Good day dear friends.

Ive been reading posts on this forum occasionally. Now it is time to get some advises.

Short about myself

Oilfield engineer/adviser. But more to that mechanic, electronics engineer, and huge fan of building designing manufacturing of equipment. DO NOT take is as add, but I have instagram page where I posted all the repairs, modifications. Amateur page, but well deeply engineered. FOR THOSE who can learn/take away here it is : unicapro (you will see black JK on top of volcano)

My rig: (2nd) 2008 JKU CRD 2.8 Turbo manual. VM motori. Same as on Liberty, Voyager, etc

My 1st rig, 2009 JK CRD 2.8 Auto. ZERO issues up to 167k miles. Still runs perfect.


Decided to change to 4 door. Deliberately bought problematic vehicle from my friend, who got tired at mechanics for 7 month of resultless pain. So here we go.

The car does not have power. RPMs go up to 3, 3.5k in neutral. While driving, if no load, it slowly goes up to 2.5 3k. But no power at all when loaded. Basically feels like driving 2.0 liter atmospheric diesel


Issues I have and steps/repairs I have done at my backyard so far:

The car had difficulties to start. Low rail pressure was indicated by scanner.

1) removed CP 3 pump. Test run on CRD computerised bench. Verdict: Pump is in perfect condition. Full 2000 bar pressure. All parameters are within spec. Like brand new.

2) Fuel injectors. Originally swapped to my old (1st) jk injectors, which are Bosch 445 115. When tested, 2 were gone. 2 were acceptable. Replaced 2 return valves on 2 (# 2 and # 4). No change in fuel pressure behavior... Recently bought and changed 2 more (# 1 and # 3). So all 4 injectors are perfect now. Test run the car, no changes in fuel rail pressure behaviour.

3) While CP 3 was out, removed and checked return flow valve. Acceptable. So this is out of question.

4) Removed fuel rail pressure regulator (back) . Checked for functionality. To be sure, replaced. No effect.

5) Replaced fuel rail pressure sensor (front) with new one. No effect.


6) Checked in tank fuel pump. Hooked up pressure gauge. Constant pressure of 40-45 psi. So no issues with fuel supply.

7) Removed top cover, removed timing belt. Set up ignition as per manual. No change in behavior.

Remove exhaust pipe/ cat converter right after turbo charge (thinking the cat is blocked or so). Started the engine. No change.

9) Removed turbo charger. As I have about 5 psi boost. Here it goes interesting. Turbo is ok visually, no broken blades etc. Rotates normal. Some scar marks from normal usage. Polished the rod and journal bearing. Have a little play (0.2-0.3mm). I've looked on other turbos. Same play. Rebuilt the turbo, no change. It blows air, but no boost. This is critical part. Im suspecting following:

- 7a. Either turbo is gone
- 7b. Not sufficient fuel burnt to impel the hot side, thus suction and compression part lacks rotational
power, which leeds to lack of boost
- 7c. EGR valve is gone, so it equalises the pressure from hot side to cold side. Therefore no functionality from turbo


As you can see from above list, there is almost nothing left to check, however I do believe that 2 brains are better than one, so please step in and advice what else can be a cause.

Some info to think about:

- Fuel rail itself is bad. Leacking from high pressure side (regulator side). Although I have replaced the regulator with new one, the rail side is bad thus leaking. Maybe?

- My ABS unit is not responding. Had this malfunction during purchase, so I was aware of this. One thing I'm guessing is ECM deliberately reduced engine power (limp mode) thinking the brakes are gone. But I have full brake (despite ABS is not working, who cares. Im used to drive race cars....). I have constant (P) dash light. The E-brake release does not turn it off.


Error codes I get are:

- P0101 - Mass airflow EGR.
- U0415 - which is impausable data from ABS. Sensors are ok. Its just programming issue.

and few more, but not related to engine operation.


Planning to do following:

- Although I have stripped EGR valve before, but did not pay attention. So planning to to remove and inspect

- Replace/swap the rail from my 1st JK. And see if it improves anything.

- Replace/swap boost sensor and MAF sensor from JK and see if it changes anything

- Blow pressurised air into intake manifold, and see if performance improves.


Thanks for reading till the end. Looking forward to solve the issue together.



Regards,

J

Need actual numbers to help diagnose.

What fuel rail pressures are you seeing?
At idle and under load?

A low pressure problem would set a code.
And make sure you have adequate fuel flow from tank to engine. Maybe you need a new fuel filter.

What boost pressures are you seeing?

The turbo has variable vanes inside the turbine. If the vanes dont move you will get little to no boost.
Your turbo should be all electronic. (ours here in the US are vacuum controlled)
A dirty MAP sensor (on top of the engine) will cause turbo problems.
A stuck open EGR valve will direct boost out the exhaust.

