No-start leading to multiple misfire code and white smoke...then it runs fine. Bets?
11-09-2016, 11:22 AM
#1
Advanced
Thread Starter
No-start leading to multiple misfire code and white smoke...then it runs fine. Bets?
Hello all,
Had an interesting issue with my 2004 Z06 recently, and wanted to see if CF could weigh in on what you think the issue may have been.
TL;DR
No start condition, swapped ignition relay, managed to start after but ran terribly and started flashing SES light and pumping white smoke out the exhaust. Smoke/check engine light came and went twice in a 5 minute span, then went away on its own completley. Dealer thinks issue may be moisture in fuel system and want $800 to flush the system but can't guarantee it's a "fix". Currently running normally but coolant temps seem higher than normal and oil pressure seems lower than normal.
Detailed Description
The Z06 had been parked for about a month on a Battery Tender with roughly 1/4 tank in it. I finally took it out, took it for a spin, filled it up with gas (91 octane at Chevron), the car sat overnight, and I took it to work the next day. I put maybe 30 miles on the car between the time I filled it up and when the issue came up.
Approaching work, as I went to park, I thought I noticed a slight hesistancy/stumble but brushed it off thinking I was imagining things. Well, when I went to start it next, it cranked but would not run over. Having owned a variety of F-bodies and GM trucks, I've had multiple relay issues over the years, and swapped the following in this order:
-Fuel pump relay for horn relay (didn't help)
-Ignition relay (relay #42) for cooling fan 2 relay (relay #43) (still didn't immediately start)
After swapping the ignition relay, I tried starting again but applied some throttle while doing so - the Vette finally turned over and ran but wouldn't hold an idle without keeping the rpms around 1k rpm. After doing this for a few seconds, the car held an idle but sounded rough, likely misfiring at least slightly.
I tried to baby the car home, but during the drive (stop and go traffic), the car started to stumble but never died, I noticed white smoke out the exhaust, a flashing SES/check engine light (later identified as P0300 multiple misfire), and climbing coolant temps (peaked at 230 on a 79 degree day in AZ, at least 10 degrees hotter than expected). This came and went twice in the span of a 5 minute drive, and after the second episode, I pulled over and shut the car off.
After letting the car sit for a few minutes (was calling tow trucks), I decided to fire the car up just to see what would happen. The car fired right up, idled normally, and sounded normal. I drove it 5 miles home with no issues, although coolant temp appeared warmer than normal (10 degrees) and oil pressure seemed low (28 psi at idle, 36 at cruise).
I took the car home and scanned for codes, and found none. There were no current codes in the C5's built-in code database on the DIC, and nothing historical that was pertinent.
I took the car into the dealer. After 3 days of diagnosis, they said the car appeared to be running normally after multiple road tests. They briefly saw the SES light come on once during a turn on the first road test, but that was the only issue they noted.
The dealer thinks I may have had a batch of bad gas with an appreciable, but not visible/measurable, water content to it. Unfortunately, they aren't 100% on it, it's just their best guess based on the symptoms. They want $830 to completely disassemble, clean, and flush the fuel system (injectors, fuel rails, tank). That seems like an unreasonable amount of money to spend on a "maybe".
So now with all that info, what are CF's thoughts? Here's my thoughts/possible issues:
1) Head gasket. Ruling this one out as a blown gasket would put coolant in the oil, and I think I'd see a constant stream of smoke - I only saw smoke during the two "episodes" described above.
2) Broken valve spring. Also ruling this one out - my understanding is the valve spring issues were corrected by 2004, I don't notice any additional noise, and I think I'd have a recurring misfire on a specific cylinder if this was the case.
3) Electrical/relay issue. I mentioned I swapped out the ignition and cooling fan relays (didn't have a spare handy), and since then, the car ran, but has been running hot. If the ignition relay was indeed bad, I now moved it to the cooling fan circuit; if the cooling fans aren't operating at 100%, I think I'd be seeing high coolant temps and as a result, reduced oil pressure due to increased oil temps. This means I already "fixed" the problem but need to replace the cooling fan 2 relay; could likely swap the relays back to their original spots to see if no-start returns.
