hi sl6 sages- been looking at an 80 sl6 aspen. notice it has an air pump which appears to pump fresh air into the cat. read sl6 dans report on these air pumps. would seem to me the pump takes horsepower to run and the air into the cat would cause back pressure resistance. does this measurably reduce gas mileage? also the car has two cats, one on the side of the block and the other in the usual place before the muffler. does the car really need two cats. older f bodies had only one cat. last inquiry - notice the aspen has a diagnostic plug on the left inner fender. does this mean the aspen has a computer under the dash like current cars? arent those things expensive as hell to fix/replace? never saw this setup on other sl6 cars. genuinely appreciate your kind analysis and advice. regards bf

If it has a computer, it's likely a Lean Burn computer, mounted on the air cleaner. And usually if you want to replace it, your best bet is to ditch the Lean Burn for an earlier distributor and ignition system unless you're up to something very unusual.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

Almost none. Less than the alternator with no electrical loads other than the engine's ignition system.
No, but if you delete the air pump, the catalyst will heat up, the core will partially melt, and that'll really cause backpressure!
Depending on your setup, the small converter near the engine is either a miniature oxidation catalyst located where it is to heat up fast and start cleaning up the exhaust quicker than the underfloor catalyst would do, or it's a reduction catalyst that turns NOx into N2 and O2; the O2 helps the underfloor catalyst do its job.

If you suspect one or both of the catalysts is clogged and restricting exhaust flow, and you need to pass emission tests someplace other than California, you can replace the both of them with a modern high-flow "3-way" (TWC) catalyst with air injection connector pipe, in the underfloor location. A Catco #9005 or similar would be a good pick. 2¼" inlet and outlet, with flow capacity sufficient for up to a 7.5-litre (458 cubic inch) engine. It's a good idea if you go this route to wrap the headpipe from the manifold to the converter with heat blanketing wrap such as the Thermo-Tec stuff. This will get the underfloor catalyst up to temp and working in a bigger hurry than without wrap, replacing the purpose of the mini headpipe converter with much less backpressure and underhood heat.
Naw, it's in the engine compartment, hanging off the air cleaner housing.
Lean Burn! How costly they are, that kinda depends on how you go about replacing/fixing 'em! They can be had in rebuilt form from the likes of these fellers, or used via www.car-part.com (searchable used auto parts nationwide). Or, again depending on what kind of emission tests you have to pass, you could delete the computer, put in a conventional electronic ignition distributor (w/vacuum and mechanical advance systems, absent on the Lean Burn distributor), either run a Mopar type control box or upgrade to HEI and either put in a conventional carb or modify yours to provide vacuum advance signal. Usually the results of deleting the Lean Burn are improved performance, driveability, and mileage.

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Too many people who were born on third base actually believe they've hit a triple.

Actually, most of the 80 aspens with slant sixes where not lean burn.(maybe all, but I'm not sure) The black plug with the orange cap labeled 'diagnostic' is NOT an indicator of lean burn. My 80 aspen has the connector and is conventional electronic from the factory. You should find the electronic ignition box mounted on the other inner fender. This is a good system and shouldn't be cause for concern if working properly and is very easy to maintain.



As for the smog pump, If it ain't broke, I wouldn't fix it. Then again, I'm in PA, and the state inspection requires all that junk in order to pass.

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1980 Aspen 225 super six

I'm thinking the twin cats were used in '80 only in conjunction with Lean Burn, but I could be wrong on that count.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Nope. I've had 3, '80 F bodies and all were slants all had air pumps, all had 2 converters, "regular" electronic ignition and all had that orange plug. Ive seen it on several other 79-80 vehicles, including trucks. I believe that was an assembly line only sort of thing as I don't even remember the FSM mentioning it being used for anything. My dads old 82 Gr Fury with a slant also had reg. electronic ign (no that one wasnt changed over either) and 2 converters. If you like the car and its reasonable go ahead and get it.

Then I stand (sit) corrected!

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一期一会
Too many people who were born on third base actually believe they've hit a triple.