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Older Link D423SGTE on 190 GT-Four Celica


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Hi guys,

I'm Mark, a new member of the Link forums. 

I purchased an old ST185 Celica GT-Four with a matching Link pulg in ECU of a similar era (early 1990's.  

Its been a steep learing curve to get the car running again, having been parked up for 13 years.

I'm trying to identify which model Link unit it is and to find out if it will talk to a laptop.

I have the led display hand controller but that only allows access to limited functions and is not ideal for displaying data on the fly.

I have detonation problems at higher throttle settings and on boost.  Tried pulling back maximum advance with minimal effect.  Tried increasing master fuel a little with little effect.

Perhaps its as simple as increasing fuel at higher throttle positions to allow for fuel supply as the boost increases.

I'm installing a new fuel pump to  make sure there are no fuel starvation issues that may be causing lean-ness.

Inj / Oxy display tells me injector capacity and in theory the mixture but I'm struggling to make sense of the oxy display.  It ranges 0 to numbers in the 90's but I'm not sure what the units are and what they mean.  What units is this measured in (I expected 0-1.0 volt as a measure of air/fuel ratio).

Any comments or assistance would be appreciated.




Edited by Mark1104
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I'll let @Simon ID the device but I will make a couple of comments about the tune side in the mean time.

Ignition timing and air temps would typically have the biggest influence on an engines susceptibility to knock.  So assuming your intercooler system is working correctly and air temps are under control then the most likely cause is ignition timing.  It could be something as simple as the base timing isnt set correctly (so the whole operating range is over advanced) or it could be the ignition map is too aggressive just in specific zones.  Note the "maximum advance" setting will have little effect as you would typically only hit maximum advance under high vacuum/overrun conditions.

You will really need a standalone wideband sensor/display to confirm the fueling side is ok.  You will not get any useful feedback from the hand controller as that ECU probably only has a narrowband sensor connected (if at all).  The "INJ" display is injector duty cycle in %.  If you are seeing numbers in the 90,s your injectors are too small.  "OXY" shows the voltage from the oxy sensor (if connected).



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Hey AdamW.

Thanks for the input.  I'm just feeling my way and trying to learn on the way, but still may be well out of my depth.  I'm cautious of changing the settings that came with the ecu too much for fear of messing it up.  I set the base timing at 10 degrees as per the instructions with advance set to "0" .    The car has the original top mount intercooler but being here in Tasmania air temperatures are on the low side at the moment.   The comment about the advance curves is possibly correct but I'm struggling to access advance curves with just the hand controller. 

I need to check the duty cycle of the injectors.  The numbers of 0-90-ish are from the oxy sensor.  I'm guessing that is 0 volt to 0.9 volt?


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  • 1 month later...

Thanks for the input on the issues I was having.  Turned out the solution was very simple.  Rust particles were blocking the filter on the immersion fuel pump to the point that the motor was leaning out under high fuel demand conditions.  Driving for any length of time made the problem worse.   A thorough clean of the fuel system and treatment and internal coating of the fuel tank should have things heading in the right direction.

This older Link ecu uses a narrow band O2 sensor.  Is this ecu able to work with the signal from a wide band sensor if I were to install one or would there be no benefit?  

Narrow band works in 0-1.0v and wide band is 0-5.0v??  Is that correct?

Alternatively I can install a stand alone wide band sensor and gauge to at least monitor fuel mixture.

Thanks again and regards,


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4 hours ago, Mark1104 said:

This older Link ecu uses a narrow band O2 sensor.  Is this ecu able to work with the signal from a wide band sensor if I were to install one or would there be no benefit?  

It would offer no benefit with this ECU.  I would go for a standalone wideband controller/gauge and just use that as visual feedback to any tuning changes or diagnostics.

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  • 2 months later...

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