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Big repair job done by dealer & now new knocking noise on cold starts


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Good morning, been a while since I've posted here. 

Brought my 2010 SRX in to my local Cadillac Dealership because it was idling rough, trying to stall, and and throwing codes that both banks were running rich. They diagnosed it as both catalytic converters being clogged due to faulty fuel injectors. All 6 fuel injectors were replaced, both cats, I had them put in new plugs too as it was about time for that anyway, plus a bunch of misc required gaskets...$4700 later....:blink:

Since getting it back it now has a new problem. Anytime the car sits for at least 4 or 5 hours (or overnight), on a cold start the engine has a random knocking noise. After about 30 seconds (when the engine revs down to it's normal idle RPM) it goes away and never comes back (until the next cold start).

All other issues were solved by the repair, and this is new and started right after the repair. Something isn't quite right....here's the video. You will notice a low, not steady (random) thumping/knocking noise once I get the camera under the hood....more pronounced near the air box. 

https://youtu.be/eH1Kcgo28Gg

Any ideas? Car has 89k on it currently, NEVER did this before the repairs, and runs perfectly otherwise. 

 

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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Did they change the oil?  What did they use?  What gaskets did they change?  Was the engine disassembled?

If they didnt change the oil maybe fuel diluted it?

Hi davedog!

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Hello BBF - good to see some familiar 'faces' around here. :)

That was actually one of my thoughts. They said they did not change the oil. They said they didn't detect any fuel in the oil. I checked the oil level and it's normal. I'm no expert but I didn't smell any obvious/overpowering smell of fuel. They did ask if I checked the oil level (my first thought to that question was 'DID YOU?!?')

As far as I understand the plenum (sp?) was removed to change the fuel injectors and the plugs. 

Besides the two cats, the six injectors, and the six plugs, the following parts are listed:

12631646 (injector seal kit)

20893953 (exhaust manifold gasket), they have two of these listed

20952540 (converter & pipe gasket)

92202996 (exhaust clamp)

I've used this dealership in the past and generally had good service, but this has me scratching my head....and they have no answers yet.

EDIT: Something I just noticed looking over the ticket. It was my understanding that the gasket under the plenum (GM part# 12609163) needed replaced when the plenum is removed/reinstalled. Read this when I was reading up on doing the spark plugs on my car myself. This part is no where to be found on the list...

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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I dont like that at all, that noise is affecting vacuum levels.  

P0172 - System Too Rich Bank 1

Possible causes

Faulty front heated oxygen sensor

Ignition misfiring

Faulty fuel injectors

Exhaust gas leaks

Incorrect fuel pressure

Faulty Mass Air Flow (MAF) sensor

That code probably keeps it out of closed loop.

My guess is a leaky injector, a vacuum leak would give you lean codes.  Do you feel like its popping or backfiring internally?  No P030x misfire codes.  

I would get this back to the dealer.  I think that is a huge amount of money for what they did.  Were the cats covered under an emissions warranty?, or did they void it because of the "faulty injectors"?  Its running rich again and can hurt the cat again.

Dealers really need to be looked into, this should never happen

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By the way, what engine monitor are you using?

You live in New Jersey no?

Good to see you to Dave!

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Dropped it back off at the dealer yesterday. This time they provided a loaner so that's good.

It's out of the emissions warranty (89k miles).

I'm hoping it's something simple like that gasket they didn't replace (that IMO they should have) and it's creating a vacuum leak.

I was promised several times by the service adviser that these repairs would fix the issue.....if they find something else major I'm not going to be a happy camper as I was already on the fence between the repair work and just selling it for something else. But I like the car and it's paid for so....

I'll let you know what they come up with. 

And good memory, while I live in GA, I do vacation in NJ every year (Ocean City).

I use the android app 'Torque Pro' and a cheap Bluetooth OBDII adapter.

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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I spent 22 summers in North Wildwood, Ocean City, Somers Point and Cape May, I am due to make a trip down there, I miss going there.  I was baptized at St. Ann's in Wildwood.  My parents worked in Wildwood (entertainers) from the summer I was born till I was 22.  This is the Club Avalon in North Wildwood, they worked here and we lived near it.  

