I bought a 1994 WRX Sti about 2 years ago. At that time it started losing power between 2000 and 3000 rpm. It only did it about once a week at the time. I read through everything on here and started fixing. It took me this entire ~2 years and it has been getting worse over that time to where it had finally become undriveable. It would stall before I could even get it out of the neighborhood. But now finally I solved it, and I'm embarrassed by how dumb I am.
1. MAF : First I read about the most common issue being the MAF. I hunted for a green label MAF and found one out of Japan. It arrived and did not have the green label but I threw it in. It did not fix the problem but did not make it worse. It must not be the problem.
2. Coil packs : I read about coil packs breaking up. I updated to a later generation coil pack based on what I read here. As well as new plugs. At that time the car was still running well enough that I noticed a slight increase in response but did not fix the problem.
3. Vacuum leaks : This comes up as one of the most common problems to cause the issue but is more involved to diagnose and fix because of the age and rarity of some parts. I checked for leaks and found one. There was a tear in the down pipe off the intercooler. This part no longer exists in the world but I tracked down a cast iron one made in Australia. Ordered and installed. I will never have to replace this part again but it did not fix the problem.
4. ECU : I updated from the original 250hp ecu to a later model 265hp ecu. I did not notice a difference but it also did not fix the issue. It did however give me an extra ECU so that I could send the original to Oregon for a Rob Tune 550cc chip, which I did.
5. Robtune : I installed the RobTuned ECU with 550cc tune, 550cc injectors and an AEM electronic boost controller and guage. This did not fix the issue as I did not expect that it would but it did drive me to get it solved because it is so much better than stock.
6. Finally : I took the original MAF and re-soldered the connections and re-installed. Then pulled out and reset the ECU. SOLVED. I had ruled this out because of the new one that I bought and tried as the first solution. I hate myself for not just fixing it right the first time. I took what would have been one hour of work and free parts to fix and instead spent two years and a not insignificant amount of money. The only thing that gives me a sense of relief is that the previous owner definitely knew about the problem, couldn't figure it out either and sold it to me for less than actual value because of it. So I'm not the only one that overlooked the most immediate and easiest fix.
The Bonus : What I now have is a 1994 Sti with 550cc injectors, 16psi of boost and launch control. Along the way I also installed a new radiator, coolant lines and just changed the oil. This thing is now the single most fun to drive car that I have ever owned and should be good for a while with the rest of the work that was done. I don't really have a point with this post other than to say double check the MAF if you are losing power anywhere.
11-08-2024, 05:34 PM
1994 WRX Sti EJ20G stalling 2k - 3k rpm (solved)
Linear Mode
