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Reluctor sensor hot start issues

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I had an instance where my car would not start at a track day, been looking into it and have a few leads to try.

its a 3sgte (stock distributor) running a haltech PS1000, it has always started apart from a few times at the track.

I have found that Toyota reluctor sensors can loose voltage when they get hot, leading to a no trigger event.

before I swap to a hall set up (custom) I want to try changing setting, but lacking an oscilloscope I am curious if any one has a method to do so? particularly the voltage thresh hold? currently it is stock haltech so 0.25v at 100rpm and 0.86v at 1000rpm.

with the filter set to level 1.

I cant easily replicate this apart from hard track days and mountain runs (maybe) so im looking to make a few educated changes before the next track day and then log if it still occurs to assist in diagnosis.

my instinct was to drop 0.05v across all RPM values from 0 -1500, concern is, is that a large change or negligible change? also will turning of the filter help my issues or hinder it (filtering removes noise, this may help the ecu to "see" the trigger event?

how would you guy set about problem solving and diagnosing given lack of a dyno or even an oscilloscope?


You are correct about scope and treshold. Measure the signal amplitude with the scope during cranking and on different RPM on normal conditions. Multiply measured values by 0.75, the found values you can use as a treshold. If it still some miss counters, use lower value as a multiplicator, but I found that 0.75*signal amplitude treshold numbers work pretty well on 3SGTE, however I have Motronic 36-2 crank trigger.

I've found the Toyota reluctor signal levels to generally be quite low and this sounds like exactly the problem you're having. A scope is a nice way of seeing exactly what the signal is doing however you can still make adjustments and simply test the outcome. My own experience would suggest that a threshold of closer to 0.1-0.15 V would be better at 100 rpm. I doubt you will need to adjust the 1000 rpm threshold as it's normally only an issue at the cranking speed when the signal level is very low.

If you go too low you're simply going to have the ECU see noise as a valid signal and the rpm will be erratic so there is no danger to adjusting the setting incorrectly while you're trying different thresholds.

@GRaF_ST205 my personal recommendation is to set the arming threshold at approximately 1/3 of signal amplitude which should be enough to allow the ECU to clearly see the signal while rejecting noise. 3/4 could be quite marginal with some ECUs.

ok sounds good,

what about the filter levels?

just leave them as it is unlikely related to my issue?

dropped my 100rpm to 0.15v and linearized to 0.8v at 1000rpm,

havnt yet got to the track to verify the issue is solved, but an added side affect is my starts seems to be smoother.

Sorry I missed the question on filtering. Generally the filtering you need will depend on the number of teeth on the pickup as well as engine speed. If you increase the filtering too far it's likely that the ECU will begin ignoring valid trigger inputs at higher rpm. You want to use as little filtering as possible and increase it only if you start getting unstable triggering at high rpm. A scope is a useful tool to help you set this up of course as both the trigger level and the filtering may need to be adjusted.

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