_________________
U.S. Army Retired

Your MAF error code i believe is taking you in the right direction.

Does your intake have the "Mercedes" sensor? A loose or disconnected wire at this sensor could also trigger your Limp Home Mode.

If you have a single dead cylinder, that wouldn't be due to low rail pressure. Rail pressure affects all cyliinders equally.

A single dead cylinder would be electrical or mechanical (physical)
Faulty connector or broken wire to injector
Dead or damaged injector. Possible broken glow plug tip (ceramic) could damage the injector tip, or, more likely, damage an exhaust valve when leaving, causing loss of compression.

With this possibility, I wouldn't rev the engine or put it under any load unless you find an electrical fault that gets the cylinder firing correctly again.
If you are lucky enough to drop a cylinder with just a bent or damaged exhaust valve, don't push it to the point of the valve head breaking free and taking the piston / rings / cylinder sleeve / cylinder head along with it. These parts are NOT cheap.

_________________
'06 Lbrty Sprt CRD 150K

Sasquatch
DSS Turbo
CAT-elimntr
Weeks Stg1&2 EGRfix
PV-200
BLING
vent gauges

IDParts
head
cams
rockers
Timing set
ARP studs
eTn1 GX2123 5v GPs

YETI Custom Tune
Flowmaster 8325508
Carter P76611M
GM 12611872
Hayden 2986
GM 15976889
PATC Custom Billet
2010 Ram Hemi Trans
Sonnax 44957
Transgo kit
Cooper 51770

Well, after reading your last sentences, I got concerned... When I stripped the top, for the cam timing, looked over the valves. Rotated the cams, no obvious damage was felt. It was rotating freely.

HOWEVER....here is the part I forgot to mention...

The engine makes a knock noise when starts. For 1 second. Feels like oil is not getting to the one of the bearing or so. It dissapears right after 1 second. Engine runs as smooth as modern high tech gasoline engine. No noise at all. Im guessing the oil is crap (it was left in car since last change out by my friend, and the car stood at dealer for 10+ month, so oil maybe degraded so is the filter) Going to change the oil/filter and see if starting knock goes away.


well..all things were looked at. I may strip the engine to check the valves, rods, etc. But before that I want to make sure there is nothing other left.

btW, Ive been driving in this condition about 4 month now...at least 6-8k miles this way. If that was some bent rod or valve, would not that blow engine already?

That would depend on when, how, (and if), it actually happened.

Remember, the vehicle is with you, and all we have to work with are the details you give us, and all we can give back are possibilities based on our individual experiences. It's up to you to collate our inputs in a way that makes sense against what you are seeing and hearing there.

I'm a little confused though. You say you've been driving it for thousands of miles and at the same time, that it has one completely dead cylinder.
Based on this, I've made the assumption that some event has recently happened to cause that, which would make the thousands of miles really unimportant, since there was an event that separates them from what exists now.

That would seem to be wrong, though, since you say that ALL cylinders change the sound of the engine when disconnected. For that to be true, All cylinders are firing to some degree.

Now, back to the point of the possible damaged valve...
1) If you're getting some ignition... but not enough for an even and smooth firing count... It's possible to have a damaged valve or seat (but not yet broken) where that could happen. It's unlikely, but possible.
2) This is why, in your diagnostic process, I recommend that you not rev it or put it under load. If this is the case, so far, you have REALLY lucked out, in that the valve head (or "coin") has not yet separated from the stem.
This is not something you can see looking at the tops of the valves. If you can see a problem there, you already have serious internal damage.

Again, we're talking about "possibilities", not absolute diagnoses.

Regarding the part you mention about the knock starting... It's possible that it could be something concerning, and for that reason, keep note of it, and IF IT CHANGES, look into it. If it's NEW look into it.

I'm willing to bet it's been there since you bought it, as diesels tend to make a noise like that on startup. They are electronically governed, and when you start them, they over-fuel in order to attain proper idling RPM.
Similar to when you disconnect one of the injectors. In addition to running rough, they will make a loud knock noise when the cylinder following the one you disconnected fires. The RPM has lowered due to the miss, so the next cylinder firing over-fuels to compensate, making the loud knock. Most likely this is what you're hearing, especially it's not really a new thing.
Just a diesel thing.

Keep proper 5w-40 diesel rated engine oil CI or better in it. CK is current, and is backward compatible in all brands. Use a good oil filter, and change it regularly. (Not Fram).

