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Old May 13, 2025 | 09:57 AM
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Default Help with stranded LS 7

I took a road trip from Ft Myers, FL to Illinois recently. On the way home my 13 427 suddenly started running poorly and put up a message "Service active handling" and stopped running. I had the car towed from the highway to a Chevrolet dealer in Carbondale, IL. In the process of diagnosing my problem they told me they went through all the "electrical systems" and said there were no issues found. They then told me they removed the plugs and "scoped" the engine and said they think my problem was mechanical. During my discussions they repeatedly told me they were in contact with GM for guidance on servicing my car. At one point they said they had no experience with "a car like mine". It seems to me the LS7 valve issue got me. I don't have confidence in having them fix my car.

Does anyone know of a reputable, competent shop in proximity of Carbondale, IL that could fix my car?
Does anyone know of a reputable, competent car hauler that can get my car from Carbondale, IL to Ft Myers, FL?
Does anyone know of a reputable, competent shop in proximity of Ft Myers, FL that could fix my car?

Thanks in advance for any help.
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Old May 13, 2025 | 10:31 AM
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Doubtful the "service active handling" error has anything to do with the valve guides.

I'd go over to Walmart or Costco & pick up a new battery.

https://www.corvetteforum.com/forums...ng-system.html
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Old May 13, 2025 | 10:45 AM
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IF you had the valve guide issue and broke off a valve that dropped off into the cylinder the car would have abruptly and violently died, they don't just stop running but more like grenade before they die. The dealer would see the pieces left in the cylinder and there would be no doubt about it, no "I think". I agree with JBCAT, get a new battery and see if that fixes it. Did you try to restart it after it died? Did it turn over like normal with no noises coming from the engine? IIRC when that message comes up it will limit the speed you can drive the car and not kill it from restarting.
I think it is CS Corvettes in Sarasota that is Corvette specific.
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Old May 13, 2025 | 11:06 AM
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You don't have a valve guide problem. I agree with Jabcat, try a new battery. Screwy voltages create screwy problems and a new battery is the easiest and cheapest attempt to fix your problem.
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Old May 13, 2025 | 12:07 PM
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Agreed with the others. Get a battery and go from there.

If you dropped a valve, you'd know.

The Chevy dealer on US41 in Fort Myers was good back when I lived there. They loved a lot of Corvettes.
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Old May 13, 2025 | 12:37 PM
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What did the dealership say the problem was ??...if something other than internal damage I'd be happy to look at it if you get it back to Ft. Myers...if "heavy" internal work go to Legendary Auto off 41 on Courtney Drive...I'm going there on Friday to get my tires changed out and an alignment....BTW, the first thing is to check for any trouble codes...if you don't have a scan tool now may be a good time to get one...and NOT a code reader.

Last edited by C5 Diag; May 13, 2025 at 12:57 PM.
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Old May 13, 2025 | 01:03 PM
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Could be as simple as a plug wire falling off although you would think even a Chevy dealer could find that.
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Old May 13, 2025 | 01:23 PM
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Originally Posted by dr_gallup
Could be as simple as a plug wire falling off although you would think even a Chevy dealer could find that.

Now you’re stretching it…LOL !!
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Old May 13, 2025 | 08:43 PM
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Ditto, and would say that at least one or more of the spark plug wires came loose from the coils above or from the spark plugs below, may be the only problem alone.

If you snapped the head of a valve to send that into the cylinder, then engine cranking even one rotation, is going to let you known you have problems big time instead.
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Old May 14, 2025 | 06:46 AM
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Originally Posted by sidebycycle
During my discussions they repeatedly told me they were in contact with GM for guidance on servicing my car. At one point they said they had no experience with "a car like mine".
You are on the right track of getting your car out of that dealership, they want nothing to do with it and will just bleed your wallet dry.




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Old May 14, 2025 | 07:13 AM
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I had a plug wire come off of one of the coils of my 2011 Grand Sport and it did the exact same thing.

Other likely possibility is you just need a new battery.
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Old May 14, 2025 | 09:18 AM
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does the engine turn over? crank? You said the engine stopped running. Would you please provide more detail, was there a loud sound? banG! smoke? Oil on ground?

