Loss of engine power at 2500 rpm in any gear - JeepForum.com
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post #1 of 22 Old 10-13-2021, 12:20 PM Thread Starter
skysgt
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Loss of engine power at 2500 rpm in any gear

Good Afternoon Forum,

Thank you in advance for any advise this forum may offer to help solve my problem.

For the last 6 months I have been chasing a problem with my 2006 TJ. It has manifested itself into loss of power at 2500 rpm in any gear. It originally started at 3500 rpm but now it is consistently losing power at 2500 rpm.

Background history is I had a check engine light come on over two years ago. I ran the code and replaced my O2 sensors. That did not solve the check engine light. The year prior to the last 6 months my TJ sat in storage. Upon removing it from storage, I installed 2 batteries and a solenoid. The next day I blew the computer.

After I replaced the computer that is when I started losing power. This was 6 months ago. Since then, I have replaced the spark plugs, cam shaft sensor, crank shaft sensor, fuel pump, and been to the mechanics shop more times than I wanted.

It has been in the shop now for 3 weeks and everyone seems to be at a loss.

Can anyone help?

Thanks,

Skysgt

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post #2 of 22 Old 10-13-2021, 01:00 PM
pshivers
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If you ran codes, did it come up with O2 sensor issues? Could it possibly be a clogged cat causing the codes and loss of power?

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post #3 of 22 Old 10-13-2021, 01:20 PM Thread Starter
skysgt
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PShivers,

Thank you for your reply. I just spoke with the mechanic and there hasn't been any blockage codes indicating the cat. Additionally, they were able to identify the problem does go away after the engine has been running away.

Typically, my problem exists in the morning time and it would disappear after I restarted my engine 3 times from a cold start.

But even they are stumped as to what the problem is.

Respectfully,

Skysgt
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post #4 of 22 Old 10-13-2021, 02:33 PM
jtec
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Something appears missing in the post.. any info to add?
1st - suggest you find another mechanic.

with a scanner -
copy and post ALL codes.
looking at Live data - ECT, MAP, FUel trims long and short, o2 sensor voltages ie .3 tp .7
this will give us some ideas.

For a DIYer - rent borrow some gauges, check fuel pressure wih a gsuge and exhaust back pressure.

A tip: a code does NOT indicate a component is bad just tells what and where to check. Your o2 codes may have been wiring BUT knowing codes is helpful.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #5 of 22 Old 10-13-2021, 03:45 PM
CJ7-Tim
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Everybody in that shop must be a Moron. Since the Jeep has OBD-II Self Diagnostics, finding and fixing the problems should not be that difficult. The first thing I would do is find a more diagnostically skilled and Jeep experienced mechanic.


If you do not have an OBD-II Trouble Code reader with Live Data display, you need to get one. Without any OBD-II Trouble Codes to focus diagnostics or give suggestion on where to start trouble shooting, you might want to suspect the most recent parts replacement and repairs.

I would guess: a failed PCM, incompatible O2 sensors, a faulty OBD-II engine sensor, or wiring issues between the PCM and the O2 sensors or other engine sensors.

“We the people are the rightful masters of both Congress and the Courts,
not to overthrow the Constitution but to overthrow the men who would pervert the Constitution” Abraham Lincoln, 1859.
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post #6 of 22 Old 10-13-2021, 04:44 PM Thread Starter
skysgt
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CJ7-Tim,

Thank you for your reply. Actually my TJ is with the dealership being worked on after having gone to 2 other mechanics that both took 2 weeks each and did not even have time to diagnose the problem.

I due admit that I am not technically capable to accurately describe the what it is I am experiencing. However, I have dropped off and gotten back my TJ multiple times from the dealership after having the computer reset at least 3 times. Each time the problem returned. 1st time took 5 days. 2nd time took 80 miles. and the last time took 20 miles before the check engine light came back on and the sputtering returned.

Respectfully,

Skysgt
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post #7 of 22 Old 10-13-2021, 04:53 PM Thread Starter
skysgt
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Jtec,

Thank you for your reply. At this point, my TJ is with the dealership. I wish I had more pertinent information to add. I can only thing of the time it took for the check engine light and the sputtering engine to return might be helpful in this discussion.

However, I admittedly know I am not technically capable to accurately describe my issue.

