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nyt nyt is offline
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Question Exhaust back pressure - 11-03-2014, 12:43 PM

Due to suspicion of clogged cats I'm going to hook up a back pressure gauge to my exhaust soon and monitor during a pull. What range would you expect to see here? I imagine it shouldn't be much under ideal circumstances.


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blackhat75 blackhat75 is offline
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Default 11-03-2014, 02:02 PM

you probably don't have clogged cats. I much more common issue is low exhaust fluid. the symptoms are the same. just fill it to the full line and your done.
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Default 11-03-2014, 02:31 PM

Wtf! Exhaust fluid?????? What fluid are you filling in your exhaust and to what level?

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Default 11-03-2014, 04:12 PM

Getting consistent and large timing pulls at around 5000rpm across all the cylinders then it recovers around 6000rpm. I've added fuel, removed fuel, pulled timing, etc. Running E70 still seeing it. Can't think of anything else that cause that. Going to hook the gauge up tomorrow and do a pull, just curious if anyone had an idea of the range this should be.


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Default 11-03-2014, 06:03 PM

Map 4 with E70. Targeting 13 degrees advance and 12.3 afr. AFR held dead steady here.

I'm hoping its clogged cats, will be an easy fix if so. I've never tested a performance car with this gauge, so not sure what to expect under WOT. It shouldn't be more than a few PSI I imagine.




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Default 11-04-2014, 07:27 AM

Quote:
Originally Posted by nyt
Map 4 with E70. Targeting 13 degrees advance and 12.3 afr. AFR held dead steady here.

I'm hoping its clogged cats, will be an easy fix if so. I've never tested a performance car with this gauge, so not sure what to expect under WOT. It shouldn't be more than a few PSI I imagine.


Sad to see it's more than just cylinder 5 now

You running a SMFW or DMFW? I recall timing problems at high load in some set ups with DMFW.
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Default 11-04-2014, 10:30 AM

Quote:
Originally Posted by drfrink24
Sad to see it's more than just cylinder 5 now

You running a SMFW or DMFW? I recall timing problems at high load in some set ups with DMFW.
6AT. Going to go test this in a minute.


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Default 11-04-2014, 10:40 AM

how many miles do you have on the car? i'm assuming you're talking about your two rear cats as you've removed your two fronts when you installed your *********. I've had dirty cats when my stock turbos were going out. they were burning a qt of oil a week. the ECM continuously through codes for inefficient cats(can't remember the codes off hand). I think if you had clogged cats, even alittle, your ECM would let you know. ...did you check your exhaust fluid for contamination? Might wanna just flush it to be safe.
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ShocknAwe ShocknAwe is offline
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Default 11-04-2014, 02:18 PM

flush it. lol


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Default 11-04-2014, 02:40 PM

61k miles, got it on the lift late, didn't feel like pulling out the ********* to get to the rear o2 sensors, too much of a pita to reach. Yes rear cats. I'm just going to drop the exhaust, cut it, gut them, and then weld it back up soon and see if its any better :/


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Default 11-04-2014, 08:50 PM

While they're off go for a drive and see if that was the problem before going through the trouble of gutting them.
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Default 11-05-2014, 03:47 AM

Quote:
Originally Posted by loesch
While they're off go for a drive and see if that was the problem before going through the trouble of gutting them.
+1
Just unbolt exhaust from cats you do not need to remove the exhaust then go drive, it will be loud but if there clogged the power will be back when you go wot.


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nyt nyt is offline
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Default 11-05-2014, 11:14 AM

Quote:
Originally Posted by deltalima0
+1
Just unbolt exhaust from cats you do not need to remove the exhaust then go drive, it will be loud but if there clogged the power will be back when you go wot.
The exhaust is solid from the ********* back. No bolts.


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ShocknAwe ShocknAwe is offline
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Default 11-05-2014, 11:25 AM

Quote:
Originally Posted by nyt
The exhaust is solid from the ********* back. No bolts.
I think they're saying go test without the midpipes attached.


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Default 11-05-2014, 12:28 PM

NYT, according to your logs, your midpipes are not clogged.
if it was the case, you wouldn't be able to reach your boost targets.

just try without your midpipes to be sure(yes, it'd be louder).


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Default 11-05-2014, 04:39 PM

Just unbolt from the back part of ********* you can leave everything attached back pressure will be released dumping under car from the ********* it will be loud as **** but it will do the trick to check if mid cats are clogged


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nyt nyt is offline
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Default 11-05-2014, 11:06 PM

yeah, gonna do that soon I think.

Once the car is warm timing pulls are far worse. Going to be silly loud.


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