Wastegate - Sucking air - 99 7.3 PS
 

I have a 99 F350 7.3 Powerstroke. My truck was manufactured in July of 98.

The problem that I am having is mainly in the winter time when it is cold. I live in Wyoming. Whenever I first drive my pickup, it sounds like it is sucking extra air and I have loss of power. If I let off of the throttle and punch the throttle it will get the truck to quit sucking extra air for a bit, but eventually it will starting sucking extra air again. It only does this when the engine is cold from not being run down the road. It will even do this after I idle the engine and start to warm the engine before I drive it or even if I idle the truck up to operating temperature. Generally, after I have drove the truck for about 5 miles or so at a good rate of speed, it will quit all together.

I do not have any of these issues in the summer time.

I had one of my daughter's male friends mention about wiring the wastegate either open or shut, I can't remember which one, but I would rather not do this as I don't like over riding controls on my vehicles.

My question is this: Do I only need to replace the waste gate actuator or the whole turbo or could there be a temperature sensor for the waste gate that is bad causing it to not work properly in the winter?

Some of the 7.3 engines especially in cold climates have an exhaust back pressure valve that is designed to close in cold weather which causes an exhaust restriction to warm the engine up faster. It sounds like it is closing at the wrong time. It would make a hissing noise and severely limit engine power. It is mounted on the bottom of the turbo. Tying the waste gate closed is not a good idea because it can cause the turbo to overboost the engine and damage it.

If the charger overboost it will fail and most likely cause a catastrophic engine failure when chunks of wheel go through the valves and everything else. Alot of times the EBP sensor will fail and cause the symptoms you describe!

That sounds exactly like what is going on with my truck. It does sound like a hissing noise and like I said, I do have loss of power as well. Is this something that I will have to remove the turbo to fix or does it have a sensor that needs to be replaced to fix the problem. I will also look in my manual as well for this back pressure valve.

Could be the sensor, After it warms up is it not cutting off? It should remain on until a specified temp or a time out action takes place, at which time the valve opens. Sometimes they hang. There's also a peice that deletes the warm up valve all together!

Its also called a "turbo surge". It will surge until the truck warms up. The amount the turbo surges can be based on your exhaust length and diameter.

No...All 7.3's had a warm up valve. A turbo surge isnt caused by the truck's temps.
And has NO affiliation to exhaust size or length


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Let me explain in better detail so no one gets upset.
Turbo surge is caused by lack of drive pressure around the turbine. When pressure drops the turbo lacks the pressure required to the compressor side. Things that cause this are up pipe leaks, incorrect housing sizes, incorrect wheels , insufficent fueling.

Now, if this was the problem, the truck wouldnt exhibit this only while cold except for the lower exhaust velocity produced while cold. Turbo surge is visible in the boost gauge for the most part and you'll hear a sound SIMILAR to what your talking about but would be a miss type symptom, almost like instant power loss with the sound. Then power would return to normal. Another issue that causes turbo surge would be wastegate issues which are controlled diffrently by the ECM at lower temps.


With that said, the most commonly seen problem is the warm up valve can and will operate above the temp parameter and therefore activate.

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The bold items are what I feel show that the problem being sought is the warm up valve. If it was surge, It would do it most all the time, if cold weather effects the truck enough to cause surge, there's a fuel issue in the first place. If it was a up pipe, it would be present at all times. I feel this shows a common failure of the warm up valve sticking or operating out of range. I'm not a powerstroke expert but diagnosing trucks everyday of the week leads me to this area. I'm not trying to say turbo surge isnt the problem, In reality i cant diagnose a truck from the computer. BUT all symptoms and signs lead to somthing OTHER than turbo surge!

My apologies

I did look in my manual and it did mention about a back pressure sensor.

What the manual says about it: The amount of "boost" (intake manifold pressure) is controlled by a "wastegate" (exhaust bypass valve). The wastegate is operaed by a spring-loaded actuator assembly which controls the maximum boost level by allowing a cetain amount of exhaust gas to bypass the turbine in accordance with the intake manifold pressure. An exhaust backpressure sensor is used to detect exhaust system backpressure information for the PCM.

What I am thinking that is happening after reading the posts is that when it gets to be colder temps, my sensor is sticking or not registering correctly and once the whole engine compartment warms up sufficiently, it then makes this sensor work correctly. I am almost wondering if through the course of the years that it hasn't gotten condenste into it and in the colder temps, might actually be frozen causing it to not work correctly. I started owning this pickup when it had 144,000 miles on the engine and it currently has a little over 308,000 and I have yet to replace that back pressure sensor.

Now let me ask another question on this. Could that also be possibly causing this truck to have a litle more problem turning over in the winter as well, cause I am assuming from what it sounds like that this is almost like the flap on a carburator that will come open once the engine warms up to temp?

Well Like Mystery said it is hard to daignose from a computer. but it doesn't really sound like anything is out of the ordinary to me.

And you are correct about the flap part. The only difference is that it is in the exhaust after the turbo. It operates the same as a exhaust brake. And actually you can buy a DP chip and load a tune on it that turns it into exactly that. OR do a DIY with just a switch.

Now my friends 99 PSD sounds like a damn jet when that thing closes. But he also has a 5" exhaust and a straight pipe. His will also start doing it after it sits and idles for a little while. However his cancels when he touches the throttle (or brake I Don't remember). In which case yours could be hanging up. THE EBPV uses oil pressure to operate which could also be sticking.
The EBPV solenoid is part of the turbo pedestal put the valve is located in an right after the turbo.

EDIT: I just realized you had an early 99. They had different turbos and different pedestals than the late 99. However everything should operate the same. My best guess is something is sticking. However you could also measure the voltage of the wire going to the solenoid. It should have 0 volts on it after you touch the throttle. If it doesn't then the PCM isn't cutting off the signal for some odd reason.

You could also try cleaning the Exhaust back pressure sensor and tube as well. http://www.guzzle7pt3.com/ebps.html

EBPV Closing while driving - Diesel Forum - The Diesel Stop.com

More detail about the sensors http://www.thedieselstop.com/forums/...2/#post1699432