Jeep loosing power (Ignition?)

[jfrabat]

Here's the deal; I have been chasing this problem for over a year with no solution as of yet, and I am running out of ideas.

THE PROBLEM: when I am driving the Jeep, it sometimes (no particular situation triggers it except that it happens under load, like when accelerating), the Jeep simply starts cutting out. The best way to describe it is to imagine as if there is a bad connection to the coil which makes it cut out sporadically. If you give it gas, there will be some detonation (probably the unspent fuel reaching the exhaust manifold). I should probably point out that the Jeep would also toast coils on a regular basis, but I checked current levels, and it's showing fine. I also relocated the coil to the firewall to rule out heat as the cause.

Here's a 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 (both at the filter and on top of 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 (AKA Distributor Sensor)
IAT
MAP
Oil Pressure Sensor (was also acting up)
ASD Relay
O2 Sensor

Vacuum:
Replaced all the engine bay vacuum hoses with silicone hoses and made sure there are no leaks


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, like I said, I think it is the unburnt fuel hitting the exhaust manifold).


TOnly 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). So any idea as to what could be causing this?


Felipe

 

[dc_jeep]

I had a problem like this. My issue was the new spark plug developed a crack around the tip of the spark plug, the ceramic center broke off and more ignition area got exposed. You might want to. pull the plugs and inspect them for damage ?

 

[Utah_jeepster]

two problems come to mind, and neither are a fun fix. One I would suggest and its cheaper is to wrap your fuel rail and injectors with heat shield tape and socks on the injectors. the last is a known problem with pre 03's is a weak exhaust spring. No need to tell you what the fix is.

 

[jfrabat]

I changed all 4 plugs and the problem persists... If it IS the springs (you mean valve springs, right?), I do have a new spring set at home that I could try... As for the fuel rail problem, what would be the need? I am trying to understand the problem that would require wrapping the rail in heat shield (I can't wrap my head around this one).

 

[flatie46]

Check and clean body to frame and engine to frame grounds.

 

[jfrabat]

Check and clean body to frame and engine to frame grounds.

Do you know where they are located? I have not checked, but just to save some time...

 

[superj]

I was going to day add some more grounds to your system.

 

[Catoctin Jeep]

You said you replaced the cam position sensor. Did you have it set at a shop with a scan tool. If its not set correctly it will not be in time with the injector pulse. That will throw everything off.

 

[jfrabat]

You said you replaced the cam position sensor. Did you have it set at a shop with a scan tool. If its not set correctly it will not be in time with the injector pulse. That will throw everything off.

If that was the case, it would ALWAYS act up, not just some times...

 

[JPNinPA]

A crank position sensor will cause intermittent stuttering and cutout. Without setting a code.
What about a stuck injector or leak around the injector?
Have you checked your timing and are sure your distributor is clocked correctly?

Do check the plugs for fouling or burning. One Is too rich the other too lean. Both may lead to a stutter condition at speed.

 

[69jeepcj]

Only thing I can add is it does sound like too much timing while under load. I would verify the timing is correct, not only initial timing (at idle) but total timing as well. I would also follow up as others mentioned about having the cam sensor set, which affects timing. The purpose of wrapping your fuel lines is to eliminate heat. If your lines are too close to exhaust or manifold they can get hot and the fuel can vaporize (vapor lock), wrapping them insolates them. I thought timing or carb adjustment which you don't have when first reading your post.

 

[jfrabat]

The crank position sensor and the injectors were replaced, so its not that. No bad signs on the plugs either. Timing is not adjustable in a YJ as far as I know... how do you adjust the cam sensor?

 

[JPNinPA]

The crank position sensor and the injectors were replaced, so its not that. No bad signs on the plugs either. Timing is not adjustable in a YJ as far as I know... how do you adjust the cam sensor?

The timing is set by the distributor but if it is loose or set improperly initially, it not adjust properly. The cam position sensor is in the distributor and gets its continuously adjusted along with the timing.

 

[flatie46]

Do you know where they are located? I have not checked, but just to save some time...

On my CJ5 their's one at the engine mount that goes between the engine and frame, not sure about the body. Seems like their was one somewhere around the gas tank, I'm sure that wasn't the only one. A friend of mine had a drag car that would give the same symptom and it ended up being a bad chassis ground. When he replaced/repaired it it shaved a considerable amount off his 1/4 mile E.T. It's something that's often over looked but does make a big difference and kinda goes along with what you were saying about it burning up coils.

 

[Bounty__Hunter]

Where did you purchase your sensors like the Crank Position Sensor? Quality varies widely among sensors from different vendors.

Also check for a short in the wiring harness to the Crank Position Sensor, very common.

 

[jfrabat]

Where did you purchase your sensors like the Crank Position Sensor? Quality varies widely among sensors from different vendors.

Also check for a short in the wiring harness to the Crank Position Sensor, very common.

Sensors are all from Crown. I'll check the wiring, thanks for the tip. I am also checking/cleaning grouds...