Megasquirt for LH 3.1?

[vvpete]

Something I posted for Linuxman51 over in the f/s forum:
"Anything available that works for LH 3.1?
I just picked up a '91 245 w/ LH 3.1 and have this really nice B21F N/A motor with a rally cam I'd like to drop in. Not willing to go +T yet, since it was a 185 hp N/A in K-Jet 242GT, and need to look at better fuel management.
Any suggestions are welcome."

Here's the issue, if I use the rally cam which has lots of overlap and lift, will any system get the engine to pass emissions? I have a VX cam also, and can use it if necessary.
This motor I have is equivalent to a B23E, 10:3 compresion, ported 391 head. Optimally I would like to drop it into the LH 3.1 car using some bigger injectors (I have a set of green tops fom an '89 740Ti), B230F manifold or K-Jet manifold and '91 TB with TPS.

Will I be better off with the Hi-Z injectors to control low rpm fuel for emissions?

What systems will have the best flexibility? I have a turbo, manifold, and T+ from a '89 780 for 'stage 2', after I get the motor to work as an N/A in it's present state.
Thanks, Pete :)

[linuxman51]

you could certainly wire it up on there, but if you're refering to a PNP setup, no not readily, as Ive not seen a wiring diagram for lh 3.1 (if you can dig one up with the pinouts for the two ecus i could probably hack out something).



green tops will work fine, i'd run reistors to keep life simple and you should be able to tune it for emissions just fine.

[vvpete]

Thanks, Linuxman51. I am new to LH 3.1, and not familiar to what is different inside the ECU. I can only go from what others have told me and that the fuel map is somewhat fixed compared to LH 2.4 where it has adaptability to changes in engine flow of about +/-10%.

I would think the basic wiring is the same, XXX572 ECU, as any 2.4 box, but has the TPS wired differently. I think the wiring harness is the same as 2.4. Also the AMM uses fewer connections. Not sure that would make any difference.

The reason I ask about the cam, is that just after I got it from IPD in the late '80's, they stopped importing it becasue it wouldn't meet emissions in any of the B230 motors. It seemed to run fine in the 242GT w/K jet using a turbo fuel dist and injectors, but I never went as far as emissions testing. I have the ressitor pack for the green tops as well.

At this point, a fuel control box would be a good start, leaving the ignition as it is. I have two old (semi-working) xxxx561 boxes to play with if it can be done with those.

[linuxman51]

From what I've heard about 3.1 its got a variable tps vs the 2.4 switch type, and iirc it only came in cars equiped with a manual transmission (?).

but like i said if you can come up with a wiring diagram, i can probably work something out for ya.

[vvpete]

Yes, the LH 3.1 came on 240's with M47 in '90-'93, mostly in wagons, and mostly in high emissions controlled states in the US, as far as I know. This one came fron Denver.
The car runs strong and smooth, better MPG than any 2.4 I've had even with the 5-speed.

I'm digging for some more wiring info. Yes it has the variable TPS, and as mentioned a different AMM.

Another question, when I put the motor together, would there be any advantage to using the 242GT manifold with the manifold mounted O2 sensor? I had put in a wide range O2 sensor for the motor w/K-Jet. The car has a heated O2 snesor mounted in the cat. I recall seeing a type of two O2 sensor feedback circuit, placed like this in the '96 960 I once had. Is there any way to do this or should I just keep it simple and use one O2 sensor, and which location would be better?

[vvpete]

I'm digging for some more wiring info. Yes it has the variable TPS, and as mentioned a different AMM.

Looking at the Bentley manual for '91 LH 3.1, it shows a different connection to the ECU for the throttle potentiometer (TPS):

Y-W from TPS goes to pin #2 on the 572 ECU (this connection is used for a Y-W wire to EZ-116k ign unit pin #7, which ties into Y-W wire from throttle switch on LH 2.4)

BL-W wire from TPS goes to pin #10 on the 572 ECU (this connection is not used for LH 2.4)

Pin #3 not used on 572 ECU (this is used for BL-W wire from throttle switch on LH 2.4)

It looks like the AMM for LH 3.1 is wired the same as LH 2.4 but ommits the white wire from pin #4 on the AMM to #8 on the ECU

Pin #8 on the 572 ECU has a yellow wire that goes to pin#7 on the EZ-116k Ign control unit.

