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Hello all. I am new to the forum and I want to share my recent repair history. I am a very seasoned Master Technician but I haven't worked in a shop in 16 years since I started an unrelated business. It would be accurate to say I have a good solid understanding of Automotive Repair against most platforms. I am a Mercedes Benz Master and I was a trainer, team leader, SLR McLaren Technical Specialists, and I worked as a Foreman before hanging it up. I grew up Ford Trucks. I have owned about 12 Powerstrokes, but this one is my baby. Bought it new. 98,400 miles and all OEM stock condition. This is the second repair. About 8 or 9 years ago I had a shop change oil and fuel filters and I think then it needed some injectors all of the sudden. Never had issues before that Fuel Filter Change.

I used many valuable posts here to help me out. While I have skills. I did not have a scanner so I took a step by step approach. So thanks for all those other posts and very qualified contributors.

Code P0299 Turbo Underboost. I could hear the Turbo was different physically. In order to prove up a path I went through the motions. So I started with checking the EBP sensor and cleaning it and the pipe/port. I used a caustic cleaning solution in ultrasound. It all came out like new. No visible issues in the pig tail, no Ohmic issues, or Voltage signal issues. Ran truck and code came back immediately. Drove same but I knew it was sluggish compared to 14 years ago.

I was prepared for and suspected the Turbo VGT system was seized. $11.00 mounting seal kit from Ford was the only purchase necessary so I commenced this repair. Watched a youtube video for tricks and tips. Gents, this literally could not be any easier. I could see a 10 minute removal for a prepared and experience guy. I think I spent 20 without a good combination of tools for the clamps. Here is what I recommend. Electric or air 1/4 drive ratchet. 1/4 to 3/8 adapter. a 11mm or 7/16 deep 3/8 Sockets. Hit everything with your favorite penetrating oil first. Once clamps are very loose (nut to the end of the rod you will have to knock the clamp base to free it up. Splay open clamps and walk them to turbo side for ease. There are Qty 3 10mm bolts to remove and the oil feed line. Watch a you tube video. You can get the the rear one best with a 6 inch 3/8 extension and a short 10mm socket. Break free carefully. Mine came out. Kit comes with new bolts. one of my bolts had some electrolysis damage. Penetrating oil is a must. The passenger side exhaust pipe is easy to break loose. The drivers side took a little prybar effort. I stressed a heat shield which bent back easily. Pop up the turbo and walk it out. Note: be sure to disconnect the Voltage Regulator feed wire from the passenger positive battery post. Not required but a wise tip I saw in a video. The center housing clamp should get an indexing mark and lots of penetrating oil on that flange to help break it. Support the turbo (aluminum side up) and use a brass drift and a solid hammer to tap around the hot section to liberate. I had to stroke mine pretty good. Once apart it was obvious mine was massively frozen. My truck sits a lot as I have extra vehicles. This should have been a replacement. I chose to repair. I ultrasonically cleaned everything I could. I de-carboned the housings. I modified the diameter of my roloc arbor base and made it work on the hot-side. My center housing unison ring contact area was a nightmare. Still I am patient so I blended it with course sandpaper. I applied a very liberal amount of Permatex anti seize high temp lube. This is mentioned in a Ford Bulletin I ran across. after cleaning inspection and blending I got everything lined up and back together. Note: the VGT actuator arm and the locator pin are the two points of interest. As good practice I cleaned and refaced the exhaust mounting points on both the truck and the turbo. I put some Anit-Seize there too. I'm old school, but I could see some people not liking this. Do what you choose. To confirm functionality of the Turbo VGT you need to pull the VGT solenoid. If you are going to reinstall keep the spool valve area in fresh motor oil. No lint or any contaminates recommended. BTW more on this later. With the piston cap removed on one side and the VGT solenoid out you can with a long skinny tool actuate the VGT Unison Ring manually and observe for binding and see the action partially through the exhaust side. If this works you should be okay. Orient the clamps and slide them onto the turbo for reinstall. Replace the Orings and lube with oil for the return line (still on truck side). Reinstall everything. Super easy. Watch videos if need be.

So now I inspect the Charge Air hose connections and intercooler. I see nothing wrong anywhere and I am careful. I also clean the MAP hose fitting and inspect the MAP hose. All is good. I see the Engine Crankcase Breather O-Ring is bad. Turns out a thin large A/C O-ring is a good replacement. Otherwise its a 30-40 dollar hose. Everything is perfect. at this point. Idle Smooth and so on. I needed Fuel Filters and Oil Change anyways so I did my maintenance before test driving.

Vehicle drove worse on this test drive than before start of repair. I immediately went on to diagnose drive-ability issues. The turbo sounded healthy so I suspected something else was the cause of low end power loss and massive lag.

I saw no issues with work and noticed same code coming back nearly immediately. I contacted an old colleague and borrowed a Matco Maximus Scanner. Super neat tool.

I was able to verify all electrical circuits were okay and data streams appeared plausible (more on this to come). I didn't like to VGT position being at 15%. I read never 15% or 85% is what you want to see. So I agreed this was suspicious. I got the engine hot and pulled the VGT Solenoid. I reinspected it and Ohmed it. The unit was very hot as it should be and ohmed 4.6 which was good. I knew this worked and I knew the PCM could send it commands and it would respond. However, I was suspicious as under load pressures there is no way to see its performance on this truck. There is an inspection port and you can get a transducer with the Ford IDS System or I could have perhaps gotten a Fluke O-Scope Pressure Transducer on the port and monitored the VGT Waveform and the transducer. I would have loved to, but I didn't have quick access to these resources.

