JN1AS4
10-26-2012, 02:04 PM
First off, HELLO ZILVIANS! Im getting kinda bummed now because i've been working on my s13 first thing every morning for the past and I cant quite figure out the issue. The problem ONLY occurs while the motor is cold after sitting all night in the garage. When I go to crank the car up the fuel pump primes very weird. Instead of priming smoothly for 3-5 seconds(normal) it primes for 2-3 seconds with a slight interrupted/pulsating sound. And the car cranks up and runs >10.0:1 afr while sputtering and backfiring it fouls the plugs out in the matter of mins. Earlier this week when the problem occurred I replaced the spark plugs and unplugged/plugged the CAS/ coolant temp sensor and it fired straight up and ran perfect. And it car ran perfect for the rest of the day. But the next morning it did the same thing. So I tried replacing the plugs again but this time it didn't work. So I went ahead and pulled ECU codes and the only code that it threw was 55 - Other Malfunction. CONSULT Terminal Required. So I pulled the positive battery cable off for 10 mins. Then went to start the car, And it fired straight up and ran perfect for rest of the day. The next morning same thing happened and the car ran like shit. So I pulled off the positive battery cable again and it fired straight up and ran perfect. Im leaning towards a faulty coolant temp sensor or a malfunctioning ECU. I don't think that wiring is an issue because the car ran perfectly for the past several years without me even touching a single electrical component. IF ANYONE CAN HELP ME PLZ DO.
Yesterday 10/27: I unplugged the coolant temp sensor while the engine was still cold, and it cleared up the problem. But I plugged it back up when the engine got to operating temp, and it kept running good.
Today 10/28: I tried unplugging the coolant temp again while the engine was cold but it didn't work this time, I guess the plugs were fouled out already. Because I replaced the plugs and it fired right up and quickly got to operating temp. Then I drove it around without the coolant temp sensor plugged up and it drove fine. So I pulled over and plugged the coolant temp back up just to see what it would do. And to my surprise it ran kept running fine. Tomorrow I may hard wire my fuel pump to a constant 12v power source to see if that eliminates the funny priming that it like to do which indicates that my car is going to run like shit.
Yesterday 10/27: I unplugged the coolant temp sensor while the engine was still cold, and it cleared up the problem. But I plugged it back up when the engine got to operating temp, and it kept running good.
Today 10/28: I tried unplugging the coolant temp again while the engine was cold but it didn't work this time, I guess the plugs were fouled out already. Because I replaced the plugs and it fired right up and quickly got to operating temp. Then I drove it around without the coolant temp sensor plugged up and it drove fine. So I pulled over and plugged the coolant temp back up just to see what it would do. And to my surprise it ran kept running fine. Tomorrow I may hard wire my fuel pump to a constant 12v power source to see if that eliminates the funny priming that it like to do which indicates that my car is going to run like shit.