WJ CRD Full Throttle/Load Cut Out

[OceanWanderer]

Hello All!

This is a re-post of my original post on 4x4Community (http://4x4community.co.za/forum/showthread.php?t=119922), Fillistyn and LuckyLuke have been very helpful, but I thought I would post here as well as I got such a great response from previous post!

Basically I am looking for some general advice/starting points on this one. I have the high output 2.7 (150kw) engine in my WJ/G 2004 Grand Cherokee with 142000kms. Shortly after buying the following four errors appeared:
P0349 - Camshaft position sensor (sensor replaced, problem solved)
P0700 - General Transmission Control Module (Could be anything most likely a service is required as it changes very nicely, doing that this weekend)
P0539 - Odd one this as it is a cruise control error?!? But the cruise works perfectly
And lastly the problem code that is stumping me:
P1130 - Fuel Rail Pressure

The high pressure diesel pump has been overhauled twice (first time R10000 @ 130000kms & second time just before I bought R4200 @ 142000 to cure a no start problem [I think this was actually the cam shaft position sensor])

Right, so on to the problem, if you drive on a flat or downhill section and use 100% throttle the motor flies! Likewise if cruising at 120km/h with or without the cruise control no problems are encountered (up to half/three quarter throttle) up or down hill. I have only been able to try this in first, second and third but if you floor the throttle on a steepish hill the engine cuts out almost immediately anywhere between 2500-3000rpm, the engine stalls and the MIL light comes on. Placing the transmission in neutral and restarting the engine returns the car back to "normal" operation. Sometimes the MIL burns other times not.

I am changing the fuel filter this weekend as it looks like a Chinese knock off (non Mopar nor Mercedes [Mercedes filter being installed [last changed at 90000kms] although the price would suggest otherwise). I will also try to do a home made leak test as I have read that if an injector is worn/damaged/stuck open the leak back to the tank is excessive thus dropping the pressure causing the fuel rail sensor to throw an error.

So my question is assuming the diesel filter doesn't do the trick where do I start checking from there? The system is actually incredibly simple with very few items to go wrong but from what I understand the error basically means that not enough fuel pressure is being built up in the rail hence shut down. I will also be checking out the three plastic pipes as I have read that a common fault is that the rubbers in the pipes perish causing air to leak but not diesel out!?! Another note is that the high pressure pump is very dry and there are no signs of leakage. The last thing I can think of that may be relevant that much like Fillistyn when I took ownership (last weekend) the town consumption was 16l/100km if I reset the computer while doing a steady 120km/h and let the cruise do the work the computer recorded consumption of 6.5l/100km. I was of course driving reasonably efficiently. After driving around for a while (50/50 free way & town) the consumption has settled at 11.5 but this is with a very light foot so not as to invoke a stall.

Ok I think that is all, oh yes on day two of ownership I did a full oil filter and air change. The engine has no clacks or clicks sounds great when I can get it on song, there is no smoke, which after owning a Ford is a bit weird!

Finally, my thoughts are that the diesel filter may at a long shot be the problem, second in line could be those plastic pipes, third the fuel rail pressure sensor, depending on the leak back test a dud injector(s) and finally the only thing that is left is to buy a new high pressure pump, estimated at R10-R12k

Please feel free to post your thoughts, I love this Jeep and desperately want to start enjoying it! Itching to take it off road!

Cheers

David

Update: Other things I have tried:
I can rev freely at 100% throttle with no hesitation cut out etc
I can go up and down hills with no problem as long as I dont floor the throttle
If I use the manual option I can get the revs well past 3000 rpm again using no more than 50/60% throttle

Any advice would greatly appreciated!

