my son has a 1994 honda civic dx 5 speed 1.5l. he says it doesn't have a spot to check codes but i feel like that is wrong. can someone help? he's having major issues with it and i want to help

 

There is a blue or grey two wire plug with a brown wire and a green wire in it... found just above the bottom edge of the dash on the far right hand side. If it has never been accessed before, it will be a few inches up and inserted into a bright green rubber plug holder taped to the dash harness. There will also be a three wire plug in/close to the holder... ignore this one... just know you are in the right area. Pull it down so that you can access the pin plug end, bend a paperclip into a "U" shape and insert it into both pin slots. Turn the key on and watch the amber MIL (Check Engine Light). Count the blinks and watch them repeat a few times to make sure you have the count correct... they will go from smallest to largest, but they may not begin at the smallest. If you don't have a factory service manual (or equivalent), Google the OBD-1 code list and go from there.

Good luck.

 

ok thank you. he will check this tomorrow at school. we are concerned with the fact that his d15b7 has an extremely high idle. it almost sounds as if its rapping out. pushing in the clutch makes it worse and hes burning through 2 quarts of oil in a couple days. it all started when he replaced his exhaust. he's also replaced the iac and the tps

 

If it's 1994 it's too old to have an OBD2 port, those started in 1996 (although maybe some cars had them before that).

 

Swapping this and not calibrating it will mess everything up.

Throttle fully closed the TPS should have an output of 0.48 volts and wide open throttle should be close to 4.8 volts.

The most important part is the 0.48 volts when closed.

I suspect the TPS was thrown on and not calibrated so the ecu thinks the gas is always partially depressed.

 

Yes you must calibrate the TPS. Also check that the throttle cable goes slack and the throttle plate closes all the way when no one is pressing the gas pedal.

Then warm up the engine and unplug the IACV. See if idle speed drops. It should slow down to about 450 rpm (i.e. barely running) with the IACV unplugged. The air screw on the top of the throttle body can be used to adjust that. Never adjust the screw that stops the throttle plate linkage. When you plug the IACV back in it should pick up to a normal idle. If it does slow down to 450 unplugged but still goes too fast when plugged back in, you need to check the ECT sensor.

Unplugging the IACV while running should instantly turn the CEL on with a code 14. This is a good way to be sure you can read codes.

Oil consumption is a different issue. Making oil smoke that gets worse when you floor the gas while driving in gear, and continues to smoke badly for as long as the gas is floored, means the rings are worn out.