Thanks for the info on the Torque Pro, I use a Galaxy S7, Ill check into it.  

Please update us, there is no excuse for this.  I don't think lean vacuum leak, unless it is a leak at the exhaust manifold messing with the O2 sensor readings, driving the mixture rich. It seems to be cycling.  Maybe when its hot the leak seals up.  Dealers really hurt GMs reputation

424896_251636181593097_439750442_n.jpg

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Yeah, and this is why I do 90% of my own repairs. But when I started researching the original issue, I decided it was outside of my comfort level and felt like I'd be throwing parts at it. But now I feel like they may have thrown parts at it. No doubt the cats where probably clogged, but were the injectors the actual cause?

I've had overall good luck with this dealer in the past. Hope that continues...

 

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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Hadn't heard anything since I dropped it off late Thursday. Just called to check.

They are telling me that it 'was the valves' and there was build up and they are using some 'official GM top end engine cleaner' - something about something about putting in the cleaner letting the cleaner sit overnight, changing the oil, running the cleaner again...

Dunno about all this. Sounds....odd

I mean, how could this issue all of the sudden show up AFTER they work on it, and it simply be build up. I'm no expert but....

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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Sounds odd to suddenly happen.

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Agreed. I guess the proof will be in the pudding. As long as it works when I pick it up then whatever. They want to keep it an additional day or so to be sure it's fixed. I'll keep you updated. 

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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The saga continues....

I hadn't heard anything since I called on Tues, so I called & checked this afternoon. They said it seemed to be running better after the cleaning, but then this morning when they were driving it around it threw the same code again (bank 1 rich). So now they are saying will be running the cleaning process a 2nd time....

My confidence the money I spent is fading....

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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17 hours ago, davedog said:

The saga continues....

I hadn't heard anything since I called on Tues, so I called & checked this afternoon. They said it seemed to be running better after the cleaning, but then this morning when they were driving it around it threw the same code again (bank 1 rich). So now they are saying will be running the cleaning process a 2nd time....

My confidence the money I spent is fading....

 Absolutely terrible service, they replace the injectors after blaming them and it is still running rich.

I am having the same type of problem with my mother in laws Lincoln that is at the dealer out of warranty.  Tranny fluid leak.  They come back and tell her it needs cooler lines, and it will cost $750.  On rockauto the lines sold as a pair sell for $45 (dorman).  Even doubling that to $100, they are billing 6.5 hours at $100 per hour.  She went back and complained and they dropped it to $600.  I went on line  to Repair Pal and found that the job should be $258 with the parts costing  $100, implying 1.5 hours labor at $100 per hour.  The service writer when questioned by her, knew nothing about what was wrong and he said, "we don't think its the radiator" leaving a gaping hole for a higher charge.  

Up front the service writer said, the inspection charge will be $132 because they dont want to do diagnostics and have people take the car someplace else or do it themselves (and I add, after they hear $750 with an open end about the radiator)

Personally, I dont think it needs cooler lines, its a 2010 with 45K miles unless an animal ate through the 12 inch rubber section. 

If the dealers were only fair and honest and competent instead of being more concerned with generating income they would do more business and not ruin the reputation of the manufacturer in the process.  

I think having a subscription to mitchell hourly labor estimate would be advantageous in these situations.

Good luck, its odd that the dealer with all their expertise can not figure out a rich condition, I question whether they replaced the injectors and am stunned they returned the car to you with a rich code.

23192.jpeg

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By the way when they do that upper engine cleaning the oil is supposed to be changed I have heard Kevin speak of this procedure often and the oil needs to be changed maybe that's the reason why she's been knocking because they did that service instead of replacing the injectors and didn't change the oil I don't know

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Yeah, I don't know what to say. This particular dealership has been good to me in the past. Their labor rates are actually about the same as the local shop I sometimes use, and cheaper than a national chain I've used a couple times. Parts costs are higher than they should be, but other than that I've been generally pleased with their work in the past.

They did say they changed the oil after the 1st cleaning. 

My gut says that they missed something big the first time and either haven't figured it out yet, or are hoping this 'cheap' fix will band aid the issue enough for them to not have to deal with whatever is truly wrong. In their defense they have provided me with a loaner and they have not quoted me a penny in additional anything so far.