4) Fuel issue. If there was a moisture content in the fuel, it could have caused the white smoke when it entered the combustion chamber. I've never had a bad batch of gas before, but I'm thinking I could save the $830 and run a can of Seafoam through the gas tank, run it as low as possible, and refill it with good 91 octane. My concern with this is water having possibly pooled at the bottom of the tank, if any, being that water is heavier than gas.
So those are all my thoughts. I've stumped 3 techs at the dealership thus far. What are your thoughts?
My compromise action is to have the dealership drain the tank (not service the entire system) and add a few gallons of gas so I can get it home, and then I'll refill it myself and run Seafoam through it, which should eliminate the possibility of any water being left in the tank.
Had an interesting issue with my 2004 Z06 recently, and wanted to see if CF could weigh in on what you think the issue may have been.
TL;DR
No start condition, swapped ignition relay, managed to start after but ran terribly and started flashing SES light and pumping white smoke out the exhaust. Smoke/check engine light came and went twice in a 5 minute span, then went away on its own completley. Dealer thinks issue may be moisture in fuel system and want $800 to flush the system but can't guarantee it's a "fix". Currently running normally but coolant temps seem higher than normal and oil pressure seems lower than normal.
Detailed Description
The Z06 had been parked for about a month on a Battery Tender with roughly 1/4 tank in it. I finally took it out, took it for a spin, filled it up with gas (91 octane at Chevron), the car sat overnight, and I took it to work the next day. I put maybe 30 miles on the car between the time I filled it up and when the issue came up.
Approaching work, as I went to park, I thought I noticed a slight hesistancy/stumble but brushed it off thinking I was imagining things. Well, when I went to start it next, it cranked but would not run over. Having owned a variety of F-bodies and GM trucks, I've had multiple relay issues over the years, and swapped the following in this order:
-Fuel pump relay for horn relay (didn't help)
-Ignition relay (relay #42) for cooling fan 2 relay (relay #43) (still didn't immediately start)
After swapping the ignition relay, I tried starting again but applied some throttle while doing so - the Vette finally turned over and ran but wouldn't hold an idle without keeping the rpms around 1k rpm. After doing this for a few seconds, the car held an idle but sounded rough, likely misfiring at least slightly.
I tried to baby the car home, but during the drive (stop and go traffic), the car started to stumble but never died, I noticed white smoke out the exhaust, a flashing SES/check engine light (later identified as P0300 multiple misfire), and climbing coolant temps (peaked at 230 on a 79 degree day in AZ, at least 10 degrees hotter than expected). This came and went twice in the span of a 5 minute drive, and after the second episode, I pulled over and shut the car off.
After letting the car sit for a few minutes (was calling tow trucks), I decided to fire the car up just to see what would happen. The car fired right up, idled normally, and sounded normal. I drove it 5 miles home with no issues, although coolant temp appeared warmer than normal (10 degrees) and oil pressure seemed low (28 psi at idle, 36 at cruise).
I took the car home and scanned for codes, and found none. There were no current codes in the C5's built-in code database on the DIC, and nothing historical that was pertinent.
I took the car into the dealer. After 3 days of diagnosis, they said the car appeared to be running normally after multiple road tests. They briefly saw the SES light come on once during a turn on the first road test, but that was the only issue they noted.
The dealer thinks I may have had a batch of bad gas with an appreciable, but not visible/measurable, water content to it. Unfortunately, they aren't 100% on it, it's just their best guess based on the symptoms. They want $830 to completely disassemble, clean, and flush the fuel system (injectors, fuel rails, tank). That seems like an unreasonable amount of money to spend on a "maybe".
