Re:2010 Equinox misfire at idle horribly worse when warm in closed loop.

Hello forum users. This is my first time attempting to use a forum so bare with me please.

I have been trying to pin point a misfire on a 2010 equinox 2.4l, only at idle and engine warm in closed loop mainly. I believe I have narrowed it down to vvt being set to 5 degrees on the exhaust cam at idle. Mitchell diy states it should be at zero at idle. With no codes being set other than the random misfire and exhaust cam sensor a couple of times and the fact I tested and swapped the cam sensors hoping the fault would jump to the intake cam I found only normal readings during testing and the code hasn't come back in quite some time.

Once the misfiring starts the cam becomes more erratic in it's attempt to return it to zero. If I unplug the connector for the exhaust cam solenoid the engine settles right down so I am pretty certain it might be an input signal telling ecm to set it to 5 degrees when it shouldn't or the ecm has a bad driver for this one cam solenoid.

Not being horribly familiar with variable valve timing this diagnosis has been a bit of a challenge. I have begun testing every input sensor, I am continually working my way through them but if the ecm isn't detecting anything out of range I feel as though I am testing things that need no testing. Everything so far seems to be within range.

Does anyone have any advice? I appreciate any help you might give. Thank you.

Troy

troy.villeneuve wrote: Hello forum users. This is my first time attempting to use a forum so bare with me please.

I have been trying to pin point a misfire on a 2010 equinox 2.4l, only at idle and engine warm in closed loop mainly. I believe I have narrowed it down to vvt being set to 5 degrees on the exhaust cam at idle. Mitchell diy states it should be at zero at idle. With no codes being set other than the random misfire and exhaust cam sensor a couple of times and the fact I tested and swapped the cam sensors hoping the fault would jump to the intake cam I found only normal readings during testing and the code hasn't come back in quite some time.

Once the misfiring starts the cam becomes more erratic in it's attempt to return it to zero. If I unplug the connector for the exhaust cam solenoid the engine settles right down so I am pretty certain it might be an input signal telling ecm to set it to 5 degrees when it shouldn't or the ecm has a bad driver for this one cam solenoid.

Not being horribly familiar with variable valve timing this diagnosis has been a bit of a challenge. I have begun testing every input sensor, I am continually working my way through them but if the ecm isn't detecting anything out of range I feel as though I am testing things that need no testing. Everything so far seems to be within range.

Does anyone have any advice? I appreciate any help you might give. Thank you.

Troy

VVT preliminary check your oil, oil pressure, and that it’s the correct oil. That’s is key.

What is the exact code for the exhaust cam sensor? The actual code itself not what part it’s related to. You could have circuit codes or correlation codes. I’d imagine it’s correlation codes but I me making assumptions won’t help yours

Really appreciate the reply and bouncing ideas back and forth. So thank you.

Bit of additional info that leads me away from cam crank correlation issues is the fact that I did the timing chain and tensioner on this buggy 4 times double checking my work. First time was because I did time it incorrectly because I did not know there was a shim on the face of the crank and used a different mark and did have a correlation code. Re-timed it and that code never came back. Permanent code cleared for cam crank correlation.

I then aimed my sites at solenoid, problem persisted then aimed at actual cam actuator. Then bought an actual Autel scanner along with the maxiscope with the intention I could see more and test more.

What I did find is that the scanner says exhaust cam desired is 5 degrees at idle and the Mitchell diy manual says it is supposed to be zero any other info I found on the net said back to zero at idle. When I unplug the solenoid the actual timing reading on the scanner goes right to zero and the engine smoothes right out.

Sadly I don't remember the actual cam sensor code but it was not a correlation code last time, although I expect the computer expects timing to stay steady and in a specific position and it doesn't stay at a steady zero degrees at idle unless the exhaust cam solenoid is disconnected and forced to zero bypassing input from ecm but the ecm still says desired exhaust cam angle is 5°. So either there is an input from another sensor telling ecm to set it to 5° or the ecm has a flaw setting it to 5°.

I am starting to doubt input sensors because they'd likely throw a code but not all sensors will trigger codes when they fail intermittently but the ecm always states 5° at idle so maybe that indicates steady input sensor signals.

Appreciate any additional thoughts/input.

Thanks
Troy

With the P0300, does the OEM data show which cylinder(s) is misfiring? GM products will flag a P0300 over cylinder specific misfires. :silly:

As I recall, the PCM commanding the exhaust camshaft to 5° at hot idle is not unusual on these engines. Some intake advance isn't unusual, either. Not saying the problem isn't VVT related, just noting what I've seen on other LEA/LAF engines.

What do the Exhaust CMP desired and variance PIDs say during the misfire? If the desired PID shows that the PCM is asking for 5°, then I'd argue that the PCM is getting what it wants. If the desired shows zero, then there's definitely a problem there.

Hello and thank you. Looking at actual misfires on the scan tool doesn't indicate only one specific cylinder sadly. Seems to jump from one to the other, from one day to the next the majority of misfires will switch cylinders. There will be more misfires on one of the cylinders but never reliably the same one.

