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Discussion Starter · #1 ·
Hello,

We are working for month on a 04 MX-5 with MP62 and EMU setup.
Basicly the car is running close to perfect in every way.
Unfortunately we have 1 major problem, maybe you have some ideas?

The car goes to rich condition AFR 9-10 on idle and cruise
suddenly without any reason we see.
The problem is coming just sometimes, we can`t force the MX-5
to go in that mode.

When the problem apears, the car is only driveable with boost.
The EMU + O2clamp force the system to AFR~12 under boost.
The car is difficult/not startable in the problem mode.
We leave the car for 15-20min untouched...everything fine.

For sure the direction seems temperature on first view.
We found in the EMU datalogs a strange water temp rise up to
120? celsius (248?F) in a very small time, but we don`t think
this is related to real water temp, more it looks like a
sensor/cable or ground issue.
Sensors was renewed, grounds was checked/rechecked+redone.

All ideas welcome!
Just one specific question:
Is there a safe mode in the ECU which forces the
car to very rich condition above 120? Celsius/248?F water temp?

thanks in advance
Falk
 

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are you using an innovate LC1 to feed the ecu the o2 readings ?

These default to read a very rich afr if they go into a state of error.

It could be something this simple.. especially if the engine management is relying on the o2 signal to provide do fuel adjustments.

Usually this will be due to it overheating or cooling overly quick.

though non of this would relate to the water temp rise unless the rise in water temp is happening due to the engine running rich or lean.
 

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RSNick is NickRS backwards, wtf?
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Have you turned Autotune off?

Even if your lappy is not conneccted your Emu will fight with the OEM Ecu.It will run fine for 10mins then go horrible. You stop, turn off the engine, the Emu reverts to the last saved map when you turn it back on and then it starts fighting the Oem Ecu again, etc etc.
 

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Sounds like a temp sensor fault, possibly even a grounding fault if it's so intermittant.

i.e. engine up to temp and runs well with coolant at a true temp and when the fault occurs a whole load of fuel is injected.
 

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Discussion Starter · #5 ·
Skuzzle: we are using Zeitronix ZT-2, this is for me the bulletproof WBO2 system.
I suspect no problem here.

RSNick: Autotune is on and off, but is not acting with 0 throttle.
more, we see in the EMU datalog that the injection INPUT signal is far to rich at idle for example,
If the EMU reads correct, the ECU causes the rich condition.

Craigo: Do I understand correct, that the MX-5 ECU will inject more fuel when the water temp goes above
health areas?

What I will try next is to simulate hot condition using a 50 OHm resistor instead of the water temp sensor.
Lets see what the ECU will do then.

thanks so far
Falk
 

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RSNick is NickRS backwards, wtf?
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RSNick: Autotune is on and off, but is not acting with 0 throttle.
more, we see in the EMU datalog that the injection INPUT signal is far to rich at idle for example,
If the EMU reads correct, the ECU causes the rich condition.
Not sure I understand how it can be on and off at the same time, I don't mean to be rude but are you in the Uk?
 

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Discussion Starter · #7 ·
Sorry, my english is not the best, I have problems to describe these things.
we had the problem with autotune ON and with autotune OFF.

...I am not in the UK, I am in Germany


Falk
 

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9 points, $20,000 and a lot of happiness.
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Check the TPS and set it to the factory specs.
 

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with a 1 bar cap, you dont have any water above 120c its steam.
does the emu&stock ecu share a single temp sender? If so, i would suspect that. Its perhaps going open circuit, leaving the cars ecu and the emu just wired together. The emu see's a 120c reading and the cars ecu puts the choke on(cold running enrichment)
 

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Discussion Starter · #10 ·
Check the TPS and set it to the factory specs.
Hello Gixer,

I had the TPS in focus for a short time, but put it beside for one reason:
Under boost the car is running well in the problem mode.
Shouldn`t a TPS problem influence the boost area too?

But maybe you can describe your idea a little more in detail?

thanks
Falk
 

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9 points, $20,000 and a lot of happiness.
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No idea if your 04 has the same TPS as my 94, but on my 94 the TPS has 2 functions.

1/ Is a 0v to 5v variable signal
2/ Is a 0v or 5V idle switch

On my car if the idle switch is not correctly calibrated the car starts suffering from inconsistent idle and runs very rich.

As i say i have no idea if the 04 is the same, but it should only take a few mins to check the TPS is set correctly and at least it rules it out.
 
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