Not sure how valve guides and service active handling system go together. Makes no sense. Will the dealer provide you a list of codes?
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Old May 14, 2025 | 01:31 PM
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Default Help with stranded LS 7

Thank you all for your input. If I was more tech oriented I would have posted a picture of the invoice I got from the dealer. Below is what was described on the invoice:

A C/S THERE WAS A CLICKING NOISE WHILE DRIVING AT LOW SPEEDS
CAUSE: NEEDS FURTHER DIAGNOSIS
10A PERFORMED MULTIPLE COMPONENTS TESTS TO BEGIN DIAGNOSIS, TORE DOWN AND SCOPED BELOW SPARK PLUGS, NEEDS FULL TEAR DOWN ($3335)

33579 NEEDS FURTHER DIAGNOSIS CONFIRMED COMPLAINT. FOUND CODE P0106 MAP SENSOR PERFORMANCE. COMPONENT TESTED MAP SENSOR, CHECKS GOOD. USED GDS TO CHECK LIVE DATA AND FOUND ERRATIC READINGS FROM MAP SENSOR SUGGESTING PRESSURE ISSUE. STARTED TAC CASE #9-152227222101. TAC RECOMMENDED REMOVING SPARK PLUGS AND INSPECTING WITH SCOPE TO LOOK FOR INTERNAL DAMAGE. NONE NOTED. WILL NEED CYLINDER HEADS REMOVED TO INSPECT PISTONS FOR DAMAGE. POSSIBLE DROPPED VALVE. TOTAL TEAR DOWN COST $3335. CUSTOMER DECLINED FURTHER DIAGNOSTIC PROCEDURES.

B C/S SERVICE ACTIVE HANDLING SYSTEM MESSAGE CAME ON THE DASH, VEHICLE BEGAN TO RUN ROUGH.
10A SEE LINE A, NEEDS FURTHER DIAGNOSIS

C C/S VEHICLE WILL NOT START
10A SEE LINE A, NEEDS FURTHER DIAGNOSIS

Upon questioning the service manager, he told me the car will start and run but does so very poorly. When I asked him what they saw when they scoped the cylinders ( I asked if they scoped all cylinders and he said yes), he told me it looked like a valve had dropped but they couldn't tell if there was any damage to the pistons etc.

I am not currently with the car. Any thoughts?
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Old May 14, 2025 | 01:39 PM
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It doesn't sound like they are BSing you. if they opened a TAC case then the tech is under the direction of GM's Technical Assistance Center. I've been down this path with a Silverado and sat with the TECH as he was getting direction from TAC on what to check and report back.

The choice now is do you pay them to tear it down, a GM LS7 service block is around $18,000. If they find it's a dropped valve the only option I see is a service block from GM. If it was me, and I didn't have the $20k to go all the way. I would tow the car home, park it, and come up with a game plan for all scenarios. otherwise you'll end up towing home a blown engine with parts in boxes and a $3000 bill for diag.
I would get GM customer Service involved today. I would explain the issue and formally request 'good will' assistance to cover the cost for the service block if it turns out a valve dropped. See if they would be willing to provide assistance with the diagnostics.

I would ask the dealer to write up a quote for worst case scenario. Long block, tax, labor, oil, fluids, and present that to GM customer service. You are out nothing other than time for asking.


"it looked like a value dropped" is what the service advisor said?
I would ask the following:
1. The cost to replace the engine with the LS7 service long block.
2. Ask to see the scope image of the suspect cylinder.
3. If a leak down test or compression test is possible on the suspect cylinder.
4. Possible rocker arm failure? cost to pop off valve covers for inspection.
5. Was metal was found in the oil.

I would ask those questions. If engine dropped a valve it would be VERY VERY noticeable. I would think it would be plain as day without having to scope the engine.
if TAC is telling them to pull the heads then it's probably a dropped valve.

Last edited by Bluewasp; May 14, 2025 at 02:04 PM.
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Old May 14, 2025 | 01:52 PM
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Here is the replacement LS7 engine GM sells for LS7 failures.

https://sdparts.com/i-24531268-genui..._cM7-h0VXA5E-h

I have a 2013 427 with 61,000 miles. Serviced at the same dealer since new. I've had multiple discussions with them about the dropped valve issue and they say it's blown out of proportion and the only cars they've repaired (dropped valves) have been because of mods to the engine or tunes. You are in the middle of my nightmare scenario when we take the car on road trips. ugh.

