Clogged cat, how do I know?
- Thread starter Berra
- Start date
SikVSix
New member
Re: Clogged cat, how do I know?
If you have a temp gun you could take the temp in front and behind the cat. Should be around 100* hotter after the cat if its working.
And from that description it could be the cat, could be other things too Does it idle ok and only feels like its choking off under power or is idle poor also?
If you have a temp gun you could take the temp in front and behind the cat. Should be around 100* hotter after the cat if its working.
And from that description it could be the cat, could be other things too Does it idle ok and only feels like its choking off under power or is idle poor also?
Berra
New member
Re: Clogged cat, how do I know?
Well, the idle is o.k. but sometimes, when hot, i have 1600-1700nRPM idle so I have to restart the motor to get normal idle (about 700 RPM) I think I have to test the oxygene sensor. I just don't understand why I don't get any codes of whats wrong....just the knock sensor code.
I use the simple "paper clip check".
Well, the idle is o.k. but sometimes, when hot, i have 1600-1700nRPM idle so I have to restart the motor to get normal idle (about 700 RPM) I think I have to test the oxygene sensor. I just don't understand why I don't get any codes of whats wrong....just the knock sensor code.
I use the simple "paper clip check".
dgoodhue
BuSTeD 4.3
Re: Clogged cat, how do I know?
Replacing the cat is shot in the dark and its most likely going to cause boost control issues if you have the stock turbo.
I would start with the basics Make sure it has the correct plugs, cap, rotor, wires (make sure they are routed not to touch the exhaust manifolds or down-pipe). Replace the vacuum lines.
Replacing the cat is shot in the dark and its most likely going to cause boost control issues if you have the stock turbo.
I would start with the basics Make sure it has the correct plugs, cap, rotor, wires (make sure they are routed not to touch the exhaust manifolds or down-pipe). Replace the vacuum lines.
mattw
Active member
Re: Clogged cat, how do I know?
IIRC Code 43 is usually tripped when the computer attempts a self-test of the knock sensor and it fails. Basically the computer creates a scenerio that it knows will create knock(too much timing). It then listens for the knock and if it doesn't hear it it will throw code 43 and put you in limp home mode(reduced power, timing, boost).
You should hook up a scan tool and start logging with the engine off.. Then lightly tap on the block with a hammer and see if your knock counts increment. If they don't start troubleshooting your knock sensor, wiring from knock sensor to ecm, etc..
Good luck..
IIRC Code 43 is usually tripped when the computer attempts a self-test of the knock sensor and it fails. Basically the computer creates a scenerio that it knows will create knock(too much timing). It then listens for the knock and if it doesn't hear it it will throw code 43 and put you in limp home mode(reduced power, timing, boost).
You should hook up a scan tool and start logging with the engine off.. Then lightly tap on the block with a hammer and see if your knock counts increment. If they don't start troubleshooting your knock sensor, wiring from knock sensor to ecm, etc..
Good luck..
midnightbluS10
Banned
Re: Clogged cat, how do I know?
Since when can changing the cat cause boost control issues? Code 42 is set when tan wire is unplugged.
I'm betting the bogging is timing being pulled because of detonation. Do you have anything to monitor your truck? Datamaster, Tunerpro, Scanmaster?
Since when can changing the cat cause boost control issues? Code 42 is set when tan wire is unplugged.
I'm betting the bogging is timing being pulled because of detonation. Do you have anything to monitor your truck? Datamaster, Tunerpro, Scanmaster?
Re: Clogged cat, how do I know?
The bogging could be from a vacuum leak. Verify ALL of the small, very brittle, hard to see, REAL pain in the ass to reach lines, hoses, elbows etc are in place . One SMALL leak can cause that problem..Ask me how I know one:rotf:
The bogging could be from a vacuum leak. Verify ALL of the small, very brittle, hard to see, REAL pain in the ass to reach lines, hoses, elbows etc are in place . One SMALL leak can cause that problem..Ask me how I know one:rotf:
The Bronze
New member
Re: Clogged cat, how do I know?
It can be a clogged cat. The pre/post temperature check can sometimes identify a cat that isn't "lighting off", but it won't tell you the catalyst is plugged. The best test is to remove the O2 sensor and put a pressure gauge in it's place. If you don't have a gauge, just leave the O2 sensor out and see if it improves. A smart guy would log and review MAP (or use a vacuum gauge), since it will be showing you the decrease in vacuum as you increase engine rpm if indeed there is a restriction.
I am betting on lack of fuel, incorrect timing/detonation or restricted exhaust. Some way to look at the engine data would be really beneficial so we all aren't guessing.
It can be a clogged cat. The pre/post temperature check can sometimes identify a cat that isn't "lighting off", but it won't tell you the catalyst is plugged. The best test is to remove the O2 sensor and put a pressure gauge in it's place. If you don't have a gauge, just leave the O2 sensor out and see if it improves. A smart guy would log and review MAP (or use a vacuum gauge), since it will be showing you the decrease in vacuum as you increase engine rpm if indeed there is a restriction.
I am betting on lack of fuel, incorrect timing/detonation or restricted exhaust. Some way to look at the engine data would be really beneficial so we all aren't guessing.
Throws
Active member
Re: Clogged cat, how do I know?
I got my back into shape (from the PO's neglect), and tracking down a boost-limiting fault was a pain in the ass. BUT, damn... it's so much more fun now.
-P
I got my back into shape (from the PO's neglect), and tracking down a boost-limiting fault was a pain in the ass. BUT, damn... it's so much more fun now.
-P