The dealership has reset the computer multiple times, checked the fuel pressure, and ran diagnostics indicating anything from 19 degrees off TDC to emissions. However, after reseting the computer these issues disappear from the tool and reappear when I have brought it back. (19 degrees was a one time thing)

Respectfully,

Skysgt
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post #8 of 22 Old 10-13-2021, 05:18 PM
CJ7-Tim
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It is not clear if a refurbished or used PCM was installed. Refurbished PCM's, most often bought on-line, have terrible quality control and numerous premature failure issues.

A blocked Cat converter is unlikely to be the root cause of the symptoms.

When you state the PCM was reset, I would suggest instead it was rebooted to clear the trouble codes. During a PCM reboot the memory is cleared and the computer runs the engine on factory pre-set parameters. As the engine runs, the PCM stores current operating data and likely notes the presence of the as yet unresolved defect or failure that causes the sputtering, and then the Check engine Light should turn ON.


In my opinion, Dealerships are not very good at diagnostics. The Dealership makes money replacing parts that they charge retail prices for, often based simply upon the Check Engine Light Trouble codes. They find trouble code number XYZ123, look in the book that says replace this part, and then hope it is fixed. Doing "repairs" this way does not build up technical knowledge and the critical thinking to resolve difficult issues. Most of the mechanics in the Dealership shop are trained and schooled on the current vehicles on the lot, and any old farts that used to work on TJ's are probably long gone.

Hopefully the Dealership will have more success than the previous shops.

“We the people are the rightful masters of both Congress and the Courts,
not to overthrow the Constitution but to overthrow the men who would pervert the Constitution” Abraham Lincoln, 1859.
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post #9 of 22 Old 10-13-2021, 05:31 PM
Boojo35
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Quote:
Originally Posted by skysgt View Post
PShivers,

Thank you for your reply. I just spoke with the mechanic and there hasn't been any blockage codes indicating the cat. Additionally, they were able to identify the problem does go away after the engine has been running away.

Typically, my problem exists in the morning time and it would disappear after I restarted my engine 3 times from a cold start.

But even they are stumped as to what the problem is.

Respectfully,

Skysgt
First off. There are no blockage codes for Cats. Cat codes are P0420 and P0430. These are catalyst efficiency codes. They have absolutely nothing to due with the catalyst being plugged. They are related to its oxygen storage capacity which it needs to have to convert stuff coming out the exhaust into less harmful stuff by "catalyzing" it. Plugged converters do not generally set these codes. Plugged converters are more likely to set lean/rich codes.

If you hollow out or remove a converter, you WILL set P0420 and P0430 code for sure... With it hollowed out or removed it certainly is not plugged. Just more explanation of one of the most understood codes ever.

There are basically only three things that cause your problem given that your engine truly runs smooth with no misfires up to this RPM. Does your engine run smooth or does it vibrate and feel rough? A restricted air flow system. More obvious and common is the exhaust but the intake side, air filter, etc. can matter. Next is timing. Basic ignition timing but also valve timing like as bad timing chain. The third is fuel delivery. Too rich or too lean can create havoc. Usually the condition you have is too lean like a weak fuel pump.

If you cannot fix it with a hammer then it has to be an electrical problem.
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post #10 of 22 Old 10-13-2021, 07:00 PM Thread Starter
skysgt
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Boojo35,

Thank you for your reply. My engine runs great until I hit 2500 rpm and then it turns rough. Like jerking. but there is no backfiring or bangs.
I did install a throttle body spacer over 2 years ago and did not have an issue at that time. I only mention that because you made reference to air flow intake.

I did replace the timing chain (far before needed; and i was getting a code the timing was off) Since then the computer was adjusted for the difference in engine and the installation of a refurbished PCM.

Respectfully,

Skysgt
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post #11 of 22 Old 10-13-2021, 07:07 PM Thread Starter
skysgt
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CJ7-TIM,

Thank you for your reply. As a matter of fact, I did buy the PCM online and I did have it rebooted. (Forgive my previous choose of wording to describe the issue)

I'm just at my wits end because this is my only driver. I was hoping others may have experienced this same problem. I wish I had more information to provide.

