97 4.0 misfire issues

[tworley]

There was a TSB issued for the 43 codes, they are fixed by replacing the valve springs. The factory's first batch of the TJ's valve springs was bad, they were a little too weak. I had the same problem in my previous '97 TJ and replacing the springs completely fixed all the 43 codes, misfires, etc.

Yes--I am aware of the TSB. I even researched it when I was experiencing the same 43 codes. However, replacing a sensor or two (and even checking the Ohms and resistance) is easier than pulling a head and replacing springs. A new CAM sensor, CPS sensor and coil in my jeep and I haven't had a 43 code in 70k miles.

All three work together to determine the firing order.

 

[Jerry Bransford]

Yes--I am aware of the TSB. I even researched it when I was experiencing the same 43 codes. However, replacing a sensor or two (and even checking the Ohms and resistance) is easier than pulling a head and replacing springs. A new CAM, CPS and coil in my jeep and I haven't had a 43 code in 70k miles.

All three work together to determine the firing order.

DId you not install new valve springs with the new cam?

 

[catbones2010]

There was a TSB issued for the 43 codes, they are fixed by replacing the valve springs. The factory's first batch of the TJ's valve springs was bad, they were a little too weak. I had the same problem in my previous '97 TJ and replacing the springs completely fixed all the 43 codes, misfires, etc.

btw, she did also had a catalytic converter replaced and fuel pump. Maybe PCM still running and trying to figure out the issue with that. I've got to do more testing on the Crank and O2 sensors to rule those out as well.

 

[tworley]

DId you not install new valve springs with the new cam?

New cam sensor. Clarified above.

 

[catbones2010]

New cam sensor. Clarified above.

So you replaced just the Cam, CPS and Coil sensor without doing the springs?

 

[tworley]

So you replaced just the Cam, CPS and Coil sensor without doing the springs?

I've never touched my valve springs. They're the same 27 year old springs that came from the factory.

 

[catbones2010]

I've never touched my valve springs. They're the same 27 year old springs that came from the factory.

Good to know the sensors help you. I've so far replaced the CAM, did everything else from wires, to sparks, to injectors to a catalytic converter that died during this issue ... I'll test the O2 sensors to see their voltage and resistance, and get a new CPS. See how that works out.

Honestly don't feel like dealing with springs and with my luck, dropping a valve.

 

[tworley]

Good to know the sensors help you. I've so far replaced the CAM, did everything else from wires, to sparks, to injectors to a catalytic converter that died during this issue ... I'll test the O2 sensors to see their voltage and resistance, and get a new CPS. See how that works out.

Honestly don't feel like dealing with springs and with my luck, dropping a valve.

Download the service manuals on this site. They're a wealth of info.

 

[macleanflood]

You can get an adapter and pressurize your combustion chamber through the spark plug hole...holds the valves in place (assuming you still have a seal.)

Makes changing valve springs easy. And with the 4.0 rocker arms and no lash adjustment it's really a simple job.

-Mac

 

[catbones2010]

You can get an adapter and pressurize your combustion chamber through the spark plug hole...holds the valves in place (assuming you still have a seal.)

Makes changing valve springs easy. And with the 4.0 rocker arms and no lash adjustment it's really a simple job.

-Mac

I've done quite a bit in my past, never replaced springs or torn an engine apart but I guess theres a first time for everything. I just hope I don't drop a valve because I guess I'm going deeper with head removal and that no fun. Besides air and strings, etc.. any other tips?

 

[macleanflood]

I've done quite a bit in my past, never replaced springs or torn an engine apart but I guess theres a first time for everything. I just hope I don't drop a valve because I guess I'm going deeper with head removal and that no fun. Besides air and strings, etc.. any other tips?

That's just it...you don't need to pull the head...

-Mac

 

[catbones2010]

That's just it...you don't need to pull the head...

-Mac

Not unless you drop a valve.