Last edited by Bluewasp; May 14, 2025 at 02:07 PM.
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Old May 14, 2025 | 02:04 PM
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I'd get the car out of there and find a DIAGNOSTIC shop in that area...the dealership can do a "relative compression" (if they know how) test which takes 2 minutes vs a few hours (and costs much more) with removing the spark plugs to see if you have a cylinder sealing issue... incylinder testing can be done with a pressure transducer and any issues like timing, valve sealing issues can be checked...I doubt a dealer can do this but a diagnostic shop with this advanced equipment can check without ANY engine dissassembly...ask the dealer if they can do this testing...relative compression and in cylinder waveforms below...if the dealership doesn't know what they are looking at below...run !!...BTW, if there is a valve sealing issue this can affect the MAP reading...if a dealer tech has no idea how to diagnose something they will open a TAC case.







Last edited by C5 Diag; May 14, 2025 at 02:10 PM.
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Old May 14, 2025 | 02:19 PM
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Originally Posted by C5 Diag
I'd get the car out of there and find a DIAGNOSTIC shop in that area...the dealership can do a "relative compression" (if they know how) test which takes 2 minutes vs a few hours (and costs much more) with removing the spark plugs to see if you have a cylinder sealing issue... incylinder testing can be done with a pressure transducer and any issues like timing, valve sealing issues can be checked...I doubt a dealer can do this but a diagnostic shop with this advanced equipment can check without ANY engine dissassembly...ask the dealer if they can do this testing...relative compression and in cylinder waveforms below...if the dealership doesn't know what they are looking at below...run !!...BTW, if there is a valve sealing issue this can affect the MAP reading...if a dealer tech has no idea how to diagnose something they will open a TAC case.
Couldn't they just remove the valve cover for the suspect cylinder, remove the two rocker arms. Then perform a compression test. That way they don't have to turn the engine over for TDC. Right? That should be what? 2 hours of labor? If a valve dropped the value on the gauge would be Zero! 0

From the google search I just did. I found photos of broken springs and cracked heads that occurred when the valve dropped.

Thoughts?
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Old May 14, 2025 | 03:11 PM
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Originally Posted by Bluewasp
Couldn't they just remove the valve cover for the suspect cylinder, remove the two rocker arms. Then perform a compression test. That way they don't have to turn the engine over for TDC. Right? That should be what? 2 hours of labor? If a valve dropped the value on the gauge would be Zero! 0

From the google search I just did. I found photos of broken springs and cracked heads that occurred when the valve dropped.

Thoughts?
If the valve dropped there would be catastrophic engine damage...if the dealership couldn't recognize this they should close their dealership and sell hot dogs...even with an old school compression test with a gauge or a "relative compression" test with a labscope if an intake valve fails to open the compression will be low...if a valve fails to open or close an incylinder capture will see that in a few seconds...no engine disassembly...a cylinder is really just an air pump and a good cylinder will look like the one I posted...watch the video from 1:15:25...a Corvette with an LS1...John Thorton is the best automotive Instructor in the country and a mobile diagnostic tech in Chicago...he'd be the one to have look at the OP's car.


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Old May 14, 2025 | 04:06 PM
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The manager said...
"he told me the car will start and run but does so very poorly. When I asked him what they saw when they scoped the cylinders ( I asked if they scoped all cylinders and he said yes), he told me it looked like a valve had dropped but they couldn't tell if there was any damage to the pistons etc."

Would an engine with a dropped valve run; I guess it's possible, but there would be a lot of noise? Was there a lot of noise?

Since they found no debris, it sounds like a valve spring...

A compression test will isolate which piston is the culprit. Ask them for a price to perform the compression test, find the bank involved and to pull the valve cover. If they find a broken valve spring, also ask them for a price for the fix. Apparently the heads have never been fixed, or did I miss something??? The heads fix would be in addition to the R&R labor.

Nick
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Old May 14, 2025 | 04:08 PM
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I am not sure about the Carbondale area but there are some reputable shops up in the STL area. Omega Performance is one that comes up a lot for LS cars. HPJ is in Belleville to be a little closer. DSX Tuning, Performance by Joe, Shane Hinds, etc are some other STL based locations that do LS work.
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