Oil Leak & Stumbling Problem
Thread Starter
Instructor
Joined: Mar 2009
Posts: 220
Likes: 0
From: Newbury Park Ca
Oil Leak & Stumbling Problem
Ok so I'm having a few issues with my '93 that I think have surpassed my ability to diagnose them.
Stumbling Problem
First of all, I've had a stumbling problem with the Corvette. I consulted with a few people and replaced the fuel system:
So, I know its not the fuel system. I included a few videos below to show what the stumbling is like:
This is the corvette stumbling. I revved the engine a bit to keep it going:
This is the Corvette Dying: I started it a moment (a few seconds) before the video started. This happens some of the time I start the car unless I rev it like i did in the first video.
This is the final video and it shows the fuel pressure during the stumbling. It stays steady at 45psi. It also shows (at the end) the smoke that comes out of the exhaust.
Any ideas? I checked the codes using the paper clip method (connecting A to G) and its reporting codes H22 and H64.
Smoke Problem
Ok so I have no idea what could be causing the engine smoking problem. I have an oil leak on the car coming from the engine.It seems to be leaking from the rear of the engine (inbetween the engine and the firewall has smoke coming out during running) however when I look under the car it is dripping down from the front of the engine.
The drip is coming off of that rail/lip. Any help is greatly appreciated.
Stumbling Problem
First of all, I've had a stumbling problem with the Corvette. I consulted with a few people and replaced the fuel system:
- New Injectors
- New Fuel Pump (Racetronix)
- New Fuel Pressure Regulator
So, I know its not the fuel system. I included a few videos below to show what the stumbling is like:
This is the corvette stumbling. I revved the engine a bit to keep it going:
This is the Corvette Dying: I started it a moment (a few seconds) before the video started. This happens some of the time I start the car unless I rev it like i did in the first video.
This is the final video and it shows the fuel pressure during the stumbling. It stays steady at 45psi. It also shows (at the end) the smoke that comes out of the exhaust.
Any ideas? I checked the codes using the paper clip method (connecting A to G) and its reporting codes H22 and H64.
- H22: TPS voltage was under 0.23 volts when the engine was running.
- H64: Right oxygen sensor voltage was below 0.2 volts for 50 seconds of closed loop operation.
Smoke Problem
Ok so I have no idea what could be causing the engine smoking problem. I have an oil leak on the car coming from the engine.It seems to be leaking from the rear of the engine (inbetween the engine and the firewall has smoke coming out during running) however when I look under the car it is dripping down from the front of the engine.
The drip is coming off of that rail/lip. Any help is greatly appreciated.
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
Nice videos. Fuel system seems good how about the fuel itself. 
Did this problem start "out of the blue" or is there more info you can post about what is going on? 
I'd pull some plugs and take a look at 'em.
Did this problem start "out of the blue" or is there more info you can post about what is going on? I'd pull some plugs and take a look at 'em.
Thread Starter
Instructor
Joined: Mar 2009
Posts: 220
Likes: 0
From: Newbury Park Ca
I mean I only use 91 octane from major suppliers, Shell, Chevron, Mobil. I use the same stuff in my Volvo and my other 'vette with no problems. I'll pull the plugs and have a look. I'm thinking it would also be prudent to pull the opti and have that checked. It has failed in the past and that way I can have easier access to the front of the engine to check the seals for the oil leak.
It started pretty out of the blue. I don't do any racing and I don't even drive the car very hard.
Thread Starter
Instructor
Joined: Mar 2009
Posts: 220
Likes: 0
From: Newbury Park Ca
Well I changed out my throttle position sensor and this solved the problem for a while but now it's back. It seems like if I start the car with the TPS disconnected it goes away for a while. Any ideas?
Help!
Help!
Pro
Joined: Sep 2004
Posts: 505
Likes: 1
From: Guntersville Alabama
I guess it does not throw a code. The ignition system can do this without throwing codes. Have the coil and igntion module tested. The ICM can do some crazy things. It made my engine seem like it was out of time. An opti failure can cause this type of stumble as well.
