Intermittent Limp Mode

captaincrd · **Posted:** Thu Feb 23, 2012 2:46 am

I drove over 400 miles to day and my CRD went into limp mode 3 times. Each time I was driving on the highway, it went into limp mode and I had to pull over. I turned off the motor and restarted and everything went back to normal each time. It was probably about 100 miles between each account. I just got home and check for codes but there are none. Anyone have any idea what it might be?

racertracer · **Posted:** Thu Feb 23, 2012 3:06 am

captaincrd wrote:

I drove over 400 miles to day and my CRD went into limp mode 3 times. Each time I was driving on the highway, it went into limp mode and I had to pull over. I turned off the motor and restarted and everything went back to normal each time. It was probably about 100 miles between each account. I just got home and check for codes but there are none. Anyone have any idea what it might be?

Most likely a clogged fuel filter, replace the filter and your troubles should be gone.

Make sure that when you remove the old filter, to also locate and remove the old rubber gasket that tends to remain stuck at the top of the threaded rod and get lots of air in the filter head because it is hard to see, so feel for it.

One of the main causes of air in the fuel lines is that little un-noticed round black rubber gasket left in there.

geordi · **Posted:** Thu Feb 23, 2012 3:26 am

Also check on the wiring of your two airbox hoses - If the wires are bent at the plug and break internally, they might have intermittent contact which will translate to the computer as garbage readings. Sometimes not enough to toss a code, but the computer will STILL magically manage to throw you into limp mode.

I think the programming should be changed that limp mode is completely disallowed from happening, UNLESS a code is stored alongside it. This phantom limp mode nonsense is really annoying.

mikey1273 · **Posted:** Thu Feb 23, 2012 10:29 am

even I get phantom limb mode every 6 - 9 months so it seems mine happened just last week and I can't say why. It was on the morning drive to work I was almost there and it started to loose power then idle funny at the last traffic light. I got to the parking lot shut it off and restarted it a twice and it was fine again..... has been since.

I checked the fuel primer and it pressed nice and firm not weak like air might be in there. so IDK what the issue was but it doesn't do it often enough ( thankfully) that I can try much to figure it out.

captaincrd · **Posted:** Thu Feb 23, 2012 1:56 pm

I changed the fuel filter about 1800 miles ago so I don't think it is plugged. I went out this morning and pumped the plunger on the fuel head and it was soft. I had to pump it 3 or 4 times until it firmed up. Is this normal or is it an indication that I have air the system. I think I will bleed it today and see if that solves the problem. We I did the filter change I was conscious to no double gasket so I don't think that is the issue. In the past I have always pre filled the fuel filter with diesel but this time I just hooked up a line to the bleeder and pumped until it was flowing without air so maybe I didn't get it all.

papaindigo · **Posted:** Thu Feb 23, 2012 3:14 pm

Maybe but the only way to tell is to actually bleed, see Sam's NOOB guide video for how although I too am a fan of hooking up a vinyl tube to the bleeder then to a catch bottle so I can see things. Even if you got all the air more can creep into the system thru the fuel line quick disconnects or a burned fuel heater element on the filter head.

Watch all the way to the end of that video then check to see if you have a 1s or 2n gen fuel head. If 1s gen then at minimum pull the heater element plug and if there is even a hint of diesel replace the assembly which by the way comes with a new filter and WIF installed.

captaincrd · **Posted:** Wed Feb 29, 2012 1:17 am

Thanks for all your help. I bleed the fuel head and there was lots of air. No limp more for the last 300 miles.

BlackLibertyCRD · **Posted:** Wed Feb 29, 2012 1:35 am

captaincrd wrote:

Thanks for all your help. I bleed the fuel head and there was lots of air. No limp more for the last 300 miles.

A lift pump will keep it air free. I had the same problem many time before the lift pump, no more afterwards.

Tulmaster · **Posted:** Thu Apr 26, 2012 11:10 pm

Is limp mode an official term and function or is it a slang term for running poorly with no power?

