I've recently developed intermittent problem starting the car.

Once in a great while, over the last week, 1/25 starts (3 times total), seemly randomly...
What happens is the car starts and then won't idle and dies. Then won't start again.

I pressed the start button probably 25 times one time, stepped away, for a minute, came back and it started.

Today, I had the same issue, I started the car, it didn't idle and died while I was rolling backward down the driveway. This time pressing the starter button over and over never really got it started.

How I got it started this time was pressing the start button, and while the starter was turning over I let out the clutch while in 1st, and essentially push started the car with the starter motor? How strange is that?

Again with the starter spinning, I dropped the clutch in 1st, the car jumped forward a few inches, and the forward movement of the car turned the motor over enough to get it running enough to rev it up, let it back down and it idled and runs fine.

What could be the problem here? I find this issue no where in the F.A.Q.

FYI this is an 05 stock C6 44k miles with the only modification being I had an NPP exhaust, and the 'NPP in a box kit' installed two weeks ago by IPS Motorsports (and they're good), so I don't think that is the issue just coincidence, or is that an issue with 'NPP in a box' installs? The only change was they tapped a vacuum port for the muffler control unit. I have no check engine light or any errors. Again being very intermittent, 3 times in the last 1-2 weeks (and I drive a lot).

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only possible ideas I have are battery issues, starter or starter relay issues, worn teeth on flywheel or starter or slippage, or something related to the new vacuum line installed, or some kind fuel issue... loose battery or bad battery connections or grounds? ?? I'm completely guessing. Spark plugs and distributor? Do I need a tune-up? Could I have a cylinder not fully functionally (not igniting) and not know it? with no codes I don't think it could be that without a misfire code.
-- it's weird how I used the starter, popped the clutch into first, and that little movement jump, kick started the engine...

Any ideas or anyone seen this and fixed the issue? Any number of things could be going faulty, but with it being to intermittent, I can't duplicate the problem as it is randomly intermittent.

 

I would check out the new vacuum line. Seems like it started after that. Try disconnecting it and make sure it is connected correctly like it was before the work was done.

 

since it is an LS2 I believe they installers of the 'NPP in a Box' kit, just uncapped an unused vacuum port and connected the vacuum line to it. Which shouldn't be causing these problems. I also know the vacuum line is still hooked up correctly because the mufflers are functioning fine, which they wouldn't without vacuum.


Additionally to what issues I posted above. Today while cruising the engine completely lost power and throttle response for 5-10 seconds, but it didn't completely die.

It lost power/throttle response and I pressed in the clutch and let it idle while cruising for a few seconds and then the power/throttle response came back. For a few seconds I thought it was gonna just die and leave me completely stranded.

This is related to what I posted above, because 2/3 times when the car doesn't start, it actually starts for a second, looses power and throttle response and dies.

If this happens when I'm switching lanes or doing some close cut maneuver, the issue could cause an accident or worse if I were to loose power while switching lanes on the highway.

 

I am no expert. But could it be a problem with the throttle body or throttle postion sensor. Since these cars are drive by wire if there is an issue with how far the computer opens the TB it could be causing the problems you are experiencing, ie not allowing enough air creating an extemely rich condtion and causing the car to have a rough idle or die as a result.

 

it sounds like it probably is some kind of extremely rich situation and rough idle...


Today, for the 4th time, the car refused to start. (3rd time in that location, on a slightly upward inclined driveway)
Again it started, and roughly tried to idle around 200-300rpm. Giving it throttle did nothing, then after 5-10 seconds of it trying to idle, died.

So at the first start 3/4 times it will start, but barely idle at 200-300rpm. Then 5-10 seconds later, die and not restart or only restart with the possibly rich condition but for sure rough idle, or well, failing to idle.

I think I got it started by using the starter to spin the engine, then drop the clutch, causing movement, push the clutch back in, then let out the clutch again doing sorta a push start style fix. Either that or it simple started on its own at some point after enough starts. I did learn that if you hold the start button in long enough, it has a special mode that doesn't run the starter for a certain length of time, but simply leaves the car cranking as if it had a key ignition.

I got it started eventually but it is becoming more frequent. I'm worried about not only being stranded somewhere, but worried it could loose throttle response during a tight cut lane switch maneuver on the highway and cause an accident or death.

 

It wouldn't start three different times today. I eventually got it started each time but now it has gone from intermittently to often intermittently.

Since it cut out once while cruising I don't think it is the battery or alternator, unless those could still cause that.

I'm wondering, by 45k miles, what regular maintenance should have been done?
I bought the car with 34k w/ a 500 mile old rear differential. Depending on the maintenance schedule, it could need new spark plugs, wires, transmission fluid change, coolant flush, any number of parts. I haven't checked the manual yet but if not there is there a recommended maintenance schedule posted online anywhere?

If I'm behind on plugs, wires, fluids, etc... the combination could be causing issues.
Never had the issue before but if the plugs are original could old/dirty/bad plugs and/or wires be causing this?

I hope it is something simple like plugs or an easily diagnosable sensor... and not fuel pressure or fuel issues.

Actually speaking of fuel issues I haven't looked yet but is the fuel filter serviceable? (not in tank)

 

It could be fuel or ignition, a bad fuel filter could be the problem also. Especially since it died while cruising. I would doubt the spark plugs or wires would be bad especially at 44K miles, but anything is possible. Could the car have been modded then returned back to stock before you got it? If so, a poorly tuned, modded car could foul up or burn up the plugs. Pull the plugs and take a look at them, they are not hard to remove.

Good luck getting it worked out, car trouble is so frustrating!

