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Having Everyone, i'm brand new to the forums and am looking for help!

I recently got a 2009 acadia for a great deal due to the engine having a hard knock. I was able to swap the engine and everything seemed fine. Ran it for a few days and then a cat under efficiency code was thrown. I made the mistake of throwing parts at the problem before diving deeper and replaced the corresponding cat (bank 2) and the o2 sensor after the cat.

I cleared the code but in looking at the live data it hasnt changed from what it was before when the code was first thrown and i hadnt thrown any parts at it yet. O2 sensor before the cat oscilates as its suppose to however the downstream O2 sensor ALSO oscliates alot and at times matches what the up stream is doing I know this is wrong because i can look at the other set of O2 sensors for the other bank and see that they are working normal. One oscilates and the other that is downstream of the cat holds perfectly steady.

I pulled the plugs for the bank in question and the didnt look dirty, infact they had a slightly lean look to them which id assume is correct given todays gas efficiency standards. However, both the upstream and downstream O2 sensors inquestion were completely black. I'm pulling my hair looking for an answer to this because although its running fine i know its running rich and will most likely destroy a cat again if unchecked.

I thought of vacuum leaks and plugged all orifices going into the intake manifold except the throttle body with no difference. I've spray water/starter fluid where possible around the intake manifold gasket to see if there was a leak with none found. I've thought that maybe i had a fuel pressure leak so i turned the car on then off and watched the PID for the fuel pressure and it dropped about 1 psi over the course of one minute or so and this was based on my bluedriver not an actual gauge hooked to the rail.

Im thinking of hooking a injector cleaner to the rail if an injector isnt seating properly. Or maybe the computer is just spraying fuel too longer (every slightly after combustion sequence?) Idk send help, SOS! lol

Oh also i will most likely be checking for exhaust leaks just to rule it out.
 

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Welcome to the forum.
Cleaning the injectors sounds like a good track to take for now. A dirty injector won't necessarily throw a trouble code. Let us know how it turns out for you. The service manual may be helpful to you. There's a link to download one in reply 7 of this thread: Link To Owners Manual. The model year may not be the same, but the engine is similar. Good luck.
 

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Welcome to the forum.
Cleaning the injectors sounds like a good track to take for now. A dirty injector won't necessarily throw a trouble code. Let us know how it turns out for you. The service manual may be helpful to you. There's a link to download one in reply 7 of this thread: Link To Owners Manual. The model year may not be the same, but the engine is similar. Good luck.
Thank you so much! I'm downloading now!
 

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Ok update 1:

Got a fuel injector cleaning kit locally and some purple power fuel injector cleaner. Had my whole setup with the low pressure air at 40-50 psi mimicking what the first fuel pump would output. Made sure to disconnect the original fuel hose so it’s running just on my purple power. Welp it ran for about 1 minute just fine then started bumping and fumbling and I noticed if I let off the gas it would almost die.

Cut it off, checked my compressor pressure still between 40-50. This time starting it became harder and I noticed some noises similar to an actual engine knock. By this point I’m terrified so I cut it off to re inspect my set up. Nothing out of the ordinary, I have lost some purple power and there is LOTs of haze, not really smoke.

Out of stupidity I spray a bit of starter fluid into the throttle body and she purrsssss to life! But then as I try to keep her alive by giving it gas she dies.

Next I set everything back to as it should be and still she just cranks over with no start. I remove the original fuel hose again and fuel sprays everywhere. So definitely have fuel pressure to the next fuel pump. However I think I’ve done 1 of 2 things just now. Destroyed every single injector or destroyed my high pressure fuel pump. Luckily I have a spare of both of these items on the original engine I removed although removing the injectors is the BIGGEST pain. (I only know this because I practiced on the other bad engine first.

In any case I’m going to let it sit over night and possibly do a hard reset of the vehicle battery wise and try to retest in the morning. After that I’m going to try and swap the hpp if I still get a no start, followed by the dreaded injectors although I may need an injector o ring kit if I go the route.

Thoughts anyone?
 

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Discussion Starter #5
Bump for help.
I switched out the high pressure pump with the old one with no success.

I’m trying to hold out hope that it’s not the injectors. I know I’m getting fuel to the high pressure pump. And it will start right up with starter fluid so I know spark and timing are most likely good.
 

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Discussion Starter #6
Update: In case this helps someone else. I individually cleaned each fuel injector which fixed but my no start and my CAT codes. All is solved now!
 

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Good to hear!
So no more codes and runs fine now?
How did you "individually clean" each fuel injector?
 

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I had to remove both fuel rails and all the connecting plumbing. Then take each injector out and actuate it using the battery terminals and sprayed brake cleaner through each one till the spray pattern was uniform. Those little suckers got HOT when actuating since they only actuate for a split second during normal operation were as i was actuating each one for a few seconds at a time. In any case it worked. Thank goodness because i was really pulling my hair on this one!
 

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I had to remove both fuel rails and all the connecting plumbing. Then take each injector out and actuate it using the battery terminals and sprayed brake cleaner through each one till the spray pattern was uniform. Those little suckers got HOT when actuating since they only actuate for a split second during normal operation were as i was actuating each one for a few seconds at a time. In any case it worked. Thank goodness because i was really pulling my hair on this one!
Ingenious . . But, yes, the duty cycle is very short for the fuel injectors.
So good thing you didn't burn them out manually doing it.
Surprised the brake cleaner worked that well, but it is strong stuff.
Being an electronics guy I think I would have connected up a function generator and drive a relay supplying the 12 volts, pulsing it with a short "on" duty cycle.
 

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I had to remove both fuel rails and all the connecting plumbing. Then take each injector out and actuate it using the battery terminals and sprayed brake cleaner through each one till the spray pattern was uniform. Those little suckers got HOT when actuating since they only actuate for a split second during normal operation were as i was actuating each one for a few seconds at a time. In any case it worked. Thank goodness because i was really pulling my hair on this one!
That's a lot of work!! Good on you!!! BTW, you probably should have pulsed the injectors a little more rapidly to keep them from getting too hot. Happy to know holding them open so long didn't damage anything internally. Any hotter and they could have been spitting out fire!! 😱
 
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