Mark

05 sport with crd

geordi · **Posted:** Fri Apr 27, 2012 12:37 am

Official term and official function of the computer, hopefully followed with / concurrent with storing of a code that would help determine WHY it limp modes.

Limp mode limits top speed to 70mph, greatly reduces power and limits turbo boost pressure to about 5psi. Shift points may also feel extended (higher RPM before shift) because the torque is so reduced. Even GETTING to 70mph takes forever, so in reality, you are more limited to about 45 in normal traffic.

This is different from the slang term of "just running like crud." which happens all the time for varieties of reasons.

Tulmaster · **Posted:** Fri Apr 27, 2012 10:28 am

Hmmm, Thanks for the info geordi! Sounds exactly like my problem and that would perhaps explain the low turbo boost code. I am down to pulling and checking for obstructions in the exhaust and doing a function check and easy of clean of the turbo, but still looking.

Mark

05 2.8 crd sport

papaindigo · **Posted:** Fri Apr 27, 2012 11:59 am

Tulmaster - pardon me if you have already done this but the most common cause for a low boost code and poor running is a "leaky" OEM turbo>intercooler>engine hose due to long term soaking in oil from the CCV. If those hoses have a woven sleeve covering and are oilly to the touch you need to pull them and check the bottoms for leaks/cracks/tears and if totally oil soaked replace with Samcos. The 2 most common cause is a bad boost pressure soleniod on the vacuum tank (the odd vertical plastic thing with hoses connected to in between the air box and the firewall. If you shot me an email I can send you a how to on checking the solenoid function. After that you may have sticky turbo variable vanes, again there is a simple check I can send you.

Exhaust system clog is unlikely but not impossible.

Tulmaster · **Posted:** Thu May 10, 2012 5:01 pm

Update, Well it is still going to limp mode after a about 3 +- miles of warm up. I checked the vacuum lines around the turbo and all seem to be fine and the vacuum operated vane rod on the turbo moves freely as checked at idle. It moves about 1/2 in or more when the vacuum line is attached and removed.

On searching through my manuals I was only able to find one reference to the limp-on mode. It said that when the ECM detects a problem with the Throttle position sensor it will limit the rpm of the engine to 1100 rpm. I find no other ref about when the ECM might cause a limp mode. So I understand the throttle pedal is the wire resistor, but have no idea how to go about testing it properly or even where to find the connectors. any suggestions on how to test the TPS?

Thanks

kissfan79 · **Posted:** Thu May 10, 2012 6:44 pm

Ok.....not to sound stupid....but what exactly happens when it goes into limp mode? Do you just notice a sudden loss of power or does the Jeep actually do something or make any sounds to indicate that it has gone into limp mode?

Jim

Randy B · **Posted:** Thu May 10, 2012 7:20 pm

kissfan79 wrote:

Ok.....not to sound stupid....but what exactly happens when it goes into limp mode? Do you just notice a sudden loss of power or does the Jeep actually do something or make any sounds to indicate that it has gone into limp mode?

Jim

Most of the time just loss of power, sometimes the check engine light will turn on, and store a code

Joe Romas · **Posted:** Mon May 14, 2012 8:45 am

Mine has never gone into limp mode but I believe another symptom is it shifts out of over drive into 3rd no matter what your road speed is:furious:
Both 4th and 5th are overdrive ratios :mrgreen:

Having a scan guage or other type of scanner hooked up has also been know to cause it :dead:

bugnout · **Posted:** Mon May 14, 2012 9:36 am

Joe Romas wrote:

Mine has never gone into limp mode but I believe another symptom is it shifts out of over drive into 3rd no matter what your road speed is:furious:
Both 4th and 5th are overdrive ratios :mrgreen:

Having a scan guage or other type of scanner hooked up has also been know to cause it :dead:

Thats happened to me a number of times when I've had the Scangauge connected, I don't think its a function of limp mode, rather bus resetting because communication between the ECM and TCM is lost. Always fun when this happens.

Intermittent Limp Mode

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