Between Driveability issue and my experience I knew to suspect the VGT Solenoid. I noted a few things from data stream. EGR Position was out of range. The EBP showed what appeared to be good but I took note on three readings and had to dig deeper to understand the theory and operation. I will outline this last....

I took out the EGR and it looked really good. I cleaned it anyhow and ran it open and closed. I was able to clean the valve faces and seats. That guy looked closed. I suspected an issue causing a false stuck open reading on EGR valve, but I was cautious as it takes almost nothing to stick open an egr valve. Also, aside from a smooth idle the drive-ability characteristics could have been classic egr stuck open.

So I replaced the VGT Solenoid. and BTW it looks as if you can just get the Garrett version. Its half of what Ford OEM is and this is a garret Turbo/VGT and the VGT is common to other makes too.

The truck was running so much better. So lets say to the level of normal testing the VGT Solenoid tested okay, but it was weak and causing the VGT to not be in the perfect/commanded position. The truck was now running very close to perfect and the check engine light and codes came back.

I had studied the theory and operation of the data for EBP and here is some good intel for the average Joe or even mid level technicians. The MAP signal is a variable as it is related directly to sea level. Hence the Ford PCM treats it as such. let us call the EBP Sensor Values something like an algebra formula where X=Atmospheric pressure. And in SoCal Im almost at sea level. So Ford needs Algorithms that work here as well as Denver. so it doesn't have a hard value or learned value. You have to do a little math here. The Difference between Atmospheric Pressure and Engine Exhaust Back Pressure Absolute needs to match Exhaust Pressure Gauge (Matco's definitions could be different elsewhere I suppose) needs to match up exactly with BARO and MAP pressure signals and boost pressure. If it does not you have a bias and a mechanical failure most likely in the EBP sensor transducer. In a running engine the exhaust back pressure fluctuates. So Key on Engine Off is where I did the math. First check... The MAP Baro and EBP seemed closely matched. This shows me functioning sensors and plausible values. Second when I disconnect electrically the EBP it shows max pressure (around 36) and this shows me functionality is there. When I did the math I had a .8 to 1 psi variance. I will call this a bias and it was to the positive side of pressure (hence drive-ability issue). To me this confirmed a suspicion that EGR gets it's open signal from EBP so therefore that was the cause of (no code) it's out of range data stream.

So I went to ford and got the OEM sensor. Quick install. No signs of wire failure so no pigtail. Cleared the codes and retest. Truck runs like it did in 07. No kidding.

So this is a great snap shot of three problems of which were mechanical in nature and the codes where useful but not indicative of the solution. There was repair efficiency and a logical approach. I do not throw parts at problems. So this was done in the carefullest manner I could muster in a driveway scenario. Turbo being stuck probably lead to the stress on the VGT Solenoid and the EBP may have developed a Bias during cleaning, but it is not something easy to see without a known good voltage to reference. There is no electrical fault in the EBP it is a pressure transducer issue.

Anyone who is experiencing this issue I would suggest doing the EBP, VGT and Turbo refurbish. Clean the ports and tubes and do best practices. Use quality OEM EBP and Seal kit and I would prefer VGT from OEM but the aftermarket is half the cost and has a longer warranty. Seeing as how the VGT Solenoid is a sub 1 minute removal and install I was okay with it.

I will also say that this truck had stiction injector issues in the past. I used Marvel Mystery Oil in my engine for a long time and it cleared up. Been completely gone for two years now. I ran a compression balance test for fun and saw 0 defects. The Injectors all looked good when I tested for fun.

I think my OEM truck has great power and while I am tempted to tune it I am equally tempted to leave it alone. I always said maybe after 100k.

I know this is a novel but I wanted to lay everything out flat for anyone struggling with it. You probably won't prove up electrical failures and you really need to do the math a deduce the problems.

I will tell you this. I am sure if I started with replacing EBP sensor I would have cleared the codes and had a sluggish 6.0 with a frozen VGT issue and no codes. I am quite happy I fixed all the issues not just the CEL.

Thanks for reading!!!!!!!
 

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Good post, thanks for the info.

I was having some VGT issues on my last truck. After pulling hills, I would back off on the pedal, boost would come down, then it would "stick" and I would have no power. After throttling on and off a bit it would free up and turbo would work again. VGT would max at 85% while doing this. Pulled and cleand/rebuilt the turbo, swapped in a good used unison ring (mine was slightly divoted is all at the pin).

On a long trip it was still doing in. Mid trip I swapped out the EBP sensor, no change. Got to my race, and pulled the turbo again, cleaned what I could, resintalled. No change.

I got home and got a good code from a buddy and rebuilt that one. That fixed it, I suspect it was the VGT solenoid all along.
 

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Discussion Starter · #3 ·
Wow, that’s awesome. I’m glad you got your truck fixed and you truly had a good grasp on everything. Most repairs get down to a root cause of failure and usually it’s one underlying issue. Thats what made this interesting. There were three related failures. EBP is sneaky when it fails this way. I like failures where there are no codes or codes which are not narrowly focused. Logic Chain Faults——
 

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Yeah, I had no cides with mine. Just the intermiitent lack of boost, and maxing out VGT % on the scanner. SInce the VGT isn't monitored, the Ford PCM only shows commanded VGT. Where on a Duramax with the same turbo it monitors actual VGT position.
 
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