Other that that, everything else looks the same as LH 2.4. Let me know if this makes sense and can work with it.

[Forg]

2.4 uses a throttle pot, rather than a switch, does it? The majority of B230's used a switch for wide-open-throttle & don't have the variable signal, but I don't know ECU's this matches up to.

One other thing - how tough are the emissions tests in Texas? In the state I live in, I'd have Buckleys' of passing an emissions test with an aftermarket-computer car without having tuned the car using a 4-gas analyser. Truth be known, most factory 20yo cars probably wouldn't pass either, but unmodified cars aren't measured.

[linuxman51]

2.4 uses switches, 3.1 uses a pot.

[linuxman51]

Looking at the Bentley manual for '91 LH 3.1, it shows a different connection to the ECU for the throttle potentiometer (TPS):

Y-W from TPS goes to pin #2 on the 572 ECU (this connection is used for a Y-W wire to EZ-116k ign unit pin #7, which ties into Y-W wire from throttle switch on LH 2.4)

BL-W wire from TPS goes to pin #10 on the 572 ECU (this connection is not used for LH 2.4)

Pin #3 not used on 572 ECU (this is used for BL-W wire from throttle switch on LH 2.4)

It looks like the AMM for LH 3.1 is wired the same as LH 2.4 but ommits the white wire from pin #4 on the AMM to #8 on the ECU

Pin #8 on the 572 ECU has a yellow wire that goes to pin#7 on the EZ-116k Ign control unit.

Other that that, everything else looks the same as LH 2.4. Let me know if this makes sense and can work with it.


doesnt change anything that I mess with

[vvpete]

doesnt change anything that I mess with

How do you interface the throttle pot and AMM? Are these components by-passed through the stock ecu?


One other thing - how tough are the emissions tests in Texas? In the state I live in, I'd have Buckleys' of passing an emissions test with an aftermarket-computer car without having tuned the car using a 4-gas analyser. Truth be known, most factory 20yo cars probably wouldn't pass either, but unmodified cars aren't measured.

Texas has gotten very tough, as tough as California, but only in the counties in and around major metro areas. We actuallly have smog vans that get randomly located at freeway entrance ramps and highways entering metro areas to catch polluting vehicles that drive to the city from the ranchland. They take a picture of your car, map the exhaust fumes as you drive by, and send you get a ticket in the US mail.
Before my '89 245 was wrecked in Oct, I just passed the test with numbers as low as my brand new Volvo ULEV emissions rated V70 2.5T (note all the cars sold in these metro areas must meet ULEV spec's after '04).
The 245 had modified VX cam, new Carsound cat and IPD 2 1/2 sport exhaust, everything else stock (except I used a 940 ECU), and 287k miles, cleaner than most new cars on the road.
I, too worry about passing these strict emissions reg here.

[linuxman51]

I dont use the amm at all, and on lh 2.4 i dont use the tps. I could hook that up on yours if you would like though.

[vvpete]

Thanks Linuxman51. This sounds like some progress, at least from an understanding point of view.
What do you require on your end to configure the system with the TPS. This should be able to give my more fuel map precision throughout the rpm range, correct?

What would be my end of the install/interface? would you simply replace the stock ECU with a modified box or would you interface the engine wiring harness with a new control unit and by-pass the stock box? Does this sound like a normal LH 2.4 MS application except for the TPS?

Also, if you by-pass the AMM, how do you compensate for air density/pressure changes? Is this simply an O2 sensor feedback closed loop using fuel interval control, aka, Lambda Sound on K-Jet w/ frequency valve? (btw, a very efficient system compared to K-Jet w/egr, or even early LH 2.2)

Excuse me for my ignorance, as I am new to the MS world. I understand the Bosch systems pretty well and would like to get a better idea of what you would be doing with/to the system.

Pete

[thelostartof]

MS uses a MAP sensor built into the ECU that you hook up

[volvo9]

I'm probrably digging up an old thread here, but I've got one question that goes along with MS ing a 3.1 car.

Does the 3.1 flywheel and distributor work with MS?? or will I need to go junk yard hopping to find a new flywheel and distributor?

I take it they will work, but I'd just like some reassurance.

Thanks again!