Limp mode? Doesn't accelerate over 3000rpm

[Willperalta]

Hello everyone, I’ve been a guest member for a little while (I’ve been looking at posts, I just never created an account)

I bought a 2001 Jeep Wrangler 4.0 Auto trans, I have a problem every time I accelerate hard and then do a completely stop. I did some research and I saw it’s called “limp mode”. But it throws me P0300, P0303, P0304 and it doesn’t rev over 3000 rpm
Someone told me that if I remove the upstream O2 sensors then it can be the catalyst converter being clogged. So I did that and the Jeep was running better, only thing is that it sounded like a straight pipe truck.
I changed the catalyst converter for a Flowmaster catalyst converter that I bought from Amazon, and it still gives me the same problem and same codes. (If i remove the O2 sensors it runs fine) I changed camshaft position sensor and throttle Position sensor.

Every time i turn off and turn back on the Jeep, the problem disappear but appears again once I hit the gas pedal again.
I really would appreciate any kind of help.
Im uploading a video of the problem I have.

 

[Rubicon John]

You have misfires. Inspect your spark plugs first. What do they look like?

NTK o2 sensors are also the only recommended option around here. You might try swapping those in if the o2 sensors are creating that much issue.

 

[Willperalta]

You have misfires. Inspect your spark plugs first. What do they look like?

I changed my spark plugs twice, the first pack was NGK but then I saw a video and it said Autolite was better, I changed them with the 0.035 gap and still the same problem. I changed the coil pack as well.

 

[Rubicon John]

If the plugs are new then I would perform a compression test and a leak down test to check the health of each cylinder and go from there. If good, look into your coil rail. (Pretty sure 2001 has a COP ignition?)

 

[Willperalta]

This is the compression test I did (I did the test before I installed the new Autolite spark plugs tho) and the the coil packs is a like a rail, it isnt individual.

 

[Rubicon John]

As far as I understand the modules on the coil rail supply cyls 1-2, 3-4, and 5-6

 

[Willperalta]

As far as I understand the modules on the coil rail supply cyls 1-2, 3-4, and 5-6

Yes, but I changed the coils and nothing has happened, I just don’t understand why it runs fine when I take the upstream O2 sensors. Also this is the video, I don’t think I uploaded it correctly.

 

[Khaled]

I think you need to timing cam/crankshafts check below link:

 

[ctjunlimited]

Yes, but I changed the coils and nothing has happened, I just don’t understand why it runs fine when I take the upstream O2 sensors. Also this is the video, I don’t think I uploaded it correctly.

Was there any resolution to this? I have exactly the same symptom.

 

[Tj4.0 2004 automatic]

Was there any resolution to this? I have exactly the same symptom.

I have the same problem 2004 jeep 4.0 auto, my car revs Over 3k rpm good when the car is in park or neutral, but if it’s in drive or reverse the revs are Under 3k I already change the sparks plugs and the coil pack

 

[Tj4.0 2004 automatic]

I

I have the same problem 2004 jeep 4.0 auto, my car revs Over 3k rpm good when the car is in park or neutral, but if it’s in drive or reverse the revs are Under 3k I already change the sparks plugs and the coil pack

 

[Tj4.0 2004 automatic]

I replace the coil pack and spark plugs because I have a check engine light flashing when my cars goes into limp mode, but now I don’t have the flashing check engine light, just the loss of power and not accelerating just under 2500 rpm I can go over

 

[tr21triton]

could be your cats. thats the way mine acted when the honeycomb in 1 of them came loose. Feel if you have good pressure coming out of your tailpipe.

 

[Tj4.0 2004 automatic]

could be your cats. thats the way mine acted when the honeycomb in 1 of them came loose. Feel if you have good pressure coming out of your tailpipe.

I also have low rpms at idle I notice that today I think at idle like 500 rpms

 

[Tj4.0 2004 automatic]

could be your cats. thats the way mine acted when the honeycomb in 1 of them came loose. Feel if you have good pressure coming out of your tailpipe.

It could be the tps? Or no I also have shifting issues, but not a check engine light

 

[ctjunlimited]

I have the same problem 2004 jeep 4.0 auto, my car revs Over 3k rpm good when the car is in park or neutral, but if it’s in drive or reverse the revs are Under 3k I already change the sparks plugs and the coil pack

The issue final resolved after I put in new cats and O2 sensors... my sensors where only 68k old and the cats looked fine (back cat was clear and front looked in tac). However... my wife's driving habits over the past 2 years, were those of clogged cats issues (short, short and short).. Cats where at 168k.

Anything, I have met others since that experienced the same issue and the same resolution.


Remove all your O2 sensors and see if the issue goes away.

TIPS: just rip those old head bolts out... and replace with new clips and bolts
make sure your air wrench is spec'ed for at less 50 ft lbs.. when putting the new ones back

I used extreme 4x4 Accupart cats.. about $400
NTK O2 from rockauto
local farm equip store for new better head bolts

Again... my cats looked fine and No rust.. this jeep has been in GA and AL since 2005 and 168k miles.