Possible Cat Problem.

Topic: Possible Cat Problem. (Read 3324 times) previous topic - next topic

Possible Cat Problem.

October 20, 2013, 12:35:00 AM

Does anyone know if this can happen. Brief Story, 86 with 5.0 SO. Car was worked on and mechanic was up against the EGR recirc valve on the passenger side. It is corroded just enough the short connector hose broke off the at the piece that goes around behind the engine. I'm sure he didn't notice it, at least I hope he didn't. Hate to think he knew about it and didn't fix it. But anyway, wife picks up the car and drives it about 15 miles home not realizing the piece is broken. Parks it in the garage now three days later car doesn't run worth a . I found the broken EGR spot and got it reconnected with what was left of the metal. It is sealed once again. But like I said before, the car doesn't run. It will start, but as soon as you give it any type of gas the engine shakes very hard and stalls out. There is a terrible smell of a combination of gas and putrid smelling exhaust. There is a large amount of moisture and black soot like stuff coming out of the exhaust as I try to run the car. It won't even move under its own power. As soon as I put it into gear, it stalls immediately. Again, the car ran just fine three days ago when parked in the garage.

My question is, it is acting just like one of my other cars did when the cat was plugged up. Is it possible that the direct open exhaust from the broken EGR system overheated the cat and it melted itself out. I realize those cats are fragile like that and this one is probably the original cat on the car. The car has absolutely no power and will not stay running. I am just curious if this experience has ever happened before or even could happen. If not, I got a problem because I don't know where to start looking for that type of engine issue. This is definitely not your typical engine miss from a misfiring cylinder which I did verify all 8 have spark. Going to contact my ler guy on Monday but wanted to ask if anyone else has experienced this issue. I've been looking to do dual exhaust but if that isn't the problem, I need to concentrate on that issue first.

Possible Cat Problem.

Reply #1 – October 20, 2013, 03:57:09 AM

Forgot to mention that I do have a BBK dual cat H pipe sitting here ready to go. Just haven't had proper funds right now.

Possible Cat Problem.

Reply #2 – October 20, 2013, 07:04:53 AM

If you are talking about the EGR feed hard line or EGR adapter it does not matter if it is rotted out. Are you sure it is an EGR related pipe?? All it will do is make an exhaust leak and sound py. But if the adapter if that is the system you have can corrode and allow exhaust gas in to your engine. That will make the engine run like . As far as a plugged cat that is possible but is not caused by an exhaust leak. As the matter of fact tuns of cars actually inject air(OXYGEN) directly in to the cat with absolutely no issues., If you think you have a bad cat do a back pressure test. You should not have over 1.5 LBS @ 1500 hundred RPM'S Good luck and post some photos so we are on the same page!!

Possible Cat Problem.

Reply #3 – October 20, 2013, 10:35:17 PM

This is the part that I was talking about. the red hose was disconnected at the back fitting.

Possible Cat Problem.

Reply #4 – October 20, 2013, 11:07:49 PM

same pipe rotted out on me where it connects to the y-pipe. I capped the lower half and haven't had any issues whatsoever.

it sounds to me like you have a vac leak. this will make the car run bad and even put out black soot on the ground. check the large vac line going to the map sensor on the firewall. as the motor mounts let go, they breakers and stretch the vac lines and hoses

Possible Cat Problem.

Reply #5 – October 21, 2013, 03:45:17 PM

If the check valve is ok leave it. But most all of them i check are shot . If so you can replace the valve and or remove the pipe and block it off. That is not an EGR TUBE It is an ASPIRATOR to let fresh oxygen (AIR) to be drawn in to the exhaust system to reduce emissions.

Possible Cat Problem.

Reply #6 – October 21, 2013, 04:10:03 PM

Quote from: Haystack;423626

same pipe rotted out on me where it connects to the y-pipe. I capped the lower half and haven't had any issues whatsoever.

it sounds to me like you have a vac leak. this will make the car run bad and even put out black soot on the ground. check the large vac line going to the map sensor on the firewall. as the motor mounts let go, they breakers and stretch the vac lines and hoses

I will have to check for a vac leak first. Who knows what the mechanic working on my a/c pushed on, bumped or whatever. Some of those hoses are original hoses being I've owned the car since 88. I actually had a guy today at work tell me to check for a vac leak.

