1993 WRX struggle with 22, 23 and 24 codes
 

Hi there, I believe I need some help before going shopping for parts.

I have recently got 1993 import WRX, with FMIC, HKS dump valve and a lot of absolutely undocumented other mods that I am still investigating. After couple of weeks of light use, check engine light came on. How it is now, it is alright for some time after starting engine, then it goes on for a while only when rpm are less than 2000, then some time later it stays on, and when it does, the car is hesitating, and occasionally idling rough. Read the codes multiple times, I usually get 23 and 24 (I assume these ones are when check engine is on under 2000rpm), sometimes 22 as well.

So, cleaned MAF to see if that may help, put it back together, ECU reset, and problem is still there, however 22 was the first one this time.

I know then MAF goes south, it can trigger 22 (knock sensor circuit) as well, but while resetting ECU, it was knock sensor only, 23 and 24 codes appeared slightly later.

Obviously I need to sort it asap, but I am not sure if I should start with replacing just MAF, or is it actually knock sensor that is causing a problem? Or idle control.

Btw, just to let you know, I am fairly new when it comes to tinkering, I have some theoretical knowledge, but generally speaking, I have no clue most of the time. So, asking you guys to shed some light.

Has the car been mapped for the mods?

Tricky question. Judging on the amount of work done to it, I would say must have been. Problem being, I bought my car from a trader, and with no paperwork apart from logbook and MOT certificate, he said the car was remapped, but didn't know any details. But when it works, it feels more powerful than fully stock Ver 2 that belongs to a friend of mine (mine is Ver 1 btw). It will probably need new map anyway, as it was showing a bit of confusion around 4500 rpm from day 1, but error codes only started a bit later.

Yes, I know I should know better by now, and not just trust in previous owners sanity. But so far I am still mainly sorting problems as they appear, making the car run in general, before making it run better, if you know what I mean.

No then.

It has V5 ECU now, not the standard W6, but it's anyone's guess what exactly was done. Question is, does it just need a map, or there's actually something wrong with MAF? It worked mostly fine before. I am going to remap it but not sure if I should do it before sorting out error codes, or it's the wrong map that causes them in the first place.

In the end I have replaced MAF and knock sensor, reset ECU, all codes gone, car now behaves as it should. It looks like it even solved problems it had when I bought it, so it seems like it was mapped correctly, but then sensors were on their way out.