What's up everyone,

It's been a while since my last post so here is my current setup:

VT Built Engine @ 10 psi (for now)
Portfueler Fuel Management

It seems as when the car is under slight load (no boost - crawling up a hill real slow in the low rpm range - 1000 rpms to 2000 rpms) the air fuel gauge gives wacky readings. The gauge will light up a bunch of lights (like half of the gauge) or a couple of bars in the lean and a couple of bars in the rich at the same time. Sometimes, the gauge will even go completely out (no lights). I can even cause the gauge to display wierd lights by putting the parking break on and slightly easing the clutch out to gently put the car under a small load.

Here's some additional background info. The car has been turbocharged for 3 years now and the gauge has worked fine with no problems. The signal wire for the gauge is soldered to the o2 sensor wire (no clips to come loose). The power wire for the gauge is fused directly to the battery and the ground for the gauge is connected to the batteries negative terminal (ensures good ground for the gauge as this is critical to good readings).

Has anyone ever have this happen to them? Is it a sign of an o2 sensor aging and going bad?

Thanks,
Kurt

mine did a similar thing when the resistor to the exhaust sensor came off. But then again mine is a 95 and had that stupid pipe/sensor on the downpipe. Mitsu put a couple resistors on it...no one knows why....

Kevin
The old:


The new:

Yesterday, I worked on the car and found my problem. Since the air/fuel gauge was working correctly when the car was idling, I figured the sensor is not the problem (good thing because the dealer here in New Jersey wants $220 dollars for a new one). When I put the parking brake on and eased the clutch out to put a load on the motor, the gauge would begin to show random light patterns as mentioned above. I then got the idea that the random light pattern occurs when a load is put on the motor which means that the motor is twisting in the engine bay. This causes the intercooler pipes to twist against the wires leading into the ECU - the exact same place where I soldered the signal wire for the Air/Fuel gauge to the ECU signal wire for the front o2 sensor. Over the years of rubbing, the edges of the solder worked it's way through layers of electrical tape and was shorting out against the flexing intercooler pipe. I fixed this by removing the sharp edged soldered connection and putting in male/female crimp connectors (the female plug is electrically shielded - it has a plastic cover to protect the eintire connection from shorting). Once everything was connected, the connection was wrapped in electrical tape and then all the wires leading to the ECU were retapped. I am glad I found this problem as the shorting o2 singal was really causing the car to run badly.

Here's a picture of the intercooler pipe and it's relation to the wiring harness:



Here's a picture of part of the solder coming through the electrical tape where it was rubbing against the intercooler pipe:




--Kurt