Roen

iTrader: (2)

Well, I noticed that my TPS was wayyyy off spec, so I set out to adjust it in the hopes of stopping the bucking/lurching and the pulsating idle that I have. Here's a funny little log of many problems of a first time TPS adjuster. If you're looking to adjust it, you might want to read this to avoid some of the errors that I made.

First off, I read every possible thread on TPS adjustment, plus articles from FC3S Pro, Johnr's site, and teamfc3s. Then I set off on actually trying to set it.

First, I sourced a multimeter and tried that method. I disconnected the TPS, (I have an S5, so I have the 6-pin connector). Here's where I made my first mistake. Instead of using the engine block as a ground, I used the ground plugs as the ground, and put my negative lead in there, and then I inserted my positive lead into the data lines. To add insult to injury, I inserted the leads from the front, instead of the back of the connector/harness. So......as you can imagine, I got ridiculous readings all over the place and didn't really do much to adjust my TPS. Lessons learned: Read instructions carefully. If using the voltmeter method and 6-pin method, use engine block or battery post as ground, not the ground in the connector.

Plan B was adjusting via the 3-pin test connector. More mistakes were made. I assumed that, after rereading the instruction regarding the voltmeter method, grounding to the engine block was the same for all adjustment methods. Wrong. Instead of hooking the negative lead up correctly, I touched it against the block and used the positive lead in the switched ground sockets within the 3-pin test connector. Again, readings that didn't make sense and wasted time. Lessons learned: Once again, READ INSTRUCTIONS CAREFULLY!

After rereading the instructions on the 3-pin test connector method one more time, I set out to adjust it properly. Instead of using a test pin checker (the mazda gismo with 2 lights that light up that costs ~$35), I used my handy multimeter. This method is much easier done with two multimeters, but one multimeter will suffice. Actually, one voltmeter will suffice. I will say, that before I go any further, this solely adjusts the TPS, but doesn't really give you accurate readings on if your TPS may be failing. If you can, use the 6-pin TPS connector with a multimeter method. Measure both resistance and voltage. IF you're really ****, do the 3-pin test connector method, and then do the 6-pin method, but you might just be wasting time. The fault of the 3-pin test connector method is that it only adjusts the narrow TPS sensor range.

Continuing on, I correctly hooked up the positive lead into the bottom socket. I then chose one of the top two sockets to insert my negative lead. I then fiddled with the adjustment screw until I passed the threshold, from when the socket was reading voltage to when it read zero volts. I memorize the screw position and repeated the same process , switching the negative lead into the other socket. I fiddled with the screw again until I crossed another threshold. From one screw point to the other is the good TPS zone, about half a screw turn. This is where you want your TPS to be set.

Tangent: While reading an article on the TPS adjustment, I came across a tip. It read, "The best method is to turn the screw counter-clockwise, until both lights turn on (assuming you have the Mazda test light, or a similar device), then turn the screw clockwise until the light turns off. Add another 1/8th turn clockwise and you're good to go." Now, maybe my TPS is screwy, but when I turned my adjustment screw counterclockwise, I read zero volts from both sockets. Turning the screw clockwise and passing both thresholds, I read voltage from both sockets. Correct me if I'm wrong, but won't the Mazda test lights turn on if there's voltage, and stay off if there is no voltage? It sounds like my test socket is working in reverse. The funny thing was that I tested a variety of TPS settings and the smoothest one is, turning it counter-clockwise until both sockets read no volts, then turning the screw clockwise again, until one of the sockets became active. I added another 1/8th turn and it was golden. That position was the same as the article suggested, even though the TPS voltage on my TPS, I think, was reversed. Just thought I'd share that.

This weekend, I plan on working on the 6-pin method to get my TPS as close to smooth as possible. My car still has a pulsating idle when it starts up cold and warms up. I still have light bucking when I lay off the throttle and get back on, but the bucking is reduced by a lot. I'm thinking I have a vacuum leak and my TPS is probably busted, but we'll see this weekend!

BTW, if you have two multimeters, hook both positive leads into the bottom socket, and hook one negative lead to each top socket. Turn the adjustment screw until one meter reads voltage and the other doesn't. My additional tip, based on my TPS is that, if you first hook up your multimeter(s), check voltage in both top sockets. If both sockets are giving voltage, turn the adjustment screw all the counterclockwise until both sockets are not giving voltage, then turn the screw clockwise until one socket gives voltage. Add another 1/8th turn and you should be good. If both sockets are not giving voltage, it's handy to have two multimeters in this case. Turn the screw clockwise until one socket is giving voltage and add an 1/8th turn.

I tested four positions of the TPS. Threshold from the left arrived at by turning screw clockwise, 1/8th turn added onto threshold from the left, threshold from the right arrived at by turning the screw counterclockwise, and 1/8th turn added onto threshold from the right. The best position for me, was 1/8th turn added onto threshold from the left.