EGR and Dual exhaust?

[HAZZARDJOHN]

Ok, I am asking about an issue that came up with my 1992 Roadmaster sedan that also had a TBI 350. When I put duals on it with magnaflows and no cats when I would drive for a while at 60+ it would trip the Check engine light. Since it was OBD1 it never stored the code so It would go away when I restarted it. It was an EGR code every time I ran the codes.

My Question is, I know EGR needs a little back pressure to operate, and I am putting exhaust on my Burb this spring. Should I leave the Cat or not? I want to do a new better flowing Y-pip to a 3” exhaust pipe to one magnaflow muffler with dual exhaust outlets. But I don’t want to do an EGR delete (Too much crap to deal with on the computer) and I don’t want to be staring at a check engine light on every road trip.

Thoughts?

~HJ

 

[bucket]

Sure it's not just a coincidence? Have you tried cleaning the EGR and passages? I'm assuming your EGR code is for lack of flow.

 

[HAZZARDJOHN]

It could be a coincidence, but there is anecdotal evidence on the interwebs that this happens on some OBD1 vehicles. Also, My burb is having this issue sometimes as well since the muffler disintigrated. Never happened before and the day the muffler opened up like the gates of hell, I started getting Check Engine lights when I drove for a long period of time. They came back as EGR codes as well.

 

[bucket]

It probably can't hurt to try cleaning the passages. Personally I don't like EGR valves, the problem you are having is one reason. I'll spare you of my rant, since you want things to work how GM intended

 

[foamypirate]

My Caprice does this as well...

I remember Jim mentioning this happening to his Burb' when he had a high flow exhaust on it. I don't have much input, but I might suggest running a heavy duty cat. My 84' has a TBI 305 in it, 2.5" piping, heavy duty cat, and a Magnaflow, and it doesn't throw the EGR code. I'm thinking the heavy duty cat (as opposed to a regular cat) restricts flow just enough now to trip the EGR CEL...tis' but a theory, of course, but it's what I've got.

 

[Linville33]

My truck does the same thing although the po cut off the exhaust after the cat. It was doing it for awhile and I haven't changed anything and now it has stopped and I haven't changed anything. I have a lot of gremlins in my truck

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