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Discussion Starter #1 (Edited)
HI,

We bought a 2009 GMC Acadia with knowing it was not running. After charging the battery it started cranking but no start. Changed spark plugs. Then checked catalytic converter, it was clogged. Cut catalytic converter and it started but ran rough. Did a diagnostic scan and got codes:

P0300 Random Misfire Detected
P069E Fuel pump control module requested MIL
P0301 Cylinder 1 misfire detected
P0306 Cylinder 6 misfire detected
P0137 O2 circuit low voltage (Bank 1, sensor 2)
P0304 Cylinder 4 misfire detected

Did a fuel pressure test and got no key on pressure, and low pressure while running (I believe It was 40-50).

Replaced the fuel pump in the tank. Now the codes are gone and car is still having some problems. Runs a little better than it did at idle. The problem is when we accelerate (like passing a car) or have a load on it, it stumbles. It does not actually die though. Did a compression test and everything is normal. Did another diagnostic scan and now getting just one code:

P0193 Fuel rail pressure sensor circuit too high

Replaced the fuel rail pressure sensor and STILL getting the p0193 (cleared codes prior). Car runs no different with new sensor. Checked fuses and they were good. Replaced the Fuel pump control module, still not fixed.

Took to a stealership to diagnose and was pretty much screwed as I was told for $70 they would tell me more than just a code and actually diagnose. Let's just say I left there with being told P0193 and it would cost another $300-$400 to test the wiring to see if that is the issue. Decided to take it home.

Took it to a different service shop and was told $75 to diagnose and would probably take one hour, but if it was more than that it was $75/hour on top of that. After 3 hours, was told it was the Fuel Rail Pressure Sensor and we most likely got a bad one out of box when we replaced it. Thought we would try to take it home and replace it but then told it was $250 to take home without fixing it or $350 for them to do it. They said if it was not the FRPS, it would most likely be the PCM. Mechanic noted that he tested the circuitry and wiring, which all passed. Next day received a phone call that it was not the FRPS and that it was the PCM and it needs to go to a dealership for that.

Took it home and replaced the PCM and reprogrammed the keys so it would start with the security system. Car starts up and guess what?! Same code, P0193 -- and runs the exact same.

At a loss about what to try next. Mechanic at the 2nd shop told us the PCM needs to be flashed and that is why it is giving that code, but from what I have read is that if the PCM was having problems it would be throwing a bunch of codes at us and running terrible, if at all.

Called to get pricing on flashing/updating PCM and one mechanic told me there is no way it was the PCM and that it would be a waste of money. Said if it was him, he would replace the high pressure fuel pump that is located near the motor.

Needs opinions/ideas. Not wanting to keep paying for diagnostics or putting money into something that it isn't. How likely do you think it is the PCM needing flashed? Or maybe it is the high pressure fuel pump?
 

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A fuel pump issue would be my first guess. Second guess would be chaffed wiring somewhere in the harness.
 

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Welcome to the forum.
Do you have a service manual available to you? It could be a great help. You can find the link to download a factory service manual in another forum thread.
 

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Discussion Starter #6
So what is weird is that the hesitation isn’t as bad but the code is still there. Drove it and we can accelerate quite a bit now without it falling on its face. It struggles at around 35-45 mph but then does great after that. Before I was hardly able to get up to 60mph unless I was really easing into it.
 

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It sounds like it’s not getting enough fuel pressure to the injectors hense your needing to feather it to get up to speed. I ran my dads traverse out of gas once but it would restart and idle but any throttle and it would die. Not enough volume to create the needed pressure.
I second the HPFP in the engine compartment.
 

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I have the exact same problem with my Cts LLT P0193 . Already replaced the fuel tank pump and hpfp last 2 months for p0087-p0089 p0300 , now I replaced fuel rail sensor and no results. I will check tonight every ground contact for rust/ corrosion
 

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We hooked up our scanner and looked up live data. I feel like this should not be this way. Can someone help? We are having the p0193 code pop up and trying to use this to help diagnose further.

8894

8895


(mod edit: merged from post of duplicate images)
 

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Follow instruction from both vids
. I have short somewhere in the ref 5V and I’m not getting 5v between the signal and ref . I only get 3V
 

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Discussion Starter #14
So, we narrowed it down to a wiring issue we believe as EVERYTHING else has been replaced. Noticed that the rear camera keeps blowing a fuse immediately and smelled something hot like electrical. Wondering if there is a wire that is shorting out the camera that also is touching a wire to the FRPS that keeps causing us to have the P0193 code (which could be due to an electrical fault).

Does anyone have any ideas or a wiring schematic to help us chase down the wiring issue?
 

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Does anyone have any ideas or a wiring schematic to help us chase down the wiring issue?
Search the 'net for a factory service manual which matches the year, make, and model of your vehicle. You'll find some free downloads as well as paid subscription sites and available hard copy for purchase. The manual should have all the wiring diagrams and guides for troubleshooting the problem.
 

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It's odd there would be a short in the rear camera system, unless someone added it after the vehicle was built and botched the job somehow. Look for RPO code UVC on the SPID label in the glove box to verify the vehicle was built with the rear camera option.
 

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Discussion Starter #18
It was factory as we have the original sticker tag with options on it. The fuse is a 10A under the hood in that fuse box. It shows it on the back of the fuse box top cover also.
 

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Discussion Starter #19
The review mirror is where the backup camera is supposed to show up but the light only flashes and when you replace the fuse it pops immediately. Just like when we clear the P0193, it comes up instantaneously.
 
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