The rare LA Computer

[Rob Hughes]

I have the LA installed in my SVO. I swap back and forth between my LA2 and LA3 in an attempt to determine any difference.

And..........?

[Scroggo]

I have experimented with the PE, LA, LA2 and LA3 processors.
PE (Calibration Code D6J02) Uneven or hunting idle. Good boost at mid and upper RPM Band Rev Limit ~6400.
LA (Calibration Code D6K0?) Good idle w/occasional miss. Good boost at mid and upper RPM Band w/ Rev Limit ~6500 Feels slightly stronger than PE
LA2 (Calibration Code D7C18) Excellent idle, rarely if ever misses. Most well behaved of all processors tested, but lacks the grunt at upper RPM. RPM Limit ~6200.
LA3 (Calibration Code D8H02) Good idle w occasional miss. Performance seems to be somewhere between PE and LA2. RPM Limit ~6300
*** Caution Butt-O-Meter perception ***, dyno will give solid data.

[Rob Hughes]

Great info...thanks.

[8T6 SVO]

I have experimented with the PE, LA, LA2 and LA3 processors.
PE (Calibration Code D6J02) Uneven or hunting idle. Good boost at mid and upper RPM Band Rev Limit ~6400.
LA (Calibration Code D6K0?) Good idle w/occasional miss. Good boost at mid and upper RPM Band w/ Rev Limit ~6500 Feels slightly stronger than PE
LA2 (Calibration Code D7C18) Excellent idle, rarely if ever misses. Most well behaved of all processors tested, but lacks the grunt at upper RPM. RPM Limit ~6200.
LA3 (Calibration Code D8H02) Good idle w occasional miss. Performance seems to be somewhere between PE and LA2. RPM Limit ~6300
*** Caution Butt-O-Meter perception ***, dyno will give solid data.

What Mods? All stock?

[Scroggo]

Ported E6, 40Bob Gutted Upper, Ported 88 Lower w/ACT wired for LA series conversion, 3 in down pipe. G-Tech reading for LA2 - 14.52 @ 98mph – air temp 61F - spinning thru 1st & 2nd. I was waiting for a 60 degree day so I can test the LA & LA3.

[Scroggo]

One other change, I installed a Ranger roller. I was searching for a better idle and the ability to tune w/VSS and possible Mass Air conversion. I think switching to the LA platform is the correct move. If you want stock then keep the PE, although it was interesting when I had the 237, ATR & cold air pipe installed.

[GT350R]

Had one too. Explains the boost. Mine did the same thing or similar to what SVOBROWN stated. It felt strong , but not so strong that I felt it was anything other then a fluke.

[chalkys_explorer]

Ok, my terminology may be a bit off, but you'll get the jist......

My understanding is that the LA series computers, including the LA2/3 were a faster/ higher resolution than the earlier, PE,TE,TF etc. ,hence their tendancy for better idle manners???

I'm assuming that the variable boost levels you are talking about would be negated with an aftermarket boost controller?? Is the pin configuration the same as for the LA3???

Actual dyno sheets would help end any confusion on the matter. Let us know when you do it.

Thanks
Chris

[unrealford]

Chris, Dont quote me on this , but after reading many websites including here, I remember reading that the speed of the processor, was quicker on the la3, from 8,to 12 or 16 Megahertz

[dagenham]

the rare la computer

OK , I am not a computer controlled car guy by any stretch of the imagination. So here is my question, could this be why my early '84 does not seem to idle smooth? And would it be worth the time and money to change to a later computer on a bone stock car??

[Rob Hughes]

We've covered this before, but I'll post one more rehash.

The original Ford 8061 CPU in the EEC was a DIP 40-pin design. It clocked at 7.5 Mhz and used two 8361 memory chips with 16K address space. That was a time when 16K of memory was about a weeks wages.

The later one, circa MY1987+, is a 68-pin PGA that clocks at 15 Mhz. And has a larger memory address space, starting at 32K. There are more inputs and outputs to/from the CPU than the reduced-profile 40-pin unit but they both have the same A/D converter (one of them) so "interpretation" of voltages ain't no better. Granted the "faster" CPU can take more inputs versus time, and resolve to a greater crank degree of accuracy - for the same calculation time period - but that doesn't get you much. The 7.5Mhz chip will resolve ignition timing to 2.4 microseconds at 6000 RPM so increasing that to 1.2 microseconds don't gain you much when the distributor end-play is generally 2-3 crank degrees (btw - ~27 microseconds is equal to 1 degree of crank rotation at 6000 RPM). So it's kinda like using a 0-1" micrometer to park your car.

The additional outputs were used on the v-ate models for "Sequential Fuel Injection" where eight (8) separate injector drivers were needed (versus two in the 4-cylinder turbo), gearbox shifting, converter control, ....

ALL OF THEM use the same slow inputs - the PIP from the distributor. You can compare this to formatting a floppy disk using a 386-20: takes about 2 minutes. So how long does it take to format that same floppy using a dual ZEON 3.6Ghz box? About 2 minutes.

The "program" (algorithms to those that speak Engineerese) is much newer in the 87+ EECs and idle control is probably better also. But this has absolutely nothing to do with a faster CPU cause it's still dependent on the same PIP signal - 4 pulses per crank turn.

Do not forget that the SVO was the second engine designed to use the EEC IV management system. (the 1.6L turbo EFI being the first, although concurrently) so the programmatic learning curve was very early in the development/learning stage. By the time the 87 model year came around EEC-managed EFI had spread across the rest of the Ford product line to the tune of >70% - like a cancer. By then engine management was almost a science rather than the artwork it started as in the early 80's.

If you want to understand more of the Ford/Intel/Toshiba 8061/8361 chipset, get some documentation on the Intel 8096 controller.

My sentiments exactly.

[8T6 SVO]

OK , I am not a computer controlled car guy by any stretch of the imagination. So here is my question, could this be why my early '84 does not seem to idle smooth? And would it be worth the time and money to change to a later computer on a bone stock car??

In my opinion,

Your dealing with a car that is 23 years old - this is why your car doesn't idle smooth. I have no idea of the condition of your car. It was designed however, to idle smooth 23 years ago. I am very sure that there are lots of reasons other than your computer why the car doesn't idle smooth.