Thread: fault code 12 and after that 43, best practice?

Hello,

In short: when I bought the car, the fuel filter was clogged so much the engine was running lean. Filter is replaced, after 10km the sparkplugs showed less lean running engine but it still didn't look good.

I wasn't able to get the car in to timingmode and I think I should try harder somemore, I got a decent howto and FSM instructions. But now I'm not able to adjust TPS or ignition timing. I suspect the TPS is a little off, it shows 0,24 Volts when measuring at the pins and it should be 0,45 Volts. But I'm not sure measuring at the pins with a running and connected TPS gives reliable results.

I did manage to read fault codes from the ECU, I got 12, MAF problem.

So I measured everything according to the FSM but one thing, a certain pin from the MAF to pin 17 on the ECU for signal. My cables aren't that long. But I assume that wiring is intact based on what I experienced.

From measuring I got these results: The output Voltage of the MAF is with ignition on, 0,81 Volts and this has to be according to the FSM, 1 Volt. But when I turn the key to ignition, my Volt meter jumps to 1 Volt to drop off to 0,81 Volts in ample seconds.

The output Voltage of the MAF with running engine is 1,81 Volts and that is the maximum according to the FSM. (I believe the minimum is 1,5 Volts but thats out of my head bc I left the printed manual in my car).



But the engine was cold and I needed to measure this with warm engine, which seems logical because then the Voltage went up and down between 1,6 Volts and peaking to 2,06 Volts. That means my MAF Voltage output is still 0,26 Volts too high.

But, errorcode 12 is not showing in the ECU no more and the FSM stated that a test drive and re-reading the errorcodes was necessary. So I got errorcode 55 which means all is ok, no error found. I tried driving it some more a couple of hours later, again errocode 55.

I'm certain that the ECU now uses the output of the MAF, my mileage wasn't any good and in low rpm the car is more responsive now and runs better. With WOT I didn't notice any difference.

Today I again read the error codes from the ECU and this time I got error code 43 which is:

43 The mixture ratio is too lean despite feedback control; fuel injector clogged / Throttle position sensor circuit is open or shorted

I do believe the ECU is right about the lean running engine. What I did before is running a tank with STP injector cleaner stuff and after that the engine became more responsive and noticably better. So the injectors are not like new but I did got noticable enhancement from them.

I managed to loosen the TPS connector, which took me some time coz it seemed stuck. But I put the connector back and it still is in place. Because I can't get the engine in timing mode, or else I would be able to correct the TPS Voltage.

Now I wonder, is the MAF really beyond repair and is it that why I get error code 43 or do I have to, after not receiving error code 12, look out for a bad TPS or injectors?

I'm not yet at the point to do big expenses on the car but on the other hand I wonder if the MAF is the problem. The output Voltage is too high, and it's initial Voltage is too low. I would expect that high MAF Voltage means lot's of air and so, rich mixture.

I hope that you can give me some good tips or advice.

For now, I'm about to check the sparkplugs again (after some miles of driving) if the ECU is only thinking the engine is running lean and so gives error code 43 or that it after for a long time not seeing a MAF or didn't use the MAF output for a long time, it might be using it now.

There are so many things to look for and I hope somebody knows more about this kind of error codes and ECU behaviour. Maybe my fuelpressureis bad and I don't want to end up with an extra MAF just to find out mines is bad.

I'm especially interested on what to look for before I go looking for parts.

Someone enlighten me if I'm wrong, but I didn't think you needed to be in timing mode to adjust the TPS. I though the timing mode was only for adjusting idle and timing.

All you need to do is loosen the screws on it so that you can rotate it. As you rotate it just watch the voltage, once you see .45-55V tighten the screws down and you should be good to go.

When measuring the MAF voltages use the intake manifold as the ground since this is where the ECU is grounded. (From the pics it looks like you are using the battery negative terminal from the pics, probably won't make much difference though)

Also if you have access to a laptop you should look into picking up a consult cable, it makes this kind of troubleshooting much easier.

Yeah, I checked FSM and it's not mentioning timing mode. Now I have adjusted the TPS, I can do it without starting the engine, just put it on contact.

I'm about to reground the MAF, it's not that that couple of mV stress me but I've heard that the MAF output voltage can drop quite a bit (tenths of Volts) by regrounding it.

Indeed, measuring via intake manifold or MAF itself yielded no difference bigger then <0.02V

I'm still interested in getting an OBD cable but now I have come this far, all I need to do is quite straightforward and I could do without Datascan.

On the other hand, it's kinda unclear to me what I can learn from Datascan. I'm also looking in to chiptuning or replacing the ECU.

Since its an NA, that won't do much, but after owning a 1.6, now upgraded to a 2.0, I'm learning what I can do myself and what kind of diagnose/repair/upgrade I can do.

So I might go with an upgraded ECU, if I find out that I can take it to the next car, which should be a turbo'd version to keep the learning curve steep

I'm just glad I didn't buy a SR20DET powered car, since the SR20DE is hard enough for me right now.

Now I learned getting some headers is the first thing to look at, the extra HP I will get from those are about just as high as I would get from chiptuning.

And pricing is also about the same overhere in Holland. And no matter what, I'm gonna keep this DD fuel economical, so no Weber like boosts for me.

Now I just would need to get the headers, but only after the whole car is in the shape I would like it to be and then upgrade the ECU or chiptune it. I'm planning to drive this one for another 3-5 years or more. Depends on rust and engine , I'm not gonna sell it for something with more stock HP.

But for the ECU part, maybe it's better to get one first and play with it before I put it in a turbo'd car. I always need to tweak the **** out of anything anyway.

It's a $/knowledge/help$$$ kinda thing So I just need to make sure I won't need to pay someone big bucks for my DD and I'm happy. No rush.