Need Help in diagnosis!
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Joined: Jul 2000
Posts: 590
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From: Suffolk New York
Need Help in diagnosis!
There I was, driving along thinking, my car is 10 years old, I should trade up to a newer Z06 (I think I jixed myself and insulted my car), but my car is running fine and it looks good, etc. Stopped for gas, usual place, I had 1/4 tank but filled up anyway. 93 Octane Mobil.As I pulled away, the engine didn't feel quite right, didn't acccelerate the way it normally does. Slight bogging, some backfire, just not pronounced but obviously something wrong.
Is it the gas? Is it a misfire?
Pulled absolutey no codes from the DIC, at least none related to the engine.
This morning when the engine was still cold, the engine was quite responsive, like something cleared and she was back to normal! Yeah!
Not Quite! after it warmed up a bit, I got on it to see if she was truly back to normal. It's not. It still bogs and has a slight stumble at idle with some back fire. Dirty plugs?
Any Ideas would be welcomed. TIA
EDIT: I now have some codes:
U1016 Loss of Communication with PCM
U1064 Loss of Communication with BCM
U1096 Loss of Communication with IPC
Last edited by cam99; Jul 2, 2009 at 03:53 PM. Reason: added codes
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You're not giving us much to go on. How many miles on the car, plugs, plug wires, O2 sensors, air filter. Any previous problems?
There I was, driving along thinking, my car is 10 years old, I should trade up to a newer Z06 (I think I jixed myself and insulted my car), but my car is running fine and it looks good, etc. Stopped for gas, usual place, I had 1/4 tank but filled up anyway. 93 Octane Mobil.
As I pulled away, the engine didn't feel quite right, didn't acccelerate the way it normally does. Slight bogging, some backfire, just not pronounced but obviously something wrong.
Is it the gas? Is it a misfire?
Pulled absolutey no codes from the DIC, at least none related to the engine.
This morning when the engine was still cold, the engine was quite responsive, like something cleared and she was back to normal! Yeah!
Not Quite! after it warmed up a bit, I got on it to see if she was truly back to normal. It's not. It still bogs and has a slight stumble at idle with some back fire. Dirty plugs?
Any Ideas would be welcomed. TIA
There I was, driving along thinking, my car is 10 years old, I should trade up to a newer Z06 (I think I jixed myself and insulted my car), but my car is running fine and it looks good, etc. Stopped for gas, usual place, I had 1/4 tank but filled up anyway. 93 Octane Mobil.As I pulled away, the engine didn't feel quite right, didn't acccelerate the way it normally does. Slight bogging, some backfire, just not pronounced but obviously something wrong.
Is it the gas? Is it a misfire?
Pulled absolutey no codes from the DIC, at least none related to the engine.
This morning when the engine was still cold, the engine was quite responsive, like something cleared and she was back to normal! Yeah!
Not Quite! after it warmed up a bit, I got on it to see if she was truly back to normal. It's not. It still bogs and has a slight stumble at idle with some back fire. Dirty plugs?
Any Ideas would be welcomed. TIA
Thread Starter
Pro
Joined: Jul 2000
Posts: 590
Likes: 1
From: Suffolk New York
78K on Miles
Taylor Wires
Bosch Platinum +4 Plugs
O2s haven't been changed, at least I don't recall changing them.
I just realized the Wires/plugs were changed, about three years ago. I did have a burnt wire a year ago because of the headers.
I've ordered the GMPP wires and NGK TR55 plugs, whick I'll be changing as soon as they get delivered.
Taylor Wires
Bosch Platinum +4 Plugs
O2s haven't been changed, at least I don't recall changing them.
I just realized the Wires/plugs were changed, about three years ago. I did have a burnt wire a year ago because of the headers.
I've ordered the GMPP wires and NGK TR55 plugs, whick I'll be changing as soon as they get delivered.
Pro
Joined: Mar 2004
Posts: 653
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I've never had good results w/ Bosch Platinum +4 plugs in the L98 or LS1 engine, it's good you're swapping them out. With that said, I'll be surprised if they're the culprit in your case.
Usually a car that runs well cold (PCM in Open Loop mode) and then misbehaves when it's warmed up (PCM in Closed Loop mode) is either a malfunctioning O2 sensor or MAF.
Here's what I would do:
1.) Disconnect the MAF sensor, tie off the harness safely so it doesn't get damaged, and re-test the car.
2.) Inspect your forward O2 sensors' wiring for signs of damage, burns, abrasion.
3.) Replace both forward O2 sensors using Delco replacement pieces.
Let us know what you find.
Usually a car that runs well cold (PCM in Open Loop mode) and then misbehaves when it's warmed up (PCM in Closed Loop mode) is either a malfunctioning O2 sensor or MAF.
Here's what I would do:
1.) Disconnect the MAF sensor, tie off the harness safely so it doesn't get damaged, and re-test the car.
2.) Inspect your forward O2 sensors' wiring for signs of damage, burns, abrasion.
3.) Replace both forward O2 sensors using Delco replacement pieces.
Let us know what you find.
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Thread Starter
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Joined: Jul 2000
Posts: 590
Likes: 1
From: Suffolk New York
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Joined: Mar 2004
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I used Radio Shack electronics cleaner years ago when I got carried away oiling my K&N air filter, and it worked fine as well.
