WTF Happened Now?

NYSpeed Automotive
1

What a surprise. The DSM is frigged up again…Seems like the more gentle I drive it, the more often shit breaks.

Basically, right now I’ve got 2 issues that have come up since I had that electrical issue with the ground wire of my car.

First off, the temp guage is always in the middle. Even when I first start the car. When the car is off, it’s down at zero. Then when I start the car, it immediately goes to normal operating temp range.

Second issue, a bit more serious…

The car is dumping a shitload of fuel under part throttle. On the S-AFC controller, you can check the o2 sensor voltage. And under normal driving it usually cycles and the voltage readout bounces from high to low to high again very rapidly, and on the autometer it gives you the nice little light now. As of right now, the autometer is ALWAYS pegged at rich unless my foot is totally off the pedal, and on the S-AFC, the voltage readout off the o2 is always .094 volts or around that area, regardless of throttle position, unless I’m totally off the throttle. And the other thing is, the car is dumping so much fuel, that when I first get on the gas, from a stop, or even after shifting, the car actually stumbles, I’m assuming because there is too much gas and it is so rich.

As for the S-AFC, I have some full throttle corrections made, but no part throttle. The car had been driven for about 2 hours total time before the A/F problem popped up. The temp guage problem has been consistent since the electrical ground problem. I’ve got a CEL too, that I haven’t been able to get checked out so not sure what the code is. Also, the MAF readout on the S-AFC is on par with what it has been all along, so I know my MAF is reading right.

What is going on? Is it possible that the ECU needs to learn with no corrections being made via S-AFC so it learns a good stock setting before adding corrections? Or do I have some other issue around?

2

  1. Your O2 sensors are shot. Check them both, but it’s probably the front one (in the engine bay by the exhaust manifold). Break out your service manual and run the tests.

  2. Stop depending on the S-AFC to diagnose fuel issues. It sucks at that. Get a datalogger.

  3. Getting a decent datalogger will help you diagnose the temperature problem. The datalogger can pull temp measurements from the ECU so you can cross reference. It is very possible that you have a thermostat issue as well.

  4. Dump that POS autometer gauge. It is useless, unless you are trying to have a disco-tec in your car.

Seriously, how many times are you going to run into things you can’t diagnose properly before you decide to get a datalogger?

3

Well, I reset the ECU. And zero’d out all settings on the S-AFC. Car is running fine now. So it was the corrections on the S-AFC weirding out the ECU while it was reprogramming itself.

As for the datalogger. Trust me, I’m in the process of getting one. It’s been a rough month financially after my timing belt tensioner took a shit unexpectedly and I was basically put out $400 total at a time when work isn’t going all that great. (I get paid $8/hour base pay, with bonus structure off that, and if I don’t hit bonus, I don’t get anything else and can afford to pay my bills only). It WILL be the next thing the car gets. I already know I need one.

As for the autometer, it’s useless for getting an accurate readout. I’ve known that from the every start. What it IS good for though, is knowing immediatly when something is wrong as far as air/fuel. And I didn’t actually buy it so I could care less about taking it out.