Happy Turkey Day! (Less so for some...)

Gypsy62 · **Posted:** Thu Nov 25, 2021 4:55 pm

Another year gone by, another CRD mystery.

I was convinced that my running symptoms of hot + gutless + smoking = Timing Issue.
Just revealed & checked crank-cams-CP3: all still spot-on.
Now I'm at a total loss as to what's failing.
Strange to wish that your timing was off, lol.
- Re elevated temps under load, if water pump or thermo were failing the jeep would still accel normally and not smoke. I replaced the pump & thermo around 5k ago.
- Re gutless & smoking @ accel & load, I REALLY thought that pointed to slipped timing, but no.
WTF???

After re-assembling timing-access, I see my next steps as:
- Completely removing & inspecting the air intake path for obstructions (blocked/leaking CAC?)
[Done: entire Airpath clear and holding pressure] and,
- Pulling valve cover & cam assembly to inspect rockers. Obviously, this requires R&Ring the tbelt etc and is much additional work: do the rockers seem suspect at all? And,
- Whipping out the laptop & flashing the ECM back to stock (from delete + basic performance-upgrade flash).

Thanks for your thoughts and
Happy Turkey Day!

bugnout · **Posted:** Thu Nov 25, 2021 8:18 pm

Happy Turkey day to you too. what about the turbo? original or replaced? How many miles on your ride?

Steve777 · **Joined:** Fri Oct 16, 2015 11:31 pm **Posts:** 279

Happy T'day to you too Gypsy62, sorry to hear of your CRD problems.

A couple of thoughts, could be a fuel/air issue, might be good to check boost pressure to see if it is where it should be or close when you are getting low power and smoke. Maybe leaky injectors, although that would seem less likely.

And you are right, pulling the intake/VC is a pain. So before you do that you might want to check that the intake and exhaust valve spring pressure on each cylinder are the same. I'm speaking of removing the tbelt cover, putting the crank in the midway position as though you were removing the VC, and removing the tbelt, then turning the cam sprockets by hand say with a ratchet (locking pins out of course). Should be a matched amount of force and snap back at each cylinder. If not then you've likely lost a lifter, and it's hard to know after the VC is off whether you knocked it off in the removal or it was that way before, so this can be good to know. And before you take off the tbelt, you'll be able to check the belt's condition and tension setting.

Not sure how other are thinking but I have taken off and replaced a low mileage tbelt before on other engines without issues; one just has to keep it all clean and note which direction it was running to keep it the same upon re-assembly. This may save you pulling the intake/VC, and at a minimum will give you an idea of how the valve train and tbelt are looking before you pull everything.

And of course, if you do end up pulling the VC, the injectors will need to come out, so perfect time to have them tested too.

Good luck with it.

WWDiesel · **Posted:** Fri Nov 26, 2021 10:34 am

Gypsy62 wrote:

Another year gone by, another CRD mystery.

What is the actual real boost pressure at the intake manifold you are getting while hard accelerating and getting black smoke and gutless performance?
Is your EGR parts removed, or blanked off, you did not say. You stated you had a EGR delete tune, but a tune does not prevent an EGR valve from leaking by and causing loss of boost pressure.

Before you start taking things apart, you must know the actual boost pressure you are getting when accelerating and getting lots of black smoke and poor power!
More diagnosis is needed to try and pinpoint the actual cause of the problem before tearing things apart.
If you don't have a mechanical boost gauge, get one, they are not expensive and the information it can provide you is invaluable for diagnosing performance issues.
(there is a small boss on the intake that you can drill a small hole into and tap it to screw a fitting into for connecting a boost gauge)

DO NOT rely on a boost pressure reading via the OBD port, it could be very misleading if the MAP sensor is not functioning correctly.
Speaking of MAP sensor, have you tried a new one? A bad MAP sensor can cause the running issues you have described.

Once you know the actual boost pressure at the intake manifold, or lack thereof, that will tell you where to start looking for low boost problems.
If the boost pressure is good~20 psig or a little better at full pedal acceleration, then you have ruled out a lot of things that is NOT the problem, like turbo, CAC, hoses, etc...

:SOMBRERO:

Gypsy62 · **Posted:** Fri Nov 26, 2021 12:39 pm

Thanks, folks. I'm going to double-check the CEL codes; maybe something new popped-up (MAF code post snorkel install, but the MAF couldnt cause such extreme mayhem).

I've done everything to this pita-beast:
- Delete performed 5 years ago, ran fine; current prob unlikely related.
- Installed a boost gauge a couple of years ago; functions fine. Currently low boost, but that could be a chicken-egg scenario. If the ECM is unhappy with sensor readinfs, etc, it may be governing systems, no?
True, upon accel/load its clearly running "rich", but rich and gutless and heating up. Seems like strictly a rich mix wouldnt steal power, or?
- Turbo? Please, no. I'm on my fifth in two years! Original was starting to leak, then two from Ohio Joe (first arrived damaged, 2nd spewed oil upon installation), then beergineered a cooled ball-bearing Garrett, after a few very fun months that died, then the Mex rebuild died ( destroying the housing, too) and now I'm on a new identical replacement (Mex shop paid half).