Possible Cat Problem.

Reply #7 – October 21, 2013, 04:17:40 PM

Quote from: TOM Renzo;423644

If the check valve is ok leave it. But most all of them i check are shot . If so you can replace the valve and or remove the pipe and block it off. That is not an EGR TUBE It is an ASPIRATOR to let fresh oxygen (AIR) to be drawn in to the exhaust system to reduce emissions.

How do you check to see if that valve is OK? I know just enough to be dangerous and get myself in more trouble and cost me more money to fix what I messed up. Has happened before. I'm more comfortable on the body or something than I am at diagnosing engine trouble. Give me brakes any day and I'm all over that stuff. But like I said in my previous post, I'll be looking for a vacuum leak first tonight or tomorrow depending on when I get off work tonight.

Possible Cat Problem.

Reply #8 – October 22, 2013, 03:25:28 PM

pull codes and it will tell you if its bad. should also tell you if you have a vac leak bad enough to effect anything

Possible Cat Problem.

Reply #9 – October 23, 2013, 12:02:06 AM

Quote from: Haystack;423678

pull codes and it will tell you if its bad. should also tell you if you have a vac leak bad enough to effect anything

I checked and checked last night and I couldn't find any obvious leaks in the vacuum. None that was glaringly obvious. I was stumped. I checked all connections and fittings that were anywhere in the vicinity of where the ac lines were that were being worked on both electrical and vacuum related. Nothing. So I broke down and had it hauled out of here today to the shop once again. I don't have a code reader (yet) so I needed the codes read. Code was for the MAF sensor. Shop claims it isn't working at all. Guess that was what I wanted to know. Expensive boogers. Anyway, part should be in tomorrow or Thursday at the latest. Have my fingers crossed that was all there was to it. Guess I have to expect something to be wrong once in while on a car that old that has set for that long. Hope that is all there is because it snowed today and I want to put her away for the season to keep her out of this nasty stuff.

Possible Cat Problem.

Reply #10 – October 23, 2013, 12:13:46 AM

I hate to say it John but I hope it aint working if the Code came up for a Mass Air Flow Sensor, your 86 doesnt have one. Did they say what the code was exactly?

Possible Cat Problem.

Reply #11 – October 23, 2013, 12:17:09 AM

Quote from: Tbird-fanatic;423713

I hate to say it John but I hope it aint working if the Code came up for a Mass Air Flow Sensor, your 86 doesnt have one. Did they say what the code was exactly?

No. Just mentioned the MAF sensor, or after looking at my DIY book I think they said MAP sensor. Manifold Pressure/Vacuum Sensor. Does that make more sense?

Possible Cat Problem.

Reply #12 – October 23, 2013, 01:14:44 AM

Yes a MAP sensor does make more sense since your Speed Density system uses that along with other inputs and programming for guessing how much air has entered the engine. In a Speed Density system the MAP sensor is a biggy and unless they have sky rocketed in price the sensor itself should be to expensive, now their diagnostic, labor, and mark-up of parts can make it pricy!!!

Possible Cat Problem.

Reply #13 – October 23, 2013, 03:10:58 AM

the map sensor is what I was expecting to have a problem with, as per my post earlier on the page.

I'm willing to bet you had one vacuum line off between the intake and map sensor..I say this because I've.had it happen.

pulling codes is a 5 min procedure that only takes a paperclip and a test light or volt meter, or nothing if your check engine.light works correctly.

Possible Cat Problem.

Reply #14 – October 23, 2013, 04:28:37 PM

Haystack, you were correct on your vac issue as the problem. Tony and Tom, I appreciate your input as well. Makes me realize that I definitely need to get more versed in these cars now that I'm more involved with them and plan to be into the future as well. Towing and diagnostics, labor and the part $300. It could have been worse. They claimed no vac line was bad. Didn't mean one wasn't off from all the AC work been done lately. But car's running great, and as of now, no codes. Hope for a good spring. My new (gently used) TC hood, TC front clip and factory TC fogs are begging for installation with fresh paint on them. Might even be able to get Dual exhaust put on. But for now, She's going into hibernation for 6 mos. Thanks again for everyone's input.

John