Cherry red converter but light still flashing

[white98mo]

New member with a 98 3.8, car has lost power and has started smoking last week. Converter was glowing cherry red, so I thought it was clogged. I cut the converter off last week but the engine light still flashes, code indicates a random cylinder misfire. Fuel filter was replaced. Sparl plugs and wires are new. Coils have been replaced. I read a thread yesterday about a glowing catalytic converter but I didn't see if replcing it fixed the problem. I'm suspecting the ignition control module but I'd like to confirm it is bad before replacing. Has anyone experienced a P300 - random misfire to the point where the converter got so hot. Thanks, I really like the car and would like to get it going again.

[black98V6]

Re: Cherry red converter but light still flashing

I hate to tell you this but the only way to really diagnose this is going to be to take it to a professional who can put a techII or something simliar on the car and really decipher what is going on. While your problem isn't unheardof it is somewhat rare. To have a radom misfire indicates your problem is not localized to one cylinder.
There are a number of things that could be causing this from something as simple as having the wires run to the wrong cylinder to a short somewhere in your ignition system.

If your cat was glowing that means your car was dumping raw fuel into the exhaust and your cat was overloaded with trying to burn it off.

The real kicker to the whole thing is that while focusing on the ignition system might allow you to find your problem you need to remember that to run an engine you need 3 main things, air, fuel and spark. You are only looking at 1/3 of the possible problem by focusing on the spark.

Honestly though the first thing I would do is recheck the wires and make sure they are running to the right cylinder.

[crushedout]

Re: Cherry red converter but light still flashing

This happened to me 9 months after getting a remanufactered motor. I took it back and they said that wasn't covered under the warranty. I replaced just about everything and pulled stuff from my buddys camaro. I ended up changing plugs, wires, coils, ignition control module, egr valve, fuel filter, water remover in tank, I can't even remember. I ended up giving up and went to the dealership. They said that I had contaminated gas and showed me a sample, they replaced a clogged fuel injector, fuel filter, again, and cleaned all the fuel lines out. I came and got it and before I got off there lot I knew it was still bad. I pulled out and before I went to 2nd gear the SES light was on. I pulled a U-turn and drove the car right to there garage and told them it was still bad. They said another injector was clogged. They changed it and charged me no labor. It was still bad. Then they changed them all and charged me labor and guess what it was bad. They had all these hoses and gauges taped to my windshield out of the hood and ended up calling me in for a meeting with me, my buddy with the camaro, "top service man", service manager, service lady working my situation. They ended up telling me it would be in my best interest to take car. They would continue to troubleshoot but at a rate of $100 an hour. So I paid my 3rd bill or so for a grand total of $2000 or so and left pretty mad. I took the car to the motor shop and told them they needed to figure out why it didn't work as they put it in and started looking for another car. (I didn't have a car for 3 months) They ended up borrowing a smoke machine and found my upper intake manifold was leaking, and a by the way set of plugs that had 70 miles on them were "bad".
Would you believe that a year later, this febuary, the same gasket went bad again.
Sorry for the long post but wanted to give you the whole story. Hope this can help you out some.

[white98mo]

Re: Cherry red converter but light still flashing

This is the type of information I'm looking for. I do have alot of experience with cars but the vagueness of a Random Cylinder Misfire gives me the willy's because the code doesn't tell me any more than I already know, the engine stumbling at idle was enough to know there was a problem without a DTC telling me there is a misfire. It will be interesting to investigate the manifold leak since I did notice a RPM drop (I hope caused by loss of vacuum) when I came to stop followed by an increase in RPM .

Thanks for the insight, I will update once I get under the hood this weekend.

[slow6]

Re: Cherry red converter but light still flashing

This happened to me 9 months after getting a remanufactered motor. I took it back and they said that wasn't covered under the warranty. I replaced just about everything and pulled stuff from my buddys camaro. I ended up changing plugs, wires, coils, ignition control module, egr valve, fuel filter, water remover in tank, I can't even remember. I ended up giving up and went to the dealership. They said that I had contaminated gas and showed me a sample, they replaced a clogged fuel injector, fuel filter, again, and cleaned all the fuel lines out. I came and got it and before I got off there lot I knew it was still bad. I pulled out and before I went to 2nd gear the SES light was on. I pulled a U-turn and drove the car right to there garage and told them it was still bad. They said another injector was clogged. They changed it and charged me no labor. It was still bad. Then they changed them all and charged me labor and guess what it was bad. They had all these hoses and gauges taped to my windshield out of the hood and ended up calling me in for a meeting with me, my buddy with the camaro, "top service man", service manager, service lady working my situation. They ended up telling me it would be in my best interest to take car. They would continue to troubleshoot but at a rate of $100 an hour. So I paid my 3rd bill or so for a grand total of $2000 or so and left pretty mad. I took the car to the motor shop and told them they needed to figure out why it didn't work as they put it in and started looking for another car. (I didn't have a car for 3 months) They ended up borrowing a smoke machine and found my upper intake manifold was leaking, and a by the way set of plugs that had 70 miles on them were "bad".
Would you believe that a year later, this febuary, the same gasket went bad again.
Sorry for the long post but wanted to give you the whole story. Hope this can help you out some.

by "take car" do you mean get a new engine? what does "take car" mean?
sorry for your bad experience! All that work done just to find out it was just an upper intake manifold gasket, sounds like you should pull out your EGR from now on. LoL What kinda plugs were they that went bad in 70 miles? That is soooo hard to believe!! Well, I guess I can believe it if your intake was making the car lean.

