Can a datalog fry the ecm?
01-27-2009, 11:34 AM
#1
Melting Slicks
Thread Starter
Can a datalog fry the ecm?
Just curious, I was trying to datalog with my laptop, usb/adl cable and tuner pro and my car was running "ok" at the time.
When it died during the datalog, it won't start up now It'll turn over but never actually fire up.
I've went through and checked every possible cause of not firing up at least twice (timing, fuel pressure, plugs, wires,) Everything looks ok.
Before someone says check the timing, I know 100% I'm at TDC, my plugs are new, wires are in the correct firing order....so it should fire up technically. I used a spark plug firing checker and I'm getting spark.
I just didn't want to rule datalog out as a possibility since it was running prior to dataloging. Can this process damage the ecm or has anyone ever heard of this happening.
Also, if the ecm is bad would the car still start?
It's a 1982 with a 1991 speed density TPI swap. 7730 ecm.
Thanks!
When it died during the datalog, it won't start up now It'll turn over but never actually fire up.
I've went through and checked every possible cause of not firing up at least twice (timing, fuel pressure, plugs, wires,) Everything looks ok.
Before someone says check the timing, I know 100% I'm at TDC, my plugs are new, wires are in the correct firing order....so it should fire up technically. I used a spark plug firing checker and I'm getting spark.
I just didn't want to rule datalog out as a possibility since it was running prior to dataloging. Can this process damage the ecm or has anyone ever heard of this happening.
Also, if the ecm is bad would the car still start?
It's a 1982 with a 1991 speed density TPI swap. 7730 ecm.
Thanks!
02-20-2009, 01:24 AM
#2
Any luck getting the car running again? I know with an LT1 computer, you can have some gremlins ruin your day if you're trying to upload a new program and something interupts the process - like the computer battery dying. I'm not sure if the TPI would do the same, since it has a chip with the program embedded.
I'm gathering parts for my own speed density TPI install so I'm quite interested in your outcome.
I'm gathering parts for my own speed density TPI install so I'm quite interested in your outcome.
02-20-2009, 06:24 AM
#3
Melting Slicks
Thread Starter
nope, I'm real close to pulling the TPI back off it and putting a carb back on it. I tried a different ECM just to be sure that's not the problem.
If your going to do a TPI swap I HIGHLY recommended getting a complete running engine / transmission out of a donor car. Don't piece one together like I did.
When the weather get's nice I may play with it some more. It may give me the incentive to work on it.
If your going to do a TPI swap I HIGHLY recommended getting a complete running engine / transmission out of a donor car. Don't piece one together like I did.
When the weather get's nice I may play with it some more. It may give me the incentive to work on it.
02-20-2009, 01:51 PM
#5
Team Owner
Spark, air and fuel is necessary to work. You have spark and air. What about fuel? Yes, you say you have fuel pressure. So we know the pump is pressurizing. What about the fuel injector fuses? Are those good? Is the injector getting pulses? I mean, just because the ECM is sending it doesn't mean it is firing at the injector.
02-20-2009, 01:54 PM
#6
I won't say it's not possible, but not very likely.
You should be able to start the data log with just the key on and the engine not running. If your software won't talk to the ECM there, then you have a potential ECM problem. If it talks to the ECM and you can see everything like it should, I would say start somewhere else.
Just my opinion, but you REALLY don't want to deal with a carb. You might get it running faster, but you lose all the benefits of what the computer can do for you.
You should be able to start the data log with just the key on and the engine not running. If your software won't talk to the ECM there, then you have a potential ECM problem. If it talks to the ECM and you can see everything like it should, I would say start somewhere else.
Just my opinion, but you REALLY don't want to deal with a carb. You might get it running faster, but you lose all the benefits of what the computer can do for you.
02-20-2009, 01:54 PM
#7
Melting Slicks
Thread Starter
Yeah I thought about that, I sprayed some starting fluid in the throttle body and it tried to run for a second.
I don't really have injector fuses because it's a custom harness, the only fuse I have is the fuel pump.
I can use a test light to test the injectors to see if they are firing correct?
Thanks again
I don't really have injector fuses because it's a custom harness, the only fuse I have is the fuel pump.
I can use a test light to test the injectors to see if they are firing correct?
Thanks again
02-20-2009, 02:03 PM
#8
Hmm... I had a very similar issue with my IAC got out of adjustment. Again, check to make sure the data log is working with just the key on. If it is, see what the IAC position is supposed to be. Then you should be able to disconnect the IAC, wait about 30 seconds, and then start the car. It'll probably idle really high or really low, you might have to play with the throttle to keep it running. As the car warms up it should idle down and take less throttle to keep it running. Once it'll run on it's own, while it's running, reconnect the IAC and see what happens. If everything is working properly it should idle down to normal and you can watch the IAC position on the data log. If the IAC position on the data log never moves, or the IAC is bad nothing will happen, etc.
02-20-2009, 02:06 PM
#9
Melting Slicks
Thread Starter
I didn't think about the IAC, I had it unhook for a second and didn't realize it....if I'm not mistaken about the time it quit running.
I'll look at that here in a second.
Thanks again
I'll look at that here in a second.
Thanks again
02-20-2009, 02:08 PM
#10
Here's what I ran into
My saga continues on day 2. I went right on out to the car this morning and was going to take it for a spin to see how everything was working. The car ALWAYS fires right up when it's running right. Ah, but I had disconnected and removed the IAC, how I had forgotten the joys of that.
