[Sweway Racing]

Hi. I have a F250 99 7.3 that is slow as dirt.

I have chased this problem for a while now and I´m starting to run out of stuff to replace.

THE PROBLEM:
I´m building about 7psi of boost without a chip, with MASSIVE turbo lag.Throwing code P1248 (No boost detected)
With a hypermax switchable maxchip (330+) i got up to about 15psi. Still with some turbo lag. Throwing code P1247 (low boost pressure detected)
Second to no black smoke. No whitesmoke at startup. Running fine and firing on all 8 at all times.

THINGS I HAVE TRIED/CHANGED:

1. Have tried disconnecting red vacuum line and wired the wastegate shut. No difference at all.
2. Have had the turbo out of the truck checking both wastegate and ebpv. Nothing wrong, the turbo is i great condition. (No play, good turbine wheel)
3. Have resealed the HPOP and IPR valve.
4. Have changed MAP sensor. No difference. Also checked for leaks, all fine.
5. Have changed ICP sensor.
6. Have changed exhaust back pressure sensor and line.
7. Have changed IDM.
8. Buzz tested the injectors. All sounds nice and crisp.
9. Have compressiontested the engine all fine, no blowby.
10. Have pressuretested the whole charge air system up to 2.5 BAR (36PSI) all good.
11. Have cleaned the pickup in the tank and changed the fuelfilter.
12. Changed the original exhaust for a 4" straight pipe.
13. Hooked up a fuel pressure guage, under no circumstance will it drop below 4BAR (58psi) no matter
the load I put on it.
14. Checked the IPR%. Flat out about 40% (under a load) and about 8% @ idle. I think thats All ok?
15. ICP. Have yet to hook up a machanical guage to see a true pressure. The ICP pressure is fine when
i look at it in the laptop.

At idle It stays at 3300-3400KpA (475-500psi)
At Full throttle under load 17000 KpA (2460psi)
In all records ivé found these are ok values...?

Think I got most things Iv`e changed and tested chasing this problem...

The truck has 247k miles on it without tuning. Had no hitch registered in Sweden, so I´m positive he didn´t tow with it since 2006 (when the truck got imported) Have no idea if it was towing in the US before it came here.



This is a well maintained, clean truck.
I Build racecars in all my free time and think I know my way fairly well around engines/cars and trucks.

Do anyone have a good recomendation on what to do next?

 

[Jack-Stand]

This may be a silly question, but have you checked to see if the signal line to the MAP sensor from the spider is plugged and/or cracked?

 

[Sweway Racing]

Yes i have.
To be shure the mapsensor is reading corectly i also hooked up a "real" mechanical guage. The mapsensor pressure reading I get on the laptop is matching the accual pressure so im pretty shure the problem isn´t mapsensor related...

 

[Mike Gs]

Any exhaust leaks pre turbo?
Up pipes/ manifolds?
My up pipes had leaks under the collars. Could not see the holes until they were removed.

 

[Hydro]

Do you think the EBPV is opening all the way? A lot of people delete this troublesome valve, if it is not opening could be your problem.

 

[Jack-Stand]

Do you think the EBPV is opening all the way? A lot of people delete this troublesome valve, if it is not opening could be your problem.

Can completely vouch for this... also it can be a huge pain point as far as turbo reliability and oil leaks... The valve got stuck open on my truck and toasted my turbo (starved my turbo of oil)... EBPV delete was done with the turbo

 

[Jack-Stand]

What does the compressor wheel look like? You mentioned the turbine wheel, but not the compressor. Are all edges fine, with no chips?

When you did your pressure test, how did you pressurize it, and what all was hooked up? We're the spider to intake plenum boots Included, or was only the tubing/intercooler boots/intercooler tested? Have you checked to see if the O-ring from the spider to compressor is ok? How about the compressor housing to compressor baseplate O-ring?

 

[Sweway Racing]

Have checked the up pipes with the transmission out of the truck, so I´m quite shure a leak is not the case.
Had the turbo out of the truck and checked the EBPV. Nothing mechanically wrong with it, have unhooked the actuator and wired the valve open, no difference.
Also I have no "hissing" sound wich you would get in the case it is partially closed?

When I pressuretested the system it included the intercooler, intercooler piping, spider. Basically everything above the plenums.

Yes the compressor wheel is looking fine, You can see it`s been used with a little bit of ware on the outer edge of the blades but we are talking minimal, nothing that would effect the power output this way.

The compressor o-ring towards the spider is in great shape.

Missed checking the compressor housing toward baseplate o-ring. Common failure?

I was out mind******* myself driving around with the laptop hooked up and while I was driving around I reset the codes and tried replicating it. BUT NOTHING....

So I´m smelling somthing fishy with the PCM...
I should be getting a P1247 or 1248 since I get no boost at all until after 15 seconds or so holding it to the floor, and after that I´m getting about 7psi.

Will change PCM next since it´s the least amount of work...

Other suggestions?

 

[Jack-Stand]

I'm not sure about the PCM, so I'll let someone else chime in, and the compressor O-ring isn't that common, but that's about all you've got, or so it sounds.

