280e Ehaust Fumes

[280EZRider]

My '77 280E (110 engine) has started to have a rather strong exhaust smell. It starts after the engine is at operating temp, after the EGR has kicked in. Below operating temp, when the EGR is at rest, the exhaust smells like that on newer cars, which I have to conclude is cleaner. This should be just the opposite.
Any ideas?

[ctaylor738]

I don't understand your reference to the EGR. If the problem is at idle, it should be closed. You can test it for proper operation by connecting vacuum to it at idle to open it and seeing if it makes the engine stumble.

Other possible problems are worn injectors, dirty spark plugs, high fuel pressure (fuel pump on the way out), low control pressure (bad warm-up regulator), mixture too rich, dirty air filter, leaky cold start valve. You need to work through the problems one by one, starting with the cheap ones.

[300SDog]

Or did they have catalytic converters back in '77? Could be backed up CC if it stinks like a sewer.

[280EZRider]

Yes, it did have a converter but it was discarded 7 years ago when it clogged up due to a frozen air pump.

The EGR valve is connected and I believe working properly. At idle, when the engne is cold and the EGR is supposedly closed, the exhaust smells normal. At idle and operating temp, the exhaust smells bad. The plugs are new - the old plugs read good, which should negate injectors, fuel pump pressure, cold start valve, and mixture setting - air filter is new, no fuel leaks.

This is why I am purplexed??????????????????????????

[ctaylor738]

You can have a pig-rich mixture and the car will run well and the plugs will look good. Suggest you get the CO checked at the tailpipe.

[thorsen]

Once the exhaust starts smelling bad, disconnect the vacuum line to the EGR valve. This will shut the EGR valve and help you determine if it is the cause.

[280EZRider]

Thanks for the ideas! I will disconnect the EGR to check for a difference, and have the CO checked at the tailpipe.