From all of your recent answers, it sounds like no major injuries though. Glad they had the brains to put a pump in the JKU fuel tank! Not having one in the Domestic KJ's is one of their greatest driveability, and reliability issues.
If your boost still isn't coming on, don't forget to check your intake filter, and both CAC hoses. From there move to EGR exhaust blockoff so no boost can exit through the exhaust. If that doesn't do it, cut your exhaust between the cat converter and the exhaust flexy section. If your cat has plugged from too much city driving or whatever else, it can't move enough exhaust to develop enough boost.

_________________
'06 Lbrty Sprt CRD 150K

Sasquatch
DSS Turbo
CAT-elimntr
Weeks Stg1&2 EGRfix
PV-200
BLING
vent gauges

IDParts
head
cams
rockers
Timing set
ARP studs
eTn1 GX2123 5v GPs

YETI Custom Tune
Flowmaster 8325508
Carter P76611M
GM 12611872
Hayden 2986
GM 15976889
PATC Custom Billet
2010 Ram Hemi Trans
Sonnax 44957
Transgo kit
Cooper 51770

Thanks Gordon for all your inputs, yes you are right you are analysing the issue based on my feedback.

And I'm trying to put all the little details into the picture, as we go on.



The vehicle was like this. I bought it with this malfunction. The engine did make knock just from beginning, i.e. 4 month ago since I bought it. The interesting thing is it only does it for 1 second, during firing. Then engine works like clock. No other sounds.


I drove it 6-7k miles in this limp mode. My work is about 7 miles away from my house. So I drive 10 mins one way daily.


You really got me concerned. Now I was out for lunch, started the car. No sound...fires normally.


What the heck...


I'm thinking 2 out of 4 injectors were almost at their end life. So 2 firing correctly and 2 was leaking back more than normal to return. Since I change the injector return valves, about 3 days now. Engine got used to new injectors. So the sound dissapears slowly


Yes, having an electric lift pump is a bonus. But on JK it got stuck once, I was in the mountains


I had to jump it with 24v, i.e. 2 car batteries in series. Just to give it a good kick. Was able to start the car, came back to town. Replaced.

One thing I thought, maybe the head gasket is gone, thus leaking antifreeze into the cylinder. And I'm getting hydraulic lock for a second, until engine starts and in exits via the exhaust valve.

Thoughts on this?

If that were the case, there would be symptoms.

Mysterious loss of coolant and white smoke out the exhaust after a cold startup.

_________________
U.S. Army Retired

Flash is correct. Two thumbs up.

Also, if you have a leak large enough to hydralock, you would have either oil or coolant, whichever is leaking, flowing out the tailpipe in liquid form.

You haven't mentioned anything that would change my mind that it's a normal startup thing.


There would be other factors involved when starting, such as engine temperature, so be aware of those.

_________________
'06 Lbrty Sprt CRD 150K

Sasquatch
DSS Turbo
CAT-elimntr
Weeks Stg1&2 EGRfix
PV-200
BLING
vent gauges

IDParts
head
cams
rockers
Timing set
ARP studs
eTn1 GX2123 5v GPs

YETI Custom Tune
Flowmaster 8325508
Carter P76611M
GM 12611872
Hayden 2986
GM 15976889
PATC Custom Billet
2010 Ram Hemi Trans
Sonnax 44957
Transgo kit
Cooper 51770

A few things I’d like to discuss here.

Given fact is I have low rail pressure. Mechanical parts of this issue are solved. I.E pump is fine, injectors are fine, regulator changed, brand new. No visible leaks. Only thing left is rail. But, how critical is it..


So I need to know what governs the fuel rail pressure regulation. Obviously something is reducing power electronically (opening regulator more, so fuel leaks back to return)

I have brake light constantly on. Maybe ECU thinks I have brake malfunction?...I got an error of U0415, impausable data from ABS unit. I don’t have functioning ABS (I don’t need it anyways..) and speedometer is not working. Can this be some how contributor?


Before, the car was choking badly at about 1800 rpm. White smoke all over from the exhaust. I was disconnecting the fuel pressure SENSOR harness. And rpm was going all the way to 3.5 4k. No smoke. But no power also. Been driving like that for a while.

When I fixed injectors, things got improved. Now the pressure sensor harness is back in place. Car gained some marginal power, I can feel it.

Need to get behind what governs the fuel pressure. Some suggests that turbo is gone, but I stripped the turbo, everything is ok. I don’t have enough fuel burnt so the turbo does not spin and produce enough boost. That’s the reason I have not changed the turbo yet.

Your engine actually has two fuel pressure regulators.
One is on the injection pump.
The other is on the fuel rail.
If you disconnect the one on the fuel rail, the engine will not run.
If you disconnect the one on the injection pump, the engine will run but with reduced power and a code will be set.
Disconnecting the fuel rail pressure sensor will also force it to reduce power and set a code.