I find it odd that 5 would be okay when the manual says expected desired at idle is zero for both intake and exhaust. But the actual position when it starts to misfire becomes erratic with a variance from about zero to 9 degrees if I am remembering correctly possibly higher from desired 5 degrees at idle. Which could possibly be the reason for this cams sensor code I think. Never staying at 5° at idle and rarely hitting zero where the manual says it should be. I should also mention this misfire always disappears as soon as the throttle is depressed and the variance also goes to virtually zero when driving this buggy. Also desired cam angle when coasting in gear and in neutral I believe shows zero with no misfires being logged. So it seems the ecm can set it to zero possibly. Much of this is from maybe my not so great memory but I am certain actual cam angle becomes quite erratic when misfiring starts. And misfire stops as soon as solenoid disconnected and starts misfiring very shortly after reconnecting.

So it is possible it is an erratic signal being sent to the cam solenoid from ecm vs commanded to zero that is the problem here if you've found others running fine at 5°.

Before replacing the solenoid and cam phaser I did find when commanding the solenoid via scan tool it wasn't quick to respond like the intake and it rarely was able to max out to 25°, 20° seemed to manage. Not sure if redoing this test cold vs hot now would show anything helpful but yes seems to me it is the cam timing system being that it smooths right out when the solenoid is unplugged. I would almost consider leaving it unplugged but it seems to lack power and the engine light stays on. It being a small engine it needs all the help it can get.

Thanks again Tyler. I really appreciate all of the content you put out here on the web so thank you for that too.

Troy

troy.villeneuve wrote: Hello and thank you. Looking at actual misfires on the scan tool doesn't indicate only one specific cylinder sadly. Seems to jump from one to the other, from one day to the next the majority of misfires will switch cylinders. There will be more misfires on one of the cylinders but never reliably the same one.

You're way ahead of me. :blush: Ah well, thought I'd ask.

I find it odd that 5 would be okay when the manual says expected desired at idle is zero for both intake and exhaust. But the actual position when it starts to misfire becomes erratic with a variance from about zero to 9 degrees if I am remembering correctly possibly higher from desired 5 degrees at idle. Which could possibly be the reason for this cams sensor code I think. Never staying at 5° at idle and rarely hitting zero where the manual says it should be.

The variance of 0-9 seems suspect, IMO. Like the PCM can't get a hold of the exhaust cam.

For whatever it's worth, I dug up a known good capture from a 2013 Equinox. LEA engine, VIN K:

www.scanshare.io/share/RR6x5wkks0OwIsJzZRperg#0,2,4,6,8,11,13



Not trying to prove it to you, as much as prove it to myself. :silly: Hate to say stuff like that in a public format and not be able to back it up.

Before replacing the solenoid and cam phaser I did find when commanding the solenoid via scan tool it wasn't quick to respond like the intake and it rarely was able to max out to 25°, 20° seemed to manage. Not sure if redoing this test cold vs hot now would show anything helpful but yes seems to me it is the cam timing system being that it smooths right out when the solenoid is unplugged.

Would it be possible to repeat the solenoid command test cold and hot? If the exhaust camshaft timing responds correctly when cold, but struggles hot, then that'd suggest an oil pressure/volume/aeration problem.

I appreciate any and all ideas as well as proof. My eyes go a bit crossed when reading graphs but I do see at idle it is clearly not bottomed out at zero. Not sure if I can trust anything now in this manual... The scan images are worth a lot, thank you. I don't think my scan tool graphs them this well if I was trying to do that. I don't think the time base is as fast or adjustable but I did run this test cold vs hot yesterday. While it wasn't misfiring badly enough to log misfires yesterday I could feel them and the variance and command were both erratic during misfire. The command to keep it stable is erratic as well when the variance at a higher value than what you'd think is acceptable the command usually drops to zero percent but seems to be jumping around when the variance is not stable but more stable if that makes any sense. On the rare occurrence it hit zero variance you can see command is at 50% When doing the active test on the cam phaser I did not see any noticeable difference cold vs hot. And was able to get it up to 25 well 24. With only 30 seconds to run this test it failed just before it would have needed for a millisecond to catch up with the command. Remembering back to doing this phaser/actuator test before and after replacing the phaser the new phaser was much more responsive and was able to get past that 20° limit it had before. I had previously pondered oil pressure or flow thinking that the same oil is giving the intake cam good performance I was thinking it was probably okay. When I had the phaser and solenoid out I made sure to blow through the oil journals in the cam end into the block to be sure there was no blockage there but can't be 100% sure there isn't a blockage somewhere in the head but I imagine it likely uses the same flow path as the intake cam supply. Looking forward to any thoughts/advice you might have. Thanks againTroy

Apologies for my last response and it being laid out terribly. Saw that I posted two of the same image, tried to edit and it seems to have been turned into one big paragraph.

Either way I am hoping for some tips or advice on how I should proceed in determining why the exhaust cam angle actual and command becomes erratic at idle.

Thanks very much.
Troy

short answer, oil pressure, worn parts, loose parts. long answer, theres a lot of things that can cause this I would start with base oil pressure test cold vs hot if you stay in spec during both of those than you can move onto cam solenoids timing chains and phaser issues (it appears as though you've replaced most of those) but like we all learn in this business new does'nt mean its good. just curious what brand parts were used?

