I can’t find the answer that I’m looking for and can use some help, my truck developed a stumble from stop and I can’t figure it out. It’s only doing it from a dead stop, if it’s rolling a little there isn’t a problem but if it’s on a uphill take off it’s really hard to get it going from a stop with a bunch of black smoke. I’ve cleaned the Turbo and EBP and Map sensors. My VGT is 85% at idle but once I get past the stumble it goes down as it builds boost. I checked for air leaks in the Boost tubes and exhaust system. EBP is 16.4 at idle MAP is 14.5 at idle and barro is 14.5 at idle. Fuel pressure is 65 psi at idle and drops to 55 psi under hard acceleration. From a stop I see the vgt start to drop down in % and then go back to 85% for a bit and after the stumble goes away it drops down and leaves black smoke. I have the Egr shut off with my tuner and don’t know if it being dirty would cause a problem so haven’t looked at it yet to clean. I have about 10,000 since I put the motor in and checked out everything. If I’ve missed anything please chime in with something that would help.

I take it that "cleaning the turbo" means ensuring the unison ring is free and clear? Did you just clean or replace the unison ring? When mine stuck again after cleaning, I replaced it. I could swear that Ford opened the inside diameter of the unison ring hole just a smidge to ensure it stays free to move.
Your vgt's at 85 sound like its sticking again.
If not, it could be an injector with that black smoke. Fuel pressure sure looks good but no guarantees. Maybe have a shop run a contribution test?

Thanks for the input, I cleaned it completely and it moved smoothly after. I had cleaned it not to long ago and it was pretty clean when I recently cleaned it. I don’t get any codes at all is also strange. I feel like I know my way around these trucks but I’m stumped on this.

I have some other things to add. After I’m moving it never does it. It’s just from a dead stop. It really does it if starting on a uphill grade. It’s taking a long time for it to begin to spool up before it clears out and builds boost. After it’s rolling and vgt starts dropping it’s just as smooth as it should be. If I’m rolling along and it’s at 85% and stab it it goes like normal. It’s almost like I’m trying to start off with it in second gear if that makes sense. But it’s not anything like that because it’s not starting off then shifting down to take off. Any other ideas about this no matter what you think of it might spark something up that I can build on or someone else might have an idea.

Nobody has 2 cents to throw in? If everyone is stumped let me know.

Did this happen before or after the turbo cleaning? Did you take the VGT solenoid out to clean it? Are the wires to the VGT ok? MAF sensor is it clean if you have one? How do the MAP and EBP correspond with each other?

I bought my ‘04 X with 13K miles back in ‘05. Ran fine for a while, then the stumble showed up. Step on the diesel pedal and it would not go or go enough to get in traffic and there I set. Removed the cat from the stock exhaust system. Significantly reduced the stumbles and improved throttle response since the turbo no spins at idle. Installed a MBRP 4” turbo back exhaust with no cat. It has never stumbled again. I now have 144K on it and the turbo is original and never been cleaned. If you have a stock exhaust with a cat, that is probably your problem since your upgraded engine breaths better. Your turbo is stalling due to high exhaust back pressure at idle. My turbo sounds like a commercial airliner’s APU. I have used Royal Purple synthetic 20W-50 oil since I have owned the X. Never had a motor problem.

Ed

I had this happening and that’s why I cleaned my Turbo. It’s straight piped and the information about those sensors is in the beginning of my thread.

Here’s where I’m at now, put a new Maf sensor in, cleaning didn’t help and it was from my older motor that would puke coolant and some residual crud was around it. I double checked and cleaned the EBP sensor and tube, Map sensor hose and connection into the manifold. Pulled Egr valve and was very clean probably because it’s turned off from programmer. Put in new Vgt solenoid, pulled the end cap off the turbo and checked the vains for smooth movement. After everything I went through the only thing that seems odd is mine being an 04 has the throttle sensor on the intake which I thought only was for the butterfly valve but it’s gotten some oil in the connector. I don’t think this is used anymore because it doesn’t have a butterfly. With my FORScan monitoring all sensors to check with the tech folder every is as it should be.
I think it’s something to do with the throttle petal. If I’m at idle in neutral I’ll revs up fast now if it’s in gear and only press a tiny bit the vgt readings go from 70 to 85 and it just Boggs and won’t rev up any. In neutral it’s like it should be. How can I verify that the petal is the problem. Also can you tell me if the one underneath the intake elbow does anything that can cause the trouble I’m having.

Bismic thanks for your input, I have zero coolant loss and egr system is in tact. Turbo cleaned and new vgt solenoid.after pulling the egr valve it was dry and fairly clean, but I still cleaned it and replaced. I’ve been running stock tuning for the past week. New EBP sensor, Maf checked and cleaned hoses and connectors to all other sensors. Map and Ia2. I’m running FORScan with all perimeters that would be something to give pcm information. Everything possible and crossed information from the tech folder you have provided. I’ve had zero Dtc codes pop up in over a year when I replaced the motor and all sensors and engine harness. After all of these things if I start it it’ll idle like a new truck. Never a hiccup, in neutral it revs exactly as it should. When in gear with foot on brake applying a small amount of throttle it starts to bog down and then keeps doing it with a little more throttle applied. The vgt was at 68-70% when doing it but slowly moved to 85%. Tried multiple times. I’ll starting to think it’s something with the throttle area of the system. Looked at wiring and couldn’t find anything that looked chafed but that was last night around 2:00am and gave up for the night. Going back into it now. Thanks for chiming in.

The inside of the manifold was slightly dusty with soot and dry as it could be. No signs of a leak. I put a bulletproof egr cooler in with the new motor last year and haven’t lost a drop of water looking at the degas bottle. Vgt solenoid shows 3.4-3.6 ohms. Any and I mean anything that you can throw out for me to look into would help.