I asked this on CZ28.com but didn't get much of a reply.

Last fall I upgraded my 86 LG4 to a dual snorkel air cleaner, including all of the vaccuum hoses. Since then when driving at highway speeds my check engine light comes on with a code 44 (lean condition). When I slow down to city speeds the light goes off.

When increasing the amount of air to the engine are there any tuning or adjustments needed? Did I somehow create a vaccuum leak? Could I have a weak fuel system which ws borderline lean with the single-snorkel system?

I know you can't know without seeing the car but any thoughts on why I would run lean at highway conditions only after upgrading the air cleaner?

PS, yes I did search this forum before asking :-)

Thanks!

 

The dual snorkel itself wouldn't do it. The ECM will compensate when in closed loop.

Note that the ECM thinks the O2 sensor is indicating lean. That means the O2 sensor can be weak such that it won't indicate rich.

Change the O2 sensor and see what happens.

 

Ditto, change that O2 sensor first. They are very fragile and easily poisoned. If it is bad and has been lying to the ECM, then the ECM is running the carb too rich!. This can clog up the cat converter.

A weak fuel pump/regulator only gave me problems when stepping on the gas, not during cruse.

 

Check the basics (cap, rotor, plugs, wires, compression, opening secondaries, fuel pump, etc.) and if all checks good then go with an AH hanger and G rods. They are the ones GM used in the smog legal ZZ4 engine upgrade package.

 

UH, thats fine to richen the secondaries for WOT. But the question is about crusing, when the carb is only on the primaries.

Oddball, FYI- An exhaust leak near the O2 sensor will make it read lean.

 

I probably should do a complete tune-up anyway including O2 sensor. Then I guess check for exhaust leaks.

thanks for the tips.