P0093 causing Limp mode

Tulmaster · **Posted:** Sat May 12, 2012 10:53 pm

This has been a continuing problem so will try to bring everyone up to date. First, I have posted similar problems on other threads and wanted to start a new one Not only because of the new symptoms but because I did not wish to pollute another members problem thread.

Okay for back ground this problem has been going on for months and has progressively become more frequent. What I thought at first to have been bad filters, I see now was simply a recovery time and the jeep ran fine for a while. As time passed the time between problems became less and less until it was continuous. Original codes were P0093, P0299 and P0401 and another one which has never returned. the 401 and 299 referenced the turbo boost and EGR. I performed the normal checks indicated in Lost jeeps and removed CAC hoses for inspection, clean MAP an other sensors. I replaced the fuel filter head and added a electric lift pump. Installed a clear fuel line to inspect for possible air in the fuel. I inspected the operation of the air flow valve and everything is operating as should be. I operated the system with the MAF unplugged and it made no difference. I also checked the vacuum lines behind the turbo and the turbo vanes all seem to be operating as they should. I unplugged all connections several times on the sensors and ECU that I new of and could find, worked them and reconnected....

The only thing that is different is that before I replaced the EGR I did not get a P0093 except rarely when I was working on the fuel filter head area. Now, since I replaced the EGR, no matter what I have tried, I continually get a P0093 code and no others unless it was due to something I did, like the MAF sensor being unplugged. Obviously there is no air in the fuel lines at this time.

Operation is: Always starts fine. Drive for 3-4 miles acting normal and accelerates as would expect even under heavy load. Then suddenly, goes into limp mode. If you accelerate to heavily engine dies but will restart normally right away. Engine will always die if you apply to much throttle. Runs normal again when cold until it warms up as before and the cycle starts over again

So the bottom line seems to be, that everything is working as it is supposed to except that a sensor is malfunctioning when hot. Problem is which one... Now the question is, which sensors or?,,, can continually set a P0093 code to send the engine into limp mode?

While I have read similar problems being cured by replacing the cam sensor, I think pulling it and bench testing it may be my next step,,, cam sensor perhaps,,,,,but will these sensors cause a P0093 and Limp mode?

Thanks guys for all the help in the past as well as upcoming future.

Mark
05 2.8 crd sport,,,,stock, except for the fuel filter head 80K miles

Silver and....Oh that has got to be the problem the color!!!! :5SHOTS:

Tulmaster · **Posted:** Sat May 12, 2012 10:57 pm

opps am I bad,,,,I meant to say,,,cam AND Crank sensors, above!

Mark

papaindigo · **Posted:** Sun May 13, 2012 8:20 am

I know you have an 05 but the 05 FSM does not have diagnostic codes and the 05 diagnostic manuals I have in PDF also lack that code. Looking at the 06 FSM P0093 shows as FUEL RAIL PRESSURE MALFUNCTION POSITIVE PRESSURE DEVIATION and points to a possible problem with the fuel pressure or quantity solenoids wherever they are; see text beginning on pg. 9-737.

I offer for what it is or is not worth.

Joe Romas · **Posted:** Mon May 14, 2012 8:13 am

I know you have a 05 so take this with a grain of salt :juggle:

On the 06 models the fuel filter is raised slightly to clear the larger ABS unit for traction control and the large wiring harness running behind the filter head's bracket is no longer in the rolled over edge of the bracket and it can get chaffed hitting the sharp edge of the filter bracket. This has caused intermittent weird problems for some :furious:

Tulmaster · **Posted:** Wed May 16, 2012 10:34 am

Papaindingo, Thanks for the info. I have the FSM for the 05 and downloaded the 06 and other info from a web link here a few days ago so will do some more research as that sounds like a place to continue looking. All of my lists of code definitions simply indicate it to be a Large fuel leak (P0093) but what ever it is seems to be heat related. I'm so busy that I can only devote time to it seldom right now and so it sits in the drive for the most part. I can putt around town as long as the trips are short and I don't get heavy footed. Will continue to keep you guys posted.

I will also check the wiring behind the fuel filter just to be on the safe side. If there is a plug in the area under the filter perhaps some spilled fuel has caused a poor connection after changing filters.

Mark

05 crd sport, stock except for replaced filter head and electric lift pump.

Tony P. · **Posted:** Wed May 16, 2012 9:40 pm

viewtopic.php?f=65&t=40074
DTC's for the KJ

ChooChooman74 · **Posted:** Sat May 26, 2012 11:52 am

I was having the same issue. My problem was the line coming from my lift pump got kinked and was not providing enough fuel at WOT. Quick fix and no more code P0093.

