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Help with building your Speeduino, installing it, getting it to run etc.
User avatar
By panjaycee
#49948
Hi everyone! I’m almost ready to start my engine, and the tps calibration on tunerstudio seems to keep holding me back. The problem I’m having is that when ever I try to hold the throttle to get a reading, the map readings move instead of the tps. The tps guage stays at zero, no movements at all but the map gauge can move up and down. I have the control algorithm set to map and the board has the 400kpa map sensor that comes integrated in the speeduino. Engine is an L28et with a Nissan 240sx tps. I have no idea what the problem could be, I’m thinking it could be the ground. I have all my grounds and sensor grounds going to a junction grounded on the engine.
#49950
Wrong board selected in "Engine Constants".

All sensor grounds should be connected at the ECU on any ground pin (pick 1).

NOT to the engine block, cylinder head or chassis.

While this is NOT going to be the cause of your issue, the way you have done your wiring is not best practice.

Please in future supply tune and ideally a log when requesting help else we can only make assumptions.

https://wiki.speeduino.com/en/configura ... _Constants
User avatar
By panjaycee
#50042
Ok switching to UA4C worked and I got my tps nice and calibrated. Now I have to figure out grounding to the ecu.
So what I need to do now is just to tie all the sensor grounds into one of the 4 grounds going to the ecu?
Do I have to run them back to a thicker guage wire, then back to the ecu?
#50061
Take the extra mile and run each single sensor ground back to the ECU. That way they can not interfere with the current running back from another sensor. The wire going in is just as important as the one going out.

I know that 95% of installers do not understand that concept and just tie all grounds to one wire or a bolt just somewhere.
Two extra meters of cable are expensive and the people that write instruction manuals are stupid nerds any how.
User avatar
By panjaycee
#50091
Chris Wolfson wrote:
Tue May 04, 2021 10:59 pm
Take the extra mile and run each single sensor ground back to the ECU. That way they can not interfere with the current running back from another sensor. The wire going in is just as important as the one going out.

I know that 95% of installers do not understand that concept and just tie all grounds to one wire or a bolt just somewhere.
Two extra meters of cable are expensive and the people that write instruction manuals are stupid nerds any how.
I’m just having trouble seeing where to mount more than one sensor, I’m only seeing 4 ground outputs on the UA4C pin out (pin 10,11,21, and 22). Sorry about the lack of knowledge, this is my first stand alone project.
#50093
Just connect two wires at one port of the ECU. That is not the problem. What you should not do, is to run one fat wire from the ECU ground to the engine and then connect sensor ground to it. The usual "it's more convenient" mistake.
Something that works well for a tail light might not work for a bunch of sensors...

Take a sensitive voltmeter, connect one lead to the battery negative and move around the car with a long test lead, touching bare metal parts, while the engine is running. You will read a different voltage at any part. If ground was the same at any point anywhere, you should see zero volt at any metal you touch. This is not the case. On older cars you often find voltage difference of more than 1 volt. You can reduce that by cleaning and changing old ground wires.
If you look careful, you find ground wires on many different points. The more electronics the car has, the more ground straps. Imagine what happens when you ground sensitive, voltage reading sensors at different points. You get any kind of reading you do not want, as the individual potential of the ground point is unpredictable.
User avatar
By panjaycee
#50817
Finally got to wiring up all the grounds to one wire into the speedy. So far I got all the sensors to work, rpm even reads when cranking the engine over. Only problem I have now is that it’s does not have spark. I’m trying to turn the engine on with starter fluid, but I don’t have the pump or injectors connected, would that keep the coils from firing?

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