There are sooo many things that can cause misfires!
bad PCM, bad timing chain, intake leak, vacuum leak, something wrong with the bottom end (like bent rod), running lean, and of course the Hopefully usual easy stuff like ICM, coils, plugs, wires, etc

[StevenC]

Re: Cherry red converter but light still flashing

Check for fuel & spark at your cylinders. If you've got them all solid, check for mechanical issues. If not, check the appropriate system. (A vacuum leak of some sort usually shows up as rough idling and performance and usually shows up immediately.) The good news is that if you've got fuel & spark, a simple compression/leakdown test will pinpoint whether a mechanical issue is in your cylinders. If not there, then continue testing the other components for issues. TEST the components, do not TOSS components at it.

[white98mo]

Re: Cherry red converter but light still flashing

I was able to get under the hood this weekend and look for signs of a upper intake manifold leak. It looks like there is some seepage where the manifold bolts on. Has anyone pulled the manifold to replace the gasket? I'd like to know an estimated time for completion because I have alot of other activities I have to scheduled around. Is this a 4 hour job or an all day thing? If anyone can give me a ballpark estimate on how long it will take I'd really appreciate the info.

[benavidez19]

Re: Cherry red converter but light still flashing

You know if you look up chevy camaro recalls you might end up getting it fix for free. I had a bad cylinder misfire 8 mths after i had bought my bird. Took it to ponitiac and they told me their was a recall on somthing to do with one of the cylinders not arching right so i got it fixed for free. They did tell me if it wasnt that recall i was going to have to pay the diagnostic charge. But it was and was fixed.

[StevenC]

Re: Cherry red converter but light still flashing

benavidez19, I'm from Midland! What they fixed was a recall they had on the ignition coils. I had mine go out when I was in college in Dallas years ago and had to pay for it myself. Later on I got the notice on recalls but never bothered demanding my money back. Later on, those coils broke down too. LOL they probably just reused someone else's.

white98mo, you need to take this diagnosis one step at a time. Just because someone mentioned an intake manifold leak doesn't mean you have one. I just got done replacing my belt, two sensors, and the wiring, but that doesn't mean that's your issue. (My belt frayed and took that stuff on its way out, only 2 years old at that)

If you really think it's a manifold leak, why don't you rent a vacuum gauge and check it first?

[BobbyZ72]

Re: Cherry red converter but light still flashing

Could it be a totally shot fuel pressure regulator? I replaced mine a few months back, but it would only do this at start up.

[white98mo]

Re: Cherry red converter but light still flashing

Thanks, I'll take that advice. I have a vacuum gauge that I can use to check for the leak. I sprayed some WD-40 around the manifold with the engine running and did notice a change in idle speed so I was going by that information as I look further at the manifold. I can't agree with you more on the one-step approach. By the way, the service manual suggests the following order plugs, wires, coils and ignition module for DTC 300 so that's why I considering a bad ICM. I was planning on taking the ICM off and have it tested before approaching the manifold but the first thing I have to do is finish welding the converter back on since it was cut off after being suspected as clogged.

I do appreciate everyone's advice. I will share what I learn .

[white98mo]

Re: Cherry red converter but light still flashing

Had a chance to hook up the vacuum gauge. Only seeing 8 in of Hg. Does anyone know what the 3.8 typically runs for vacuum? I would expect 15 to 18 inches of mercury from the smallblocks I usually mess with.

I noticed there is considerable intake noise with the engine idling, as if it is trying to suck more air than it can. I thought this was becuase the engine was cold but it seems to be sucking more than normal. No pun intended.

[StevenC]

Re: Cherry red converter but light still flashing

Your expectation on vacuum is in-line, that's too low. When you blip the throttle, what happens?

[Ace]

Re: Cherry red converter but light still flashing

I hate to tell you this but the only way to really diagnose this is going to be to take it to a professional who can put a techII or something simliar on the car and really decipher what is going on. While your problem isn't unheardof it is somewhat rare. To have a radom misfire indicates your problem is not localized to one cylinder.
There are a number of things that could be causing this from something as simple as having the wires run to the wrong cylinder to a short somewhere in your ignition system.

If your cat was glowing that means your car was dumping raw fuel into the exhaust and your cat was overloaded with trying to burn it off.

The real kicker to the whole thing is that while focusing on the ignition system might allow you to find your problem you need to remember that to run an engine you need 3 main things, air, fuel and spark. You are only looking at 1/3 of the possible problem by focusing on the spark.

Honestly though the first thing I would do is recheck the wires and make sure they are running to the right cylinder.

Well your right about needing 3 things to make the engine to run. But its fule, spark and compression. Fule and air are the same thing.

[white98mo]

Re: Cherry red converter but light still flashing

I was able to get the upper intake manifold off the car this weekend. It looks like the gasket had been leaking for a while. The carbon build-up on no.1 cylinder intake runner was noticably lighter than the other 5. While I've got the upper plenum off, are there any routine maintienance items I should complete? I was going clean-up the carbon from the plenum's insides, anything else you guys are familiar with?