Hey guys my car keeps getting code 4. Is it a problem with the engine possibly? I have had the ecu gone through I have tried a new distributor. I have rewired the wires from the dizzy to the ecu. The runs idles fine starts fine. The problem comes after you drive it I dunno 10 mins after it gets the operating temp. Then it kinda back fires then throws the code the engine doesn't run any different afterward. When you try to rev past 3.5k it cuts out. So the ecu is in limp mode. Is there anyway around this or what are your thoughts.

 

Code 4 is also vacuum switch what is that exactly? Could it be possible to not have a vacuum line or whatever that is hooked up properly??

 

I ohm tested the female plug at the dizzy with the ground to the battery post and the positive testing the bottom row on the plug. I get from 68 to 70 with the ohm tester set on 200 ohm. Am I doing this right or what do I need to do different. That doesn't seem like the correct reading either any help?.

 

I just tested it at the ecu the two ckp wires and got .356 ohms that's low isn't it? Does that mean I need to swap the dizzy?

 

I HAVE THE SAME ISSUE, but i can tell u if the ohms are between 350 to 700 ur good and if urs is above 350 at the ecu ur probly good cuz u lose some ohms from the dizzy to the ecu, also test it by touching one to each pin on the ecu and the other one on a ground for example touch b15 and touch a ground with the other wire of ur multimeter if theres any reistance u could have a short or need to replace the dizzy also u need to set ur dizzy at the correct timing or u will also get code 4

 

Year make model?

 

OP - This^ information is required. Add it to your first post. Also mention any mods to the car.

 

MINE IS A 91 CIVIC WITH A D16Z6 OBD1 CONVERSION AND A STOCK P28 THAT I CONVERTED FROM A AUTO

 

ok guys just in i have the solution if you bought your conversion harness from rywire or a reputable source or made it you probly never had this intermitent code 4 issue well for those of us who bought fromebay (me) which looked like a good quality harness is actualy only one snip away from perfect.... ok now there is two wires on ur obd1 ecu side that control your crank angle sensor well for some reason the people who made it ran a extra wire to b16 it comes from c15 and controls issc im not sure wat tht is but i u snip that wire your code 4 will not come back idk why they ran another wire to that pin on the ecu but i will do further investigation but for now i hope this solves your guys issue as well , btw just did a wot run from 2nd to 5 with a nice top speed of 140 i belive went way past the 125 mph speedo in my ef