Exhaust Back Preasure
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Senior User
Joined: May 2008
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From: OR
Exhaust Back Preasure
I know the EBPV closes when cold to help warm the truck up faster. When should it open back up. I have heard of them sticking and I think that may be the case with mine.
My EBP gauge reads aroung 13 psi at idle when the engine is warm. When I start it on a cold morning it sits at 18 or 19. The other morning just after I started driving it(still cold) I noticed the EBP spike up to 32psi. It was just after I had got up to about 40mph and let my foot off the throttle. In normal driving conditions at full operating temp it doesn't go over 23psi. Usually rides around 17psi cruising.
So is the EBPV sticking closed or is it supposed to stay closed until the engine is close to warm.
My EBP gauge reads aroung 13 psi at idle when the engine is warm. When I start it on a cold morning it sits at 18 or 19. The other morning just after I started driving it(still cold) I noticed the EBP spike up to 32psi. It was just after I had got up to about 40mph and let my foot off the throttle. In normal driving conditions at full operating temp it doesn't go over 23psi. Usually rides around 17psi cruising.
So is the EBPV sticking closed or is it supposed to stay closed until the engine is close to warm.
Lead Driver
Joined: May 2007
Posts: 8,608
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From: Belair md
ok, let me try to explain this without confusion. the gauge key on engine off should read atmospheric pressure. the ebp, map and baro pid should all be within .5 psi of each other. 13 psi sounds too low, your sensor sounds biased to me. aside from that you also have to take into account that when your reading is 32 psi the exhaust backpressure is really 14.5 psi less then that to account for atmospheric pressure, so with a gauged reading of 32 its only actually 17.5 psi exhaust backpressure.
also, the ebp pid should be within a few psi of your map pid at all times (ebpv activated aside) since our turbos have a 1.15 ratio exhaust housing and a 1.0 ratio intake housing it wont be exact but close. the pressure on both sides is virtually the same, ebp reads exhaust side and map reads intake side.
also, the ebp pid should be within a few psi of your map pid at all times (ebpv activated aside) since our turbos have a 1.15 ratio exhaust housing and a 1.0 ratio intake housing it wont be exact but close. the pressure on both sides is virtually the same, ebp reads exhaust side and map reads intake side.
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From: OR
I'm at 3500 feet elevation which may account for the 13psi at idle. My sensor reads low at high elevations and the boost reads in the negatives -3 to -4 when I'm way up there(around 10K feet).
What worried me was the 32psi EBP when I wasn't making any boost???
What worried me was the 32psi EBP when I wasn't making any boost???
Lead Driver
Joined: May 2007
Posts: 8,608
Likes: 13
From: Belair md
what kind of gauge do you have? are you reading the pid on a scanner or an aftermarket mechanical gauge?
if its mechanical then the numbers dont sound too bad. even the 32 psi on the ebp is normal if the valve kicked on while driving (also normal) the valve is allowed to come on at any time under 1/4 throttle when the oil is cold. there is an ebp limit built into the pcm and i cant remember what it is, but 1/4 throttle is enough to set it off.
if its mechanical then the numbers dont sound too bad. even the 32 psi on the ebp is normal if the valve kicked on while driving (also normal) the valve is allowed to come on at any time under 1/4 throttle when the oil is cold. there is an ebp limit built into the pcm and i cant remember what it is, but 1/4 throttle is enough to set it off.
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Senior User
Joined: May 2008
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From: OR
It's an Aeroforce Scangauge. I have no mechanical gauages installed yet to compare it to.
That clears it up for me. Thanks. It must have shut while I was up over 2000 rpms and let my foot off the gas. Before the rpms could drop back down it maid some serious back pressure.
On a side note my EBP numbers dropped a couple of psi when I put the down pipe in.
even the 32 psi on the ebp is normal if the valve kicked on while driving (also normal) the valve is allowed to come on at any time under 1/4 throttle when the oil is cold. there is an ebp limit built into the pcm and i cant remember what it is, but 1/4 throttle is enough to set it off.
On a side note my EBP numbers dropped a couple of psi when I put the down pipe in.