93cruiser
93cruiser
Last edited by 93cruiser; Feb 20, 2010 at 10:02 PM.
Thread Starter
Instructor
Joined: Mar 2009
Posts: 220
Likes: 0
From: Newbury Park Ca
I guess it does not throw a code. The ignition system can do this without throwing codes. Have the coil and igntion module tested. The ICM can do some crazy things. It made my engine seem like it was out of time. An opti failure can cause this type of stumble as well.
93cruiser
93cruiser
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Le Mans Master
Joined: Jul 2009
Posts: 6,381
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From: SF bay area C.A.
C4 of the Year Finalist
take your time and clean up all the oil, then run it and look for your leak, dripping points can be deceptive, it could be leaking from one area and the oil travels and drops down at a different area. I had a leak and thought it was comming from the front and blowing back, it ended up being my seal on the dipstick where it goes into the block. Good luck.
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
The stumble is ignition related. In general, it may need a tune-up just so you have a good to start the real troubleshooting from...
- Plugs. How old? Have the gaps been checked
- Wires. How old?
After the above, in order of probability...
1) Ignition Control Module (you can have this tested at an Autoparts store)
2) Opti
3) Coil
The oil leak looks like the intake. With age, the RTV seals at the front and rear of the intake break down. You can get a pretty nasty leak when this occurs. The fix is to r&r the intake. Pretty simple procedure since the LT1/4 intake is dry. Since no coolant runs thru it you don't have to drain the radiator or worry about coolant spilling into the lifter valley when you pull the intake. Takes a couple hours total.
- Plugs. How old? Have the gaps been checked
- Wires. How old?
After the above, in order of probability...
1) Ignition Control Module (you can have this tested at an Autoparts store)
2) Opti
3) Coil
The oil leak looks like the intake. With age, the RTV seals at the front and rear of the intake break down. You can get a pretty nasty leak when this occurs. The fix is to r&r the intake. Pretty simple procedure since the LT1/4 intake is dry. Since no coolant runs thru it you don't have to drain the radiator or worry about coolant spilling into the lifter valley when you pull the intake. Takes a couple hours total.
Thread Starter
Instructor
Joined: Mar 2009
Posts: 220
Likes: 0
From: Newbury Park Ca
The stumble is ignition related. In general, it may need a tune-up just so you have a good to start the real troubleshooting from...
- Plugs. How old? Have the gaps been checked
- Wires. How old?
After the above, in order of probability...
1) Ignition Control Module (you can have this tested at an Autoparts store)
2) Opti
3) Coil
The oil leak looks like the intake. With age, the RTV seals at the front and rear of the intake break down. You can get a pretty nasty leak when this occurs. The fix is to r&r the intake. Pretty simple procedure since the LT1/4 intake is dry. Since no coolant runs thru it you don't have to drain the radiator or worry about coolant spilling into the lifter valley when you pull the intake. Takes a couple hours total.
- Plugs. How old? Have the gaps been checked
- Wires. How old?
After the above, in order of probability...
1) Ignition Control Module (you can have this tested at an Autoparts store)
2) Opti
3) Coil
The oil leak looks like the intake. With age, the RTV seals at the front and rear of the intake break down. You can get a pretty nasty leak when this occurs. The fix is to r&r the intake. Pretty simple procedure since the LT1/4 intake is dry. Since no coolant runs thru it you don't have to drain the radiator or worry about coolant spilling into the lifter valley when you pull the intake. Takes a couple hours total.
Just an update: the engine started getting a wondering idle and it is pretty much impossible to drive. So I had it towed to my mechanic's shop and its throwing a H36 code. So it appears the opti is dead. Not sure what to do: I can't get the car into my garage to fix the opti myself and I don't have the money to have the mechanic fix it.
So, barring a miracle, the car is stuck. Worse: it has a leak and its raining. One of those days...
