Car only fails to start after writing
12-30-2016, 10:48 AM
#1
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Car only fails to start after writing So, like the title says, having a rather strange issue. I couldn't find it in search, but it's a weird thing to search for anyway:
It started after a heavy rain, and I think the ECU got wet. It simply would not start. The starter would turn, engine would catch, stumble and die. I pushed it into the garage, disconnected the battery, and put a light bulb over the ECU all day to dry connectors out. When I got home from work, I fired it right up, and all good.
Now, I swapped out the intake for dyno comparison (stay tuned - har har), and it started up and ran fine. I logged all my fueling stuff to see where changes would be needed. Made some edits to VE table in a parking lot. Wrote the tune, and it starts, "idles" (if you can call it that) for about ten seconds at 300-400 and dies. If I even touch the throttle, it immediately cuts fuel and dies. So, I thought "bad write", so I re-wrote, same issue. So, I re-wrote the prior tune, same issue. After about 20 start attempts, it finally caught itself and idled. Once it did that, everything worked just like it should - i.e. throttle did not autocut fuel. In hind sight, this is exactly what it did that morning I ended up pushing it into the garage...
So, I drive the car home. Drives absolutely perfectly. I back into the garage, shut the car down. Start it right back up to test it, and it fires up beautifully - text book start. So, I re-wrote the tune to the car again with zero changes. And it did the same thing it did in the parking lot. A ton of restart attempts later, and it started fine.
I have since repeated this several times. As long as I DON'T write a tune, it restarts fine - even a day later and dead cold. Once I write a tune, it is hell to restart.
During all this, the only thing I got was a "PENDING" cpk - i didn't notice if it was 1335 or 1336. When I got that code, I had no RPM signal on the tach. It sat at zero while it was "idling" at 300 rpm. I deleted the code in the scanner, and next start attempt, Tach was working properly but still only stumbled and died. Disconnected battery, reconnected, and it fired up on the third attempt and idled.
So, I guess I'm looking at two possibilities - Crank Position Sensor is flaking out or the ECU went bad. Has anyone even heard of this before? I guess a third possibility is a corrupt tune, but how do I fix that?
It started after a heavy rain, and I think the ECU got wet. It simply would not start. The starter would turn, engine would catch, stumble and die. I pushed it into the garage, disconnected the battery, and put a light bulb over the ECU all day to dry connectors out. When I got home from work, I fired it right up, and all good.
Now, I swapped out the intake for dyno comparison (stay tuned - har har), and it started up and ran fine. I logged all my fueling stuff to see where changes would be needed. Made some edits to VE table in a parking lot. Wrote the tune, and it starts, "idles" (if you can call it that) for about ten seconds at 300-400 and dies. If I even touch the throttle, it immediately cuts fuel and dies. So, I thought "bad write", so I re-wrote, same issue. So, I re-wrote the prior tune, same issue. After about 20 start attempts, it finally caught itself and idled. Once it did that, everything worked just like it should - i.e. throttle did not autocut fuel. In hind sight, this is exactly what it did that morning I ended up pushing it into the garage...
So, I drive the car home. Drives absolutely perfectly. I back into the garage, shut the car down. Start it right back up to test it, and it fires up beautifully - text book start. So, I re-wrote the tune to the car again with zero changes. And it did the same thing it did in the parking lot. A ton of restart attempts later, and it started fine.
I have since repeated this several times. As long as I DON'T write a tune, it restarts fine - even a day later and dead cold. Once I write a tune, it is hell to restart.
During all this, the only thing I got was a "PENDING" cpk - i didn't notice if it was 1335 or 1336. When I got that code, I had no RPM signal on the tach. It sat at zero while it was "idling" at 300 rpm. I deleted the code in the scanner, and next start attempt, Tach was working properly but still only stumbled and died. Disconnected battery, reconnected, and it fired up on the third attempt and idled.
So, I guess I'm looking at two possibilities - Crank Position Sensor is flaking out or the ECU went bad. Has anyone even heard of this before? I guess a third possibility is a corrupt tune, but how do I fix that?
12-30-2016, 01:44 PM
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12-30-2016, 04:03 PM
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I had the exact same issue last year - after even a trivial re-tune it was very difficult to start, taking 10x+ tries over 5 minuted. Sometimes it acted like a VAT problem - it might fire for a second and then die.
I never figured out the reason - I finally went back to a much earlier tune and re-tuned the car from there without further problems.
I never figured out the reason - I finally went back to a much earlier tune and re-tuned the car from there without further problems.
