My AE software shows a DTC for the exhaust backpressure sensor (sensor is bad). What does this sensor do if it is bad? For that matter, what does it do when it works? I have heard that someone offers a plug that does away with this sensor and stops the code from comming up. What are the dis-advantages and/or advantages of doing this?

 

I was told that if the SES light come on then you engine will start to defuel. If the light doesn't come on then there is no problem. I just bought the plug that you mentioned and it got rid of the P0476 code but it triggered a P0472 code. THat code is a low voltage code. In hindsight if your ses light is not coming on I would save the money for something else.

 

I bought the plug to get rid of the P0478 code, but mine too now has the P0472 code. The exhaust backpressure sensor, which gets it's reading from the passenger side manifold, does a couple of things. For one, I've been told that it does de-fuel if the exhaust pressure is too high (the P0478 code). Kwikk did a test of sorts by flipping on his exhaust brake (the stock EBPV rigged on a switch) then flooring it. He saw no rise in the EGTs but didn't have power either. Thus, indicating that it does de-fuel if it senses too high of an exhaust backpressure. This can be a problem in modified trucks which are running higher than stock boost levels. It senses too much pressure in the exhaust and de-fuels. This is what the code eliminator plug from Black Cloud is supposed to eliminate. Second thing the exhaust backpressure sensor does, is if your EBPV is stock and not modified for an exhaust brake, the sensor will open the EBPV when it senses too much pressure. Of course, this is only happens on cold starts when the EBPV is operating, since the EBPV is designed to help the truck warm up faster. Now, a problem may arise if you have a stock EBPV hooked up and you get the code eliminator from Black Cloud. That is, the truck may close the EBPV when cold, but have no way to know that it needs to be opened since you are overriding the exhaust backpressure sensor with the code eliminator. So, you run the risk of having no power and possibly sending the EGT's skyrocketing.

Since I purchased the code eliminator, both of these things have come to light for me. So, I unhooked my EBPV and have it wired up to function manually. That way, I can use it to help warm up the truck and as an exhaust brake, but it will not have the problem of staying shut if I don't want it to.

I've never had the SES light come on just due to the exhaust backpressure sensor though. Kwikk's test made me see that the truck is most likely de-fueling when it sees too much exhaust backpressure, and since I am running higher than stock boost levels, I decided to purchase the code eliminator so my truck won't de-fuel. If you're looking for power, I think it's a decent invenstment at $30.00, but be prepared to modify your EBPV too (if you haven't already) so you don't run the risk of high EGT's and damage to the engine.

 

Not faulting the test or the logic behind it, but I don't believe that is an indicator that the truck defuels. When the backpressure valve is closed the turbo can't spool, and if the turbo can't spool the MAP reading is way low for the RPM reading, so the PCM doesn't know to add any more fuel.

When the truck defuels, it simply selects the lowest fueling curve available in it's programming, and that only happens when the SES light is triggered, and it will remain in the "defuel" mode until the next drive cycle.

 

I'm with you cookie, not faulting the logic behind the test because it does make sense to me, but I'm not sure if there's really a way to tell if the truck de-fuels. That is short of asking a Ford engineer or programmer that designed the fuel programming for the truck. I mean, even in an over boost situation when the truck does de-fuel, I can't really feel it. The truck keeps pulling/accelerating and doesn't fall flat on it's face. I do wonder though, if the sensor's readings and the computer's interpretation of those readings is in the programming, would a chip overcome how the computer sees the sensor's readings? I know the programmers don't because my Predator still caused the P0478 code.

 

You're right that it is difficult to feel a difference, but you can see it quite clearly on a dyno. It defuels about 20-30 HP worth on a mildly modified PSD. That part of the PCM's programming cannot be addressed by a chip or tuner.

 

I guess that's why we have to use such wonderful devices like the pressure regulator on the boost line and the code eliminator for the exhaust backpressure sensor.

Do you know of anything else that would cause the truck to de-fuel, besides these two? The over boost and exhaust backpressure sensor (which is still up for debate).

 

As far as I've been able to tell, if it turns on the SES light, it also cmmands the lowest fuel setting from the PCM....But that does not address the ICP codes, which can be set by almost any chip or programmer. I'm not sure how, or if, they're getting around it there....maybe the agressive IPR duty cycle does the trick?

 

ICP codes are nothing I've got any experience with. I remember occasionally seeing it in the code list, but it never triggered the SES light to stay on. In fact, the only time I ever saw the SES light even flash was during over boost. But, I guess the ICP codes probably were triggered at the same time too.

 

I am actually getting a P470 code. It is there all the time. I cleared the code, didn't start the vehicle, hooked back on and it was back. I assume this mean that the sensor is faulty. What are the advantages/disadvantages of simply replacing the sensor vs one of the "fixes" that Black Cloud offers?

 

If you're getting a P0470, try removing the sensor and inspecting it and the tube it bolts to. I'll bet you dollars to donuts that one or both is packed solid with carbon. That's exactly the situation I just ran into with my truck. I ramrodded the tube coming off the exhaust manifold, then started the truck with the sensor still disconnected to blow all the crud out the tube instead of through the turbo. Then I carefully (and I stress CAREFULLY) removed as much of the carbon from the sensor as I could with a small pick. Reassembled everything and started it up - no more P0470.

 

Good call. Worth checking out for sure. You can use carb cleaner to break up/flush out the end of the sensor.

westpsd: If you "delete" the EBP sensor and leave the EBP valve active, you'll get the same P0472 (low input) code that jtharvey is dealing with....and the valve probably won't work anymore.

 

I do have that code. Although, I would tend to think that a "low input" code is not causing the truck to run any differently. No defueling or the like. I would think that a P0472 code is more of an FYI that the sensor is clogged or for some reason not working, but not cause a running issue.
Any thoughts?? I might need to call Black Cloud tomorrow to ask what's up with me still throwing a code even though I've got their code eliminator in place. But their eliminator was only designed to stop the P0478 (high input) code.

 

I just got off the phone with Black Cloud. They tell me that the P0472 code does not cause any de-fueling or performance related issues. They do make a new code eliminator that does address and eliminate all codes. It's $69.00, but not on the website yet. The guy at BC also said that the reason they developed a new eliminator to eliminate all codes, if the old one wasn't causing a performance issue, is that some scan tools will not let you continue until all codes are cleared. The new eliminator is designed so that those scan tools can continue if you wanted to run a code eliminator.

 

Good info...thanks.