jfrabat]

Maybe it is the O2 sensor.  I have known of some problems here locally when they don't put in exactly the right one.

But the problem has persisted through 3 sensors, so I don't think that's the problem...

[dwtaylorpdx]

Right by the oil filter kinda is a stud with a bunch of ground wires on it.. that nut got loose on mine once and raised havoc.. It affects ignition and fuel injection... Or did on mine.

If both ECU are old there is a known problem with the primary capacitors in them getting old and dieing.. Has more to do with age than use, and it causes several random ignition issues, as well as occasional charging issues.  YJ's are all getting old enough that I see this coming down the road just like the cj's with the variable venturi carb..

How old is your gasoline, and is the tank full? Mine will back fire if the fuel level gets below 1/8 tank and I go up a steep hil or around a sharp corner (Fuel starvation) and it get worse with throttle.

SOunds like you still need to get a diag scanner hooked up and see whats happening when it pops..

Dave

[jfrabat]

According to the mechanic, the grounds all checked out fine.  He did find a problem with the O2 sensor (probably caused by the excess fuel not detonated), and with the fuel pump (both were recently changed).  He says the Jeep is no longer acting up when he replaced these 2 items, though, and, according to him, the Jeep feels more powerful now (for a 4 banger).  Also, the seal on the FPR was bad, so fuel pressure was really crappy.  As for the Hesco one, I gave it to him to install, but it seems it is not the right size (maybe a 4.0 FPR?).  Anyway, I will report how the jeep is working once I get it back (today or tomorrow, depending on when I have time).

[neale_rs]

Sounds good, hopefully that will be the end of the problems.

[jfrabat]

Guys, one question; here in Panama they JUST started using gasoline mixed with ethanol; anyone had any issues as a result of this?  In theory, it should be fine (IIRC, the gas I used to put in the Jeep in Miami when I lived there up to 2009 had 10% ethanol, and I had no issues, but just in case...).

[neale_rs]

On Road Kill they said that it goes bad faster than normal gas (they had to clean a carburetor that had a lot of greenish buildup in it).  So the Jeep needs to keep being used, not left to sit for extended periods.  Other than that, it should be ok.

[jfrabat]

On Road Kill they said that it goes bad faster than normal gas (they had to clean a carburetor that had a lot of greenish buildup in it).  So the Jeep needs to keep being used, not left to sit for extended periods.  Other than that, it should be ok.

I guess that's just a perfect excuse to wheel more often than I have been!   

[jfrabat]

Well, i got the Jeep back yesterday; drove it home without issues, and drove to the office today without issues.  Tomorrow I am going to the beach, and I will take the Jeep on a bit longer test run (it's about an hour drive each way, so I am guessing if the problem will come up again, it will show it's ugly face during the 2 hours of the drive).  Anyway, I am keeping my fingers crossed in the mean time!

[jfrabat]

Well, so far so good!  I drove it to the beach (80 km away, which is about 50 miles), and so far so good.  I did notice I have 5th gear back (I can actually accelerate in 5th in flat ground), so the Jeep does feel a bit healthier than what it was.  Fuel consumption is still crappy (I got 12.3 mpg with this tank), but, considering that I was doing 70 mph most of the way trying to catch the wife in her Edge, it's not surprising (plus, the Jeep was only getting 14 to 15 mpg during its best times!)-  I am just happy it did not cough or backfire once during the trip!

On a side note, though (it's not a Jeep if nothing else fails after you fixed your current problem), the cruise control finally gave out.  I don't know if it is the system itself, or if a connection has come loose.  I also still need to install the automatic fan control from Flex-a-Lite, which is sitting at home, but I think I am all set for the wheeling trip this weekend!

[neale_rs]

That's good news about the previous problem.  Hopefully the new problem is something easy.

[jfrabat]

That's good news about the previous problem.  Hopefully the new problem is something easy.

Not too worried about the cruise control; worse case scenario, I run without it...

[aw12345]

Not all that good a gas milage and yes modern gas with ethanol does affect milage adversely.

My fat &ss Jeep gets between 10-13 mpg mixed highway, heading to the mountains and city driving. Not terribly disappointed with that.