TPS Voltage / Calibration - 84-86 2.5 (Page 1/1) 82-T/A [At Work] DEC 17, 10:56 AM Hey guys, I just wanted to confirm that the correct "closed" / idle voltage value for the TPS sensor for our cars... it's supposed to be 0.525 Volts, correct? Is there a benefit to making it lower, or making it higher? Does making it .53 (for example) give a little bit more fuel? Just trying to understand completely what the ECM expects and how it responds. I saw a video where someone adjusted it slightly higher on a different car, and it responded better off-idle. Note, we haven't checked the voltage yet, but I couldn't find anywhere that said what it should be (I'm sick, so my search skills may not be working). I did see a TBI-400 with the same TPS sensor, and it said 0.525v was optimal, so just checking. Once again, this is on the TBI-300 in an 84-86 Fiero / 2.5. Thanks! 1985 Fiero GT DEC 17, 01:35 PM quote Originally posted by 82-T/A [At Work]: Hey guys, I just wanted to confirm that the correct "closed" / idle voltage value for the TPS sensor for our cars... it's supposed to be 0.525 Volts, correct? Is there a benefit to making it lower, or making it higher? Does making it .53 (for example) give a little bit more fuel? Just trying to understand completely what the ECM expects and how it responds. I saw a video where someone adjusted it slightly higher on a different car, and it responded better off-idle. Note, we haven't checked the voltage yet, but I couldn't find anywhere that said what it should be (I'm sick, so my search skills may not be working). I did see a TBI-400 with the same TPS sensor, and it said 0.525v was optimal, so just checking. Once again, this is on the TBI-300 in an 84-86 Fiero / 2.5. Thanks! The TPS is just so the ECM can see throttle change and how far and fast it changes, it only controls fuel when the throttle is moving, for idle or steady state, the map sensor controls the fuel. There is a wide range of normal "closed throttle" and a wide range of normal "wide open throttle", something like 0.25v-1.25 and 4-5v 82-T/A [At Work] DEC 17, 01:43 PM quote Originally posted by 1985 Fiero GT: The TPS is just so the ECM can see throttle change and how far and fast it changes, it only controls fuel when the throttle is moving, for idle or steady state, the map sensor controls the fuel. There is a wide range of normal "closed throttle" and a wide range of normal "wide open throttle", something like 0.25v-1.25 and 4-5v I've never bothered to "adjust" a TPS before... I'd always just replaced them, but I did notice that for most cars, there was a way to adjust them (rotate them slightly), beyond just bending the tab. It's always been "ok," but I was reading that really, you're supposed to adjust the TPS so that it's within proper range. I'd heard that 0.525 is supposed to be the optimal reading... I'm just trying to figure out if that's correct. It'll still work (my guess) in the range you mentioned, but probably affects the behavior somewhat. I'd like to get it dialed in properly. I've also never bothered to adjust an IAC either... just replaced them, but there's a process for that too in setting a base idle (less so on the 2.5, but more so on the V6). 82-T/A [At Work] DEC 17, 04:38 PM Ok, I've done a bit more research and trying to find similar GM vehicles and looking at service manuals. Some things I've found (and stolen from other threads on Pennocks, or elsewhere on the internet): - The TPS is only used by the ECM when its value is changing. At constant throttle the TPS has no effect at all on fuel delivery or spark timing. (more or less what you said 85) - The ideal "idle" (closed throttle) voltage should be ~.5v, but it's recommended to adjust this a bit higher to .525v ... - ... this is to ensure that when you are at WOT, it shows a FULL 5.0 volts. Ensuring you have the full range to 5 volts is key. - Testing the ability for the TPS to sweep (linearly) from .525v to 5v without missing, jumping, etc., is important (to prevent stumbling or drivability issues). - An unsynchronized voltage output of the TPS relative to throttle position can throw off the entire fuel map and cause drivability issues. - A lot of the 'China' made sensors do NOT output the voltages that are expected, and often not to the full 5v at WOT. The Gray wire (5V Reference) connects to pin A on the TPS The Blue wire (TPS signal) connects to pin B on the TPS The Black wire (Ground) connects to pin C on the TPS Patrick DEC 17, 04:42 PM quote Originally posted by 82-T/A [At Work]: I've never bothered to "adjust" a TPS before... I'd always just replaced them, but I did notice that for most cars, there was a way to adjust them (rotate them slightly), beyond just bending the tab. Do not bend the tab. Rotate the sensor only. If the sensor doesn't have slots, make 'em. Helpful video... 82-T/A [At Work] DEC 17, 07:57 PM quote Originally posted by Patrick: Do not bend the tab. Rotate the sensor only. If the sensor doesn't have slots, make 'em. Helpful video... That's a good point. I always used to bend the metal tab ~25 years ago... but never really knew why I was doing it, I just wanted it to be more 90 degree.