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Snrub
Snrub HalfDork
11/29/18 7:52 a.m.

Hi guys,

My car is exhibiting an intermittent hesitation and more frequent, but varying misfire condition, particularly when the engine is cold. I'm hoping someone might suggest ideas as to how I should proceed on both a troubleshooting and issue management perspective.

The car ran kind of rough. I thought it was just a crude engine. There was some intermittent light hesitation when the engine was cold. Then it had a flashing check engine light - multiple cylinder misfires. I take it into the dealer, they say plugs are fouled and they suspect bad gas. I only bought premium gas from national chains. I'm skeptical, but go with it. They drain the tank, put their own gas in and replace 6 of 8 spark plugs.

I take the car home and it begins exhibiting greater hesitation, particularly when the engine is cold, ambient temperature being a possible contributing factor. I start messing around with the torque app and start monitoring/logging GM misfire PIDs. The car is misfiring on all cylinders, particularly when cold, but there are some misfires at various times.

I make another appointment, they can only see the car a week and a half later. The car seems to run very rough a couple of days before the appointment. On the day I'm going to drop it off, the car runs horribly, I take it home and call roadside assistance. At that point I had only run gas provided by the dealership.

The dealership says residual bad gas must have caused the problem. I argue, but they say they can't find anything else. They say they tested the fuel injectors. Apparently the car had a CEL P0300 when they looked at it, that must have just turned on when they started the car. They replace 2 more fouled plugs, put in new gas and send me on my way. I pick up my car and find misfires in the parking lot prior to moving. I go back in and ask a service advisor to make a note in my file. The engine was warm at that point. More misfires occur on the way home, but it's not horrible. Later in the night after the engine cooled down, I take the car for a short drive and there are plenty of misfires on all cylinders. CEL P0430 comes on, bad cat.  I write the service manager a detailed email noting this and include logged OBDII misfires.

What should I do here? I'm not sure what the problem is. I suspect the plugs are fouling due to poor running conditions. I really don't want to go back there, but I'm also out a bunch of money that warranty probably should have covered. "Bad gas" seems to be the perfect excuse - in their logic, there's no way to clear it out, even if you pay them to do it and they provide fresh gas. It's also a diagnosis of exclusion - can't find anything, must be the customer's fault. GM warranty specifically calls out a exception for damage caused by bad gas. Now that the dealership has suggested that is the problem, I may not have any recourse for escalating the issue or having warranty pay for the fix. I'm guessing the P0430/bad cat was caused by misfires and poor engine operation.

In between appointments I pulled a plug myself and it smelt like gas. I put in a fresh plug and did ~35miles on it. It was pretty black when I swapped back in the original (possibly replaced once).

How many misfires does a normal 6.2L engine typically exhibit on a given drive? Has anyone ever checked OBDII [GM] Current/historical misfires? If anyone was interested in checking their car I would be very grateful. I used the torque app and logged, but here's the custom pid details if your setup is a bit different.

[GM] Misfire Current Cyl1-4: PID 221205-221208
[GM] Misfire Current Cyl5-8: PID 2211ea-2211ed
Min value 0, max 1000, scale factor x1, unit type count, equation A, OBD header Auto. 

[GM] Misfire History Cyl1-4: PID 221201-221204
[GM] Misfire History Cyl5-8: PID 2211f8-2211fb
Min 0, max 1000, scale factor x10, unit type count, equation (A<8)+B, OBD header Auto.

Tyler H
Tyler H UltraDork
11/29/18 8:29 a.m.

Did you buy the car new?  Is it still under the factory powertrain warranty?  Any modifications?

It's not bad gas.  If it's under warranty, you shouldn't have to be doing any troubleshooting. I'd recommend you escalate the issue and leave out the details about your own troubleshooting steps.  "It's broken, fix it."

WonkoTheSane
WonkoTheSane Dork
11/29/18 8:33 a.m.

1st thing I would check is after a hestitant test drive is to see whether the cats were glowing.  I'm not sure how exposed they are, but if you have an infrared thermometer, I'd check each exhaust port header area to see if they're all the same temperature.  That would at least tell you if your issue is isolated to a few cylinders on each bank or the entire engine.  Two completely different diagnostic paths then.  I'd agree that something is farked.  And it's not normal for a 2017 LS engine to go bad after a year :)

Any chance you have some proof of the gas you bought before you took it to them the first time?  A credit card payment record would be enough.  Down here, the gas stations all have insurance to cover damage caused by their products, most have it as a point of advertising pride, "100% guaranteed!"   If so, you can always see if the dealer is so sure of their diagnostic that they'd be willing to press charges against the gas station to cover the work.