I tried and tried but could not get the car to start. It would crank over all day long and wouldn't fire. I knew the IAC had to be the problem, even if one or two spark plugs were disconnected it would start. I tried until I sucked the bottom out of the battery. I tossed the charger on it, came inside and started looking for the IAC relearn procedure. All I could really find was for TPI cars so I improvised. I disconnected the IAC, waited 30 seconds, and tried it. The car fired right up instantly, but wanted to idle really high. I let it run this way for a few seconds and reconnected my IAC, it immediately walked itself down to it's proper steady idle. Great, fixed.... or so I thought.
I backed the car out of the garage and drove it down the street. I finally got to a straight road so I could get on it a little bit and see how the plugs were working. I waited till it was completely clear then I carefully eased out onto the road, got it good and straight and hammered on it. The car took off to about 4000 RPM then started to stumble then the tach fell to 0 and it completely died. Hmm, obviously that's not right. I drifted to a free spot on the side of the road. I tried the key and it started right up and idled fine. I got back on the road and tried to give it some throttle, a little more gently this time. It would drive fine at low RPM but as soon as I would try to really get on it or load it pretty heavy, it would start acting up. When I got to the first traffic light I came to a stop and the idle settled out at 2000 RPM. Now as nice as this might be for helping to charge up the battery, it's obviously not right.
I drove the car through town. As soon as I was moving I could get it to go below 2000 RPM, but press the clutch and right back up it went. I figured that the IAC was either damaged or malfunctioning so I limped it over to where my friend works where he has a tech 2. I got over there and shut it off. I told him what was going on and asked him if his tech 2 had a relearn procedure. He said it might and was willing to try it. He walked out, hooked up his tech 2, turned the key and it started instantly, and settled right down to it's normal 650-750 idle.
Since he already had it hooked up he went through the menus on the tech 2 and found the IAC relearn command. He hit that and it cycled the IAC and it reved up and fell back down just exactly as it was supposed to. Not knowing what else to do but drive it again I thanked him and went about my way. I drove the car through town and it was fine. I finally cleared all the traffic lights and got to a place where I could lay on it again, everything worked perfectly. I'm looking for a particular grocery item so I stopped at no fewer than 4 grocery stores on the way home and it behaved fine all the way home. She'll break the tires loose anywhere I want to in second gear and never misses a lick.
I brought it back home and put it back in the garage. I know alternators aren't meant to charge a dead battery, they can never really completely charge a battery. Even though I didn't have any more trouble with it, I put the charger back on it for a trickle charge that I'll probably leave on all night.
Maybe, finally, everything is working correctly again. Why isn't anything ever easy?
I tried and tried but could not get the car to start. It would crank over all day long and wouldn't fire. I knew the IAC had to be the problem, even if one or two spark plugs were disconnected it would start. I tried until I sucked the bottom out of the battery. I tossed the charger on it, came inside and started looking for the IAC relearn procedure. All I could really find was for TPI cars so I improvised. I disconnected the IAC, waited 30 seconds, and tried it. The car fired right up instantly, but wanted to idle really high. I let it run this way for a few seconds and reconnected my IAC, it immediately walked itself down to it's proper steady idle. Great, fixed.... or so I thought.
I backed the car out of the garage and drove it down the street. I finally got to a straight road so I could get on it a little bit and see how the plugs were working. I waited till it was completely clear then I carefully eased out onto the road, got it good and straight and hammered on it. The car took off to about 4000 RPM then started to stumble then the tach fell to 0 and it completely died. Hmm, obviously that's not right. I drifted to a free spot on the side of the road. I tried the key and it started right up and idled fine. I got back on the road and tried to give it some throttle, a little more gently this time. It would drive fine at low RPM but as soon as I would try to really get on it or load it pretty heavy, it would start acting up. When I got to the first traffic light I came to a stop and the idle settled out at 2000 RPM. Now as nice as this might be for helping to charge up the battery, it's obviously not right.
I drove the car through town. As soon as I was moving I could get it to go below 2000 RPM, but press the clutch and right back up it went. I figured that the IAC was either damaged or malfunctioning so I limped it over to where my friend works where he has a tech 2. I got over there and shut it off. I told him what was going on and asked him if his tech 2 had a relearn procedure. He said it might and was willing to try it. He walked out, hooked up his tech 2, turned the key and it started instantly, and settled right down to it's normal 650-750 idle.
Since he already had it hooked up he went through the menus on the tech 2 and found the IAC relearn command. He hit that and it cycled the IAC and it reved up and fell back down just exactly as it was supposed to. Not knowing what else to do but drive it again I thanked him and went about my way. I drove the car through town and it was fine. I finally cleared all the traffic lights and got to a place where I could lay on it again, everything worked perfectly. I'm looking for a particular grocery item so I stopped at no fewer than 4 grocery stores on the way home and it behaved fine all the way home. She'll break the tires loose anywhere I want to in second gear and never misses a lick.
I brought it back home and put it back in the garage. I know alternators aren't meant to charge a dead battery, they can never really completely charge a battery. Even though I didn't have any more trouble with it, I put the charger back on it for a trickle charge that I'll probably leave on all night.
Maybe, finally, everything is working correctly again. Why isn't anything ever easy?
Last edited by Nathan Plemons; 02-20-2009 at 02:11 PM.