I followed my CRD the other day for the first time and I noticed quite a bit of black smoke coming out of the tailpipe. I knew it smoked under hard acceleration, but it appears to be doing it pretty much continuously. The intake hoses are new Samco units, the EGR valve is nice and clean because I just had it off, the MAF sensor in the intake is clean and appears to be new, I have no CEL, and the Jeep seems to pull just fine. Any ideas? Injectors maybe? Could this be a side effect of the crappy fuel pump system? Any help would be appreciated.
Blowing black smoke
- Thread starter Workinman
- Start date
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Skipperau
Skipperau
My first port of call would be to look for a leak in the boost hose, next would be to check the air filter, then suspect poor fuel, then possible injectors/fuel pump.
Thanks! I’ll double check the hoses, but I think they are fine. They are the fancy blue ones and they look new. (I just bought this CRD recently) The air filter is new, as I just changed it out. If I’m not mistaken, black smoke means too much fuel/not enough air, so if the hoses are good, and tight, and the air filter is good, maybe the fuel injectors are dumping too much fuel? It runs just fine, and you don’t really notice the smoke when driving, but when you’re following behind this thing it’s just pumping out the black smoke. I’ll keep checking back here, and I’ll be checking the hoses next time I go outside.
I did read somewhere that you could unplug one of the sensors and drive it and see if it got better. If there was less smoke, I think it said the egr valve was hanging open or shut. I don’t remember which it said. I’ll do some more research and see what I come up with.
I did read somewhere that you could unplug one of the sensors and drive it and see if it got better. If there was less smoke, I think it said the egr valve was hanging open or shut. I don’t remember which it said. I’ll do some more research and see what I come up with.
WWDiesel
Full Access Member
Installing a mechanical boost gauge will tell you exactly how much boost you have or don't have! Should be round 22-24 during hard acceleration is about normal for stock tunes.
Since you have installed new boost hoses, some other items to check and rule out that can cause low boost problems.
Pull the air inlet hose between the air filter box and the turbo inlet and make sure the rubber hose has not come apart and let some of it get sucked into the inlet of the turbo. (this has happened to some owners) While the rubber intake hose is off, check the turbo by manually feeling the turbo wheel for any excess play, side to side laterally or end to end axial play and also spin the turbo wheel by hand, it should spin very freely.
EGR valve can stick and allow loss of boost backwards when accelerating. FCV can also stick/hang partly shut limiting air flow/boost into the intake manifold, they are notorious for the small gears in the valve's gearbox stripping and hanging up. Best to blank off the EGR exhaust feed line to prevent any backwards loss of boost pressure and remove the butterfly plate out of the FCV; only two small torx screws and it comes right out.
A defective MAP sensor can also cause lack of proper boost as it is what is telling the ECM what the boost pressure is at any given moment. They have been known to do this.
Vacuum problem on the turbo variable vane controls.
A leaking vacuum hose from the brake booster connection to over at the turbo vacuum solenoid and vacuum modulator valve or a bad hose/plastic pipe from the turbo vacuum modulator valve to the turbo vane actuator can all cause low turbo boost pressure especially when accelerating.
You can also bypass the turbo vacuum solenoid (they go bad), for a test to see if that is the problem. See picture.
All of the above must be ruled out to find the source of the low boost problem.
Since you have installed new boost hoses, some other items to check and rule out that can cause low boost problems.
Pull the air inlet hose between the air filter box and the turbo inlet and make sure the rubber hose has not come apart and let some of it get sucked into the inlet of the turbo. (this has happened to some owners) While the rubber intake hose is off, check the turbo by manually feeling the turbo wheel for any excess play, side to side laterally or end to end axial play and also spin the turbo wheel by hand, it should spin very freely.
EGR valve can stick and allow loss of boost backwards when accelerating. FCV can also stick/hang partly shut limiting air flow/boost into the intake manifold, they are notorious for the small gears in the valve's gearbox stripping and hanging up. Best to blank off the EGR exhaust feed line to prevent any backwards loss of boost pressure and remove the butterfly plate out of the FCV; only two small torx screws and it comes right out.
A defective MAP sensor can also cause lack of proper boost as it is what is telling the ECM what the boost pressure is at any given moment. They have been known to do this.
Vacuum problem on the turbo variable vane controls.
A leaking vacuum hose from the brake booster connection to over at the turbo vacuum solenoid and vacuum modulator valve or a bad hose/plastic pipe from the turbo vacuum modulator valve to the turbo vane actuator can all cause low turbo boost pressure especially when accelerating.
You can also bypass the turbo vacuum solenoid (they go bad), for a test to see if that is the problem. See picture.
All of the above must be ruled out to find the source of the low boost problem.