Either way, I'd agree with you that you really shouldn't take it back to them.  Do you have any other dealers in your area?

Sonic
Sonic UltraDork
11/29/18 8:57 a.m.

Keep sending it back until fixed.  On the third time start using words like lemon law and that should help.  If they can’t fix it after several tries then you have a good lemon law case. 

John Welsh
John Welsh Mod Squad
11/29/18 9:11 a.m.

Lemon Laws vary by state 

Edit: and your profile says you are in London, Ontario Canada.  I'm not sure what then.

06HHR
06HHR HalfDork
11/29/18 9:12 a.m.
Sonic said:

Keep sending it back until fixed.  On the third time start using words like lemon law and that should help.  If they can’t fix it after several tries then you have a good lemon law case. 

^ This..  Although i'm surprised no one has run a diagnostic on the PCM to see what's happening with the injectors and with the timing.  The effects of "Bad gas" shouldn't last beyond a tank full.

jharry3
jharry3 Reader
11/29/18 9:18 a.m.

Its misfiring.  Meaning spark isn't happening.  Its back to the basics time.

Something like crossed wires or some loss of continuity in the spark energizing circuits is a place to look.    I'd start tracing the wires connected to the plugs to make sure nothing is mismatched causing cross firing.  Also check every connection to verify its connected correctly.  Also examine each connection to make sure nothing inside is bent or broken.  

And saying "bad gas" is a disingenuous excuse for not knowing what to do when the computer doesn't give them directions.  You are dealing with parts changers, not technicians.

 

z31maniac
z31maniac MegaDork
11/29/18 9:39 a.m.

I think this is when you start calling GM North America. 

Also, do you have receipts/bank statements/credit statements of where you purchased the gas? So you can show you weren't buying from that sketchy place on the crummy side of town?

My Speed3 started pulling random misfire codes on the way home from being out of town one time. Took it in to the dealer, they replaced the plugs, cleared the codes, and I never had another problem, and certainly didn't pay for anything since the car was under warranty.

Vigo
Vigo UltimaDork
11/29/18 9:45 a.m.

I'd recommend you escalate the issue and leave out the details about your own troubleshooting steps

Very much this. You already caught onto the idea that they may be trying to give themselves a back door with this bad gas BS. Anything you say about touching the car yourself is more ammo for them. It doesn't really matter what's causing the misfires, only that the dealer should be able to fix it and if not, buy it back from you. I could go on about possibilities of what's causing it but i really don't recommend you try to figure it out yourself unless you are comfortable throwing your warranty out the window.  

To answer your question about how many misfires are normal on a 1 year old car, the answer is basically zero. There are cars out there with 140k miles on their original spark plugs that don't misfire. Don't let anyone put the thought in your head that any of this is normal behavior for the car! 

dculberson
dculberson UltimaDork
11/29/18 9:48 a.m.

Looks like there are four Chevy dealers in London; I'd think about taking it to another one and when they find the real issue, sending a certified letter to the first dealership asking for a refund, including copies of what the second dealership found.

Escalating the issue to GM might make sense, though.

Snrub
Snrub HalfDork
11/29/18 10:01 a.m.

Thanks guys.

Unfortunately there are no lemon laws here.

I recently took over the lease on the car, but it has plenty of warranty left. No modifications. I suspect the car had a mild misfire when I got it, but it definitely got worse.

The service manager wrote back and stood by the diagnosis and all of their actions. He's also suggesting bad gas may have damaged the cat. He said my OBDII stats didn't show anything and only misfires in the hundreds are a concern. I pointed out that I had loud backfires with far fewer (~10-15) and drivability issues with fewer still. Basically they want me to run a few tanks of gas through and see what happens. They are ignoring culpability for failing to get rid of "bad gas", sending me off without fixing the problem, etc, etc.

I don't have gas receipts, but I could pull up credit card statements.

06HHR
06HHR HalfDork
11/29/18 10:08 a.m.

You need to find another dealer, bad gas doesn't cause backfires in my experience.  That sounds like an ignition problem.  And definitely escalate to GM.

z31maniac
z31maniac MegaDork
11/29/18 10:09 a.m.
Snrub said:

I don't have gas receipts, but I could pull up credit card statements.

That's good enough. 

Not sure there, but I know down in the states gas stations like Quik Trip guarantee their gas. If you have the receipts/statements showing you have been purchasing your gas there, and the dealer/mechanic can legitimately show it was bad gas, they will pay for the damages.

AnthonyGS
AnthonyGS Reader
11/29/18 10:30 a.m.

