Fixed bent valve but still an SES light (a little long)
07-22-2006, 02:50 PM
#1
Fixed bent valve but still an SES light (a little long) To fill you guys in:
I shifted into 2nd instead of 4th some how at WOT. I drove it for about 12 miles before working on it. I then did a compression test on ALL cylinders to find out which cylinder got the treat. Every cylinder had about 125-130 psi except for cylinder #4 (passenger side). I also have hardend pushrods so I know its not them and I checked them also.
We pulled the head and replaced the slightly bent intake valve. You couldn't even tell it was bent by looking at it, but there was a nice nick in the piston.
Then we put everything back together.
Note: We didn't touch anything on the driver's side except for plugs and wires when we did the compression check.
I go and start the car and it sounds fine initially, but after a few minutes of idling to get the coolant flowing, it started idling rough and I got an SES light again.
I drove it and it ran like crap for about 5-10 minutes, misfiring a little. After that time it cleared up and ran smooth.
After the car cools off a bit from driving it acts the same when you start it up, misfiring a little and just running like crap for about a minute.
I then had a friend hook my car up to his HP Tuners software. It read that I was running very rich on the driver's side bank and that the passenger side was fine. Note: Driver's side had nothing wrong with it and we didn't mess with anything besides plugs and wires.
The software also showed that I was getting extra unmetered air on the driver's side bank. So odd since the compression check showed that we were fine and there wasn't anything wrong there.
We later figured that it could have been the intake that had a leak. My car has 114k miles on it and the gaskets for the runners are very flat and worn. I messed with the intake, no luck. I then bought a relatively new LS6 intake, still no luck fixing this problem. I made sure I didn't have any exhaust leaks at the header collectors and replaced my 02 sensors with new Bosch 02 sensors.
Having the new 02 sensors helped out a bit, but the car still runs a little off.
While driving I have this wierd ticking like sound coming from the engine that sounds like an exhaust leak but its not.
So we come down to this: I fixed the initial problem, and replaced parts that could have been causing my car to run horribly. With my new 02 sensors my Air/fuel gauge reads that I am very lean (on the driver's side because thats where the 02 sensor is that the gauge is hooked up to). If I run the car kinda hard, like up to 4k or so my air/fuel ratio gets up to the stoich area which is nicer than running lean, but after I lay off of running the car it trickels down back to reading lean.
I appologize for the long post but I am just stumped on what it could be thats wrong. I hope someone can help.
I shifted into 2nd instead of 4th some how at WOT. I drove it for about 12 miles before working on it. I then did a compression test on ALL cylinders to find out which cylinder got the treat. Every cylinder had about 125-130 psi except for cylinder #4 (passenger side). I also have hardend pushrods so I know its not them and I checked them also.
We pulled the head and replaced the slightly bent intake valve. You couldn't even tell it was bent by looking at it, but there was a nice nick in the piston.
Then we put everything back together.
Note: We didn't touch anything on the driver's side except for plugs and wires when we did the compression check.
I go and start the car and it sounds fine initially, but after a few minutes of idling to get the coolant flowing, it started idling rough and I got an SES light again.
I drove it and it ran like crap for about 5-10 minutes, misfiring a little. After that time it cleared up and ran smooth.
After the car cools off a bit from driving it acts the same when you start it up, misfiring a little and just running like crap for about a minute.
I then had a friend hook my car up to his HP Tuners software. It read that I was running very rich on the driver's side bank and that the passenger side was fine. Note: Driver's side had nothing wrong with it and we didn't mess with anything besides plugs and wires.
The software also showed that I was getting extra unmetered air on the driver's side bank. So odd since the compression check showed that we were fine and there wasn't anything wrong there.
We later figured that it could have been the intake that had a leak. My car has 114k miles on it and the gaskets for the runners are very flat and worn. I messed with the intake, no luck. I then bought a relatively new LS6 intake, still no luck fixing this problem. I made sure I didn't have any exhaust leaks at the header collectors and replaced my 02 sensors with new Bosch 02 sensors.
Having the new 02 sensors helped out a bit, but the car still runs a little off.
While driving I have this wierd ticking like sound coming from the engine that sounds like an exhaust leak but its not.
So we come down to this: I fixed the initial problem, and replaced parts that could have been causing my car to run horribly. With my new 02 sensors my Air/fuel gauge reads that I am very lean (on the driver's side because thats where the 02 sensor is that the gauge is hooked up to). If I run the car kinda hard, like up to 4k or so my air/fuel ratio gets up to the stoich area which is nicer than running lean, but after I lay off of running the car it trickels down back to reading lean.
I appologize for the long post but I am just stumped on what it could be thats wrong. I hope someone can help.
07-22-2006, 03:22 PM
#2
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I have this same problem and it has been troubling me forever. When I got mine dyno tuned it fixed the problem completely. Every time I started it up it ran fine. Then a month later, it started doing it again. I would start the car at a cold start and it ran like **** until it warmed up.
It has to do with the engine cycles. There is either a bad sensor or something that is causing it to do that.
It has to do with the engine cycles. There is either a bad sensor or something that is causing it to do that.
07-23-2006, 01:46 AM
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It didn't really occur to me after this post, but after I put my engine back together I remember some vacuum lines being cracked off so I just took them off. I recently bought some new ones from GM (about $10) and put them back on. It was the line from the back of the intake. I haven't had a problem at all.
I suggest checking for any sign of vacuum leaks and double-checking your work.
I suggest checking for any sign of vacuum leaks and double-checking your work.
07-23-2006, 02:32 PM
#6
The car isn't idling high or sparatically like it would with a vacuum leak so its probably not that , but i'll look into it.
I wonder if one bad injector on the driver's side could make it read as if there is too much air and then in turn adding extra fuel from the other three injectors to cause the whole bank to be reading as rich?
I wonder if one bad injector on the driver's side could make it read as if there is too much air and then in turn adding extra fuel from the other three injectors to cause the whole bank to be reading as rich?
