Clogged Cat?

[VernySanders]

Okay so I broke down a few weeks back. Engine went into limp mode wouldnt accelerate. I was doing a Michigan u turn and as I pressed the gas I heard a decently loud pop noise under my truck. Limped it into a parking lot got it towed home. Did some minor things at home such as throttle body cleaned switched out a throttle position sensor, cleaned MAF cleaned IACV and reset the CPU she seemed to run fine. So fast forward to today. First hot day of the year in Michigan and I'm leaving work as I go to turn out once again in the category of acceleration my truck loses all power I feel and hear the same pop under my truck. Pull over let it idle and cool a little. No oil underneath nothing. Engine idles fine but once under load she gives out. Now interestingly enough when I reset my CPU by un hooking / rebooking battery it will run perfectly fine for a while. So in my mind I'm thinking once the CPU get the data it needs from the O2 sensor it figures out it's running improperly and goes into limp mode. Can anyone confirm this? Or anyone have the same issue? Thanks everyone!

 

[19963.4lsr5]

There is no limp mode that I’m aware of. That pop under the hood is probably a lean backfire.

It could be low fuel pressure, failing O2 sensor, bad or failing MAF.

Do you have a scanner that reads live data?


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[Mudeprived]

Pull the front 02 sensor and go for a drive. If it drives normally then you got a plugged cat.


Mine got plugged last fall and It had no power and would not accelerate past 2000 rpms. My mechanic pulled the 02 sensor and it drove fine so we knew the cat was clogged.

If it is then you got engine issues causing that. Mine was a blown headgasket that was puking coolant through the exhaust.

 

[19963.4lsr5]

There is a gauge you can buy to measure the back pressure at the front O2 sensor.


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[thegipper]

Watch this and perform these tests. You'll need a infrared temp gun (cheap on amazon). It's a quick and easy way to check if your cat is bad or not.
YouTube

 

[BamaDrewski]

For about $20 bucks, you can take it to a good muffler shop and they drill and small hole and test to see if the cat is clogged. Could be your 02 sensors. When you replace them, do them both at once. Most people only replace one and as PM, it is best to replace both. The Denso for our rigs are pretty inexpensive on Amazon! Good luck!

 

[VernySanders]

Thankyou everyone for the quick replies! I'm going to delete my rear o2 sensor and cut out both cats and get a pipe welded in. (I live in Michigan so no emissions testing) But before I do that I will try a couple of these techniques and post for anyone else having this issue. Not too worried if I have something wrong engine related as long as it's nothing internal. I'm going to be tearing this bad boy down to replace everything from the head gaskets up soon as its finally spring and I have all the OEM parts sitting in my basement. I love this forum!

 

[VernySanders]

Pull the front 02 sensor and go for a drive. If it drives normally then you got a plugged cat.


Mine got plugged last fall and It had no power and would not accelerate past 2000 rpms. My mechanic pulled the 02 sensor and it drove fine so we knew the cat was clogged.

If it is then you got engine issues causing that. Mine was a blown headgasket that was puking coolant through the exhaust.

I want to say my situation is most similar to this. I'm going to do that to trouble shoot before I pull the cat. My truck wont really even go past 1k rpms lol. And at idle it will die out after sitting there for a while. Crazy how a clogged cat can give different problems depending on the situation. Some people drive with them for a couple years with no issues. However I should have expected this. When I bought the truck the PO said it had a clogged cat. That was almost a year ago.

 

[19963.4lsr5]

Just saying, when you try and accelerate and you hear a pop under the hood and the engine power falls on its butt it’s a lean backfire.


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[VernySanders]

Just saying, when you try and accelerate and you hear a pop under the hood and the engine power falls on its butt it’s a lean backfire.


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In your opinion what would be a cause of this?

 

[19963.4lsr5]

I would look at fuel flow first.

To me a clogged cat would be blubbery and doggy. But saying that I’m use to troubleshooting a vehicle that uses a MAP sensor to choose the fuel maps instead of a MAF sensor.

If you have a scanner that reads live data it would help




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