Sent from my DROID BIONIC using Tapatalk 2

Tulmaster · **Posted:** Tue May 29, 2012 3:28 pm

Hi, just an update as I have not had much time to actually work on the problem. I have done a lot of reading and thinking on the issue and over the weekend I ran the checks on the Fuel pressure Sensor, Fuel pressure solenoid (aka: POV)which are located in the fuel rail and the Fuel Quantity Solenoid (aka: MPROP?) located on the CP3 pump. I prefer to address the parts by the name given them in the Jeep manuals although there seems to be many names out there in the real world.

Anyway, I ran the checks cold, and then warmed up real good and all checks were within ranges specified. Interesting that the last step in P0093 check indicated that if everything checked yes, then replace the Fuel Quantity Solenoid (FQS) and if not the replace the ECM. I have not as yet resigned to do that as in one test procedure the manual says to replace the fuel pressure solenoid and if problem still exists to replace the fuel pressure sensor, and if problem still exists to replace the fqs (talk about using a shotgun)

However I am leaning strongly at the FQS as the symptoms fit the problems caused by a faulty FQS more so than with the FPS running a close second. The FQS seems to fail more because it is first in line to suffer problems related to water and other contaminates in the fuel system. I found the below comment by one tech on Justanswer as to what exactly happens when the FQS or MPROP valve starts to stick and why.

" Hi, You could have a sticking MPROP, they are very susceptible to scoring, this makes the MPROP unresponsive at first, because it requires more current to move it than the ECM tables deliver, eventually it may stick fast in a position, or it may live.
Your symptom is typical of a sticking MPROP, as the load comes off the engine, the ECM commands a reduced fuel flow (pressure) by closing down the MPROP to a predetermined position, however the sticking MPROP is too slow to respond, the ECM does not see the pressure drop quick enough and closes the MPROP even further, suddenly the MPROP moves and closes too far, you may get a stall or just a low pressure fault code. The Cummins (Bosch) CP3 pumps have replaceable MPROP's, I do not know about the pump fitted to your MAN engine, but you could try swapping from another pump (same part number) that has failed for a different reason, or try a Bosch dealer.
Not all MPROP's are the same, they are graded (same part number) for fuel flow, and different part numbers have different flow rates.
They are very easy to replace, just 3 Torx head capscrews.

Read more: MPROP VALVE - JustAnswer http://www.justanswer.com/heavy-equipme ... z1wHoTyizQ

After reading this, I am thinking just the opposite would be true also, if when load increases and the valve sticks there would less fuel pressure than the ecm wants thus it would ask for more and not getting it would then stall or go into limp mode and register a low pressure code. I am still researching but at this point if I have to start replacing parts I would start with the FQS. So does anyone know what that part number is for the FQS, who makes it and where I can get one?

On another subject I went to napa today looking for info on Glow plugs. They could not find any for the 2.8 and called Bosch who indicated they no longer make the glow plugs for the 2.8 crd. Can anyone give me a recommendation as to what brand of glow plug would be best and the part number for it. I would prefer ones that are not ceramic.

Thanks all.

Mark
05 liberty Sport, custom filter head and lift pump

Tulmaster · **Posted:** Tue May 29, 2012 11:14 pm

Disregard the request for glow plug info as I found several threads indicating the part numbers etc. thanks

Tulmaster · **Posted:** Sun Jun 03, 2012 7:11 pm

Okay then, after careful consideration I decided to replace the Fuel Quantity Solenoid, also called the MPROP. I spent most of the morning and afternoon on Sun. changing it out. Thanks to Keith at GDE he was able to supply me with the part at a price more than 25 percent less than Oregon Fuel injection of $215. His shipping was prompt and after ordering the $150 part on Wed I received it on Friday. A tip, if you drop parts or bolts they seem to fall into the skid plate and are lost forever unless you want to pull it off 1st. I would recommend that anyone wishing to replace this part pre order a couple extra 5mmX80 T-25 headed bolts as replacements so you are not stuck with a delay.

Anyway long story short I got the part replaced. I took it for a test drive, and it started normally with out problems. I drove it and at about the same mileage of 4 and five minutes drive time in 55 degree weather, it died under a load as I started up a hill. Restarted fine after kicking it into neutral. However this time, it ran really rough, with no power. Made it the 3 plus miles home at 40 mph tops with no power and running rough. Pulled the code when I got to the house, had 2. P0093 same as before and also a new one P0300 which after checking is for a missfire. So at this point I am hoping that, given the valve that was replaced is in the fuel injection pump, there was an air bubble (no fuel lines were removed) and is just taking some time to be purged through the system. If the P0093 code is still persistent then the next part to replace would be the Fuel pressure solenoid located at the end of the fuel rail. Comments and suggestions are welcome. Oh, and my experience with other types of injectors is that they are hard to bleed air from them without cracking the fuel line at the injector itself. Is it the same with these electronic controlled injectors?

