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G4+ Atom, Throttle position sensor interference


Ahti Peura
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Hello

We have an endurance team running with Honda CRX. The engine is D16A9 (DOCH ZC equivalent). We have the car up and running with G4+ Atom. The problem is the throttle position sensor, which seems to be interfering with something while the car is running. When only the ignition is on, car not running - the throttle position sensor works as it should, reporting from 0 to 100%.

When the car is running, it stays at 0% no matter what position the pedal is in.. There is some movement, if you move the gas pedal quickly.

I imagine the interference could come from distributor, as the motor is spinning and the triggers give out signals.

The distributor is wired according to this http://www.linkecu.com/support/documentation/technical-drawings/C28%20Honda%2024Tooth%20Distributor.pdf/view and triggering works as it should. (although our distributor is 16 tooth, not 24 - but it is configured accordingly) Trigger calibration works etc.

Things I've tried:

1. Change trigger grounds from sensor ground to body/engine ground - no noticeable effect either way

2. Disconnected the trigger shield/gnd wire - no noticeable effect either way

The original ecu had separate voltage feeds to MAP and TPS. Could they interfere with each other? Now they are connected to the same output on Atom.

 

Any thoughts what to try next? Try to run without alternator? Bypass car wiring harness, and wire the TPS directly to Atom?

 

BR,

Ahti

#82, WTF Racing team

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None of your symptoms hint at a noise issue to me - it very much sounds more likely a wiring issue.  Like maybe something is pulling down the 5v supply?  Do the MAP, water & air temp sensors give correct readings at the same time that the TPS is not?   If you hit F12 to bring up the runtimes screen have a look at the analog tab to see if anything looks odd there and also the ECU status tab to check the 5v out.

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Hi, thanks for the response. The 5V supply sound plausible, I'll give it a look. The MAP, water and air sensors give out readings as they should. Though temps are a tad high versus reality (but i recon it is because there is no pull-up resister option on Atom - and the error seems to be linear).

I'll check what you suggested and report back here.

 

BR,

Ahti

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  • 1 month later...

Getting back to this... Next time I wen't to fix the car the problem was gone. The TPS worked as it should. Next time we went to the track and the same thing occured - no signal when engine was running. Wen't back to the garage and replaced the TPS and it now works again as it should. If this occurs again, the problem has to be on the car wiring loom.

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