Couldn't take the slowness anymore.

[babywag]

Installed a 16197427 on my '90 on Tuesday morning.
Those 1227747 fossils are just too damn slow for my taste.

Also stole the WB from my '88 so I can tune it quick.
Tuning by BLM numbers is okay, but using a WB makes it much quicker/easier.

Took ~45 minutes to re-pin the harness, and wire up the WB.
Would have been quicker if the 2yr old wasn't underfoot
I was hesitant to do it on my daily driver, but glad I did.

EDIT: Just for reference it's still a fuel only system right now.
No knock sensor either...

[sgtpoliteness]

What kind of wide band are you running? Are they all 6 wire? I'm in the process of converting to the 7427 TBI and am looking at HO2 options. Thanks!

[babywag]

I'm using the Innovate MTX-L works VERY well.

Has 2 analog outputs, one reports AFR to 7427 and the other can simulate a NB sensor.
This allowed me to only weld in 1 O2 sensor bung.

eBay has great prices on the MTX.

I disable closed loop, and tune the VE tables from the WB readings.
Gets it REALLY close on the fuel, and more accurate than using BLM data.
BLM data isn't really telling you if you're running rich/lean it's just saying how much fuel it's adding/subtracting.

Used it on my '88 and made tuning very quick/easy Hoping for the same on the '90.

[FSJ Guy]

The 16197427 ECM is the cat's meow, IMHO.

You really need to add timing control. You'll be in heaven!! There are two spark and fuel tables in the '7427 ECM. One set for idle (closed throttle) and one for open throttle. A nice feature.

Good to know about the wideband tuning. More money to spend. Oh boy.

[Bill usn-1]

The PCM is nice. Been running them for TBI and MPFI for a while now.
The bigger advantage is the ability to use a late model 4l80E trans with OD and converter lock up.
Really helps on the highway.

But the old "slow" 7747 works just fine for a standard carb conversion.
Tuning with a wideband is just the same using logworks from Innovate since it's real time.
I run the wideband, my emulator and the datalog all at the same time on my laptop.

The baud rate of the sampling really doesn't make any difference when tuning with a wideband. then once it's tuned, who cares. All it's doing is making small corrections based on the changes in the enviornment.

No real "need" for a PCM unless you plan on running a later trans or want to mod it for MPFI. But then i also run the 1227730 for MPFI and it can also run software for turbo applications.

It's all personal preference and what your future plans are.

[babywag]

I didn't want to spend the extra money to log rpm/map+wb.
I can log the wb data all day long won't do me any good w/o corresponding rpm/map data.

The baudrate does matter because I can gather the data MUCH faster.
It takes a longer drive to fill the tables on the 7747, again just my opinion.

I feel the drive ability on the 7427 is also improved over the 7747.
Driven both my vehicles w/ a 7747 and then 7427..I'm sure you have to.
I have my opinions right or wrong they are mine to share.

[JeepsAndGuns]

I also have a MTX-L and really like it. It's been awesome. However, if you are using the simulated NB output of it to feed the 7427 in place of a actual NB, I will say this. I tried that, and it worked, however I would keep getting a check engine light for the o2 sensor. I would get it every couple days and have to unhook the battery to clear it. It would be fine for a couple more days then I would have to do it over again. I eventually got tired of this and went back to a regular NB o2 sensor and the problems went away. (I have two bungs, so I can run both the MTX-L and a NB) I am using the 3 wire heated o2 made for a truck the 7427 came in.
Here is a long thread I have on gearhead about:
http://www.gearhead-efi.com/Fuel-Inject ... ated-equal

[AwesomeJ10]

I wonder if a 7427 would help produce a smoother idle?

[Bill usn-1]

I don't notice any difference in idle between the two.
I've been running both for a while so maybe it's just in the tuning.
Did my first 7427 upgrade back about 5-6 yrs ago with a few guys on thirdgen.
It's gotten pretty common now and lots of smart guys writing code patches for them like dual elec fans and WBO2 input to the data stream. I'm just waiting for a turbo patch and then i will be set with the MPFI/4l80e and turbo!!

[FSJ Guy]

I wonder if a 7427 would help produce a smoother idle?

I noticed smoother idle. The '7427 uses timing adjustment to control idle speed. You can watch the timing change in TunerPro while the engine is simply at idle.

Pretty cool, IMHO.

[Bill usn-1]

I guess my question would be....
Did it have a smooth idle with the carb on it?

It didn't need to adjust the timing to help it idle.
Not saying it doesn't help, like I said i have run most of the GM computers.
But is the bad idle due to the engine, EFI, or the tune or just the version of the program used?

[babywag]

Whoosh....here we go again.

[Bill usn-1]

Whoosh....here we go again.

yep, I know.
These discussions are always good for the new guys.
Helps them to sort out the facts from the myths when it comes to EFI.

I see soooooooo much stuff that just keeps getting repeated on the web, that people to start to believe it as the truth even if they have no personal knowledge of how it works.

Sort of like the new insurance commercial.....They can't put anything on the web that isn't true.....here comes my date, she's a french super model. I met her on the web!

[babywag]

Whoosh....here we go again.

yep, I know.
These discussions are always good for the new guys.
Helps them to sort out the facts from the myths when it comes to EFI.

I see soooooooo much stuff that just keeps getting repeated on the web, that people to start to believe it as the truth even if they have no personal knowledge of how it works.

Sort of like the new insurance commercial.....They can't put anything on the web that isn't true.....here comes my date, she's a french super model. I met her on the web!

No offense Bill but that is a bit of a stretch on this thread.
I don't think anything I posted is untrue or misleading.

[Bill usn-1]

nope didn't say you did.
i was just pointing out that sometimes the benefits experience by switching from the ECM to the PCM may have more to do with the tune than with the computer change.

Another thing i have seen is some use more sensors like a MAT, and that can help with the fueling.

The faster baud rate can help the PCM make faster corrections for a slightly off tune where the older 7747 will tend to roll the idle up and down due to the O2 swing rate.
With a bigger cam, a good tune and an open loop idle can really help to keep it smooth.