Operation: Replace Fuel Injectors is underway

Update again again: I continued the game of unplugging random sensors to try to evoke any changes in performance. When unplugging the MAF sensor I didn't get any positive nor negative response. First time I did a teardown the car went buck-wild with it disconnected, then calmed down when reconnected. Here it does not care, so I dunno if that could also be a problem child.
 
Pulled plugs 4, 5, and 6 today. Those are pretty toasted. Something is commanding the cylinders to flood with fuel it seems.
I also did a compression test on 5 and 6. They were respectively 144 and 143, so that rules a mechanical failure out.
Seems like we have bad data or an electrical issue somewhere. Ugh.... This is gonna be a while.
Would the wide open bung on the EGR trick the O2 sensors into thinking it's running lean, perchance? I might getting a mobile welding service out there to cap that off, next.
 

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Another month, another singular free day, another update: It's probably clogged cats. I dropped the exhaust right at the manifold flanges and that is the smoothest it has idled since I rebuilt the top end. Welp... now to drop the rest of it.
 
After much struggling, examining, and reconsideration, I'm just going to cut the cats out, gut them, then exhaust-clamp them back on. The effort required to drop the entire exhaust system requires patience I do not have at this time given how much rust has infected the hangers and flanges. It's a mess, but at least I now know what to stab at next!

Hooray! progress! As a bonus, here's my Tbird running open headers. Doesn't sound as bad as I thought it would. Reminds me of an old tractor followed by a banger-ring car. I miss going to those as a kid. Haha!
 
Update: Cats cleared, and we're misfiring/backfiring again.

Life happened and July went by fast, but I had time the past 2 days to carry on. Cats are cleared clean though, they have been reattached, aaaaaaaand the car still misfires like mad, now with much more backfiring! Dammit. I was so close. It was RIGHT THERE. Ugh...

I presumed maybe it's stale gas since it hasn't been refilled since 2021, and it was resting just above E at this point. I got 5 gallons of 93 and some HEAT fuel system cleaner to toss in the tank. That didn't seem to help either.

I don't know what to do at this point. I'm at a loss. It borderline seems like all the injectors are being commanded to stay open given that everything still stinks of raw fuel? I need help on this.
 
September update: Tore everything apart again. Fuel pressure regulator had failed. The intake was sucking in fuel from it causing everything to run rich. I replaced it and there doesn't seem to be any change to how its behaving. I'm going to lift the car to pull and clean the plugs (ugh....) and see if there's any change in behavior. I also have a friend mailing me a secondhand DIS to see if that changes the behavior on the car.

We're back to parts cannon mode.
 
September update: Tore everything apart again. Fuel pressure regulator had failed. The intake was sucking in fuel from it causing everything to run rich. I replaced it and there doesn't seem to be any change to how its behaving. I'm going to lift the car to pull and clean the plugs (ugh....) and see if there's any change in behavior. I also have a friend mailing me a secondhand DIS to see if that changes the behavior on the car.

We're back to parts cannon mode.
Don't bother with cleaning the plugs. Install new plugs and new wires.
 
Don't bother with cleaning the plugs. Install new plugs and new wires.
You saying I can't just hit these with some brakleen and toss them back in? lol

20230911_170106.jpg

Joke aside, I got new ones and tossed the first 3 in on Sunday, then did the second 3 today. The car runs now! It still has an inconsistent backfire/knock, and I mean inconsistent. Sometimes it'll pop back to back for 2 cycles, other times it won't pop for 10-15 seconds. Seems that the longer I ran it rolling up and down the driveway the less it pop'd. I'm guessing it's either the old/bad gas in the lines or it's the EEC-IV trying to re-learn timing since the battery is still connected from when all 6 old plugs were in it. Not sure if it being catless now could be a cause too, but that's a subject I need to look up.

This pretty much concludes Operation: Replace Fuel Injectors.
The culprit in the end was the Fuel Pressure Regulator failing, then the subsequent fouling of all 6 of my spark plugs. The fuel rail remained in pressure spec, so I never suspected it up until about a month ago when it finally started to fall low out of spec.
 
Can't believe I started this thread a whole year ago. Given the space between last post and now, you can tell I hung up the coveralls as it got cold over the winter. Well spring has sprung and with the warm days this weekend I'm back on it. Rubber mat and steel plates on the stone driveway with the car parked on top this time.

So what's new?
The oil has been changed and it was more gas than oil by the smell of it. My drain pan plug had metal sludge on the magnet, so that's jolly. Cut the oil filter open and it was metal-free. Not much of anything floating in the drain pan either except for a 1x1 millimeter's worth of powdered whatever sprinkled throughout. Friend of mine in Canada with a Mitsubishi 3000GT said "a little metal sludge is not ideal, but fine enough. If chunks are coming out or if it looks like a glitter bomb like my Dodge Stealth did, then she's hosed."

Barring it over by hand I have no problems. Crank it over with the fuel pump disconnected and it's the same note every rotation. The moment I give it fuel pressure it falls on it's face so hard that at one point I had 3 cylinders fight back on me one by one, and then it stalled. At this point I'm convinced it's hydro-locking in gasoline.

So what's next?
I'm pulling the fuel pump fuse, all the belts, tearing down to the rail harness, noid testing all of the injectors, and if there's no oddities then I'm putting the stock injectors back in and seeing if that does the trick. Last Fall I replaced the original injectors before doing the fuel pressure regulator simply because they were easier to get to plus I HATE having to undo the wiper tray ever time I need to access the rear block studs. I think this time I'm going to cut a channel in the mount below the FPR so it just slides down over the stud instead of the stud needing to drive through it.
 
Wow!! that's a lot of gas-hydro locking the engine. The cat's &/or exhaust system must be full too.
Make sure you remove or disconnect it after repairs are done before attempting to start it.
 
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