Mark

Tulmaster · **Posted:** Sun Jun 03, 2012 7:40 pm

Additionally, While doing my research I have come across a number of excellent deals for some parts. like ocanee CAC hoses at $90 a pr. and other items like filter heads etc. Is there a more appropriate place to post this kind of info other than here on this thread?

racertracer · **Posted:** Sun Jun 03, 2012 9:57 pm

Tulmaster wrote:

Additionally, While doing my research I have come across a number of excellent deals for some parts. like ocanee CAC hoses at $90 a pr. and other items like filter heads etc. Is there a more appropriate place to post this kind of info other than here on this thread?

Now that you sparked some interest, why not post it here and there.

Gabe Watt · **Posted:** Tue Jun 05, 2012 4:22 pm

Tulmaster wrote:

Okay then, after careful consideration I decided to replace the Fuel Quantity Solenoid, also called the MPROP. I spent most of the morning and afternoon on Sun. changing it out. Thanks to Keith at GDE he was able to supply me with the part at a price more than 25 percent less than Oregon Fuel injection of $215. His shipping was prompt and after ordering the $150 part on Wed I received it on Friday. A tip, if you drop parts or bolts they seem to fall into the skid plate and are lost forever unless you want to pull it off 1st. I would recommend that anyone wishing to replace this part pre order a couple extra 5mmX80 T-25 headed bolts as replacements so you are not stuck with a delay.

You got a part number for the MPROP?

Tulmaster · **Posted:** Tue Jun 05, 2012 7:32 pm

Okay after a couple days and several cold starts the problem has remained the same as original. The rough running initially on the first failure after the part was replaced was apparently an air bubble going through the system as it occurred only the one time. After that it just continues to go into limp mode after about 5 min and 4 miles driving.

The part number for the Fuel Quantity Solenoid (MPROP) is :

Fuel Pressure Control Valve installs into high pressure pump, fits 2005, 2006 Jeep Liberty 5159962AA.

Still trying to solve the problem of the P0093 so it appears the next step is the fuel pressure solenoid aka: pressure control valve located on the end of the fuel rail. anyone know any more details as to how it operates, in addition to the information available in the repair manual?

Thanks, Mark

Tulmaster · **Posted:** Mon Jun 11, 2012 6:06 pm

Well hello again. To bring you up to date, I replaced the Fuel Control Solenoid, aka the Pressure control valve, mounted on the end of the fuel rail. I removed the rail from the engine, mounted it in a vice using a couple blocks of wood for cushion and removed the valve. After finding the rail rather, shall we say unsanitary, I got out my gun cleaning supply's and used a small .22 brush on the fitting areas and a 12 gauge shotgun brush in the PCV area and pushed through to clean the interior of the rail. I removed the pressure sensor and cleaned the opening with brake clean and flushed the rail with the same. blowing air through each to dry and installed the new PCV after coating it with a silicone spray lube. I tightened as indicated in the manual and reassembled the fuel rail. So after 2 days and several cold starts, no change. Problem still the same, after 5 min warm up it goes to limp mode and sets a P0093 code.

Back to doing more research.... Hoping for some suggestions as to what to look at next. if the P0093 indicates low pressure, I think I am down to a faulty pressure sensor or ECM but they both test good both cold and hot?

Mark

BikeHeritage · **Joined:** Mon Jun 11, 2012 7:20 pm **Posts:** 2

Hello,

First post but with the same problem you are having less the P0093 DTC. Only once in the last month has the P0093 DTC illuminated the MIL.

So far I have replaced the filter head with the new style due to some weeping of fuel I noticed from the connector. Performance improved but only marginally. After this did not correct the fault, I took it to the dealer and the dealer decided to replace the Pressure Control Valve on the fuel rail with no change in performance. The dealer was nice enough not to charge me for a vehicle they could not fix, but the diesel tech wouldn't even listen to me or my suggestions so now I have the vehicle back at the house.

I hope to have the time this weekend to do further diagnostics but this problem has me (and the dealer) stumped. I plan on starting from ground zero, MAP, MAF ORM...etc. and will let you know how I make out. Not really prepared to give up just yet but it's getting close.

Eric

Joe Romas · **Posted:** Mon Jun 11, 2012 8:01 pm

BikeHeritage wrote:

Hello,

First post but with the same problem you are having less the P0093 DTC. Only once in the last month has the P0093 DTC illuminated the MIL.

