which code to start with
08-29-2013, 09:38 PM
#1
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which code to start with
i have a 1990 corvette L98, the car will start up and run. after about 15-30 minutes idling it will shut off. if i give it gas it will stay running, as soon as i take my foot of the pedal, it will die out. if i try starting the car right after it dies it wont start. if i let it sit for 5min it will start up and run. after another 15-30 minutes it will die again. so far i have cleaned the throttle body and replaced the tps, iac, the ignition module and the ect that controls the computer. i have checked the fuel pump, it works. ive checked the fuel filter, its clean. ive also checked the fuel pressure regulator, it seems to be working.
i scanned the ecm today and recieved these codes:
13....O2 sensor left side
15....coolant signal voltage high
23....Mat sensor temp low
45....rich exhaust left side
46.... vats error
Finally
51....mem cal error
i know why i have the O2 codes, the idiot i bought the car from disconnected/broke the O2 sensor off. so there is a plug where the left O2 is supposed to be.
also i ohemed out the injectors and these readings.
6 injectors are reading 16.8 ohms when cold and hot
1 injector is reading 14.0 ohms when cold and 12 ohms when hot
1 injector is reading 15.8 ohms when cod and 14 ohms when hot
should i change those two injectors
this car is driving me crazy
any help wil be greatly appreciated.
i scanned the ecm today and recieved these codes:
13....O2 sensor left side
15....coolant signal voltage high
23....Mat sensor temp low
45....rich exhaust left side
46.... vats error
Finally
51....mem cal error
i know why i have the O2 codes, the idiot i bought the car from disconnected/broke the O2 sensor off. so there is a plug where the left O2 is supposed to be.
also i ohemed out the injectors and these readings.
6 injectors are reading 16.8 ohms when cold and hot
1 injector is reading 14.0 ohms when cold and 12 ohms when hot
1 injector is reading 15.8 ohms when cod and 14 ohms when hot
should i change those two injectors
this car is driving me crazy
any help wil be greatly appreciated.
08-29-2013, 09:52 PM
#2
You cannot expect to get ANY good data or info without working O2 sensors.
The O2 sensors are what the ECM bases most of its fuel decisions on...
Fix THAT 1st.
Next and just as important, its time for injectors. Like it or not, yours are borderline and they are definitely ANTIQUES.
Injectors from 1990 were never intended to be soaked in a solvent like alcohol. the inner seats/seals dry up from the alcohols and the inj starts to spray wet gas instead of an atomized 'fog' as it should. Wet gas does not burn well and coupled with a dead o2 sensor that easily explains the rich code...
new inj from FIC cost about $250 and come with all the O-rings and runner gaskets. Yes, you need to do the rails too, since the alcohol hardens those O-rings and makes them want to leak after you handle the rails swapping injectors.
Good luck, its not a hard job.
The O2 sensors are what the ECM bases most of its fuel decisions on...
Fix THAT 1st.
Next and just as important, its time for injectors. Like it or not, yours are borderline and they are definitely ANTIQUES.
Injectors from 1990 were never intended to be soaked in a solvent like alcohol. the inner seats/seals dry up from the alcohols and the inj starts to spray wet gas instead of an atomized 'fog' as it should. Wet gas does not burn well and coupled with a dead o2 sensor that easily explains the rich code...
new inj from FIC cost about $250 and come with all the O-rings and runner gaskets. Yes, you need to do the rails too, since the alcohol hardens those O-rings and makes them want to leak after you handle the rails swapping injectors.
Good luck, its not a hard job.
08-29-2013, 10:39 PM
#3
If you have the 51 , usually the radiator fans will run as soon as you turn the key on ????
because engine will be in LIMP HOME mode which you may well be given how the engine is running
Usually cause by the memcal ( chip ) in the computer no being seated correctly
If you had a VATS fault the engine would not start at all because VATS takes out the fuel injectors while cranking over
Biggest priority after fixing the injectors would be to sort the DTC 15.
If the wrong temp indication is being sent to the ECM then it throws everything out.
Engine will happily run with no O2 input ( just stays in open loop ) but a bad/ wrong / no temp input affects everything
You might consider reviewing the diagnostic charts in the FSM as how to identify and fix a fault
http://www.chevythunder.com/cts_diagnostics.htm
http://www.chevythunder.com/cts_diagnostic_pg2.htm
because engine will be in LIMP HOME mode which you may well be given how the engine is running
Usually cause by the memcal ( chip ) in the computer no being seated correctly
If you had a VATS fault the engine would not start at all because VATS takes out the fuel injectors while cranking over
Biggest priority after fixing the injectors would be to sort the DTC 15.
If the wrong temp indication is being sent to the ECM then it throws everything out.
