7747 to 7427 experience - aka why did I wait so long?

Printable View

10-20-2021
Dieselsj

7747 to 7427 experience - aka why did I wait so long?

If anyone is considering this swap, just do it. Don't hesitate.

It took a little over an hour to pin the new connectors and could probably be done more quickly but I was being extremely careful with the mapping. I also gave each terminal a little pinch on each side to make sure they had good contact when I plugged them into the new ECU.

I used the board from Moates so that I could program my own chips. I temporarily added a ZIF socket. I highly recommend this setup.

I started with a factory 454/5-speed tune and it fired up and ran on the first turn of the key.

First thing I noticed was the idle was better. I let it run while I checked things out and as soon as it got warm it went into closed loop and the INT and BLM started counting off. I was shocked at how much more quickly the 7427 reacted and made adjustments. I went for a drive around the neighborhood doing some low speed, light load (this is where I was having major issues previously) and it ran great. I could hold an RPM and the INT/BLM would adjust and stabilize within just a matter of seconds. The 7747 never seemed to ever get the BLM high enough to be happy (this may also have been an ECU issue...more on that later). Driving around the block a few times I was able to get literally hundreds of BLM counts recorded, whereas the 7747 would have had maybe 20-25 for that same time frame.

Ran that through the spreadsheet and updated the tune and went around the block again and it feels so much smoother.

I had other issues that I was trying to work through before I did the swap, but something forced my hand. I was pulling the connectors off of my 7747 and one connector would not come out. I had to pry it. The terminal on the ground wire had actually welded itself to the pin on the ECU. It got hot enough to melt the connector and melt around the pin on the ECU. A side benefit is that the drivability issues that I had been trying to work through are now gone. The extreme lean condition at 1600rpm/low load is gone. I'm wondering now how much of my problem was caused by this "remanufactured" ECU? Anyway, before the new ECU went in I loaded up the 12v and ground circuits with about a 7a load and let it sit for about 30 min and nothing got hot and it all behaved. I had previously found issues in the harness so that may have been when the hot ground happened. But more about all that story later.

tl/dr - just go swap from a 7747 to 7427 now and you will be happier.
10-21-2021
TriumphR3

What configuration are you running?
10-22-2021
Dieselsj

Quote:

Originally Posted by TriumphR3

What configuration are you running?

Not sure what you are asking...

Using $0D. Started with BHDC tune.

This is on a 87 Chevy R30 truck originally equipped with a 7747.
10-22-2021
TriumphR3

Motor/ transmission, mods to motor. I am seriously considering this mod. I have an 88 C1500 I’m redoing after hitting a deer. Mods to motor are 350; vortec heads, sum880 cam, headers, air gap intake, 46mm tbi and 700r4. Iv been following a lot of Dave W’s posts trying to soak up that knowledge.
10-22-2021
PlayingWithTBI

Have you thought about the EBL Flash-II?

http://dynamicefi.com/EBL_Flash.php
10-22-2021
TriumphR3

Yes I have seen those units. It seemed a bit pricey compared to the 7427 setup. What is needed for that system? Does it process better then the 7427?
10-23-2021
PlayingWithTBI

the EBL has 8 flash banks so, you can store up to 8 different "tunes", it can run boost (up t0 3 Bar) and a bottle. It has a 'VE Learn" function where you can drive around automatically tune your VE tables. With a WBO2 it'll even tune at WOT. It processes at 8192 Baud (like the 7427) as apposed to 160 on the 7747 with expanded VE and SA tables. I have mine in an 88 C1500 so, it has a daughter board on the original 7747. You don't even have to re-pin the connectors, well maybe a couple I can't remember for sure. it comes with its own cable for USB to your laptop, you data log/monitor with its WUD (What's Up Display), modify the tune with TunerPro RT and flash your new tune in about 4 seconds. I'm running with the WBO2 all the time but, you can switch back and forth to your NBO2 by just selecting the option in the WUD. The only thing it doesn't do is auto transmission control like the 7427.

Lot's of fun stuff :thumbsup:
10-23-2021
PlayingWithTBI

1 Attachment(s)

BTW, here's an example of the WUD when I was running at 109% DC on my TBI injectors. Also running pig rich. After increasing spring pressure and some more tuning I was able to get those under control. It also can run with an IAT sensor.
10-23-2021
Dieselsj

Quote:

Originally Posted by PlayingWithTBI

Have you thought about the EBL Flash-II?

http://dynamicefi.com/EBL_Flash.php

I did think about that. What made me go with the 7427 is that it is a factory ECU and if it fails while I'm on the road I can get a new one more quickly/easily than the EBL Flash.
10-23-2021
Dieselsj

Quote:

Originally Posted by TriumphR3

Motor/ transmission, mods to motor. I am seriously considering this mod. I have an 88 C1500 I’m redoing after hitting a deer. Mods to motor are 350; vortec heads, sum880 cam, headers, air gap intake, 46mm tbi and 700r4. Iv been following a lot of Dave W’s posts trying to soak up that knowledge.

Basically a stock 454 with an Edelbrock TBI intake and custom exhaust. Swapped out the TH400 for a NV4500.
10-23-2021
TriumphR3

When I do the swap, in leu of the EBL flash, would it be best to get the truck up and running with the 7747? I have already upgraded the 7747 (still sitting on the shelf) with a ZIF socket for the SST27SF512 chip, Or just precede with the swap and not look back?
10-23-2021
PlayingWithTBI

Quote:

Originally Posted by TriumphR3

When I do the swap, in leu of the EBL flash, would it be best to get the truck up and running with the 7747? I have already upgraded the 7747 (still sitting on the shelf) with a ZIF socket for the SST27SF512 chip, Or just precede with the swap and not look back?

I had the same setup with the ZIF socket in my 7747. Tuned for a while with Dave's help, then went to the EBL and started over. Since the tables are larger, it was easier for me to run the VE Learn on a stock tune that came with the EBL instead of modifying my tune from the 7747. If it were me, I'd jump in and get my feet wet with the 7427. YMMV:wtg:

My setup is similar to yours - Summit Racing 162108 aluminum heads, Lunati bump stick, 1.6 full roller rockers, 46mm TB with an 18LB Spring set at 20 PSI, etc. The 7747 just wasn't fast enough and tables were too small. HTH
10-24-2021
TriumphR3

Absolutely it helps. Im with ya on the 7427. I can pick one up for roughly $40-$50, And the connectors are reasonable enough at Mouser. Repining, that's the easy part. One question, will i still need the nb02 sensor or will the wb02 (I have the Spark2 and Bosch 4.9 setup) be enough to handle o/c loop modes? Before I punch a hole in my header for the sensor bung. I'm thinking the wb02 is only for data logging and fuel programming on the chip.
10-24-2021
PlayingWithTBI

FWIU the 7427 only runs INT/BLM on the NBO2 where the EBL can run either. Maybe someone else can jump in and confirm this?