Thread Starter
Pro
Joined: Jul 2000
Posts: 590
Likes: 1
From: Suffolk New York
Thread Starter
Pro
Joined: Jul 2000
Posts: 590
Likes: 1
From: Suffolk New York
I've never had good results w/ Bosch Platinum +4 plugs in the L98 or LS1 engine, it's good you're swapping them out. With that said, I'll be surprised if they're the culprit in your case.
Usually a car that runs well cold (PCM in Open Loop mode) and then misbehaves when it's warmed up (PCM in Closed Loop mode) is either a malfunctioning O2 sensor or MAF.
Here's what I would do:
1.) Disconnect the MAF sensor, tie off the harness safely so it doesn't get damaged, and re-test the car.
2.) Inspect your forward O2 sensors' wiring for signs of damage, burns, abrasion.
3.) Replace both forward O2 sensors using Delco replacement pieces.
Let us know what you find.
Usually a car that runs well cold (PCM in Open Loop mode) and then misbehaves when it's warmed up (PCM in Closed Loop mode) is either a malfunctioning O2 sensor or MAF.
Here's what I would do:
1.) Disconnect the MAF sensor, tie off the harness safely so it doesn't get damaged, and re-test the car.
2.) Inspect your forward O2 sensors' wiring for signs of damage, burns, abrasion.
3.) Replace both forward O2 sensors using Delco replacement pieces.
Let us know what you find.
How long can I drive with the MAF Sensor disconnected? I was thinking of driving about 20 miles like this?
This will keep it in an open loop?
Thread Starter
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Joined: Jul 2000
Posts: 590
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From: Suffolk New York
I got home and then disconnected the MAF, seemed to run better but not back to normal.
Still has some backfiring, but didn't bog when I accelerated.
I did remove the MAF and de-screened it, I also noticed what seemed like dried mud streaks, came off with a rag, could be dried Oil with dirt.
I sprayed the elements and OMG, they were visible cleaned, went from that muddy look to clean shiny electrodes!
I ordered new O2 sensors today, I may need a new MAF? I recall now that my Tuner had to reuse an old MAF because mine wouldn't allow a good tune, but that was three years ago!
Thanks again.
Last edited by cam99; Jun 22, 2009 at 07:03 PM.
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Before you replace the O2 sensors, try running the MAF you just cleaned. As long as the electronic elements aren't damaged they respond nicely to a good cleaning.
At this point it's likely the LTFT stored values are way off, and will clear up with mileage.
You can speed this up by resetting the PCM and clearing the tables, should be a procedure around the site somewhere and involves pulling the PCM fuse for some specified time interval.
After this, OK to swap out the O2 sensors. With 78K miles it's about time anyway. Definitely clear the PCM LTFT tables when the new sensors go in.
At this point it's likely the LTFT stored values are way off, and will clear up with mileage.
You can speed this up by resetting the PCM and clearing the tables, should be a procedure around the site somewhere and involves pulling the PCM fuse for some specified time interval.
After this, OK to swap out the O2 sensors. With 78K miles it's about time anyway. Definitely clear the PCM LTFT tables when the new sensors go in.
Burning Brakes
Joined: May 2008
Posts: 1,147
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From: Mohegan Lake New York
contaminated gas you gas up and imediate prob. let car sit overnite water will settle to bottom of gs tank) disconnect fuel line connect hose into visible container turn key off and on DO NOT START till a pint or two is in container let container sit for 1 hr then examine if h2o present will settle to bottom if so drain tank put in fresh fuel don't waste time w/dry gas thats preventitave not for fixing a tank of contaminated fuel good luck. post what u find
Le Mans Master
Joined: Sep 2003
Posts: 8,847
Likes: 795
From: Longview Texas
If it all started when you bought gas, you may have a slug of water in the tank. Some cars are more sensitive than others. I have had cars that would barely stay running until I poured an additive into the tank to dispurse the moisture.
On most cars there is a schrader valve on the fuel rail where you can cycle the fuel pump and bleed fuel into a bowl to see if there is water in it. If it looks milky, you have enough water it will cause a problem.
On most cars there is a schrader valve on the fuel rail where you can cycle the fuel pump and bleed fuel into a bowl to see if there is water in it. If it looks milky, you have enough water it will cause a problem.
Last edited by TEXHAWK0; Jun 22, 2009 at 07:58 PM.
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Joined: Jul 2000
Posts: 590
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From: Suffolk New York
Update
Not the Gas
Resetting the PCM, didnt help, still bogging on acceleration
Waiting for O2's
Do you think I need a MAF, based on the info above? maybe it's getting lazy?
Not the Gas
Resetting the PCM, didnt help, still bogging on acceleration
Waiting for O2's
Do you think I need a MAF, based on the info above? maybe it's getting lazy?
Last edited by cam99; Jun 24, 2009 at 09:20 AM.
Thread Starter
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Joined: Jul 2000
Posts: 590
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From: Suffolk New York
By resetting the PCM did I wipe out my Tune? Do I need to go back to my Tuner?
Last edited by cam99; Jun 27, 2009 at 11:35 AM.