GST with PSI
DSM Wiseman
- 2,758
- 1,664
- Jul 27, 2005
-
San Diego,
California
I have experienced 2 bad ECU's in the past month, and have learned a lot about some of the symptoms. Here are some of my experiences and also some of the things you may be experiencing if your ECU has gone south.
The first symptom I experienced was an extended crank. If your noticing you car takes longer to start in normal weather conditions, but still runs the same on the street, your ECU may be on It's last leg.
My car then would crank without starting. I would let it sit for a while (30 min?) and then it would start again. There was no rhyme or reason to it, just hit or miss. It probably did this on and off for a week before it got worse.
If things progress as they did for me, your car will begin die sporadically. No sputtering or driveability problems, just out of nowhere, die. It may restart or may not, it just depends.
Sooner or later the car will not start. It will crank and make some sad attempts to fire but will never get close to starting. If this happens you will probably smell fuel (strong). Check the tail pipe also. You may see puffs of white/grey smoke that also smells strongly of raw fuel. If this happens stop waisting your time cranking, your ECU is probably bad.
It's possible your car may skip all of the steps described above. The car my just Begin to run very very badly. The only way you may be able to start it is with the pedal at WOT during startup. After the car starts it probably will not idle on it's own. The only way you may be able to keep it running is to use throttle inputs. On a logger, timing will never settle and will be jumping all over. You will smell fuel as the car runs, and the tail pipe will likely emit black or grey smoke which will also smell like fuel.
Here are some things you can check with a logger if you have one:
If the car is running very poorly, first check your baro reading. With the key off, plug in the logger. Cycle the key on and check you baro reading, then start the car. The ECU should take a reading and hold it pretty much steady until the car is shut off (you should see a graphed straight line). If your baro reading looks like a crack attic's heart rate, your ECU probably isn't any good.
If your car is doing the sporadic dying, plug in your data logger and select some simple things to monitor (batt voltage, timing, temp, etc.). Start the car and check to see if your logger is reading normal. Let the car idle until it dies, but keep an eye on the logger. When the car dies, your readings will likely freeze. It won't matter if you turn the key off, on, or try to crank the car, your logger will be frozen. When this happens just wait. If you keep an eye on the logger, it may unfreeze. When the logger unfreezes, start the car. It probably will start and run normally until the computer freezes again. This is a sign your capacitors have probably leaked causing damage to the ECU.
Some things I've discovered don't really matter:
-I opened my ECU a 2 years before it died and examined the circuit board. I saw signs of leaking capacitors. Just because they are leaking doesn't condemn your ECU. Yeah, it's years are numbered after the caps leak, but don't fret about it.
-My ECU smelled like roses until the day it died. Bad ECU's don't necessarily smell.
-A bad ECU my operate perfectly off and on. Bad does not act bad in this case. Intermittent operation may occur.
-Got spark? Bad ECU's normally do. In my experience, a bad ECU usually effects fuel delivery and timing functions. Almost always the vehicle will exhibit flooding and poor run ability. If these are two of your symptoms, quit trying to ohm out the coil pack. You may want to start your diagnosis with the ECU.
Some things that do:
-Using a logger is the easiest way to diagnose a bad ECU. A logger is just a readout of what you ECU is thinking/doing. If it's not reading, you ECU isn't thinking/doing.
-A bad ECU may be ably to poorly run the car, but fouled plugs can't. When the ECU starts to go, it normally fuel fouls the spark plugs. Pull and clean the plugs, and then see if the car will start. you may get it to start once running really badly after cleaning the plugs, but not afterward. This may help you rule out factors before blaming the ECU. If this is the case however it's likely your ECU is to blame.
-If your car hasn't started after 30 seconds of cranking, IT'S NOT GOING TO. Last time I checked ECU's didn't come complete with a starter motor/solenoid included . Just a thoughtful hint for those of you who get frustrated easily (for my brother).
Anything to add anyone?
The first symptom I experienced was an extended crank. If your noticing you car takes longer to start in normal weather conditions, but still runs the same on the street, your ECU may be on It's last leg.
My car then would crank without starting. I would let it sit for a while (30 min?) and then it would start again. There was no rhyme or reason to it, just hit or miss. It probably did this on and off for a week before it got worse.
If things progress as they did for me, your car will begin die sporadically. No sputtering or driveability problems, just out of nowhere, die. It may restart or may not, it just depends.
Sooner or later the car will not start. It will crank and make some sad attempts to fire but will never get close to starting. If this happens you will probably smell fuel (strong). Check the tail pipe also. You may see puffs of white/grey smoke that also smells strongly of raw fuel. If this happens stop waisting your time cranking, your ECU is probably bad.
It's possible your car may skip all of the steps described above. The car my just Begin to run very very badly. The only way you may be able to start it is with the pedal at WOT during startup. After the car starts it probably will not idle on it's own. The only way you may be able to keep it running is to use throttle inputs. On a logger, timing will never settle and will be jumping all over. You will smell fuel as the car runs, and the tail pipe will likely emit black or grey smoke which will also smell like fuel.
Here are some things you can check with a logger if you have one:
If the car is running very poorly, first check your baro reading. With the key off, plug in the logger. Cycle the key on and check you baro reading, then start the car. The ECU should take a reading and hold it pretty much steady until the car is shut off (you should see a graphed straight line). If your baro reading looks like a crack attic's heart rate, your ECU probably isn't any good.
If your car is doing the sporadic dying, plug in your data logger and select some simple things to monitor (batt voltage, timing, temp, etc.). Start the car and check to see if your logger is reading normal. Let the car idle until it dies, but keep an eye on the logger. When the car dies, your readings will likely freeze. It won't matter if you turn the key off, on, or try to crank the car, your logger will be frozen. When this happens just wait. If you keep an eye on the logger, it may unfreeze. When the logger unfreezes, start the car. It probably will start and run normally until the computer freezes again. This is a sign your capacitors have probably leaked causing damage to the ECU.
Some things I've discovered don't really matter:
-I opened my ECU a 2 years before it died and examined the circuit board. I saw signs of leaking capacitors. Just because they are leaking doesn't condemn your ECU. Yeah, it's years are numbered after the caps leak, but don't fret about it.
-My ECU smelled like roses until the day it died. Bad ECU's don't necessarily smell.
-A bad ECU my operate perfectly off and on. Bad does not act bad in this case. Intermittent operation may occur.
-Got spark? Bad ECU's normally do. In my experience, a bad ECU usually effects fuel delivery and timing functions. Almost always the vehicle will exhibit flooding and poor run ability. If these are two of your symptoms, quit trying to ohm out the coil pack. You may want to start your diagnosis with the ECU.
Some things that do:
-Using a logger is the easiest way to diagnose a bad ECU. A logger is just a readout of what you ECU is thinking/doing. If it's not reading, you ECU isn't thinking/doing.
-A bad ECU may be ably to poorly run the car, but fouled plugs can't. When the ECU starts to go, it normally fuel fouls the spark plugs. Pull and clean the plugs, and then see if the car will start. you may get it to start once running really badly after cleaning the plugs, but not afterward. This may help you rule out factors before blaming the ECU. If this is the case however it's likely your ECU is to blame.
-If your car hasn't started after 30 seconds of cranking, IT'S NOT GOING TO. Last time I checked ECU's didn't come complete with a starter motor/solenoid included . Just a thoughtful hint for those of you who get frustrated easily (for my brother).
Anything to add anyone?
