Ford Powerstroke Diesel Forum banner

1 - 13 of 13 Posts

·
Banned
Joined
·
76 Posts
Discussion Starter #1
looked at a 7.3 excursion 03 today. when i first started it, it made a horrible noise almost like an exaust leak but once it ran for id say 45 seconds it went away? whats that all about. other than that for a 7.3 it was fast. drove it for about 10 mins and it was quick i loved it.
 

·
Registered
Joined
·
1,726 Posts
could have been the exhaus back pressure valve. was it a loud hissing sound? It turn on when its below 40-45 degrees ..I think?
 

·
Banned
Joined
·
76 Posts
Discussion Starter #3
yea it was hissing and it sounded identical to an exaust leak but it was 70 degrese yesterday
 

·
Registered
Joined
·
1,726 Posts
yea sounds like the EBV. It normally only turns on when its cold to warm up the engine quicker. I have no idea why it would have turned on. Just look into it a bit more if your loking at buying it
 

·
Registered
Joined
·
281 Posts
Good link here, tells you all the PCM/control functions and when they operated, EBPV is just a little ways down the page. 70 Degrees shouldn't have turned it on though, you'll see that the only two inputs are IAT (intake air temp) and EOT(engine oil temp), if these sensors are bad or acting funny it could have tripped it on.

Powerstroke
 

·
Banned
Joined
·
76 Posts
Discussion Starter #6
ok yea it didnt throw and lights or codes
 

·
Registered
Joined
·
6,168 Posts
I would say it had not been started for a while and the EBPV came on... Normal.
 

·
Banned
Joined
·
76 Posts
Discussion Starter #8
yea he didnt have plate on it. he cant afford the price of diesel so he said it was just sittn. fired right up with no problems though.
 

·
Registered
Joined
·
281 Posts
ok yea it didnt throw and lights or codes
It may or may not throw a code because the imputs (EOT, and IAT) are a little out of wack, you could have bad sensor on either of these two, or an intermittently bad sensor on the two and still not throw a code. Since those are the only two sensors that tell the EBPV to cycle on (which is what it did in your case) that would point to one of those two acting up.

I had a bad Exhaust Back Pressure Senor (EBPS) that was bad and it stored the code in the PCM but didn't throw a light, don't get confused the EBPS does not have anything to do with the EPBV cycling on, it is another imput to the PCM which controls when the EPBV will cycle off.

Here's how it works.

IAT is Below 37 degrees (50 degrees some models)
AND!
EOT is Below 140 Degrees (168 degrees some models)

Then the EBPV will cycle on. Note Both parameters have to be met, When it's 70 degrees out(in your situation) and your engine is cold, the IAT parameter is NOT met, but the EOT parameter is met ( your oil temp will be equal to 70 degree ambient temp on a cold engine) Both Parameters have to be met

Now with the EBPV on, and you hit the throttle depending on the load the PCM will kick the EBPV off so you have normal power of the motor, it does this by monitoring the input of the Exhaust Back Pressure Sensor (EBPS), the more you hit the throttle the more load you want, hence the Exhaust pressure goes up and the PCM kits off the EBPV to allow you to maintain that load.

Long story short your PCM saw both Parameters (IAT and EOT) were met based on what the sensors were telling it, so one of the sensors is probably acted up.

Make sense to you?

If it doesn't come on again at below 70 or 50 or 37 I wouldn't worry about it, it comes back I would be willing to bet the IAT sensor is the problem
 

·
Banned
Joined
·
76 Posts
Discussion Starter #10
ok thanks, yea it only did it once i turned it off and let it sit for a bit then started it again and nothing it sounded great. thanks for the help. anything ii should look for this would be my first diesel?
 

·
Premium Member
Joined
·
340 Posts
Lol, I guess I must be the only one that likes the hissing. It's funny when people walk by and the valve is closed.
 

·
Registered
Joined
·
1,086 Posts
well maybe find out if they have ever had anything done with the cam sensor cause there is a big ford recall on them right now it is free to do just good to know if they have done it already other than that there is a big write up in the 7.3 forum page i think about stuff to look for when buying one of these vehicles just good info to knwo
 
1 - 13 of 13 Posts
Top