If it’s under full warranty drive it hard until it blows up and get a new engine out of them.  I had a friend with a similar problem on his 02 Z28 that only occurred at high rpm.  Dealer never could find it until he took them on a test drive.  A lot of these issues the dealer will never drive a car hard enough or long enough to find them.  It idles fine....  must be okay.  

bruceman
bruceman Reader
11/29/18 10:38 a.m.

In your Owners Manual Customer Information section:

General Motors of
Canada Customer Care Centre at
1-800-263-3777 (English),

iceracer
iceracer UltimaDork
11/29/18 10:42 a.m.

Yep,  give it an Italian tune up.    What's the worse can happen ?

Snrub
Snrub HalfDork
11/29/18 10:58 a.m.

Thanks guys.

Misfires are happening on fresh plugs, although worse on the fouled plugs. It makes sense to me that improper combustion would leave deposits, foul plugs, cause further misfires.

I'm normally a DIY kind of person, I don't normally own cars this new. As suggested I'm trying not to do much myself because they could use it as ammunition. It felt I had to do a little bit of analysis because they weren't. The service manager made comments about me gathering OBDII logs and suggested that could cause "interference", which seemed like a veiled threat.

Do I really want corporate GM involved at this stage? I agree the dealership is using "bad gas" as an excuse, but could GM do the same and blacklist my warranty?! This is a really stressful situation.

How would the dealership go about proving "bad gas"?

Tyler H
Tyler H UltraDork
11/29/18 11:09 a.m.
dculberson said:

Escalating the issue to GM might make sense, though.

Hurry up though, before they lay off all the office folks that process these types of complaints.  

It would have to be profoundly "bad gas" to cause the issues you're seeing and damage.  Did you buy gas somewhere sketchy?  Any chance you (or someone) else put something in the tank you shouldn't have?  Bad gas hypothesis doesn't add up at all.  

06HHR
06HHR HalfDork
11/29/18 11:15 a.m.

In the OP you stated the dealer drained the tank and put in their own gas.  If that was the case the "bad gas" problem should have ceased and you would not have had to return the car for the same issue.  I agree that the bad gas explanation was just the dealer trying to cover themselves for not being able to fix the issue.  You've taken the car in twice for the same problem and received no resolution, so IMHO it's time to escalate to GM. 

Snrub
Snrub HalfDork
11/29/18 11:28 a.m.
Tyler H said:

It would have to be profoundly "bad gas" to cause the issues you're seeing and damage.  Did you buy gas somewhere sketchy?  Any chance you (or someone) else put something in the tank you shouldn't have?  Bad gas hypothesis doesn't add up at all.  

No, I did not buy bad gas. They suggested that perhaps I had purchased gas from a indigenous reserve.

Streetwiseguy
Streetwiseguy UltimaDork
11/29/18 11:44 a.m.

"Mr Service Manager, my car runs like E36 M3"

"Mr Service Manager, my car still runs like E36 M3."

"Mr Service manager, my car still runs like E36 M3"

"Mr Service manager, my car still runs like E36 M3"

"Mr Service manager, my car still runs like E36 M3"

"Mr Service manager, my car still runs like E36 M3"

"Mr Service manager, my car still runs like E36 M3"

"Mr Service manager, my car still runs like E36 M3"

Snrub
Snrub HalfDork
11/29/18 11:56 a.m.
Streetwiseguy said:

"Mr Service Manager, my car runs like E36 M3"

"Mr Service Manager, my car still runs like E36 M3."

...

"Mr Service manager, my car still runs like E36 M3"

At this dealership that's the customer's fault. As the running condition continues, the stakes are getting higher and higher in terms of the impact to other components.

Vigo
Vigo UltimaDork
11/29/18 12:10 p.m.

Catalytic converters are covered by a longer warranty than the basic bumper to bumper. I wouldn't be worried about paying for any of this. Pretend you know nothing about cars  and lawyer up (as far as your behaviour and interaction with them) until you're in the clear with a running car and an intact warranty. 

CyberEric
CyberEric HalfDork
11/29/18 12:10 p.m.

Are the techs even doing test drives after making changes to the car?! They should, and see the misfires happening immediately and go, yeah, the problem isn't fixed, back to the drawing board. The dealership I worked at mandated that. 

Bad gas, man, that is a total joke. They put their own gas back in it, and plugs are still getting fouled and it's still misfiring. It's not bad gas. You're udner warranty, keep asking them to fix it. If they can't ask to talk to the service manager, and if he can't help you, ask to talk to someone at GM, or take it to another dealer.

Javelin
Javelin MegaDork
11/29/18 12:12 p.m.

You need to call GM now:

General Motors of
Canada Customer Care Centre at
1-800-263-3777

Have you dialed yet? Your dealer is clearly giving you the run-around, and "new GM" doesn't like that. 

CALL

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