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Rough exhaust, no throttle response

Okay, so I bought it from my dad’s land lord for 900 bucks, it has sat in the yard for roughly 2 to 3 years. They have it a tune up, a new ac system, and revamped the brakes. It ran like a dream until it just suddenly started idling rough in a parking lot. Crackling and popping. We put seafoam in it to see if it would help and stated a 4 hour trip. About 1 1/2 hour into it, the car wouldn’t go over 2k rpm or else it would start jumping rpms and actively freaking out. It turned into a 6 1/2 hour trip. It was fine the next morning, but would once again so this whenever low on gas. Ran fine for 2 1/2 weeks, popping and crackling under 1500rpms. Another trip the same length, and on the way back I noticed the engine accruing up a little, sometimes refusing to accelerate until I let off and tried again. Got home, wouldn’t start the next morning. Towed it to a mechanic who changed the fuel injectors, cleaned out the throttle body, new fuel pump and fuel filter and returned it. Drove for a day, but had trouble starting and would refuse to accelerate then die, usually in reverse. That morning it quit; mechanic came and after unplugging the mass airflow sensor, got it to run, driving it to the shop. They replaced maf sensor, as well as both trottle positioning sensors, repaired chewed up wires, replaced collapsed vacuum hoses and cleaned the gas tank out. Returned it. Ran for a day, same issues. Next morning, car would start, but rpms would drop and sit at what read as 500-200rpms on the tac, and go a maximum of 10mph while exhaust was violently popping, cracking and periodically sucking in air, only occasionally revving up and accelerating. Liked to die when the gas wasn’t being touched. Made it to a stop sign, died. Would eventually start, but wouldn’t respond to throttle at all, even with peddle on the floor, aggressively cracking and popping, rpms at seemingly 100. Eventually inched it home, where I replaced the camshaft sensor, afterwards it would run fine until warm, reverting the last mentioned state. Figured it was a clogged catalytic converter, so replaced it. While it was clogged, it didn’t fix the problem. It’s costed me $1100 so far, in repairs, 200 more than what I paid. I recently got laid off as well, so I can’t, nor want to, take it to someone else. If anyone has any ideas, I’d appreciate it very much.

Sounds kinda like a transmission problem. It seems like you have trouble getting power down to the ground. One day in my car I was low on coolant and it runs the tranny cooler through the radiator so my transmission kept heating up and wouldn’t go in reverse and when I went to drive it would sputter and everytime I tried to give it power it wouldn’t accelerate anymore. I had to keep it in a sweet spot to make it home and maxed out at about 40mph. This would also make since as to your only happens when it heats up. I could leave the car overnight and start it the next morning with no issue but after running for a while it wouldn’t move in reverse and had the same issue in drive. It turned out I had a cracked coolant reservoir and it kept leaking all my coolant out.

During the initial work after you bought it, did anyone drain the bad gas out of the tank?

My God… why on earth would any competent “mechanic” have replaced all your fuel injectors. You most likely have one of the most reliable hard to kill engines ever in that Buick 3.8L V6… known as the 3800.

At first blush it sounds to me like you have a fuel supply or pressure problem, however… these symptoms are very similar to ignition problems but these things are easy to test for and verify. So just “shotgunning” this issue by throwing all those fueling parts at it is what you do when you have no clue what you are doing underneath a hood…or on engines. I’m sorry to hear that is what happened, because frankly …that was incorrect.

Knowing now that the issue is not fueling…or rather it is less likely to be fueling. I would focus on your ignition system. I believe you have a coil module with 6 outputs to the plugs… Have you tried to verify spark is not your issue… because to me…it is sounding more and more like that is the problem.

I would buy a new or known good used coil pack and try that out… Its a cheap part to try out compared to what you have already been through. Coil packs that are old or going bad…will act up when they get hot enough. Sometimes in the dark you can actually see the high voltage leaking out of tiny cracks in the module… if you see that…or if when you put your fingers on or near the pack you will get a nice shock…and you will know what to do after that.

I’d try a new coil pack and see what you get.

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I’m not sure, honestly, but it had been driven for likely a few dozen miles or so before I got my paws on her, and I filled her up from almost empty. I’d hope someone had the sense to, although the initial mechanic tightened the spark plugs so tight that half of them snapped when we removed em. So lord knows

My God… why on earth would any competent “mechanic” have replaced all your fuel injectors.

I forgot to mention that the initial testing of the injectors by the mechanic found that 1 and 4 were dead while the other 4 put out very low pressure, as they were clogged up; thus it was decided to replace the lot. Although, I haven’t the slightest idea why they decided not to clean the tank out when they initially cleaned the fuel system. He said one of em is still at low pressure.

The thing is, I could be driving it down the road at 60, then the tac would start to falter, and then simply drop. I actually had it die on me in a turn lane when I went to get off a really busy road when it started messing up after the new cat, didn’t even make it home.

It may also be worth noting that my battery will fall below it’s 8 volts and fail to start if accessories are left on for even 2 minutes, so excessively quickly. I thought about maybe an alternator issue or bad battery? There’s also a horrendous squeal from the serpentine when it’s running, didn’t notice until after I changed the camshaft sensor.

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That car could have so many problems at this point that I wouldnt make a guess.

Holy Shmokes Batman… There are a few things afoot here.

THE VERY FIRST… is to solve this voltage problem…as it can and will be the root cause for all the other problems seen thus far…aside from any physical fuel system clogging issues.

But injectors not functioning, misfires etc…is perfectly inline with insufficient voltage to operate. You absolutely MUST have the electrical sorted first and foremost. I cannot stress that enough. There is no telling what sort of crazy Sh$# you will see when voltages are either insufficient and or above normal.

The belt squealing could be simply that you did not tension the system…the belt stretched…OR…the alternator is either working too hard to correct a voltage problem and is extremely difficult to spin…or a similar related problem. If you have a serp belt…then you prolly have an auto tensioner…so again…alternator trying to work too hard.

Did I mention how important it was to sort this electrical issue? This is the first and only thing you need to be sorting out at this time. Ignore all else until this is done.

The alternator itself and the battery are good places to start sniffing around… Also take a volt reading at the battery with the cables OFF… then put them on and read…then disconnect the alternator hot lead…and take a reading. Also a running engine voltage measurement at battery… (sometimes you can see up to 50+ VDC in a malfunctioning system) Report back with those figures.

Also…do not ignore the ground lead either…its so easy to get all star struck by the Hot or positive lead that many ignore the Black ground connection…well lets just say its the other leg in a two legged system…so its just as important (some would argue more) as the Red lead. Be sure you have good solid ground to the engine and propagating out elsewhere. Mucho Importante…all of it

I hope you are up to learning how to work on vehicles… going to a shop is going to bankrupt you with the quickness.