You are right, the coils did nothing, and I haven’t read the fuel trims I’d have to actually find out how to look at them, and yes there is a noticeable misfire. The only thing I can think of is a relearn for the crank and cam, or the timing is off.

 

You said in your first post it was running fine until the knock sensor replacement, so it stands to reason something happened during the replacement to cause this and/or the knock sensor(s) you installed are faulty or damaged.

I think it’s likely there’s still a vacuum leak - on a MAF system, rough idle/stalling without throttle actuation indicates a vacuum leak is affecting air/fuel mixture at low engine speeds.

These manifolds have been known to warp and/or crack if they’re old enough, and the air intake boot could also have a tear or porous leak. Anything downstream of the MAF sensor would cause drivability concerns.

It could also be a vacuum-operated accessory that’s leaking. Disconnect and cap all the vacuum connections - brake booster, purge valve, PCV, etc - any vacuum connection at the manifold, since none of them are required for the engine to run.

If it starts/idles with them capped, reconnect them one at a time and recheck - if any accessory causes the starting/stalling problem, that’s the source.

Will your scanner read live data or just codes? I have to go for now but I can explain fuel trims in more detail later.

[Edit: PS - Did you also break down & clean/flush the fuel rail when you had the manifold off?]

 

So I took the intake boot off again and on one end there is a small hole by the throttle body that’s about the size of a tiny ball bearing, would this cause that bad of a vacuum leak? And no, I disconnected it and covered the rails with blue disposable shop towels. And the scanner I’m using should be able to, I would have to see all it actively scans.

 

It’s unlikely a leak in that position would cause the hard start/stalling - probably enough to skew the MAF sensor and cause a rich condition, though. An easy test is to seal it with a piece of electrical tape or hot glue and recheck.

Regarding fuel trims:

Fuel trim is a calculation the PCM bases on (primarily) the upstream oxygen sensor on each bank. It represents adjustments to the amount of fuel being added or subtracted to each bank by adjusting injector pulse times.

There’s short term (STFT) & long term (LTFT) fuel trims for both banks; displayed as a percentage with a range of -30 to +30. Negative numbers mean the PCM is subtracting fuel (reducing injector pulse). Positive numbers mean the PCM is adding fuel (increasing injector pulse).

STFT - An immediate response to upstream oxygen sensor readings. Resets every drive cycle.

LTFT - An average fuel trim adjustment over the course of time (multiple drive cycles).

The ideal fuel trim is at or near zero at all times, but a normal/typical range is -10% to +10% when accounting for operating conditions.

Numbers in the 15% to 20% range aren’t necessarily concerning, but 20% or more (positive or negative) is definitely indicative of a problem.

In the case of an intake/vacuum leak, the numbers will go positive, because the PCM sees the excess oxygen in the exhaust stream, and starts adding fuel to compensate.

An exhaust leak upstream of the oxygen sensor will also cause positive fuel trims, so if there’s a leak around the exhaust manifold, you cannot rely on the fuel trims until the leak is sealed.

With a helper, keep the engine running at a steady RPM while spraying carb cleaner or ether in short bursts around the intake boots, gaskets, ports, etc. At the same time, watch the fuel trims (particularly STFT) - if they start skewing back towards zero/negative side when spraying a particular area/seal, a vacuum leak is indicated.

Finally, it’s not uncommon for the fuel rail(s) to collect sediment at the rear of each bank. Since you left the rail in place, it’s feasible that sediment spread throughout the rail(s) and is affecting injector performance. It’s not likely any of the injectors are damaged or need replacement as they have a very fine screen at the inlet as a final defense against debris - but depending on the amount of sediment, it could be restricting the amount of fuel getting into the injectors.

The only way to be absolutely sure is to pull the rails and separate the injectors from it for inspection.

Clean/flush the rails with brake & parts cleaner (hot water w/ dish soap can be just as effective) and compressed air (keyboard duster works too).

Clean the injectors with aerosol carb cleaner and compressed air. A toothbrush or nylon bristle brush works well to scrub the nozzles if build up is excessive/stubborn.

Get a kit for the fuel injectors to replace both o-rings on each (SMP kit SK71 or SK119 depending on if it’s flex fuel). Apply Vaseline or silicone grease to the injector o-rings to ease installation.

Prime the fuel rail by cycling the key to ON/RUN 2 or 3 times before attempting the first start. Expect it to run rough for up to a minute as air is bled from the rail.

 

Cylinder 1 and 3 are just dumping gas into the cylinders, could that be the injectors being stuck open or the pressure regulator? Can’t check the fuel pressure, till tomorrow, but almost positive it might be the injectors.

 

The injectors, but are they dumping fuel even with the key off or only when running?

 

I meant for the short term fuel trim, it’s at about 30 whole running

 

I’m confused - are you asking if the STFT can cause the injectors to dump fuel?

I take the term “dumping gas” to mean the injectors are heavily leaking fuel into the cylinders, to the extent that it can pool on top of the piston and/or run out if the spark plug is removed.

 

Any progress?

 

Replaced all injectors, it will idle now, but barely, and will die out after a little. the fuel pressure is reading at about 50+ but it’s all over the place, and I just found out it’s a flex fuel, the l59. Bank 1 still sounds like it’s misfiring but bank 2 seems good, besides white smoke coming out of the exhaust.