When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I am currently trying to install a ms3 mini in my 1.8. To give some back story, I accidentally flooded my entire engine with fuel when trying to set up my ms3. It flooded so badly that fuel actually came out of the intake (and probably through the vacuum tube into the IAC). Every since then, there has been a pretty loud humming coming from my IAC when the car is on (but not running). I haven't actually started the car since I've replaced the ecu. Also, after solving the fuel pump issue, my next issue became the throttle position sensor. In tuner studio, when I try to calibrate it, it only reads 1023 for fully opened and closed. I am 90% sure that the sensor is fine. It worked fine with the stock ecu and I also tested it with a multimeter.
So in short, is it bad that my IAC is humming, or is that normal? And why is my tps not working when I believe it was just fine with the stock ecu?
Is the IAC set to be on with engine off? If so, you’re just hearing it function. It’s usually dampened by a little engine oil/grease/seals, but you flushed that out. I’d expect it to be a little louder.
TPS is easy. Check that you have 5v and ground, and that there’s good continuity from
the signal wire to the tps.
For 5v, you'll set the meter the DC volts, the V with a straight line and 3 dashes under it. Black probe touches a good ground on your chassis, red probe touches your 5v line. With key on, you should read ~4.95v. The rest you can do with key off. Switch to continuity (it just beeps when the probes touch), or the proper way is checking resistance in Ohms, the one that looks like a horseshoe. Again black probe to a good ground on the chassis, red probe to your ground wire. You want less than 1ohm. Then move either of the probes to the signal wire, and the other two the ECU's TPS input pin, again you want less than an ohm.
Use your wiring diagram to determine wire colors for each of these. You didn't give us the year of the car, so we can't help you there.
Another way would be to unplug the TPS, and use a paperclip or similar to jump the 5v to your ground wire, and press calibrate at no throttle. Then jump 5v and signal, and press calibrate full throttle. Now when you do this, you should see your throttle jump from 0% to 100%. MAKE SURE YOU KNOW WHAT PINS ARE WHAT BEFORE TRYING THIS. If this test works, your wiring is fine and it's either pinned wrong or a bad TPS.
So I figured out this issue... the jumper on the TPS pins had to be flipped. Now though, it reads 0 for closed and open. Just to restate it, it is a 1995 1.8, running ms3 mini. Any ideas why it reads 0 for both?
There are 3 wires between TPS and MS:
5V
Ground
Signal
It sounds to me that your initial situation was that 5V and Signal were shorted to each other. Then you moved a jumper and now Ground and Signal are shorted to each other.
1 is Ground
2 is Signal
3 is 5V
As the wiper Is moved from 1 to 3, the signal to the MS should move from 0 to 5V. But if 1 and 2 are shorted together, 2 will always show 0V.
IN your situation, I suspect that you have tied 5V to the signal input at the MS, then changed the jumper and tied ground to the Signal input at the MS.
Now that I have thought about it some more , I’m not sure my explanation is correct. I cannot picture what inputs the jumper move changes. I’m not familiar with the Mini.
Did you plug the TPS back in after the jumper move?
I suggest you tell what car year, and if Mini is the correct model for that year. Maybe one of the guys that has one can help you.
07-11-2021, 08:02 PM
IAC and TPS problems when installing Megasquirt
0
