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Resolved 1G ECU questions

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meciora

Probationary Member
28
17
Jun 8, 2025
Poland, Europe
I can't find some information about CEL on the dash. When I turn the Key in ON position the CEL stays as long as I start the engine I mean even 10 minutes, but when it starts then it disappear.

I'm asking because I run out of thoughts. When engine is cold it barely starts, feels like it works on 3 instead of 4, on 20 seconds, when i press throttle it even dare to stall in that time, sloppy reaction on gas throttle, but when it achieve operating temperature, its ok but not great, still reaction on gas is laggy. And I think its running too hot, valve cover after 3-5 minutes on idle is impossible to touch.

Done O2 sensor, valve cover seal, new spark plugs, injectors cleaned and with new gaskets, checked the MAF (working) etc. One thing I notice is small crack on exhaust manifold, but I don't believe its because of that. To be honest even if its hot outside, cold start gives water vapor, but its not coolant, not thick, just water, like in normal car in winter but it disappear fast. thanks for any advice and help.
 
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Solution
As it turns out the ecu was already struggling with some interior issues, earlier was the check engine light, then the capacitors replacement helps a little but later the ecu was developing some idle issues, changed it in this thread:
Car runs fine now, every gremlins that I encounter was from bad ecu. 👍
Still I’m going to repair it, because this things are valuable this days. Thanks!
Check to see if there's a stored diagnostic code. I'm assuming you don't have anyway to data log, so here's a guide with a test light or multimeter.

Another thing you might want to check is the ECU circuit board for leaking capacitors. It's under the radio in the center console. You have to remove it, take the case off, and inspect the electrolyte capacitors for bulging on top and/or leaking underneath. Post a clear picture here and we can help.
 
It turns out that the code from ECU was o2 sensor. Despite that its new I checked the cables, and white wire was broken and burned out, replaced it and done new plug, reset ECU and it’s working nicely. In ECU will check in some time the capacitors.

When you guys reset the ECU, BISS screw at TB should be screwed all the way? Then when is at operating temperature I should unscrew it at around 750rpm?

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When You guys reset the ecu, biss screw at tb should be screwed all the way? Then when is at operating temperature I should unscrew it at around 750rpm?

I usually bottom it out and then open about a turn and a half to start with. Once the car is up to temp you need to lock the ECU into BISS adjustment mode and then adjust for a 750 +- 50 rpm idle. You should also make sure that the ECU and engine are in sync timing wise. You make have to go back and forth with both until you get the timing correct and then the BISS.

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Ok, now I have some info about my ECU. It looks like new.. except…….. XD
thx for anyone and for this site to help with DSM.

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What is the part number of the cover, please so I can update my list.

It's interesting in that it's an NT ECU but has a knock sensor. The US NT cars don't but I've heard that some of the non-US cars do because of fuel and tune differences.

You can see that the capacitors are original and have leaked causing corrosion to various spots of the circuit board. The most sigificant is the corrosion for the traces between the Microprocessor and C19. The it the reference voltage for the processor's analog to digital converter. Also the spots on the traces going into the MPU and those at R32, R33 are starting to eat through the copper. If the copper and solder parts aren't shiny and starting to look crusty then corrosion damage is going on.

So you need to the the capacitors replaced ASAP, the electrolyte neutralized, and the various circuit traces measured to make sure they aren't damaged.
 
here you go

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As it turns out the ecu was already struggling with some interior issues, earlier was the check engine light, then the capacitors replacement helps a little but later the ecu was developing some idle issues, changed it in this thread:
Car runs fine now, every gremlins that I encounter was from bad ecu. 👍
Still I’m going to repair it, because this things are valuable this days. Thanks!
 
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