Catalytic converters glowing red?

Tiny
ALILONG99
  • MEMBER
  • 2000 FORD MUSTANG
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 99,177 MILES
Can’t figure out why my catalytic converters are glowing causing exhaust manifold to glow. Also changed spark plugs thinking it was misfiring, but no codes.
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Friday, January 31st, 2020 AT 5:42 PM

35 Replies

Tiny
KASEKENNY1
  • EXPERT
They are getting so hot because there is so much unburned fuel getting into the exhaust. Does the vehicle run like it is misfiring? Does it run rough?

If not, then if you are willing to try something we can try to pin this down. Run the vehicle practically empty and then put 5 gallons or so of the highest test fuel you can get access too (93 or higher). Then buy a bottle of one of those octane boosters (any brand) and add that to the 5 gallons. Then run the vehicle like normal and see if the converters still glow. If not, then you have what is called detonation.

If it still does it, then we need to monitor the o2 sensor data with a scan tool and see if it is in fact running rich. If it is then we can dig further into causes of a rich condition.

Let me know what you find and we can go from there. Thanks
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Friday, January 31st, 2020 AT 5:49 PM
Tiny
ALILONG99
  • MEMBER
Engine sort of shakes. Replaced cold air intake new filter and spark plugs and runs rough sort of.
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Friday, January 31st, 2020 AT 7:07 PM
Tiny
ALILONG99
  • MEMBER
Have an OBD scanner and when I test for 02 sensor and would the percent be based on the picture attached?
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Friday, January 31st, 2020 AT 7:08 PM
Tiny
KASEKENNY1
  • EXPERT
You will want to look at the short term fuel trim. Maybe abbreviated like SHRFT bank 1 and 2.

If the engine is running rich the % will be negative. Remember the o2 sensor only measures the amount of oxygen in the exhaust. If the number is negative, that means there is a lower amount of oxygen. This is because there is more fuel in the exhaust taking the place of the oxygen. So the ECM will command the injectors to shorten their pulse width which will spray fuel for a less amount of time. This is how it lessens the amount of fuel in the engine.
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Friday, January 31st, 2020 AT 7:35 PM
Tiny
ALILONG99
  • MEMBER
It was positive and exhaust manifold started glowing on passenger side.
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Friday, January 31st, 2020 AT 8:33 PM
Tiny
STEVE W.
  • EXPERT
Which side was positive? There should be two different fuel trims, long term and short term. You want to watch both. You may also be burning oil as well as gas. Both will cook a converter in short order.
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Friday, January 31st, 2020 AT 11:30 PM
Tiny
ALILONG99
  • MEMBER
Both be are positive.
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Saturday, February 1st, 2020 AT 6:59 AM
Tiny
STEVE W.
  • EXPERT
Positive means it's adding extra fuel. What are the long term and short term numbers for both banks? Has anything been done to the engine with add on parts? Like a chip? I see you have a CAI.
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Saturday, February 1st, 2020 AT 7:06 AM
Tiny
ALILONG99
  • MEMBER
No nothing with chip just brand new cold air intake, idle air control valve, TPS sensor, sec air injection pump.
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Saturday, February 1st, 2020 AT 7:08 AM
Tiny
STEVE W.
  • EXPERT
Okay. Here is a test you can try, if your scan tool reads live data bring up the fuel trims, both long and short term. Rev the engine to 2,000 rpm's and post the starting fuel trims and the 2,000 rpm's trim numbers. Also look at the O2 sensors both upstream and down and post those numbers.
If you have a scan tool that can read the mode 6 misfire counters that would be a good thing to watch as well. Misfires can dump a lot of fuel into the converter and cause them to burn out very fast.
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Saturday, February 1st, 2020 AT 7:18 AM
Tiny
KASEKENNY1
  • EXPERT
What is the actual number for the short term? Remember the short term is telling us what is happening with the exhaust at this moment so if it is positive then the sensor is telling us that there is a lean condition and as Steve said it is commanding more fuel. However more fuel is causing the exhaust to glow so we need to find out why it is saying there is a lean exhaust when it appears to be rich due to the glowing cat.

This could be faulty o2 sensors. If only one side is glowing and the short term is positive on that side, what does the other bank say? What is the short term on that bank? If the number is lower or even negative, swap the o2 side to side and see if the glowing exhaust switches sides.

Then get the MAP/MAF sensor reading. Also the intake air temp reading and engine coolant temp. Lastly test the fuel pressure and let us know what it is.

Lots of info but please let us know each reading and we can figure this out. Thanks.
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Saturday, February 1st, 2020 AT 7:32 AM
Tiny
ALILONG99
  • MEMBER
Engine coolant 22 degrees, short term bank 1 4.7, short term bank 2 4.7, long term says 0.0 for all, ignition timing advance cylinder 1 says 8.0 degrees, intake air temperature 1 degrees Celsius, Mass air flow sensor rate 14.47, absolute throttle position 18 percent, Bank 1 sensor 1 output 0.06 volts, bank 1 sensor 2 output is 0.6 volts, also says page 5 bank 1 sensor 2 short trim 99.2 percent.
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Saturday, February 1st, 2020 AT 8:11 AM
Tiny
ALILONG99
  • MEMBER
Wouldn t it throw a code thouogh there s no pending codes or current?
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Saturday, February 1st, 2020 AT 8:12 AM
Tiny
STEVE W.
  • EXPERT
It won't throw a code unless it actually thinks something is wrong. In this case it thinks everything is still okay.
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Saturday, February 1st, 2020 AT 11:38 AM
Tiny
ALILONG99
  • MEMBER
Put details up about about readings.
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Saturday, February 1st, 2020 AT 1:22 PM
Tiny
ALILONG99
  • MEMBER
Anything about info I put about reading?
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Saturday, February 1st, 2020 AT 4:21 PM
Tiny
KASEKENNY1
  • EXPERT
What is the outside temperature where you are located? Did you take these readings when the engine was cold? Clearly they are in Celsius but you coolant temperature is no where near operating temperature. Operating temperature should be around 90 degrees Celsius. Then your intake temperature is low as well unless it is currently cold there.

There is nothing alarming with those numbers. The 4.7 short term fuel trims is that big of a deal. So that tells me the glowing exhaust is from a misfire.

Even though you don't have codes for misfires, I suspect that is the issue. The running rough is what we need to chase.

Lastly, is it possible to get a picture or quick video of the catalytic converter glowing? Maybe at night so we can get an idea as to how severe it is.
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Saturday, February 1st, 2020 AT 7:22 PM
Tiny
ALILONG99
  • MEMBER
Yes and in Buffalo so pretty cold now. Could be because of not changing spark plug wires or the ignition coil pack?
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Saturday, February 1st, 2020 AT 7:25 PM
Tiny
ALILONG99
  • MEMBER
Exhaust manifold glows and the catalytic converter glows, all the way once it keeps running the whole thing. Just figured not let it get to that much and also have a video sounds like it s knocking or pinging if can hear it.
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Saturday, February 1st, 2020 AT 7:36 PM
Tiny
ALILONG99
  • MEMBER
And also the coil pack; do you hook up spark plugs according to numbering on it? Because that s how I have it now.
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Saturday, February 1st, 2020 AT 7:40 PM

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