Raith

Ok guys, I need some insight on this monster.

New engine with roughly 7500 miles on it now, has been running great, up until a week and a half ago, went and washed the car, left the car wash, and got about 4 miles down the highway, and it just died while rolling at 75 mph. Very abrupt, no warning, just sputtered and died like it was out of fuel.

Got the car towed home after adding fuel didn't get it running again. I can get it to fire up if I lay on the throttle while I crank it, but it runs like crap, and if I let off the throttle, it dies.

Checked relays, put a fuel pressure gauge on it, and it's getting a constant 58psi at the rail, so that eliminated the fuel pump as the cause. Pulled the rail and primed everything to see if there was ano injector stuck open, and none were leaking.

I changed the spark plugs out, and still the same issue, (have a pcv issue and have had oil burning issues because of it, so plugs were blackened, but still functional)

I'm planning on testing coils this evening, and pulling valve covers to check for anything visible there, but I really don't know what else it could be. Couple friends said maybe a sensor, but I'm not sure. I know if cam or crank sensors were bad they wouldn't let it fire up. Maybe maf or tps?

I'm almost at my wits end with this... if anyone has any insight, that would be appreciated. Thanks

Rob 02

When you were at the car wash, did you wash the engine by chance?

Raith

No codes that I have seen with the scanner, and no DIC codes under pcm. Will check the rest this afternoon when I get home.

No. I don't pop the hood at the car wash. I did once a year and a half ago, and had a no start situation for 2 hours. Never again. If I need to clean the engine bay, I'll do it by hand with cleaner and rags.

Rob 02

Every fuel pump failure I ever had started off intermittent. You could have 58psi but do you have it consistently even when the engine dies? Pressure should increase with revs.

A few weeks ago my neighbor replaced the fuel pump on his Suburban. It turns out, the problem was a flap of trash on the inlet screen of the pump. These kinds of things happen.

I don't think all 8 coils went out at once. I would expect to see a misfire code if one failed.

Rob 02

Did anyone at the car wash have an opportunity to put water in your tank? Gas floats on water and they don't mix. If that happened then you might be able to purge it out at the rail. You could take a fuel sample in a glass gar and look for beads of water in the bottom.


Is there any chance that you car really is running out of gas? Maybe erroneous fuel reading from the sending unit.

Raith

Nope. I hand wash it, and never turn my back on the car.

we put 10 gallons in it at the gas station on the way home on the flat bed.

Rob 02

Do you know you have gas regardless of what the gauge reads?

grantv

Either water ingestion thru intake while washing, or bad gas are my 2 guesses. Take a fuel sample...

Raith

I figure water through the intake wouldn't have let the car get 4 miles down the highway, and the fuel was added after it had sputtered and died on the highway.

that being said, I will take a sample of fuel just to see.

Rob 02

It does sound fuel related. I have heard of water getting into the gas stations gas too.

Smoken1

Diesel fuel maybe? I have seen it happen b/4

killian96ss

Having seen this so many times on multiple cars I'm gonna say you have water in a sensor, most likely a crank sensor since it's low enough to get wet even in a car wash. The exact same thing just happened to a coworker who went through a car wash with his Honda. When a crank sensor gets wet even a small amount of water will create a hard/no start condition. You can either wait until the sensor dries out or replace with a new one and keep the old one as a back up when it dries out. My co-worker couldn't start his car for nearly a week and then it fired up and ran perfectly.

Steve

Raith

Found the problem... not anything remotely close to what I was thinking. Bent a valve. So it's time to pull the top end... again.

and upon deeper inspection, it looks like the valve seat broke. It's sticking up into the intake runner. So new heads are gonna be in order.

zeevette

That sucks on a new motor. GL.

Rob 02

Another member had a similar issue, just days ago, on the track in Sebring.

I wonder it it was caused by an over rev while downshifting.

Raith

No kidding. Lol. That explains the lack of DIC codes.

that's an interesting theory

lionelhutz

Ouch, valve seat fell out of the head. Hope there isn't piston or cylinder damage. The valve and seat getting between the head and the piston tends to mess things up.

Rob 02

Here is a link to that recent thread.https://www.corvetteforum.com/forums...-thoughts.html

Rabbitman

But why would that actualy make it die altogether? Wouldn't it just make it miss and make some mechanical noises or is there something in the engine management system that kills the engine if it senses something like this.

Rob 02

1. There is probably more damaged valves than what you can see.

2. Exhaust fumes could be getting into your intake and that doesn't provide good O2 for any remaining good cylinders.