Technical Articles

Passing a smog check

California, Delaware and a few other states require a smog check for vehicles built since 1975. Here are some tips from one owner:

  • Install the smog pump and all associated EGR parts that were originally on the car. Buy the necessary missing parts used or new.
  • Replace the entire ignition with Bosch ignition parts, including the proper rev limit rotor arm.
  • Get all other new Bosch ignition parts along with spark plug wires and ignition coil (not a blue coil).
  • Install hose clamps on every air hose under your engine cowl.
  • Replace all fuel lines with name brand FI fuel hose.
  • Install new fuel filter and air cleaner filter.
  • Run Marvel Mystery Oil through your engine crank case (one quart added to existing oil (be careful not to overfill the crank case) and through the fuel system (16 oz) for approximately 350 miles or one full tank of gas.
  • Change the oil and filter, use a Mahle or Mann filter with the check valve.
  • Run the car for about an hour at highway speeds and get the engine up to full operating temps.

This is the time you want to get it smogged, after its tuned, cleaned and with a fresh oil change.

If it doesn’t pass, you’ve still spent less than $200.00 and you can get a smog professional to tweak it to pass for fewer dollars than a first approach of just replacing bunches of parts with no plan.

Other things you can do:

  • Replace the small FI rubber seals and the large retainer rubber rings - an air leak at this location can cause problems.
  • In addition, be sure the charcoal canister is connected to the fan cowling on the far left side. It makes a difference.
  • Replace the seal at the oil fill location. It’s a cork gasket between the crank case and the filler filter box.

If you have any other tips, please submit them here.