So far I have replaced the filter head with the new style due to some weeping of fuel I noticed from the connector. Performance improved but only marginally. After this did not correct the fault, I took it to the dealer and the dealer decided to replace the Pressure Control Valve on the fuel rail with no change in performance. The dealer was nice enough not to charge me for a vehicle they could not fix, but the diesel tech wouldn't even listen to me or my suggestions so now I have the vehicle back at the house.

I hope to have the time this weekend to do further diagnostics but this problem has me (and the dealer) stumped. I plan on starting from ground zero, MAP, MAF ORM...etc. and will let you know how I make out. Not really prepared to give up just yet but it's getting close.

Eric

Have you checked the pump on the fuel head for being firm when the problems occures? Neither you or the OP mentioned fuel lines at the tank and or lift pump.

The new style filter head is not the holy grail some think but just the victim . Some view the plug melting is because of it's full of air causing it to overheat.

Check the plunger for being hard when your CRD acts up.

BikeHeritage · **Joined:** Mon Jun 11, 2012 7:20 pm **Posts:** 2

Joe Romas wrote:

BikeHeritage wrote:

Have you checked the pump on the fuel head for being firm when the problems occures? Neither you or the OP mentioned fuel lines at the tank and or lift pump.

The new style filter head is not the holy grail some think but just the victim . Some view the plug melting is because of it's full of air causing it to overheat.

Check the plunger for being hard when your CRD acts up.

Hello and thanks for the reply.

Yes, I checked the fuel lines and there are no visible leaks or damage. I assume when you say plunger you are meaning the primer pump on the side of the fuel head? After a couple of days of sitting the primer pump takes about three pumps to firm it up. I can crack the bleeder screw and drain some residual air. Once the vehicle starts and runs, the primer stays firm even during the stalling conditions. I only replaced the filter head due to the small leak where the connector seats. I have no lift pump in the vehicle at the tank but i do believe his first post said he installed one. I will have to go back and read.

Eric

Billwill · **Posted:** Thu Jun 14, 2012 5:58 am

Tulmaster wrote:

Well hello again. To bring you up to date, I replaced the Fuel Control Solenoid, aka the Pressure control valve, mounted on the end of the fuel rail. I removed the rail from the engine, mounted it in a vice using a couple blocks of wood for cushion and removed the valve. After finding the rail rather, shall we say unsanitary, I got out my gun cleaning supply's and used a small .22 brush on the fitting areas and a 12 gauge shotgun brush in the PCV area and pushed through to clean the interior of the rail. I removed the pressure sensor and cleaned the opening with brake clean and flushed the rail with the same. blowing air through each to dry and installed the new PCV after coating it with a silicone spray lube. I tightened as indicated in the manual and reassembled the fuel rail. So after 2 days and several cold starts, no change. Problem still the same, after 5 min warm up it goes to limp mode and sets a P0093 code.

Back to doing more research.... Hoping for some suggestions as to what to look at next. if the P0093 indicates low pressure, I think I am down to a faulty pressure sensor or ECM but they both test good both cold and hot?

Mark

The code of P0093 means fuel pressure is too high according to the 2006 FSM

I have had several wiring problems on my 2002 CRD with wires either shorting to ground or shorting through to some other random wire in the same harness.

If I was you I would temporalily totaly disconnect at both ends the two wires going to the Fuel Quantity Solenoid.
According to the 2006 circuit diagrams that means the Brown/Yellow and Brown/Light green wires.
Cut the wires off at the ECM and at the connector to the solenoid...you can solder them back together later and insulate with shrink tubing.

Now run two new wires between the ECM and the solenoid....do not get them crossed over...and see how things go.

I also see that you have fitted an electric lift pump....is this not pumping too strong? have you tried bypassing the lift pump?

Edit to add: I see that you tested the Fuel Pressure Sensor located halfway along the rail and were thinking of replacing it.

If you have not replaced the Fuel Pressure Sensor yet then I would suggest that you do this first before any other action.

Tulmaster · **Posted:** Thu Jun 14, 2012 12:11 pm

Yes, replacing the Pressure Sensor seems like the next reasonable step, but I want to do some testing on it again before I do. In the motor both cold then hot and then out of the motor on a bench, both hot and cold. I think that would be prudent.

Billwill, I guess I am lost as to why you suggest cutting the wires as you can check for opens and shorted wires in that circuit by pulling the plug off the ECM and use a test meter between the two ends of that circuit while it is then isolated. The pressure gauge I installed in the fuel filter head indicates a steady 8psi on the 10 psi rated pump. When needed the air is bleed through a radiator petcock mounted at the outlet connection.

Mark

P0093 causing Limp mode

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