Exhaust system clogged?
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Exhaust system clogged?
Background info - My truck (86 2.9 EFI V6) was running rough and it seemed to be fuel related; I must have been partly right, because when I replaced the in-tank fuel pump and the fuel filter, it ran much better. It's not completely fixed though.
Current scenario - From a cold start, it cranks and idles fine for a while. After a few minutes, it start to sputter and blows black gunk out the tailpipe. Then, it will idle back up like nothing ever happened. Sometimes while driving it will also start to sputter. If I don't let off the gas, it acts like it is going to die, but then it seems to blow free and pick back up. I can also usually get it to pick back up if, when it starts to sputter, I clutch it and rev the engine.
I had it checked for codes, and the only code was something to do with the EGR (I don't remember the exact #). I've removed it and cleaned a clogged port, and that helped some, but it stills sputters and blows the black gunk.
I'm guessing something somewhere is clogged and chunks occassionally break free and cause the sputtering, but I'm not sure where to start. Any ideas would be greatly appreciated. Thanks
Current scenario - From a cold start, it cranks and idles fine for a while. After a few minutes, it start to sputter and blows black gunk out the tailpipe. Then, it will idle back up like nothing ever happened. Sometimes while driving it will also start to sputter. If I don't let off the gas, it acts like it is going to die, but then it seems to blow free and pick back up. I can also usually get it to pick back up if, when it starts to sputter, I clutch it and rev the engine.
I had it checked for codes, and the only code was something to do with the EGR (I don't remember the exact #). I've removed it and cleaned a clogged port, and that helped some, but it stills sputters and blows the black gunk.
I'm guessing something somewhere is clogged and chunks occassionally break free and cause the sputtering, but I'm not sure where to start. Any ideas would be greatly appreciated. Thanks
Fleet Mechanic
Joined: Dec 2003
Posts: 1,436
Likes: 117
From: Virginia
You probably do NOT have a clogged exhaust. If you did, it would most likely act up at all times, buck and stall and have no power or be really hard to rev.
There are a ton of tests you can do to determine the health of the engine. Since you seem to suspect a fuel issue, you should really do a fuel pressure test. Not to mention pulling the codes again to see what, if anything, the computer thinks is wrong. Some other tests that the computer won't help you with are a compression test, leak-down test, check your coolant for the pressence of oil, and your oil for the presence of coolant (this may tell you if you have a blown headgasket). Also, check every part of the engine for leaks as it is common for the 2.9L to develop cracked heads
You mentioned the EGR, and a plugged port, but did you check the tube that feeds the valve from the exhaust manifold? It can of course be a source of carbon build-up.
There are several places where junk can build-up in the engine and occasionally break free. Places like the intake manifold and throttle body, the head and combustion chambers, the EGR system, etc.... All of which will result in crap coming out of the tail pipe when it comes loose.
There are a ton of tests you can do to determine the health of the engine. Since you seem to suspect a fuel issue, you should really do a fuel pressure test. Not to mention pulling the codes again to see what, if anything, the computer thinks is wrong. Some other tests that the computer won't help you with are a compression test, leak-down test, check your coolant for the pressence of oil, and your oil for the presence of coolant (this may tell you if you have a blown headgasket). Also, check every part of the engine for leaks as it is common for the 2.9L to develop cracked heads
You mentioned the EGR, and a plugged port, but did you check the tube that feeds the valve from the exhaust manifold? It can of course be a source of carbon build-up.
There are several places where junk can build-up in the engine and occasionally break free. Places like the intake manifold and throttle body, the head and combustion chambers, the EGR system, etc.... All of which will result in crap coming out of the tail pipe when it comes loose.
Last edited by G2IC_Wraith; Apr 6, 2007 at 10:59 AM.
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