12-30-2016, 04:16 PM
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Originally Posted by mrvedit
I had the exact same issue last year - after even a trivial re-tune it was very difficult to start, taking 10x+ tries over 5 minuted. Sometimes it acted like a VAT problem - it might fire for a second and then die.
I never figured out the reason - I finally went back to a much earlier tune and re-tuned the car from there without further problems.
I never figured out the reason - I finally went back to a much earlier tune and re-tuned the car from there without further problems.
So, here's the thing. I thought custom OS ignored maf anyway. So either a corrupt file or I don't fully understand the custom OS.
This last time I set maf to set SES on first error, and then said don't light the light, and it started, stumbled for about 10 seconds, then caught and ran fine. But only took one start.
12-30-2016, 05:57 PM
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Originally Posted by mrvedit
I recall that the no-start problem occurred when I was running SD; IIRC it got much better when I went to MAF mode.
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12-30-2016, 06:45 PM
#8
is your maf bad, or are you in speed density?
Ive had the exact same issues youve had before, and i derp out and forget that the maf is disabled, or the maf isnt even working to begin with (in customers vehicles). If its in SD you need to make sure that the p0101 and all those maf codes are set to "0" which is i think is first error
if that doesnt work, with your maf disabled (hertz at 0), set your MAF table all to one value such as 15 (lb/min) and itll give you the fuel it needs for a second, and then SD takes over.
Ive had the exact same issues youve had before, and i derp out and forget that the maf is disabled, or the maf isnt even working to begin with (in customers vehicles). If its in SD you need to make sure that the p0101 and all those maf codes are set to "0" which is i think is first error
if that doesnt work, with your maf disabled (hertz at 0), set your MAF table all to one value such as 15 (lb/min) and itll give you the fuel it needs for a second, and then SD takes over.
12-30-2016, 06:54 PM
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Originally Posted by subeone
is your maf bad, or are you in speed density?
Ive had the exact same issues youve had before, and i derp out and forget that the maf is disabled, or the maf isnt even working to begin with (in customers vehicles). If its in SD you need to make sure that the p0101 and all those maf codes are set to "0" which is i think is first error
if that doesnt work, with your maf disabled (hertz at 0), set your MAF table all to one value such as 15 (lb/min) and itll give you the fuel it needs for a second, and then SD takes over.
Ive had the exact same issues youve had before, and i derp out and forget that the maf is disabled, or the maf isnt even working to begin with (in customers vehicles). If its in SD you need to make sure that the p0101 and all those maf codes are set to "0" which is i think is first error
if that doesnt work, with your maf disabled (hertz at 0), set your MAF table all to one value such as 15 (lb/min) and itll give you the fuel it needs for a second, and then SD takes over.
I'll try what you said for the MAF table. That is quite clever!
12-30-2016, 09:02 PM
#10
the MAF table trick should work! i hate to do that BUT sometimes some os's require that, im not sure why, BUT in the ones that i've experienced that issue with, always works. And it doesn't matter since the pcm won't even reference that table to begin with after SD takes over.
Hopefully it works!
Hopefully it works!
12-30-2016, 10:13 PM
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Originally Posted by subeone
the MAF table trick should work! i hate to do that BUT sometimes some os's require that, im not sure why, BUT in the ones that i've experienced that issue with, always works. And it doesn't matter since the pcm won't even reference that table to begin with after SD takes over.
Hopefully it works!
Hopefully it works!
I just don't like to fire the car up late in the neighborhood. Arizona has pretty open gun laws lol!
12-31-2016, 11:52 AM
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Worked like a charm. In fact all I needed was 15 in the zero column. Ran on that for a few seconds then went SD. Straight up no stumbles. Thanks for that!
12-31-2016, 06:00 PM
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Now I just need to get the SES to not come on without tripping the vehicle light.
If I just say "no mil" I get service vehicle light. If I uncheck SES I get service vehicle light
Also since making the entry to the maf table, it has not tripped the crank position sensor pending or actual. So, it must have been the extended 300 rpm run time that was setting that code.
If I just say "no mil" I get service vehicle light. If I uncheck SES I get service vehicle light
Also since making the entry to the maf table, it has not tripped the crank position sensor pending or actual. So, it must have been the extended 300 rpm run time that was setting that code.
Last edited by Darth_V8r; 12-31-2016 at 06:58 PM.
12-31-2016, 09:26 PM
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Sweet
01-02-2017, 11:41 AM
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Originally Posted by subeone
No problem glad it helped you! And i always do 0 and uncheck the SES light and never have had any issues
