97 GSX Fuel Issue, Possible fuel system upgrade needed

[bassplaya25]

This car does not like to start, I have to pump the gas to get it to start. Also, when its running, when I get to about 4 to 4.5k on the tach, the car starts to stutter and bog down. I turned the turbo down(about 8lb now), had the MAF replaced, replaced the fuel filter and the fuel pump(Walbro 255LPH) and the problem still persists. When it starts to bog down, it tends to throw black smoke out of the exhaust. Its not stock, as the previous owner upgraded the turbo from a 16g to an 18g and also installed an Apexi Exhaust and an Ingen cold air intake. As far as I know, the fuel system was not touched after these upgrades. I have been looking into the issue and think I may need to upgrade the fuel rail and injectors, but would like a 2nd opinion before I drop the money on redoing the fuel system. When the fuel filter and MAF were replaced, it seemed to fix the problem for a day or so, then it would start doing it again. Any insight?

In addition, I had the turbo checked for leaks and it checked out well. All the replacement work I had done was at a mechanics, but they ended up giving up and giving me my money back. Really trying not to take it to a Mitsubishi dealer but that is just about where I am at with this issue.

 

[MitsGray97]

Have you checked your afr? It seems like to me that your running too rich. You can keep upgrading but you need to be able to control the extra fuel flow.

 

[RoryBarron]

Have you actually done a boost leak test? Compression or leak down?

 

[bassplaya25]

After researching and working with a few people, I may have found the problem. I believe my O2 sensor has shorted out and may have fried the ground trace on my ecu. From everything that I can find, I am capable of repairing the ecu myself by simply re-soldering the ground trace on the ecu and replacing the O2 sensor. My only problem is finding the ECU at this point. Any pointers? The reason I am looking at this as the issue is, I had a friend that was assisting me in researching the issue that is a bit more savvy than myself and he found someone that was having practically the same issue as I was and that solved his problem. At the very least I can check it out, if it does pan out, then I don't have to worry about upgrading anything at this time. - And no, I have not done a leak test myself. - also, what is an "afr"? you will have to forgive my ignorance on terminology.

 

[wicked98gsx]

Your ECU is behind your radio....driver side floor board, remove the side panel and poof! you will see the wires going into it. Its going to be a little work to get it out as the AC duct runs along top of it and has to be taken out to get the ECU out.