 

check fuel pump pressure and cam sensor

 

Current Situation (2nd appointment, this time at the dealer Tuesday)

No check engine light on.

Issue: intermittent starting issues (usually on very hot days, or in a sloped driveway) (but probably having nothing to do with the starting system)
car has completely failed to start to the point of being towed once, usually starts or starts eventually.
(the day it didn't start at all was very hot, on a sloped driveway)

Issue #2: Once similarly to when it wouldn't start, cruising at 45mph completely lost power / throttle response (pressed in clutch and car almost didn't idle, wouldn't rev) for 10-15 seconds.

Due to issue #2 I feel that rules out: battery, starter, anything related to the starting system and leaves the issue being something else. Possibly the electronic throttle or a sensor. The GM Dealerships I spoke with have had no issue like this before.

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so far it could be from forum input...

crankshaft/crank angle positioning sensor
electronic throttle position sensor
fuel pressure / fuel pump / fuel filter?
cam sensor

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As for what happened at the first appointment.

Still unfixed
Car was towed after not starting to NTB for 2 days just for them to tell me my car's computer system is having communication problems and they were unable to communicate with it so they refused to touch the car because they couldn't scan for codes)

They blamed my car saying the computer is having communication problems, on what I believe to be their software's inability to interface with a 2005 Corvette computer. Unless that is a possible issue? (I would think the car wouldn't run if it were)

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As for it previously being modded...

The previous owner had the rear end rebuilt at 33k 500 miles before I bought the car, and the car came with almost completely bald tires, so it could be possible that it was modded in some form or at least driven hard.
(or just a rear end failure, seems to becoming a not-so-unique issue)

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Where do I go from here trying myself to fix it before my dealer appointment?

Is there a way to check for codes through the dash computer (to check for codes that wouldn't turn on a check engine light).

I have a generic OBD2 to USB cable, is there a way to plug my laptop into the Corvette and software available somewhere to check codes / do a diagnostics, and check the ECU to make sure it has not been flash and is unmodified.

Any pointers to other simple instructions for checking things that could be causing this?
(I no longer have lift access, so reachable sensors from the ground, either way though it'll still be helpful).

How to check for fuel pressure / fuel pump issues?

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Also, lastly, I do want this question answered.... could a bad fuel filter be causing this, and if it were bad is it serviceable because there is no part for it at napa?

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any advice greatly appreciated

 

Since I feel this seems to only happen when it is very hot and usually on a sloped driveway. Except for a couple times and the cutting out at cruising.

Just wondering if the car's timing and fuel / intake is adjusted due to temperature / humidity and pressure, and what sensor would be related to that and cause this problem if any?

Just thinking like, it's really hot, the barometric pressure is something... the maps the ECU is reading for some reason (maybe the car being previously modded, maybe not) are for some reason not running everything at the right combination to start the car.

Also It occurred to me if the previous owner had modifications and the car tuned it would have different maps which could be the entire reason for this problem. A certain map intermittently being used for fuel/ignition/timing/etc, which won't start the car unmodified. So..

That is why I asked previously if I could use an OBD2 to USB cable to check for a modified ECU? (I used this OBD2 USB cable on another OBD2 car to modify the ECU mappings / tuning on the other car)

So just another thought, and hopefully someone will help me figure out how to read the codes from the dash, or if that won't work, with an OBD2 -> USB cable.

thanks

 

Install a cheapo fuel pressure gauge right at the rails and confirm pressure's good when your having the problem.

 

Go to Walmart and get a cheap Canbus capable scanner. It's worth the few bucks to have it, it will help you keep dealers honest on any car. I keep one in my rear cubby and have used it many times on friends' cars. Your old cable probably won't read the Canbus system unless it's pretty new.

Scan the codes and post up what you find.

 

I took it to the dealer.

The problem was a "partially disconnected/loose wire", looking at the wiring diagram it was between the fuel pump relay and the fuel pump assembly.

The wire had come loose of the metal surrounding thing that holds it into the connector.

Cost $200 for a diagnosis and a total of two hours of labor, plus they also added bolts to my rear sway bar (or something like it) that were entirely missing which they said was a safety issue.

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They also found an animal stuck under the car smashed into what they call the front nerf bar. A bar which protects the parts under the front of the car. This front nerf bar was pushed into my A/C condenser by the animal. Now they want $1400 to fix the A/C condenser and nerb bar which is currently working but they say it is leaking. Including... $400 for the nerf bar. $400 for a metal bar which does nothing but block road debris from hitting vital components, and apparently doesn't do it that well. $400 seems awfully expensive for a metal bar serving not other purpose.

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Also - NEW PROBLEM
Since picking it up from the dealer, I now have a "Service Charging System" message displaying all of the time, and the Horn doesn't work.

Since they messed around under the engine fuse box (there were a bunch of scratches), somehow they caused this new issue...

Why would my horn not work? I only can guess that they messed up a connection when working on it or somehow caused a blown fuse.
(Same for this new "Service Charging System" error, or I damaged the starting system trying to start the car over and over again when it wouldn't start)

Maybe I have more loose wires because my lights around my speedometer for the computer display intermittently work, and now my horn doesn't work, one of my turn signals is not working, and I have a "service charging system" error. All of these are new problems since taking it to the dealer (except the intermittent button lighting issue).

 

Sorry to hear about all your recent troubles with your car, but we have some used parts that we would be able to install at a much lower cost then the dealership here locally, and we do general service all the time to corvettes.

Give us a call at the shop and we will diagnose the car for FREE and service it for much less

Regards