Dies after 10 seconds after perfect start

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Dies after 10 seconds after perfect start

Postby scottme262 » Mon Oct 16, 2017 8:29 pm

Running VEMS PNP on AAN 1993 S/4
Car starts cold perfectly and has a high idle as set in IAC control until 80c. No issues runs great hot and cold

But...Start the car warm and it fires right up and then dies about 7 seconds later. it sounds like when the AC clutch engages. The only way to keep it from dying is to apply throttle up to about 1800 once it gets past that initial 7 second point its perfect.

Any ideas?

I have posted my config file for review.
Thanks
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v3.3_u008311-A-2017.10.16-18.03.10.vemscfg
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Re: Dies after 10 seconds after perfect start

Postby ChrisAudi80 » Tue Oct 17, 2017 11:08 pm

scottme262 wrote:Running VEMS PNP on AAN 1993 S/4
Car starts cold perfectly and has a high idle as set in IAC control until 80c. No issues runs great hot and cold

But...Start the car warm and it fires right up and then dies about 7 seconds later. it sounds like when the AC clutch engages. The only way to keep it from dying is to apply throttle up to about 1800 once it gets past that initial 7 second point its perfect.

Any ideas?

I have posted my config file for review.
Thanks

It might be better if you post a log of when it happens.
96 S6 auto
95 80Q AEB VEMS
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Re: Dies after 10 seconds after perfect start

Postby scottme262 » Wed Oct 18, 2017 5:07 pm

Here are two log files.
the first one is cold and it starts up has a mild rpm oscillation but stays running when the ac compressor kicks on. Warms up and is fine

the second one is about a half hour later, you will see it starts and then dies when the ac clutch kicks in. does it again before it fires up and stays running.

I have been fiddling with a few IAC numbers, in the ac section as well, but don't know what I am doing.

Something that may be related is that it will occasionally die coming up to a stop light when I push in the clutch. Like the IAC is not waking up fast enough.

Thanks
Attachments
v3.3_u008311-2017.10.18-12.34.09.vemslog
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v3.3_u008311-2017.10.18-12.59.24.vemslog
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Re: Dies after 10 seconds after perfect start

Postby ChrisAudi80 » Mon Oct 23, 2017 12:06 am

scottme262 wrote:Here are two log files.
the first one is cold and it starts up has a mild rpm oscillation but stays running when the ac compressor kicks on. Warms up and is fine

the second one is about a half hour later, you will see it starts and then dies when the ac clutch kicks in. does it again before it fires up and stays running.

I have been fiddling with a few IAC numbers, in the ac section as well, but don't know what I am doing.

Something that may be related is that it will occasionally die coming up to a stop light when I push in the clutch. Like the IAC is not waking up fast enough.

Thanks


Just took a quick look. I'm no expert, but if you don't know what you are doing, I would start with simple things.
Turn off idle PID first. Try to just use ignition idle control. BTW, the 40degrees change is very high. Try backing down to 12.
It should be possible to run with AC on, it will just idle low.
Next, try to increase timing in your idle area. I saw 10 degrees. That is quite low. Try starting with 15 and increase up to 20. See what happens.
Read this: http://www.enginebuildermag.com/2012/01 ... ooth-idle/

Also, the log showed a primary trigger error. Might be because of shutting off, but that could be it.

Speaking of simple, you said it sometimes shuts off when pushing in the clutch. That could be a vacuum leak. Might be the rubber T under the intake manifold is cracked somewhere or the valve in there is gummed up.
96 S6 auto
95 80Q AEB VEMS
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Re: Dies after 10 seconds after perfect start

Postby scottme262 » Tue Nov 14, 2017 5:16 pm

Thank you for the info.
I have been gone for the past month and now can try your suggestions.
I will post the results.

Thanks again
Scott
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Re: Dies after 10 seconds after perfect start

Postby scottme262 » Fri Nov 17, 2017 3:18 pm

I found some more issues and it seems perfect now.

First were the odd timing numbers for the Idle settings that you had seen. It looks like they were corrupted somehow when I did a software update.
I found all the old timing and IAC settings that Marc had sent with the ECU and plugged them back in. (they were virtually the same as you suggested for the idle range)

After that it was mostly perfect but still had a minor tendency (1 in 20 starts) to die when the ac kicked on right after start, I plugged in a second 0/2 unit that was powered from a non keyed source and found that when it dies from the AC kicking on that the mixture was very lean. So i added additional fueling in the after start mode and gave it a little more fuel along the bottom row 30kpa and now its perfect.

Starts right up, ac kicks on and the drop is only about 50rpm then it pulls back up to the correct idle.

Thanks Chris for your help :)
Scott
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Re: Dies after 10 seconds after perfect start

Postby ChrisAudi80 » Sat Nov 18, 2017 10:53 pm

You are welcome. Glad it is (mostly) fixed.
96 S6 auto
95 80Q AEB VEMS
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