misfires, backfires, glowing cat. conv. pls help!

[Bird of Prey]

Hi folks!

Im very desperate now. My car was always running well the 3 years i own it by now.

but... now i have backfiring issues, it misfires badly and the catalytic converter glows red after driving even slowly!

I changed:

• 
  coilpack
  plug wires
  spark plugs
  O2 sensor

what i have to do next is changing the exhaust gaskets, because there is smoke out of the block at start up.

The belt tensioner pulley hits the A/C pulley at start up and when giving gas at stand-still.
Gatorback belt 1615 mm is new. Replaced the old 1625 which had hit all the time, running.

The car feels and sounds like running at 2 cylinders, my mechanic said. But there's no us-car screwer around here...

thoughts much appreciated, guys!

 

[Turbo1dr]

Try unplugging the electrical connection at the EGR solenoid and start it up. You will get a code in the computer but see if that helps running. If not plug it back in.

Remove the vacuum line from the EGR valve and see if there is vacuum present. There should be NO vacuum at idle.

Remove the EGR valve and see if it's stuck open. You can also plug the EGR ports on the intake to verify.

Try a known good MAF.


A scan tool is your friend!

 

[turbofabricator]

Might be a plugged cat, too. Very common for a cat to glow red if it is plugged. Remove it and see if it runs better.

 

[Fuelie600]

Might be a plugged cat, too. Very common for a cat to glow red if it is plugged. Remove it and see if it runs better.

Dammmmm, that was going to be my answer:biggrin:

 

[Lee_Burough]

Yup, a red hot CAT is a red flag for sure

I'd be interested in the outcome of the EGR testing and the logic behind it Turbo1dr

 

[QUIP'6']

i would suspect cat but the question is is it the missfire and raw gas making the cat glow which raw gas bieng dumped will. by chance did you disconnect the maf and try the idle

 

[Turbo1dr]

Actually, he didn't give a whole lot of information on when it acts up. At idle? During hard accelleration? During a normal red light to red light stop and go traffic?

I should rephrase my answers to clear them up a little...:redface:

Anyway, a near complete stopped up converter will act like the engine has VERY low ignition timing. It wont rev very quickly or have any power but the engine usually starts and runs very smooth at idle on all cylinders. It can super heat the converter and cause it to glow red.

and

At an idle and low rpm's, the EGR will cause the computer to under/over compensate on the fuel mixture and cause running problems. The rough running and improper fuel mixture will cause the cat converter to super heat and glow red. Upper RPM's and full throttle should still be OK....maybe.

 

[Turbo1dr]

Something else.... an injector that's stuck open will cause running problems and glowing red hot converters!

 

[Lee_Burough]

Actually, he didn't give a whole lot of information on when it acts up. At idle? During hard accelleration? During a normal red light to red light stop and go traffic?

I should rephrase my answers to clear them up a little...:redface:

Anyway, a near complete stopped up converter will act like the engine has VERY low ignition timing. It wont rev very quickly or have any power but the engine usually starts and runs very smooth at idle on all cylinders. It can super heat the converter and cause it to glow red.

and

At an idle and low rpm's, the EGR will cause the computer to under/over compensate on the fuel mixture and cause running problems. The rough running and improper fuel mixture will cause the cat converter to super heat and glow red. Upper RPM's and full throttle should still be OK....maybe.

I knew you had some logic there, just a gap in my education, thanks

 

[Bird of Prey]

ok i will check these things.

you're the elite, guys! *g*

Idle is kind of smooth, but when i rev it, you hear misfires.

so to check is: cat, injectors, egr...

a lot to do for this weekend.

thx for now, i will post an ev. progress.

matt

 

[fast400]

What was the result?

 

[Chuck Leeper]

In the "FWIW" dept..
I hang at Random Technolgy, and see the results of overheated cats, that come back for "warranty".. SCARY stuff! Some have holes melted thru the brick, some the brick is gone.
If it's been o heated much, it's JUNK.
Do not drive the car, as you will fry the exh valves...