Hi everyone, stick with me here's some background... I have a 89 formula firebird 305 tbi. My dad owned it for a number of years and did some things here and there to it. In the past couple years we had new roller rockers installed, tbi rebuilt, and a new distributor and module installed. New Accel coil and wires were put on. AC Delco 2 plugs. New fuel filter, pump, and sending unit. Headers that have been wrapped. The o2 sensor port was also welded into the headers near the collector. Smog pump delete. New water pump and aluminum rad. Polly bushings on everything. Even the motor mounts. He also bought a chip, I don't know which one, but he says he followed peoples advice on this website and picked one from there. He also has done some mods to the tbi, filing it smooth in some areas for better air flow based off a post on here. Some various other non-engine related things were also done like subframe connectiors, ect. I took over restoring the car when he started another project and I've been driving it for months as a daily to work. I also use it for small trips to the store. The car however started dying on me recently and running rough sometimes out of nowhere. I think it's when it's warm but it seems to be random sometimes. The car would pop loudly and die, sometimes starting itself back up and continuing without issue. Sometimes I would have to pull over and restart it. Well the fuel tank turned out to be nasty and corroded beyond repair so I bought a new one. I also bought a brand new Delphi pump and sock and a k&n filter. I had also cleaned the sending unit with electric parts cleaner because it was covered with bits of rust from the tank. We got it put together yesterday and it ran great. No sputtering or dying and no popping. Until later that evening trying to get to work. I also lost my fuel gauge from the start so I'll be taking the sending unit out again to check it. So far I've only been able to check the coil wire's terminal for bad contact with the coil. It wants to slip off slightly. But, I've still had the issue and had good contact with the coil. I've also tried running the car without the o2 sensor plugged in which does nothing. I've read posts on here from 2008 and 2013 with similar issues. I haven't been able to find a good way to diagnose this. The only things I can think to replace or clean or check right now would be the egr valve, the tps, and fuel pressure. I don't have a way to test the pressure other than trying to observe the spray pattern from the injectors. Someone also mused over the cts being faulty and giving a bad voltage for the warmer engine. Another person suggested timing and I'll look at that. Please give me any insight if you've had similar issues. It seems quite a few people have had similar problems but I still can't find the right issue.

 

Connect a scan tool, look at the data stream. Wouldn't hurt to see if there are any codes stored.

Verify fuel pressure.

 

I don't have a way to verify fuel pressure yet, although everything is new up until the tbi, I guess I could have gotten the short end of the stick and gotten some junk parts. Jumping the obd gives code 12. No other codes rn. Check engine light not on. I just bought a new cts, I'm going to put it on real quick and warm the car up to see if it makes a difference. Thanks!

 

Changing the cts did not help.

 

Get a scan tool, get a fuel pressure gauge.

The pressure gauge can probably be had as a Loan-A-Tool from a parts store.