The thing that I'm struggling with is that what your describing is thermodynamically impossible. If you truly got the wastegate wired 100% closed, there's no other place for the input mass flow rate to go (turbine side). That means that all heat input (with efficiency losses) HAS to be put into the compressor shaft and therefore the compressor wheel. Considering you've confirmed your pressure readings with a mechanical gauge, you've basically got
3 options. 1) you don't have the required mass and/or heat input to the turbine side of the turbo, whether that's leaks in the up pipes, choked flow from the EBPV, open wastegate, etc. 2) there's a leak in your system that truly isn't allowing it to pressurize and it failed after your pressure test (Leaky intercooler boot, etc.) 3) the turbine and/or compressor wheel is damaged beyond what your eyes can tell is acceptable, or the housings are damaged, tolerances opened up and they're allowing enough bypass flow around the wheels that the fluid isn't getting and/or receiving any work from the blades themselves.

 

[Sweway Racing]

The truck is an early 99 and therefor had the notorious issue with the front windshield sealant desolving the primer, letting go of the windowframe and letting a signifacant amount of rainwater to get into the cab and down behind the dash, into the glovebox, fusebox etc.etc. I rebuilt the fusebox...( the truck was doing all kinds of wird s**t at any time...(horn, lights, fans etc going off))

The pcm may have been waterdamaged during this time, to me it feels like the truck is defueling. Otherwise I shold be getting SOME blacksmoke??? I´m getting basically none.

I can almost put my head on the line saying that the turbo is not the issue.

And why would it stop throwing the p1247/48 codes all of a sudden when the truck still isn´t building any boost?

Talked to a lokal shop that has access to Ford troubleshooting documents of some sort, both P1247 and P1248 points primarily towards a bad MAP sensor, and secondly towards a damaged PCM.

If this does not work I will ofcourse have to go back looking at these things but I have been quite thurow doing all this testing and troubleshooting.

 

[Jack-Stand]

I'm not arguing that your PCM is potentially damaged... What I'm getting at is that there's no way for your turbo to bypass or divert flow other than the wastegate... Which the wastegate doesn't divert flow, it simply diminishes the mass flow that the actual turbine is seeing, and therefore the compressor... So if you actually got everything wired closed like you said, the only way you're not going to build boost, even for a split second before it starts to defuel is that you have what I described earlier... Sounds like death by 100 cuts

 

[Jack-Stand]

Also, if you're defueling, you'd see it in your IPR. If the truck was actually defueling, you'd see the IPR going open to pull pressure off the oil side of your injectors. What's your IPR doing when you get into it? It'll fluctuate with engine load, but when you're getting into it, it should be closing in order to provide your injectors with more pressure.

 

[Sweway Racing]

I´m with you on the fact that the pressure has nowhere else to go than through the wastegate(as long as there is no leak). The only thing that could be holding back boost except for leaks is fuel...
The IPR% will stay at about 40% as long as my foot is to the floor (it varies with the load). I see your point but I´m at a loss and at this point it can´t be much else other then the pcm unless I´ve missed something in my initial troubleshooting...

 

[Sweway Racing]

What I have noticed that gets me thinking fuel is that when it shifts I get a spike in boostpressure as the rpm drops... 1 sekond or so later I´m back no the usual 7psi, or 15 in case of the chip being plugged in.

 

[Hydro]

Something else to consider is the actual waste gate valve, it is just a stopper valve that plugs a hole in the exhaust side of the turbo. You have wired it shut, but does opening it make less boost? Possibly the little stopper valve went bye bye out the exhaust pipe.

The pcm or some of that funky(wet) wiring you referenced could also be the culprit, gotta have good connections.

 

[Jack-Stand]

When you say it's surging when you get out of it, how much are you howtaking and long does it last? If it was a gasser, I could understand because the throttle body would cause that exact thing, but on these, there's really no way for that to happen... Only real way would be that the wastegate tried to close immediately after you let out of it.

What's making you think that it's a fueling issue that's causing boost pressure to surge? If it immediately tried to "refuel" once you got out of it, I'd think you'd notice the truck surge a bit along with the boost pressure.

 

[Sweway Racing]

Something else to consider is the actual waste gate valve, it is just a stopper valve that plugs a hole in the exhaust side of the turbo. You have wired it shut, but does opening it make less boost? Possibly the little stopper valve went bye bye out the exhaust pipe.

The pcm or some of that funky(wet) wiring you referenced could also be the culprit, gotta have good connections.

I did split the turbo on the hot side and checked the wastegate valve when I had the turbo out, thinking it may be damaged or missing... It was fine.

 

[Sweway Racing]

When you say it's surging when you get out of it, how much are you howtaking and long does it last? If it was a gasser, I could understand because the throttle body would cause that exact thing, but on these, there's really no way for that to happen... Only real way would be that the wastegate tried to close immediately after you let out of it.

What's making you think that it's a fueling issue that's causing boost pressure to surge? If it immediately tried to "refuel" once you got out of it, I'd think you'd notice the truck surge a bit along with the boost pressure.

It did not surge when I got out of it, it did when it shifted...with the foot still to the floor. I can´t do anything else then agree with you that it is a wierd behaviour.

My suspicion is that the PCM sent data that was corrupt to the IPR, but still sending what would be the "right" or "optimal" data to the laptop. The way to see that would be to hook up a voltagemeter to the IPR valve and watch the signal real time...:/

No Matter what I finally solved it. My father has a E350 with a 7.3 so I stole his PCM...the truck runs great!!!

Thank you for the support guys!

 

[Jack-Stand]

That's interesting, but good to know.

Glad you got it figured out!