Thanks Ben.

I have not yet done an actual oil pressure test but will need to to rule that out. Need to buy a guage though might take me a bit. The scan tool only says ok or not it seems doesn't give an actual pressure rating. I do think that both cams would be affected poorly if pressure was low but maybe not. I had already changed all of these parts chasing this issue. Oh wait, you've noticed this.

It is my brothers buggy so he picked economy parts for the cam phaser and solenoids and after changing them there was zero change in misfire behavior but it did seem to perform better during active testing of the phaser once the new one was installed but sadly the misfire and erratic behavior persisted. The chain and tensioner kit was cloyes.

Oh no! 99% of warranty work happens because of economy parts.(I made that statistic up) I wouldn't trust either of those 2 parts to not be the problem..... as easy as it is to change I think I would replace the actuator with no expectations of it fixing the problem. Both of those parts have to be reliable in oil pressure holding and control either could be leaking oil pressure causing this problem (assuming base oil pressure is good)

Sent from my SM-G781U using Tapatalk

Gotta say, I'm with Ben on this one. I've experimented with aftermarket brands of solenoids/actuators on this engine, but none of them consistently play nice. AC Delco stuff fixes it.

However, I am OK with the Cloyes timing components. I've got the same kit on my '15 Equinox, plus tons of customer vehicles still running around.

Thanks. Going to get the oil pressure checked out. I have a fuel pressure testing guage but not an oil pressure testing guage. I am thinking they should be interchangeable and test both fluid pressures but I don't want to damage my guage. Going to consider getting AC parts I guess. Was thinking it could be a bad driver in the ecm and pondered was there a way to test it before replacing parts he already spent some cash on.

Thank you for the additional input. I was happy with the cloyes parts too and was leary on the eco parts but he just spent a pile on other work too and was dead set for the cheapest stuff available. So as I mentioned replying to Ben I was hoping to see if there was a way I could rule out a bad driver in the ecm before buying any more parts but looking like I will have to consider it after double checking oil pressure.

Well I am finally back after sorting out a proper metric fitting to attach the oil pressure guage.

I cannot find a listing anywhere for oil pressure at idle to know specifically that it is too low during misfire but it also isn't reaching the minimum of 30 at 1000 rpm the manual tells me it should be. It does seem really low at idle at about 17psi just above 1 bar. My guage is difficult to be precise at the lower end pressures but it does seem to be oil pressure related.

This engine had timing chain failure and rubbed against the guide mounting bolt allowing some filings to get into the oil. I found an article that talks about a cold start check valve in the pump cover possibly having debris lodged in it. I think this might be where I look next.

If you or anyone else has any words of wisdom I would be super appreciative.

Troy
Were you able to figure out what the problem was? I am having the exact same issue.
Please advise
Thanks

I will be honest, I gave up after doing so many things and having such little effect. I do find it improved but not fully. I do think it has something to do with oil pressure and possibly the shit cam solenoids my brother wanted me to put in. I did end up changing the oil pump because I found more scoring and pitting than I felt comfortable with, thought it could be bypassing. If the pump is like that there's likely damage through the cam and crank bearings and anywhere else oil is used to protect components.

This engine was run for quite a while with a bad timing chain guide so it had lots of filings through it. I think there is just enough damage to cause low oil pressure when the oil is hot at idle.

When you say the same problem you mean one of the Cams keeps adjusting constantly? Or that it just misfires at idle?

I installed new timing chain, and it was randomly misfiring. I tried a lot of things and no effect; spark plugs,coils, injectors ect. Then I kinda figured out the exhaust cam solenoid got something to do with this issue. Had to do timing 5 times, put oem cam sprockets, oem solenoids ect.
Random misfire at idle when engine warms up. No check engine code comes up but it idles rough and I can see misfires on all cylinders. And when unplug the exhaust cam solenoid it kinda idles better.I think it got something to do with oil pressure too but can not figure out what.

That seems to be the exact issue I've been having. Unplug the exhaust cam solenoid and it idles really well but has poor acceleration. I tried blowing air through the oil passages to the solenoids as well and no major improvement. Thinking about it now it seems a fair bit better than before changing all that stuff but yeah still there.

I just keep driving it, I get a trip to town before it acts up at a light and it's bearable now, sputters a bit at lights whereas before it would surge on incline with the brakes on and see noticable misfires on inconsistent cylinders on live data and it was bad enough to throw misfire codes and cam sensor code. Not throwing codes any more. Changing the oil pretty frequently because it gets pretty dark pretty quickly. I also ran synthetic for a while and switched to 10w30 as a hail Mary. Next step is 15w40...

I just can't see changing the engine at this point for a speculation. When it blows I will know for sure. Lol

Are you having oil consumption issues at all? Did you test oil pressures yet?

Yes exactly same symptoms.
I didnt check the oil pressure , dont have the tool for that. But it seems like i will give up on this engine at this point. It has been months now and still no improvement.
I really appreciate your help. Thanks