[Macca2801]

Just a few quickies fix the fault codes, you can't carry out diagnostics on certain systems while itnoring other active codes. You may find the engine response to one code is causing symptoms you are trying to fix.
Definately replace the fuel filter, this rules out a flow problem at high load as you are describing. But as I said earlier the cutting out at load may be the ECM protection because of other codes!!
Have you actually fixed the fault for low rail pressure? Is it a fault or just a rail pressure sensor failure and the pump is just running at a safe reduced pressure (limp).
Your transmission fault can be causing the engine power issues, ie the engine cuts the power due to fault in the transmission control module. Again sort this and you may lose the engine faults.
Have you had a scanner on the vehicle and checked the sensor readings? Check the rail pressure and I would also be looking at the map sensor. It may be clogged with blowby soot and the engine isn't getting a rise in boost pressure at load and again cuts power for engine protection.
Mainly this is going to take a methodical process of elimination to sort not just ripping and replace guesswork. Otherwise you spend a fortune, hate the vehicle And still never find the problem.
Goodluck
Matt

[fester]

I'd be with Matt on some of this. The transmission fault could be at the heart of it so you need the TCM read to determine the exact fault. Secondly given there is a fuel rail presure indicator I'd be looking to eliminate the actual pressure sensor straight up. I guess the filter is cheapish but I'd be finding somewhere how to test the actual fuel rail pressure. No point sneaking up behind it, hit the main culprit head on and work back from there. It would be false economy to replace the filter, orings and fuel lines only to find the sensor stuffed. It may be cheaper to go to a dealer or service centre that can read this engine properly and get them to at least reset codes and check rail pressure and then let you trouble shoot from there.

[bodgie]

I've seen a mil light come on in my WJ when I first bought it (150k) and was having a play in some sand dunes. One of the error codes I was seeing was fuel pressure related, from memory the fuel pressure wouldn't rise to what the computer wanted.

After pulling the injectors and having them tested I found one was faulty, leaky I believe. I've since replaced this injector and have not seen the issue again. A leakiest will help identify if this is a possible issue for you, might pay to invest in a kit to do this.

HTH,

Jason

[OceanWanderer]

Thanks Everybody, some great advice!

Originally I did try to get a code reader reset tool and do exactly what you all suggested, unfortunately it would appear for the CRD this is just not going to happen. I have made contact with a mechanic who specialises in Jeep and was recommended by a friend who trusts him, I will be going to see him next Saturday.

I understand what everybody is saying regarding the the approach to the problem, however, my thinking in terms of the transmission and diesel filter service is that I was going to do them anyway and there was an outside chance it may solve the problem, likewise doing a leak, wont take much to do and can be done quite easily and cheaply.

Once again thank you all for your advice, awesome forum! I will update this post as I go along!

Cheers

David

[OceanWanderer]

Hello All!

I think I have just had a very lucky escape! Pretty sure it was the diesel filter that was the problem (replaced this morning) but now the Jeep drives like a train and the problem is gone! Also serviced the transmission today so could have been that as well - the oild was darker than new fluid, smelt a bit odd but not really burnt, tranny filter had done its job and was very dirty! Not sure if it is my imagination but the car revs more freely (probably just using more throttle now!

Once again thank you for all of your help & patience, hopefully, one day I will be able to return the favour.

Cheers

David

[alfaitalia]

Originally Posted by OceanWanderer

Hello All!

I think I have just had a very lucky escape! Pretty sure it was the diesel filter that was the problem (replaced this morning) but now the Jeep drives like a train and the problem is gone! Also serviced the transmission today so could have been that as well - the oild was darker than new fluid, smelt a bit odd but not really burnt, tranny filter had done its job and was very dirty! Not sure if it is my imagination but the car revs more freely (probably just using more throttle now!

Once again thank you for all of your help & patience, hopefully, one day I will be able to return the favour.

Cheers

David

Great news. I hope that was you problem........however I had exactly the same problem and when I replaced the filter my prob also went away.....for about two weeks then it came back. Turned out to be the low pressure pump. Replaced it and never had the prob since. It was unable to supply enough fuel to the high pressure pump at full throttle which course the low rail pressure fault code P1130. It was much worse at starting in the cold (below frezzing) weather too due to the thicker fuel. I actually caused the prob by cranking it over for to long with no diesel in after I had replaced some o rings. According to a mate who works with Jeeps, just one or two minute of dry cranking will damage the low pressure pump. Serves me right for being lazy and not bleeding it properly!