Another LT1 High Idle issue

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May 23, 2016 | 09:54 PM

#41

ovrebo1

Burning Brakes

Joined: Jan 2007

Posts: 1,170

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Quote:

Originally Posted by AJT84

I downloaded Datamaster free... limited to 20 scans before having to register.

Would you be able to post a link? The only one I can find you have to put it in a cart and check out.

May 23, 2016 | 10:12 PM

#42

ovrebo1

Burning Brakes

Joined: Jan 2007

Posts: 1,170

Likes: 86

I downloaded it. When I plug the laptop into the car and turn the key on I don't get any info and the fan on the car turns on and the information display starts going through its codes. I'm using a Windows 10 laptop BTW

May 23, 2016 | 10:34 PM

#43

AJT84

Thread Starter

Instructor

Joined: Mar 2016

Posts: 184

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From: Bowling Green Ohio

2021 C5 of the Year Finalist - Unmodified

2020 C5 of the Year Finalist - Unmodified

http://www.tunercat.com/DataMaster/dmdownload.html I think this is the 20 free scan page.

May 23, 2016 | 10:42 PM

#44

AJT84

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From: Bowling Green Ohio

2021 C5 of the Year Finalist - Unmodified

2020 C5 of the Year Finalist - Unmodified

I'm just guessing but it sounds like your cable is shorting the diagnostic pin to ground. Mine does not do this. The car starts normally with no diagnostic display. I've only done a couple of times, but you'll need to go to File, record new Aldl file, then a second window pops up and you title the file there and hit start. This is from memory but that's the idea. A quick YouTube search may help walk you through it better. Hopefully someone with more experience can help as I'm new to this as well. Good luck!

May 31, 2016 | 09:55 PM

#45

AJT84

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From: Bowling Green Ohio

2021 C5 of the Year Finalist - Unmodified

2020 C5 of the Year Finalist - Unmodified

Problem solved, I hope.

Well I got my ECM back from SIA Electronics in Tilden, IL. They refurbished the board. I installed it tonight and went for a long drive. The car is running great! I didn't have the slightest hint of issues. This may have been the answer to my problem. I hope this helps someone else who's having similar issues. SIA did the service for $167. And now that this seems to have fixed my issue, I would have paid double, which is what some other services charge...

Thanks for the help guys

Sep 5, 2017 | 08:26 AM

#46

anesthes

Safety Car

Joined: May 2006

Posts: 4,290

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From: Salem NH

Did you ever figure it out?

-- Joe

Sep 5, 2017 | 10:23 AM

#47

AJT84

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From: Bowling Green Ohio

2021 C5 of the Year Finalist - Unmodified

2020 C5 of the Year Finalist - Unmodified

Quote:

Originally Posted by anesthes

Did you ever figure it out?

-- Joe

yes, post 45 just above. The ECM was the idle issue. Just this spring the car had this horrible flat spot in the timing which I captured with scans. I eventually discovered that there was a JET chip (#19215) in the ECM I was not aware of. (Thanks previous owner) I put the original eprom in and the car came alive. Jet chip must have become corrupted in some way. Not a fan of them in general and now I'm definitely not. Wish I had checked that first, it was so bad I almost got into the opti again for no reason.

Sep 6, 2017 | 02:27 PM

#48

anesthes

Safety Car

Joined: May 2006

Posts: 4,290

Likes: 140

From: Salem NH

Quote:

Originally Posted by AJT84

Hrmmm. So that was it.. Weird.

I have the same issue. I've done a lot, including replace PCM's, reflash, opti, intake gaskets, throttle body, check vac leaks, etc. It will idle at 1100 when the commanded RPM is 675. But sometimes it will idle fine.
It's very strange.

-- Joe