That being said I don't think they are being upfront with me. I dropped it off late last Thursday. They said they started the engine cleaning Friday and had it finished up Monday. Why then were they driving it all week (4 days)? I mean don't get me wrong, I'm glad they did since it waited until yesterday to throw the same code again, but that tells me that the tech didn't feel like the engine cleaning fixed it. There is something else going on that I'm not being told....or it sure feels that way.

Either way I contacted Cadillac yesterday and they opened a case and will look into the matter. I really hated to take that step but this is getting kinda silly. $4700 spent and it's still running rich. 

Thanks for listening to me vent all week BodyByFisher. 

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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No problem, any time.  Always glad to help.

Ready for this I had my mother-in-law take her car to a reputable repair shop and they quoted her $259 to replace the cooler lines which is $1 more than the quote I found online last night to do the same job the dealer came back and said he has to pay union rates and said he couldn't go any lower than $610 even though his hourly rate is $130 I have no idea what union rates has to do with his hourly rate what BS.

Good luck with this I can't wait to see what happens

 

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The GM 'top engine cleaner' stuff dates back to at least the mid eighties for carb engines. 

I did see a couple of part #s.......GM part numbers 1050002, 1052626. Try a Google search. 

You actually pour enough in fast enough to actually stall the engine.....then let it sit overnight if possible. 

You are suppose to pull all the plugs and crank the engine over before starting....if not you risk hydro locking the engine. You can bend valves and rods if your not careful. 

 

 

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so now, the same day the 2nd cleaning was done, they are already ready to call it fixed?!? 

smh

GM/Cadillac is involved now and recommending to the dealer that they drive/test/check it more as 'there is no way to know for sure' leaves a lot to be desired after spending $4700...

guys, I just don't even....

the whole reason I overpaid for this job was to avoid "no way to know for sure" - what a mess. The rep from GM was VERY nice and sympathetic. 

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Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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What a shame

 

Pre-1995 - DTC codes OBD1  >>

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Yup. For whatever it's worth (and for reference) this is Service Bulletin they faxed me the other day that they are going by for their diagnosis of the Engine Cleaning. Never mind the fact that the code it's been throwing even after one round of engine cleaning (P0172) isn't even listed in this bulletin, but whatever - they are the experts:

Bulletin #16-NA-383 (4630888) (sorry for the poor quality fax copy)

Also, do you guys have any opinion/information on whether or not the intake gasket should be replaced when doing things like plugs & injectors that require pulling the top of the engine off? Way before this mess when I was researching doing the plugs myself everything I found suggested this needed to be replaced (I even had one saved in my Amazon Cart). But that is literally the ONLY gasket they touched that they DIDN'T replaced. When I asked about it they said it 'wasn't needed' - again, I understand I'm not the expert here but...

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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The Guru used to say that if they were intact to reuse them, just smear a light coat of O2 sensor safe RTV on them.  

You are only getting a rich code on one bank correct?

One bank precludes the fuel pressure regulator being the problem.

Maybe they installed a bad injector?

They should be able to monitor exhaust temps at the exhaust manifold to determine which cylinder is rich it will be hotter than the rest.  I dont think you would get a misfire code because of rich.  One of those infrared temp guns should detect it.

I really don't understand the vacuum gage fluctuating like that.  

This would be easier if it were both banks.

 

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It actually was both banks before the repair. But it was bank 1 all the time and bank 2 only some of the time. So far it's only been bank 1 since the repair.

Thanks for the info on the gasket, that makes me feel better about their answer on that. 

And maybe the cleaning is the answer. I hope it's truly fixed. I guess I'm just suspicious now. They haven't instilled much confidence.

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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Check your fuel pressure regulator then for evidence of fuel at the vacuum hose, rev the engine with a white piece of paper in front of the regulator nipple.  Any fuel its the regulator.  

Is it popping back through the intake?

The intake seals would leak unmetered air and give lean codes or misfires not rich codes

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that makes sense (about the lean codes).

Once I get it back if it is still acting up I'll check into the FPR. For now, they still have the car - and I'm still piling miles on their 2018 GMC Terrain. 

and yes, I do think it was popping through the intake, the noise was much louder by the air filter box.

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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