Engine will happily run with no O2 input ( just stays in open loop ) but a bad/ wrong / no temp input affects everything
You might consider reviewing the diagnostic charts in the FSM as how to identify and fix a fault
http://www.chevythunder.com/cts_diagnostics.htm
http://www.chevythunder.com/cts_diagnostic_pg2.htm
08-30-2013, 08:10 AM
#5
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You cannot expect to get ANY good data or info without working O2 sensors.
The O2 sensors are what the ECM bases most of its fuel decisions on...
Fix THAT 1st.
Next and just as important, its time for injectors. Like it or not, yours are borderline and they are definitely ANTIQUES.
Injectors from 1990 were never intended to be soaked in a solvent like alcohol. the inner seats/seals dry up from the alcohols and the inj starts to spray wet gas instead of an atomized 'fog' as it should. Wet gas does not burn well and coupled with a dead o2 sensor that easily explains the rich code...
new inj from FIC cost about $250 and come with all the O-rings and runner gaskets. Yes, you need to do the rails too, since the alcohol hardens those O-rings and makes them want to leak after you handle the rails swapping injectors.
Good luck, its not a hard job.
The O2 sensors are what the ECM bases most of its fuel decisions on...
Fix THAT 1st.
Next and just as important, its time for injectors. Like it or not, yours are borderline and they are definitely ANTIQUES.
Injectors from 1990 were never intended to be soaked in a solvent like alcohol. the inner seats/seals dry up from the alcohols and the inj starts to spray wet gas instead of an atomized 'fog' as it should. Wet gas does not burn well and coupled with a dead o2 sensor that easily explains the rich code...
new inj from FIC cost about $250 and come with all the O-rings and runner gaskets. Yes, you need to do the rails too, since the alcohol hardens those O-rings and makes them want to leak after you handle the rails swapping injectors.
Good luck, its not a hard job.
The previous owner said he changed the Injectors already. So those aren't the originals
08-30-2013, 08:14 AM
#6
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Member Since: Mar 2013
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If you have the 51 , usually the radiator fans will run as soon as you turn the key on ????
because engine will be in LIMP HOME mode which you may well be given how the engine is running
Usually cause by the memcal ( chip ) in the computer no being seated correctly
If you had a VATS fault the engine would not start at all because VATS takes out the fuel injectors while cranking over
Biggest priority after fixing the injectors would be to sort the DTC 15.
If the wrong temp indication is being sent to the ECM then it throws everything out.
Engine will happily run with no O2 input ( just stays in open loop ) but a bad/ wrong / no temp input affects everything
You might consider reviewing the diagnostic charts in the FSM as how to identify and fix a fault
http://www.chevythunder.com/cts_diagnostics.htm
http://www.chevythunder.com/cts_diagnostic_pg2.htm
because engine will be in LIMP HOME mode which you may well be given how the engine is running
Usually cause by the memcal ( chip ) in the computer no being seated correctly
If you had a VATS fault the engine would not start at all because VATS takes out the fuel injectors while cranking over
Biggest priority after fixing the injectors would be to sort the DTC 15.
If the wrong temp indication is being sent to the ECM then it throws everything out.
Engine will happily run with no O2 input ( just stays in open loop ) but a bad/ wrong / no temp input affects everything
You might consider reviewing the diagnostic charts in the FSM as how to identify and fix a fault
http://www.chevythunder.com/cts_diagnostics.htm
http://www.chevythunder.com/cts_diagnostic_pg2.htm
08-31-2013, 03:52 PM
#7
Instructor
Thread Starter
Member Since: Mar 2013
Posts: 139
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If you have the 51 , usually the radiator fans will run as soon as you turn the key on ????
because engine will be in LIMP HOME mode which you may well be given how the engine is running
Usually cause by the memcal ( chip ) in the computer no being seated correctly
If you had a VATS fault the engine would not start at all because VATS takes out the fuel injectors while cranking over
Biggest priority after fixing the injectors would be to sort the DTC 15.
If the wrong temp indication is being sent to the ECM then it throws everything out.
Engine will happily run with no O2 input ( just stays in open loop ) but a bad/ wrong / no temp input affects everything
You might consider reviewing the diagnostic charts in the FSM as how to identify and fix a fault
http://www.chevythunder.com/cts_diagnostics.htm
http://www.chevythunder.com/cts_diagnostic_pg2.htm
because engine will be in LIMP HOME mode which you may well be given how the engine is running
Usually cause by the memcal ( chip ) in the computer no being seated correctly
If you had a VATS fault the engine would not start at all because VATS takes out the fuel injectors while cranking over
Biggest priority after fixing the injectors would be to sort the DTC 15.
If the wrong temp indication is being sent to the ECM then it throws everything out.
Engine will happily run with no O2 input ( just stays in open loop ) but a bad/ wrong / no temp input affects everything
You might consider reviewing the diagnostic charts in the FSM as how to identify and fix a fault
http://www.chevythunder.com/cts_diagnostics.htm
http://www.chevythunder.com/cts_diagnostic_pg2.htm