Data Logging/ 95 Yukon

[eagle mark]

What was the lightbulb? There is a certain procedure for adjusting IAC which effects TPS idle voltage. Usually not needed on a stock factory system and I have had 2 factory TBI systems on Chevys, both were/are fine at 125k. Always needed on rebuilt TBI unit or a conversion on another engine. It's a setting called Minimum Air, all EFI systems have one but it is more important on TBI systems as the injectors are above throttle blades. I didn't see anything far enough out of whack in your log to worry, unless I missed something?

What exactly are you trying to fix? Your a little rich everywhere but idle. That could be tuneup related! Even an old O2 sensor. Bouch says single wire O2 sensors on unleaded gas need replaced at 30k, but 100K on heated O2 sensors for my LT1 and 50 to 500 hours on wideband if leaded or race fuel is used...

When an engine runs rich it will soot up an O2 sensor, just like reading a spark plug that is black, not tan and it will read less oxygen and add even more fuel...

 

[GalDemSuga]

I recently rebuilt the TBI, added a 1" spacer, a 1/4" injector spacer and a dual snorkle setup. I pulled the IAC but never reset the minimum air. Also, the O2 sensor is a 3 wire and has over 70K miles on it. There is also no Cat on the truck at the moment. I was waiting for the exhaust to rust out before installing a new system. Presently it is all solid with no rust.

Also, she idles at about 7-800 rpms in park when warmed up and about 575 rpms when in gear?

What was the lightbulb? There is a certain procedure for adjusting IAC which effects TPS idle voltage. Usually not needed on a stock factory system and I have had 2 factory TBI systems on Chevys, both were/are fine at 125k. Always needed on rebuilt TBI unit or a conversion on another engine. It's a setting called Minimum Air, all EFI systems have one but it is more important on TBI systems as the injectors are above throttle blades. I didn't see anything far enough out of whack in your log to worry, unless I missed something?

What exactly are you trying to fix? Your a little rich everywhere but idle. That could be tuneup related! Even an old O2 sensor. Bouch says single wire O2 sensors on unleaded gas need replaced at 30k, but 100K on heated O2 sensors for my LT1 and 50 to 500 hours on wideband if leaded or race fuel is used...

When an engine runs rich it will soot up an O2 sensor, just like reading a spark plug that is black, not tan and it will read less oxygen and add even more fuel...

 

[eagle mark]

Your idle speed is same as desired Idle speed, TPS is .5 to .6 and IAC is 08, same as desired. This shows it to not need a reset. Look at your log at about 19 minutes.

One thing I did see this time looking at data lists is Manifold Air Temp is -40 ? Doesn't this ECM have a MAT? If so it is reading max cold all the time, that is where they read when they go bad, same as CTS.

 

[GalDemSuga]

I havent seen any additional temp sensors on this intake other than the CTS. Its exactly the same as my 89 K5 and there are no unaccounted for wire connectors. I need to look into this? This is a 16197427 PCM.

Your idle speed is same as desired Idle speed, TPS is .5 to .6 and IAC is 08, same as desired. This shows it to not need a reset. Look at your log at about 19 minutes.

One thing I did see this time looking at data lists is Manifold Air Temp is -40 ? Doesn't this ECM have a MAT? If so it is reading max cold all the time, that is where they read when they go bad, same as CTS.

 

[eagle mark]

I know on the TBI caprice engine it was in the air intake system, not intake manifold. The ADX file has it, doesn't mean it's right?

 

[GalDemSuga]

I just went down to the Autozone to look that up and get a new O2. It wasnt listed for my year truck. The 96 and up trucks came with the sensor on the air box. I dont have an air box just the old breather setup.

I know on the TBI caprice engine it was in the air intake system, not intake manifold. The ADX file has it, doesn't mean it's right?

 

[GalDemSuga]

Ok I've done some research and coupled with the help of Mark and Dave, I'm about ready.

For the 7747 ECM I need to order:
1. http://www.moates.net/s4-aries-28pin-lowprofile-zif-p-46.html?cPath=26 (to be modified by connecting pins 1,2,26,27 and 28)

2. http://www.moates.net/c2-sst-27sf512-chip-p-39.html?cPath=26

3. http://www.moates.net/burn2-chip-programmer-p-197.html?cPath=94

For the 7427 PCM I need:
1. http://www.moates.net/d2-28pin-dip-socket-p-59.html?cPath=26

2. http://www.moates.net/c2-sst-27sf512-chip-p-39.html?cPath=26

3. http://www.moates.net/hdr1-memcal-header-p-52.html?cPath=64

Correct me if I've missed any steps above. The pics below are of the 7747 ECM and the Memcal I removed from the 7427 PCM.

 

[dave w]

Ok I've done some research and coupled with the help of Mark and Dave, I'm about ready.

For the 7747 ECM I need to order:
1. http://www.moates.net/s4-aries-28pin-lowprofile-zif-p-46.html?cPath=26 (to be modified by connecting pins 1,2,26,27 and 28)

2. http://www.moates.net/c2-sst-27sf512-chip-p-39.html?cPath=26

3. http://www.moates.net/burn2-chip-programmer-p-197.html?cPath=94

For the 7427 PCM I need:
1. http://www.moates.net/d2-28pin-dip-socket-p-59.html?cPath=26

2. http://www.moates.net/c2-sst-27sf512-chip-p-39.html?cPath=26

3. http://www.moates.net/hdr1-memcal-header-p-52.html?cPath=64

Correct me if I've missed any steps above. The pics below are of the 7747 ECM and the Memcal I removed from the 7427 PCM.

Yes, that is the correct list of parts.

dave w

 

[GalDemSuga]

Sweet
I installed a new O2 on the Yukon tonight and I will log in the morning. I will send on the XDL to both yourself and to Eagle_Mark.

I forgot to ask whether the Burn2 will work to flash the 7427 PCM chip.

Yes, that is the correct list of parts.

dave w

 

[dave w]

Sweet
I installed a new O2 on the Yukon tonight and I will log in the morning. I will send on the XDL to both yourself and to Eagle_Mark.

I'll let you know what I find.

I forgot to ask whether the Burn2 will work to flash the 7427 PCM chip.

Yes, the 27SF512 can be erased / flashed with the Burn 2. There is an offset needed when flashing the 27SF512 for the '7747. The 7747 is only a 4K file size. The '427 is 64K file size, no offset needed.

dave w

 

[GalDemSuga]

Cool. I read about the offsets in another thread and I believe it's on Moates site too. I will be tackling that project after the winter as I plan to rebuild my K5. The 7427 PCM in the Yukon will be getting immediate attention

I'll let you know what I find.



Yes, the 27SF512 can be erased / flashed with the Burn 2. There is an offset needed when flashing the 27SF512 for the '7747. The 7747 is only a 4K file size. The '427 is 64K file size, no offset needed.

dave w