Respectfully,

Skysgt
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post #12 of 22 Old 10-14-2021, 04:49 AM
CJ7-Tim
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Refurbished PCM's, most often bought on-line, have terrible quality control and numerous premature failure issues. I would suspect the PCM and consider a used replacement rather then a refurbished unit.

“We the people are the rightful masters of both Congress and the Courts,
not to overthrow the Constitution but to overthrow the men who would pervert the Constitution” Abraham Lincoln, 1859.
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post #13 of 22 Old 10-14-2021, 07:04 AM
jtec
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As I posted above something seams missing-

Other than a TB spacer what other modifications are there? ANYTHING?
Jeep is at an authorized jeep dealer?
Did you change the PCM to address this issue - do you still have original PCM?

Running into an RPM limit - I would think fuel delivery, Restricted exhaust, Then looking at scanner ANY codes, freeze frame, pending, history and live data. All that should be SOP for a dealer tech.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #14 of 22 Old 10-14-2021, 08:11 AM Thread Starter
skysgt
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Jtec,

Yes my TJ is at a Jeep Dealership. I do have the original PCM and I am being told the problem exists there too.

I did add a solenoid for the 2 battery operation, however, after connecting the 2 batteries, my TJ cut off while driving the very next day. I was told I blew the original PCM when I took it to my 1st mechanic. But the Jeep dealership told me they installed it just to see what it would do and it also sputters at 2500 rpm. I have mounted an ARB compressor in the engine bay but have not connected it to power. Those are the only modifications that I can think off. Everything else is mechanical; lift, limited slip, etc...

I bought my new/used PCM from flagship one.

The Jeep Dealership thought it was the fuel pump as well. But I replaced that after my 2nd trip to the Jeep Dealership and since then, they have told me the fuel pressure is good to go.

I have not done anything with the exhaust because there has been no need until this point. (no leaks, noises, or holes) But it is 15 years old and I should seriously think about it. But I have been told by the dealership the cat is not blocked.

Thanks and I do appreciate your help.

Respectfully,

Skysgt
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post #15 of 22 Old 10-14-2021, 09:03 AM
ltklein
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2005 LJ checking in..


FS1 has a 1.68 review out of 5 on the sites I looked up. I ordered from them twice and both times they cancelled. First time was due to a bad zip code I typed in - my bad. They couldn't correct it to ship...they cancelled my order. Reordered and went to the back of the line. Cancelled again because the unit they pulled

couldn't be programmed due to a security mismatch. Got a refund. That part was not issue.


That's when I went to look at reviews and see large issues with the rebuilds. The 2005/2006 PCM is a different animal than any others. Rebuilding is really a matter of resoldering and cleaning connections. Possibly replacing the voltage regulator chip. I haven't seen any info from others saying differently. They're hard to work on, hard to troubleshoot and hard to replace components in.
...Of course they say they test them. But really - if the computer had an intermittent issue - do we really believe they run the testing as long as it takes for the things to throw a code? Years ago I had the "all O2 sensors are bad" issue. It would come up every 3 or 4 days. Really can't expect they test these things for 4 days to catch things like that. Imagine if I sent that in as a core...they rebuild it and send it to you...



Fast forward to today. I replaced my PCM with a WranglerFix PCM just last week. Very spendy for the manual transmission version. I only have 100 miles on it but it's not a rebuild. It's a new unit that IS NOT the original computer. It's a different Jeep computer with the proper code loaded. The expectation is it doesn't have the issues of the original.


Issues it was designed to fix are O2 sensor issues and Transmission Shifting issues.



It physically fits perfectly and installed in about 10 minutes... Obviously I can't speak to longevity but this is my Jeeps third computer and I wanted to try something that may be more reliable.



The reviews from others seem to be fantastic.


Downside - the dealership cannot program these units. They will show proper error codes and operate like the original but the actual software can't be manipulated like the original


I still have my latest original as a spare. Turns out the PCM wasn't my issue so I have a good spare.


Last note - you can buy brand new computers online if you have someone who will put the code on it. Dealers generally won't unless they sell them to you.


My dealer procured computer cost me $1300 a couple years back. The blank computer is $499 from various online Mopar source.


Autozone also has even cheaper rebuilds. They were out of stock for mine. Same potential issues with a rebuild but easier to take it back to the counter and say it's no good.


This all assumes it's the PCM.


My latest issue turns out to be the wiring harness...
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