A ABS problem will cause the speedometer to stop working but should not effect engine performance. At least not in my experience.

_________________
U.S. Army Retired

Things are a bit different in JK 2.8 CRD. That FQS (Fuel quantity solenoid) which is at the back of CP3, is normally closed. I.e. all fuel is fed to CP3 pump, thus creating max rail pressure. When activated, it opens and releases some amount of pumped (via lift pump) fuel back to tank. Ive checked it connected and disconnected. Then connected PWM controller to it. Engine died once I fed power to it (opened and released fuel back to tank)

In fact, I have full 40 psi fuel pressure, constant from the lift pump.

Agree with you on ABS part. I've disconnected the ABS on JK. And engine kept running.

What a mystery...Its frustrating being in all roots, but still not finding root cause...

The FQS uses PWM to regulate fuel up to the rail or return to the tank.
With the FQS unplugged, all fuel goes up to the rail (to me this means wide open). Then, rail pressure is regulated by the fuel rail pressure solenoid.
Under normal conditions both solenoids regulate fuel rail pressure.
When the fuel pressure sensor is unplugged, the system seems to default to max pressure of 26,000 psi. At least that’s what I see on the scan tool. You never really know what pressure is when the sensor isn’t working.

I installed a AutoMeter fuel rail pressure gauge back when I first encountered these issues.
It gets wired into the rail pressure sensor and has been a very helpful diagnostic tool.

BTW, the majority of my problems were related to bad wire connections, not failed components.

_________________
U.S. Army Retired

We are on the same page Flash. Thus unplugging FQS should not affect low rail pressure. Would have been opposite if I had high rail pressure.

Agree with you on wiring. However, when I unplug the sensors, engine reacts. This tells me that wiring is ok.

One more test I will do is hook up scope to pressure sensor cam and crank position sensor. The engine does NOT react to unplugged cam sensor, but so does the JK. Runs ok.

The car has been stable for now, and does my business slowly, so don't want to touch it yet as I m loaded with other critical projects. Will do testing soon and let you guys know.

And any other bright ideas are welcome, chip in

I experienced the same thing.
Even after replacing components.
It wasn’t until I started wiggling connectors that I identified the problem.

_________________
U.S. Army Retired

Ive connected the scope to rail pressure regulator. It is negatively controlled via ECM. I.e there is always positive on wire and negative is controlled by pulses. Scope showed full 2.5 -6 v on the solenoid as I was pushing accelerator pedal...which tells me that control mechanism is ok

Planning to swap rail this weekend with JK. Will see

Hello, J:

I am late to the conversation, so perhaps I have missed something.

It appears to me that you may have a V.M. Motori A428 engine rather than the V.M. Motori R428 engine that is in the KJ Liberty CRD that was sold in the North American market from 2005 to 2006.

Please post photos of the engine under the hood with the beauty cover removed.

If you live in North America, how did you get a 2008 and a 2009 CRD imported?

Jeff Bauer

Good day Jeff,

My vehile is Jeep Wrangler JKU (also have JK for sale)

Ive got RA428, 177 hp (130 kW); Manual transmission in JKU 302 lb·ft or 410 N·m, auto transmission in JK, 339 lb·ft or 460 N·m

Will drop few pics here after the work. Meanwhile, you can find a lot of pics and usefull info on modification, works done in my Instagram account. UNICAPRO (you will see black JK on top of volvano)

I live in Baku, Azerbaijan (Europe). But tied to USA with my host family ) Used to live in Wyoming with them, when was studying. Last time visited them in 2017.

darn politics does not let me get a proper work visa easily, otherwise I'd had the best machine shop/car center in the world, with tons of satisfied customers...

Regards,

Javid

Some more investigations revealed that all the wiring and sensors are ok.

Ive checked the voltage on pressure sensor, it is 2.5v max which corresponds to half of max rail pressure, which is 700-750 bars.

There is something that limits the pressure. Therefore I don't have enough exhaust, thus turbo is not spinning, not sucking enough air so I Have low boost.

Ive checked the return, when gas pedal is hit, injector returns diminish but the rail return increase. Ide expect both of them to diminish as engine takes more fuel.

I've got 2 questions:

- something electronically limits the rail pressure to half, what is the control algorithm? Anyuone has information about logic behind this control?

-or my rail is bad and is leaking, because I've change the pressure regulator valve.

I was thinking replacing electronic regulator valve with mechanical, those found in 5.9 cummins. Basically same thing, but mechanically bleeds pressure when above 1500 bar. Any down side of have constant 1500 bar on rail? Bad for pump? or?

Thanks..