CIS-E ECU Revealed

JimLill

JimLill

New member
With all the talk of ECU mods etc. , I thought I'd take a peak inside one of my spare ECU

cis-e.jpg
 
So have you figured out who to buy your chip from and where to plug it it?
[/b]
Click to expand...

Since there is no chip, it's not quite that easy. The chip would be an EPROM and on these antiques, they didn't use that technology.
 
Have you ever dynoed one of these or know someone who has? After you've opened up the intake and exhaust, do you get a flat AFR across the racing RPM range? Is there a way to make it give you a flat AFR? If not, it seems you're pretty shortchanged on the "useful and necessary for racing" clause.
 
The system is closed loop with lambda, so it does have that going for it. I am just starting to explore what can be done and have found several existing mods. I'm not quite up to tracing and drawing a schematic of those PCB but might. As a EE of nearly 40 years, I'm willing to try a few things.
 
>> The system is closed loop with lambda, so it does have that going for it.

Only recently have race cars utilized a closed loop system under full power.
This is dinosaur technology and it doesn't control your fueling under WOT.
Close the "ECU" back up :D

Set your fuel pressure to get your AFR around 13:1 under WOT, Set your timing at ~36* and have fun. :eclipsee_steering:
 
I did not mean to imply it was fully closed loop.... I am aware that at WOT it just dumps what it can in. Still interesting to peer in at old stuff..... especially as it was a spare
 
What's under the sticker of B5705?[/b]
Click to expand...

That was going to be next move, so thanks for the prod. It is BS705

It's an 82S129 which is a 256X4 PROM.

BS704 obviously is a micro of sort kind...... Q701 near it is a 6 Mhz rock

it's a 803x/804x 8 bit uP
 
Jim,
I had one of the best tuners and ITB racers try to help with my CIS-E system and the NARRC runoffs. Took him most of the day just to get the car well enough to get on the track. the system sucks and has always giving me problems. The system has cost me a lot of $$$ in tryin to get it right and a race car that wasn't always fast and fun to drive.
 
That was going to be next move, so thanks for the prod. It is BS705

It's an 82S129 which is a 256X4 PROM.

BS704 obviously is a micro of sort kind...... Q701 near it is a 6 Mhz rock

it's a 803x/804x 8 bit uP
[/b]
Click to expand...

To be exact, it's a 8049 which is

8049 8048-compatible microcontroller with 128 bytes of RAM and 2 KB masked ROM

So the programming is permanent in the masked part. If I thought it was worth it, I'd pull the chip, read and disassemble the code and go look through my junk for a 8749 Progammable version.

So Bill probably thinks I'm nuts, but what else can you do on a day when it's 0 degrees and you lack a heated garage!
 
Nah Jim, I dont think you are nuts. I did the same thing ~20 years ago. (wow it really has been that long)
I just didnt want you chasing something that wasn't there.

As far as CIS being junk... I think we all know that's not true.
Charlie, If you are having trouble tuning it then one of the ancient components has probably finally given up or there is probably something else wrong with the engine. May be time for replacing/testing every fuel/ignition component in the car.
 
You could run it as a closed loop system. If it never sees the WOT signal it keeps trying to reach a target AFR (which is too lean). Of course that just gets in the way of my coolant temp resistor solution, so I let it go open loop.

Honestly I really like CIS-E. The system atomizes fuel terrifically, and flows plenty for our application. If the ECU rule is reeled back in I will definitely stay with it. I may keep it even if it is opened up...

There are sources for 'reworked' CIS-E fuel boxes. One UK source appears to be gone, but there are some folks that drag race turboed CIS-E cars that have figured some things out. After looking at all the options, I just think the simple solution works very well and is very reliable.

I figure my $$ is better spent making sure that all of the components of the system are in top condition. And this takes a lot of $$ considering the prices for simple items like fuel pressure regulators, injectors, etc.
 
>> There are sources for 'reworked' CIS-E fuel boxes.

Remember we are not concerned with part throttle (or boosted) drivability.

The CIS-E system is not really a fuel computer at WOT. The duty valve is maxxed and you are basically running mechanical injection at that point. At WOT the CIS hardware can provide enough fuel to match ANY air supply you can manage to throw at it. Any additional "tuning" fuel should be able to be provided via a pressure increase and adjustment of the 3mm allen screw in the air metering unit.

There are devices on the market that alter the voltage to the system pressure regulator to give slightly more fuel but with an IT legal engine, these simple means of enrichening have always be enough. Remember at WOT the Lambda circuit is ignored and therefore none of the other "E" functions for altering the mixture are active.

Since I haven't really given this CIS stuff much thought for 10 years I could be wrong about some things... if so please refresh my memory.
 
Bill,

I was trying to say basically the same thing that you just did. What we have works very will with simple methods. Just because there are modified units available, doesn't make them the best solution.
 
Bill,
I'm changing my car to the Digifant system. I think that the faster GTI's run that system. Your car, the guys from Canada, Phil Hunt ect. The CSI-E system gave me (and people who know more than I ever hope to know) a lot of problems. At one point just about everything was changed at least once. At least with the Digifant you can make a chip.

Charlie
 
Keep in mind that Albin was CIS.
However I'd be lieing if I said we didn't like the Digi system better :D

So does this mean we need to start burning Digi chips again?
 
You must log in or register to reply here.
Back
Top