So now with all that info, what are CF's thoughts? Here's my thoughts/possible issues:
1) Head gasket. Ruling this one out as a blown gasket would put coolant in the oil, and I think I'd see a constant stream of smoke - I only saw smoke during the two "episodes" described above.
2) Broken valve spring. Also ruling this one out - my understanding is the valve spring issues were corrected by 2004, I don't notice any additional noise, and I think I'd have a recurring misfire on a specific cylinder if this was the case.
3) Electrical/relay issue. I mentioned I swapped out the ignition and cooling fan relays (didn't have a spare handy), and since then, the car ran, but has been running hot. If the ignition relay was indeed bad, I now moved it to the cooling fan circuit; if the cooling fans aren't operating at 100%, I think I'd be seeing high coolant temps and as a result, reduced oil pressure due to increased oil temps. This means I already "fixed" the problem but need to replace the cooling fan 2 relay; could likely swap the relays back to their original spots to see if no-start returns.
4) Fuel issue. If there was a moisture content in the fuel, it could have caused the white smoke when it entered the combustion chamber. I've never had a bad batch of gas before, but I'm thinking I could save the $830 and run a can of Seafoam through the gas tank, run it as low as possible, and refill it with good 91 octane. My concern with this is water having possibly pooled at the bottom of the tank, if any, being that water is heavier than gas.
So those are all my thoughts. I've stumped 3 techs at the dealership thus far. What are your thoughts?
My compromise action is to have the dealership drain the tank (not service the entire system) and add a few gallons of gas so I can get it home, and then I'll refill it myself and run Seafoam through it, which should eliminate the possibility of any water being left in the tank.
Last edited by CSX; 11-09-2016 at 11:50 AM.
11-09-2016, 11:59 AM
#2
Melting Slicks
Head gasket that leaks a little coolant into a cylinder. I had a car (VW) that did this, only leaked coolant when the engine was cold, then the leak stopped as the engine heated-up. When cold started, it had a misfire in that cylinder till the fouled spark plug cleared itself. No coolant got into the oil, only into one cylinder. Pull the plugs and inspect them, when cold.
If you suspect water in the gas, add a bottle or 2 of "Dry Gas" into the tank, which is just alcohol that binds/absorbs the water.
If you suspect water in the gas, add a bottle or 2 of "Dry Gas" into the tank, which is just alcohol that binds/absorbs the water.
Last edited by ersatz928; 11-09-2016 at 12:03 PM.
11-09-2016, 12:05 PM
#3
Advanced
Thread Starter
Head gasket that leaks a little coolant into the cylinder. I had a car (VW) that did this, only leaked coolant when the engine was cold, then the leak stopped as the engine heated-up. When cold started, it had a misfire in that cylinder till the fouled spark plug cleared itself. No coolant got into the oil, only into one cylinder. Pull the plugs and inspect them, when cold.
If you suspect water in the gas, add a bottle or 2 of "Dry Gas" into the tank, which is just alcohol that binds/absorbs the water.
If you suspect water in the gas, add a bottle or 2 of "Dry Gas" into the tank, which is just alcohol that binds/absorbs the water.
Last edited by CSX; 11-09-2016 at 12:09 PM.
11-09-2016, 12:14 PM
#4
Melting Slicks
Like I said, my VW only leaked coolant during certain points of the heat-up or cool-down of the engine. As the engine changes temperature, the block and head can expand at a different rate, which causes the two surfaces to move slightly against the gasket, which can open and then close a coolant leak path.
Is your car slowly loosing any coolant? It might take some time before you notice the level drop in the expansion tank.
I don't think your coolant temps (or oil pressures) are anything unusual. You can easily see 230F when idling in traffic.
Is your car slowly loosing any coolant? It might take some time before you notice the level drop in the expansion tank.
I don't think your coolant temps (or oil pressures) are anything unusual. You can easily see 230F when idling in traffic.
Last edited by ersatz928; 11-09-2016 at 12:17 PM.