Granted, the current problem is almost certainly related to my beergineered Snorkel & Garrett-related coolant routing mods and MAF/MAP relocations to snorkel cowl. However, it did run well with the snorkel setup & first Garrett for a few months.
MAP seems like a real possibility.

Re rockers, I replaced them less than 10k ago (along w HGasket, Valves/Seats, ARPs, TBelt/H20/Thermo, Eng mounts, etc). The crank hand-rotates normally; valvetrain not unusually noisy.

Thanks!

WWDiesel · **Posted:** Fri Nov 26, 2021 3:32 pm

Two thoughts then:
First, the MAF will not affect the running of the engine, you can unplug it and throw it in the trash, it will never be missed as it is not used for engine tuning or running input signal to the ECM, it's only function was to operate the EGR valve. But since you have removed all the EGR crap, it is no longer needed.
Second, there is only a few major things that will cause the black smoke, over fueling and / or low boost or a combination of both, or a bad MAP sensor, or faulty wiring/signal from teh MAP to the ECM.
If you are seeing low boost numbers with a mechanical gauge, then you have to find out why; i.e. turbo, vanes sticking, turbo vacuum controls not working properly, leaking hoses, bad MAP sensor, etc.
Over fueling will cause excessive black smoke even with good boost, could be a faulty injector, but sometimes when this happens, the engine will act like it is missing or skipping on one cylinder due to the excessive fuel.
Best of luck in your diagnosis! :juggle:

Steve777 · **Joined:** Fri Oct 16, 2015 11:31 pm **Posts:** 279

Yes Gypsy62, good that the engine feels fine when hand cranked. But my experience was with an engine which had a lifter fall off of an exhaust valve (likely was that way from before I got it when the PO had the lifters/rockers replaced). There were no obvious signs of a missing rocker until I had the tbelt off and tried rotating the cams, when it became very obvious that one cyl was weak.

That said, I would put my bets on your fuel/air system. This one missing lifter did not cause a massive power loss or smoking for me, which are the symptom you are seeing.

Gypsy62 · **Posted:** Fri Nov 26, 2021 11:26 pm

Thanks for the Mister Ed-ucation, WW: I'll pull the MAF out of the custom intake cowl & seal the slot!
Willl-Burrr...!!!

Time to hone in on the MAP sensor/wiring/connectors.
Cheers

WolverineFW · **Posted:** Sat Nov 27, 2021 12:57 am

Gypsy62 wrote:

Thanks for the Mister Ed-ucation, WW: I'll pull the MAF out of the custom intake cowl & seal the slot!
Willl-Burrr...!!!

Time to hone in on the MAP sensor/wiring/connectors.
Cheers

What did you do with the Mercedes labeled sensor that is on the air box? Did you remove it or move it?

That little sensor has cause people all kinds of issues over the years, usually black smoke and lack of power if I remember. I forget what the name of it is on the parts fiche.

Sent from my SM-G965W using Tapatalk

WWDiesel · **Posted:** Sat Nov 27, 2021 2:13 am

WolverineFW wrote:

Gypsy62 wrote:

Thanks for the Mister Ed-ucation, WW: I'll pull the MAF out of the custom intake cowl & seal the slot!
Willl-Burrr...!!!
Time to hone in on the MAP sensor/wiring/connectors.
Cheers

What did you do with the Mercedes labeled sensor that is on the air box? Did you remove it or move it?
That little sensor has cause people all kinds of issues over the years, usually black smoke and lack of power if I remember. I forget what the name of it is on the parts fiche.

Great thought! I did not even think about that thing, but you are very correct.
It is called: IAP sensor – OEM part no.: 05101120AB (intake air pressure sensor on side of airbox)
air inlet air pressure comparator pressure sensor on the side of the air box; sometimes referred to as the “Mercedes sensor”
I remember a couple of posts about a wiring chafing issue on the wiring going to the IAP sensor and one or two reports about a bad connector to the IAP sensor.

I actually relocated my IAP sensor from the side of the air box to the top of my air box due to the wiring connector rubbing on the side of the CAC boost hose. See picture

Gypsy62 · **Posted:** Sat Nov 27, 2021 9:50 pm

The plot thickens!
I'll double-check whether I spaced-out relocating it to the snorkel "belly".
Thanks!

aviator97 · **Joined:** Tue Apr 13, 2021 5:50 pm **Posts:** 2

Noob here, I scored a 2005 CRD on the cheap with this same problem. Did you fix it. Any updates

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