After three trouble free years, my car has developed its first real issue.

Car is a bone stock 2007 manual trans, 33K miles.

After driving the car long enough to get thoroughly warmed up, this usually takes about 20 – 30 minutes and oil temps approaching 100*C/212*F, it starts losing power under full throttle . First it’s only in the higher revs, around 5,000 RPM, and the engine will pull hard to that point then stop revving as though it has hit a rev limiter. Then as the engine continues to warm and the heat soaks into everything, it starts losing power at increasing lower revs and starts to hesitate and stumble under load. Initially, no DIC messages, no CEL or other lights come on. All gauges normal. The car continues to run fine and rev freely under light to moderate throttle, as though nothing is wrong, but will choke every time under heavy load. The first time it happened on a Sunday afternoon, I was an hour from home, and continued to drive it to get home. After about 45 minutes, the CEL came on, and the codes were p0171 and p0174, lean condition bank 1 and bank 2.

I then took it to my dealer and they diagnosed a vacuum leak at the intake manifold, and replaced the gasket. They claim that upon inspection the gasket showed deterioration. However, the problem persists. I have discussed the situation with the dealer, and they are puzzled, they were certain they had it licked. I have an appointment to meet with the SA and the service manager next week to discuss what diagnoses were already performed, and what further diagnosis they would do going forward, and we’ll see where that leads. In the past they have been good to work with, we’ll see how this goes. I do not want the m working on my car unless I have confidence that they can fix the problem without open-ended trial-and-error parts replacement. The car is drivable so long as I stay under half throttle and, since the dealer cleared the codes, they have not returned.

Just wondering if anyone knows what the problem might be, or anything particular I should try to help diagnose the issue. Any suggestions are appreciated. Thanks in advance.

EDIT/UPDATE: see post 6, looks like fuel pump is shot.

 

carefully wash out the MASS with MASS CLEANER spray. make sure it is MASS cleaner NOTHING else. then check all your clamps. does the car have a factory air filter ? intake gasket failures are very rare unless the intake has been off.

good luck

Tom

 

Yes, I should add that I used a can of CRC and gave the MAF sensor a good cleaning, cleaned out the filters, there was a little bit of dust and grit in the housing, checked the plugs and wires and they were OK. Checked all clamps. I'll get some new filter elements and put them in though the originals still don't look too bad. The intake manifold would have been removed once 3 years ago when some lifters were replaced under warranty.

 

Fuel pump,fuel pressure, fuel filters? Fuel injectors clean or partial blockage? ECU injector pulse time on maps.
Lean= too much air,,,,,, or not enough fuel,
On My tow rig we would get P0171 on a hot engine,heavy towing load in the hot afternoons on Highway5. Changed the front O2 sensors and reset codes. Next race tow, same thing again, P0171 left bank lean. finally heard the pump fuel on a cold start and it sounded slow and different. Replaced the pump , no more lean codes. the " tea bag filter" on the pump inlet was plugged big time ( 95000 miles )
Just sayin,,,,Racer86

 

I had the same issues, but it was related to my tune and high IAT.

I ended up purchasing a Redline smoke tester to check for any intake/exhaust leaks. Obviously I didn't have any.

It is also possible that you could have a rolled injector o-ring.

 

Thanks for the suggestions.

Both the pump and filter are inside the tank, going to be a little pricy to drop the tanks, so hopefully thats not the issue. I will ask the dealer first, since they were so confident about the manifold gasket, to confirm that they put everything back together correctly. If they did, then I'll see what they say about the charges for the gasket re & re, and what they recommend next and specifically what fuel system diagnostics will they do and at what price. Fortunately, even though this is frustrating, the car is still drivable so long as I don't romp on it so I have time to ask questions and hopefully get it fixed and keep the dealer honest.

 

Update:
Dealer hooked up their live diagnostics gear and determined loss of fuel pressure, they claim the fuel pump is shot. The tech could not explain to me how that would be temperature related, and progressively worsen as the car gets heat soaked, however the dealer has agreed that if they replace the pump and the problem, as shown on their diagnostics, remains, they will refund the full shot. They will also credit the half the labour for the manifold gasket replacement towards the fuel pump, even though they insist the manifold had a leak and needed to be replaced.

I am awaiting the price for the pump re & re, the tech says be ready for close to $2K all in. Does that sound right?

 

My 2008 would lean out on the track in hard pulls in third and fourth. It was a low mileage garage queen when I bought it. I began putting a bottle fuel injector cleaner and Seafoam fuel treatment in each tank when filling up, this was a suggestion from a mechanic I know, he told me what the hour charge was for changing the fuel sock. I did this for 4 or 5 tanks. The last two track days I have had zero problems.

 

Sounds right re dollars esp. in Canada.* Dealer does sound kind of reasonable if they're willing to count some of the labor for the gasket into the fuel pump replacement and give the money back (for the R&R, I presume, not the gasket replacement) if the finding remain the same after the replacement.

I guess things just wear out, either with time or mileage, but I am a bit concerned that if you've done everything right by the car, why an eight year old fuel pump would go bad with low miles.

One question on your first post: you say it's a 2007, bone stock, and it's been running fine for three years--what happened to/in the other years before the last three years?

* Might be more. Saw prior posts w. $2500+ USD.

 

Thanks for the pricing feedback, I guess this one's gonna hurt a little. It's quite an involved job, beyond anything I really want to attempt. https://www.corvetteforum.com/forums...fuel-pump.html The dealer is reasonable, they are one of, if not THE, largest Vette dealers out here, though their volume is tiny compared to the big forum dealers.

I bought the car as a used, one-owner garage queen with 6K miles on it. It was also originally sold and serviced by this same dealer.

 

I run a can of BG44K through it every other oil change, and nothing but Chevron 94 octane. Since my original post, the car had gotten worse, and would stall out and die, fortunately it happened slowly enough that I could get it safely off the road. After sitting for half an hour it would re-start, then as it warmed up the process would repeat, it would steadily weaken and die. The dealer found low pressure ahead of the injectors in the system as a whole, with the guarantee they've offered I'm giving them the go ahead on the new pump, looking forward to getting back on the road.

 

Picked up my Vette today with the new fuel pump and all is good, car runs like a champ. Dealer (Dueck Downtown) credited all the labor ($268) for the intake manifold re & re, and knocked 10% off all parts, I'm satisfied with how they handled that. I'm happy to get the car back. As for the effect of temperature, it was explained to me that the fuel pump internals were failing, but not yet 100% gone, and as the fuel that returns to the tank is warm from engine heat, it increasingly raises the temperature in the tank. The weakened pump couldn't handle the temperature increase.

 

When I road course I have to worry about heatsoak, you probably don't have that issue.

 

That dealership sounds like a keeper.... Not many are that good about potential refunds even before the work is done.

 

As dealers go, they are good guys. To my surprise, they recently beat everyone else's price on Michelin tires. But they still do just fine even after all the discounts and guarantees, but what am I gonna do, its my DD and I can't do the work myself, I'm thankful these guys do what they can