2010 GMC Acadia ECM shutting down cylinders 2,4,6,

hey I'm the tech here at O'neils garage we have a 2010 GMC acadia that we got in on trade . it had a check engine light on scanned and found out it was related to timing chains. so before christmas l did chains and tensioners. l also re-pinned cam sensor plug and cam solenoid. drove it for a bit and had a oil leak . l repaired that . now here's whats wrong it's only running on 3 cylinders now. l'm getting a fuel pressure sensor code and cylinder 2,4,6 misfire codes. l've went back to the basic checked grounds , fuses and etc. check for power and ground at coils as well.even went as far as flushing the injectors. still runs like crap. any help or areas to check would be great.

Ben
O'Neils Econo Garage and Car Sales
Odessa Ontario, Canada

If the vehicle has the vlom option that would be the displacement on demand system has issues which will necessitate removing cylinder heads and pulling lifters and inspecting camshaft.

First pull valve covers off and see if rocker arms can be pushed in on the pushrod side. Cyl, 1, 4, 6, 7 are the displacement on demand lifters. Which are known to stick and fail and rotate in bore and wipe out a camshaft lobe.

Secondly do a compression test on those cylinders if it is low then you have your answer.

Hardtopdr2 wrote: If the vehicle has the vlom option that would be the displacement on demand system has issues which will necessitate removing cylinder heads and pulling lifters and inspecting camshaft.

First pull valve covers off and see if rocker arms can be pushed in on the pushrod side. Cyl, 1, 4, 6, 7 are the displacement on demand lifters. Which are known to stick and fail and rotate in bore and wipe out a camshaft lobe.

Secondly do a compression test on those cylinders if it is low then you have your answer.

It ran great before l changed the cam solenoid seal and fixed a couple of wires , l just don't understand why it runs like crap, compression was checked threw another shops snap-on scanner. the boss and and l still think it's a wire but where is the question were asking ourselfs

Hi Ben,
Guessing you have the 3.6l dohc?
The title says "ecm shutting down cylinders". Is the PCM really taking away injector control or coil control to the effected cylinders, or are you just noticing it's that bank misfiring?
A couple things come to mind being that the misfires are all on the same head.
First, is there any way you could have the injector or coil connectors on in the wrong order? It does happen from time to time.
Second, since the timing was just done, did you replace the cam phasers as well? And are they on the correct camshafts?
Sometimes the old phasers don't lock in the rest position. If you can turn the camshaft a few degrees and the phaser doesn't move the lock mechanism is failing.
Trust me, I'm not picking on you. I just did chains on a 4 cylinder Acadia, she it started right up and ran beautiful! I shut it off to inspect an oil leak and it wouldn't restart!
Left the exhaust cam phaser bolt loose and it moved off its guide pin...

phaser were never done or any bolts loose. and it's impossible there are so long in length and fall into place. we had another shop owner come with his scanner and he went the the basics with me starting with the fuse box. checked all the wires from computer to fuse box , fuse box to component , checked for spark and injector pulse.

Did you have the injectors out? I once flipped the harness 180 car still ran.
Also, if you fixed wires I would start there and move to pin fitment next make sure that the top connectors do not have bent pins

injectors were never removed, pin is good we did check that too

Might be a bad new solinoid. Is it a gm part or aftermarket? Did you flush the hole out between parts? Sometimes debris can get in there causing a issue

Seeing as all the misfires are on the same bank did you check the VVT? Common failure item on those 3.6 motors

what puzzles the boss and l is it ran beautiful before l changed the cam solenoid. it throwing cylinder misfires 2,4,6 and fuel pressure sensor code which was changed

Put the old cam actuator solenoid in. Maybe ya have a wire shorted to ground ? Keeping the solenoid on. Have you scoped coils and injectors? Relative compression test done? Maybe you repinned the connector wrong. Mixing up signal wire with ground. Have you unplugged all cam solenoids and scoped base engine timing then look for known good I’m sure someone on here has known goods. Probably Tyler

Sorry for the late reply. I wasn't exactly implying that the phaser was installed incorrectly, just that since they were not replaced as part of the timing chain job that one or more could be failing, thus setting misfire codes on one bank.
Like I said, if you have the cam cover off the head, you shouldn't be able to move the camshaft or the phasers independent of one another.
In other words, if you can grab the phaser and turn it, it isn't locked into rest position and must be replaced.

I like Cheryl's idea of trying to old solenoid, and making sure the wire repairs kept everything in it's original orientation.

Have any other codes popped up since this started, or just misfire codes on those three cylinders still?

Noah wrote: Sorry for the late reply. I wasn't exactly implying that the phaser was installed incorrectly, just that since they were not replaced as part of the timing chain job that one or more could be failing, thus setting misfire codes on one bank.
Like I said, if you have the cam cover off the head, you shouldn't be able to move the camshaft or the phasers independent of one another.
In other words, if you can grab the phaser and turn it, it isn't locked into rest position and must be replaced.

I like Cheryl's idea of trying to old solenoid, and making sure the wire repairs kept everything in it's original orientation.

Have any other codes popped up since this started, or just misfire codes on those three cylinders still?

Another shop owner and one of his techs went over the wiring repair and also wire back to the fuse box and back to ecm.,

would a bad direct injection high pressure fuel pump cause this issue

still having issues with this guys

Hi Ben, there's still quite a lot left on the table here, I feel we don't have much direction other than 2, 4 and 6 are setting misfire codes.

oneilsgarage wrote: what puzzles the boss and l is it ran beautiful before l changed the cam solenoid. it throwing cylinder misfires 2,4,6

This may sound stupid but it hasn't been established. Are the misfire codes on the bank of which you changed the solenoid?

There are 4 solenoids. Exactly which one did you change?

oneilsgarage wrote: It ran great before l changed the cam solenoid seal and fixed a couple of wires , l just don't understand why it runs like crap. the boss and l still think it's a wire but where is the question were asking ourselfs

Exactly what wires did you repair?

Can you compare them to a diagram to be certain they are correct?

Are you willing to post pictures of all the wiring repairs for us to verify?

I know you said another tech checked your work, and I'm not doubting you or him, but sometimes when it comes to diagnostics, you just can't take someone's word for it.

oneilsgarage wrote: l'm getting a fuel pressure sensor code and cylinder 2,4,6 misfire codes. l've went back to the basic checked grounds , fuses and etc. check for power and ground at coils as well.

Exactly what are the codes you are getting?
This is important.

Cheryl wrote: Put the old cam actuator solenoid in. Maybe ya have a wire shorted to ground ? Keeping the solenoid on. Have you scoped coils and injectors? Relative compression test done? Maybe you repinned the connector wrong. Mixing up signal wire with ground. Have you unplugged all cam solenoids and scoped base engine timing

Some good advice right there.