The Miss Is Back
Thread Starter
Instructor
Joined: Mar 2007
Posts: 117
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From: San Luis Obispo California
The Miss Is Back
I posted a thread about a week ago that my car was running bad, but then it went away the next day. The car did it again tonight, but this time, threw a trouble code. It did it after riding the clutch at moderate to high RPM (3200). Tonight, the miss was MUCH worse. There was obvious resonance and power loss, low idle, and the car died once at a stoplight. When I got the car home, I shut it off in the driveway, and grabbed my code reader. Much to my dismay, it started throwing a code 12, the system pass code. Then it threw a few code 42's, an EST problem, and then it just went back to the code 12. When I started it up to pull it back into my garage, there was NO MISS. Any ideas?!? I'm used to working on simple pickups...this corvette is my baby but she's driving me nuts.
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Did you recently set timing? Unplug the EST wire and start the car again. See if the problem goes away. Try it both ways. Restart the car each time you disconnect, reconnect.
Last edited by 86PACER; Sep 3, 2007 at 03:16 AM.
Thread Starter
Instructor
Joined: Mar 2007
Posts: 117
Likes: 0
From: San Luis Obispo California
http://forums.corvetteforum.com/show....php?t=1795763
this is for the post after the car started missing for the first time.
this is for the post after the car started missing for the first time.
Thread Starter
Instructor
Joined: Mar 2007
Posts: 117
Likes: 0
From: San Luis Obispo California
Okay, so I unplugged the EST wire, and it didn't make the miss any better. The miss usually happens when the car is warm, but sometimes it goes away in a moment's notice. I pulled codes once again and got a 12 (pass code) 42, and 43. These again point to the EST. I checked the basline mechanical timing, and it was 3 degrees before top dead center, where the baseline is 6 degrees, correct? I don't think this is large enough to cause any serious problems. I decided against messing with the mechanical timing until I figure out what's causing the miss.
I'll try checking the injectors, but I definately DO NOT think that the injectors are causing the problem, but it sounds easy enough to check. The injectors are a little bigger than stock, and I'd be going with Accel injectors if I was to change them.
I'll try checking the injectors, but I definately DO NOT think that the injectors are causing the problem, but it sounds easy enough to check. The injectors are a little bigger than stock, and I'd be going with Accel injectors if I was to change them.
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Code 42 came from you and the mechanic unplugging EST to set timing, which is totally normal. When you unplugged it and nothing changed, that ruled out EST.
Code 43 is the ESC (not to be confused with EST) circuit.
Try this next. Unplug the ESC Module that is on the passenger side near the blower motor. It's a black square thing. It's mounted right above the passenger side gill panel sticking right up. Run the car with it unplugged and see if anything changes.
Report back.
Are you saying you did a physical TDC and then found that your damper is 3 degrees off? At physical TDC, the line on the damper should be in the center of the deep notch ( 6 degree mark) on timing tab. If it's not, there is damper slippage. You need to either remove the driver's valve cover to see the #1 cylinder valves, or use a piston stop to know for sure. You can't go by your dist because it might not be correct itself.
But 3 degrees should not be causing an issue. A lot of guys are running that or more in extra advance. If unplugging the ESC module fails, reset your timing back or forth those 3 degrees, wich ever the case is, to compensate and see how it runs.
Code 43 is the ESC (not to be confused with EST) circuit.
Try this next. Unplug the ESC Module that is on the passenger side near the blower motor. It's a black square thing. It's mounted right above the passenger side gill panel sticking right up. Run the car with it unplugged and see if anything changes.
Report back.
Are you saying you did a physical TDC and then found that your damper is 3 degrees off? At physical TDC, the line on the damper should be in the center of the deep notch ( 6 degree mark) on timing tab. If it's not, there is damper slippage. You need to either remove the driver's valve cover to see the #1 cylinder valves, or use a piston stop to know for sure. You can't go by your dist because it might not be correct itself.
But 3 degrees should not be causing an issue. A lot of guys are running that or more in extra advance. If unplugging the ESC module fails, reset your timing back or forth those 3 degrees, wich ever the case is, to compensate and see how it runs.
Last edited by 86PACER; Sep 5, 2007 at 12:46 AM.
Thread Starter
Instructor
Joined: Mar 2007
Posts: 117
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From: San Luis Obispo California
I didn't actually go and find TDC, I just went with the existing timing mark on the harmonic balancer.
It did give the code 42, even with the EST plugged in. It gave both codes when the EST was plugged in AND when it was not. So I'm thinking there might be issues with both, but I'll try disconnecting the ESC next time the car acts up.
I have a compression tester somewhere, and I can find TDC with that correct? By figuring out what maximum compression is in the first cylinder, and then stopping the motor at that spike, correct?
It did give the code 42, even with the EST plugged in. It gave both codes when the EST was plugged in AND when it was not. So I'm thinking there might be issues with both, but I'll try disconnecting the ESC next time the car acts up.
I have a compression tester somewhere, and I can find TDC with that correct? By figuring out what maximum compression is in the first cylinder, and then stopping the motor at that spike, correct?
Thread Starter
Instructor
Joined: Mar 2007
Posts: 117
Likes: 0
From: San Luis Obispo California
Code 43 is also the Knock Sensor, correct? Because my knock sensor harness is pretty beat up at best. I noticed it when I changed my starter on Sunday. (The miss problem has been around long before I changed the starter, however)
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Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Code 42 will remain even after you reconnect EST. The battery needs to be disconnected for about 10 to erase.
Code 43 is ESC which also contains the knock sensor.