Megasquirt Progress, Main Board complete Options

[lapuwali]

QUOTE (DNHunt @ Feb 1 2006, 02:48 PM)

I understand the rising rate FPR but, I haven't found it necessary and I'm not going to mess with it. I've only had a few grips. The idle flucuates with alternator load (I can't imagine running AC) so idle control would be nice. Over run is difficult to tune but was very acceptable with the greater resolution of the Hi-res code. I suspect that will also be the case with MSII. The IAT compensation is off due to heat soak of the sensor in the plenum. Both idle control and air density corrections are being worked on by other people with similar problems. The basic B&G codes for fuel only give a nice replacement for D-jet with the benefit of tunability. Adding ignition control helps even more but, the system is not perfect and is still short of what most of us are used to with modern FI. All in all I've been very happy with my stuff. I've had to repair a couple of solder joints, replace 1 transistor and 1 MAP sensor in 3 years and about 8000 miles. The same board has been used with 3 separate engines and in 2 forms (feul only and fuel with wasted spark distributorless ignition). I can't begin to remember how many different code versions I've used.

Idle control really is a hard thing to do. Someone noted that the early GM ECUs they were hacking on devoted 1/3 of the code just to idling.

It seems a simple task: read the idle speed and adjust things to keep it at that speed. However, there's usually a lag between tweaking a knob and seeing the change in the idle speed, so a simple feedback loop will spend all its time hunting for the right idle speed. The trick is getting the cycle time of the "hunt" fast enough and in small enough steps that the driver won't notice it.

The current state of the art, as I understand it, is to vary ignition timing to alter idle speed, as that has the fastest response time. However, this doesn't work for "fast idle" for warmup (not enough usable range), so you need an air control valve, anyway. Now you're controlling idle speed two ways. As battery voltage fluctuates, injector response time changes, so you get different fuel flow rates depending on alternator load. It's a small effect, but significant at idle, so you have an independent variable controlling idle speed in addition to the airflow and ignition timing you have control of.

Now you know why even big auto manufacturers usually bought their injection systems from Bosch rather than build their own. It's a hard problem, requiring a lot of effort and research to solve. I'm sure Dave didn't mean to denigrate B&G's efforts, just pointing out that two guys doing this part time (now along with a dozen or so other volunteers making significant contributions) have done a pretty amazing job just getting close to what Bosch has spent nearly 40 years perfecting.

I'll be interested to see how you get on with MSII, Dave. The code is still very new, so I'm going to stay away for now. I'll probably just do fuel only for quite some time, since I have a Mallory to handle ignition. The new Microsquirt board may actually be a better bet than MSII, as it uses the same processor, but with far fewer parts on board, so it should be more reliable. The MAP sensor is moved off board, which is probably a net win, really. By the time I'm ready to jump to ignition control, Microsquirt will probably be on it's second version and fully debugged.

[agrump]

QUOTE (DNHunt @ Feb 1 2006, 02:48 PM)

I've only had a few grips. The idle flucuates with alternator load (I can't imagine running AC) so idle control would be nice. Over run is difficult to tune but was very acceptable with the greater resolution of the Hi-res code. I suspect that will also be the case with MSII. The IAT compensation is off due to heat soak of the sensor in the plenum. Both idle control and air density corrections are being worked on by other people with similar problems.

I got around the IAT heat soak problem by welding a new bung in the stock location and using a GM sensor, works like a charm. For AC up idle I used an adjustable air bypass, I think it was from a vw rabbit. I just have it wired into the AC clutch. Idle still fluctuates but it doesn't stall and I don't have to run high idle speeds when the AC is off.

I have not found the overrun cutoff in MSII, at least not like MSI had. All I can find is the decel cutoff. In some ways I like the extra code better then the MSII. EGO settings in MSI was easier to understand and set then in MSII.

[yarin]

Do a search for closed loop idle on MSEFI.com forums and a few interesting topics come up.

One guy changed his spark advance table and advaned spark right below his idle level.

See this table:

(IMG:http://www.msefi.com/files/ignition-idle-control_102.gif)
http://www.msefi.com/viewtopic.php?t=15094...ight=idle+speed

Obviously this won't work for warm up enrichment because your fast idle mechanism is going to keep the engine speed far from your low idle spark advance. Question is will the idle bounce off this advance and oscillate back and forth. This is where a table larger than 12x12 would come in handy.

With the FPR issue it sounds like the modified D-jet adjustable regulator is the best bet. I've seen the thread on modifying a stock FPT to reference it to the manifold. I might give that a shot instead of buying one for $60, might as well do it myself. Here is the page.

http://www.dune-buggy.com/turbo/fuelsystem.htm

[lapuwali]

Case in point: this guy is devoting a third of his advance map to idle...

Advancing the timing below the idle speed is a common trick. Dave is doing it, too. The idea is the advance will move the speed up until it chokes from too little air, then it will fall back. This may cause some oscillation, but it's better than stalling.

[Jeff Nelson]

I think there might be some confusion as to what a rising rate FPR is versus a manifold-pressure referenced FPR. (Both change FP as a function of manifold pressure.) The later changes the FP 1:1 with manifold pressure whereas the rising rate FPR can be adjusted to change at some other ratio. For guys that run boost that can be a good thing. If you think of "rate" as "rate of change" then "rising rate" would be a rising (increase) in the "rate of change". For instance the rate may be 1:1 at idle but increase to perhaps 1:3 at boost. I'm not familiar enough with boosted applications to explain why this is desirable.

Are the specified components in MS spec'd for the temperature range experienced in the stock ECU location of a 914 engine bay? If so then that is a nice place to put it.

I've got a 2.0 and have some concerns regarding the use of the 2.0 injectors. One is the excessive flow capability and getting a good idle and the other is the electrical connection. I understand that the L-jet injectors have a superior connector. Do they work with the D-jet mounting components, that is the part that clamps the injector? What would be a specific L-jet injector that would flow more like the 1.7 D-jet parts but have the better connector? Would the 1.8 Subaru injector mount ok with the stock D-jet parts? What is the connector on the Subaru part? There is a good page at SDS showing a number of different injector styles: http://www.sdsefi.com/injectors.htm (This page indicates that the Subaru connector is not the one used on an L-jet injector.)

[lapuwali]

QUOTE (Jeff Nelson @ Feb 1 2006, 05:15 PM)

Are the specified components in MS spec'd for the temperature range experienced in the stock ECU location of a 914 engine bay? If so then that is a nice place to put it. I've got a 2.0 and have some concerns regarding the use of the 2.0 injectors. One is the excessive flow capability and getting a good idle and the other is the electrical connection. I understand that the L-jet injectors have a superior connector. Do they work with the D-jet mounting components, that is the part that clamps the injector? What would be a specific L-jet injector that would flow more like the 1.7 D-jet parts but have the better connector? Would the 1.8 Subaru injector mount ok with the stock D-jet parts? What is the connector on the Subaru part? There is a good page at SDS showing a number of different injector styles: http://www.sdsefi.com/injectors.htm (This page indicates that the Subaru connector is not the one used on an L-jet injector.)

The MS processor (HC08GP32) is a 70dC part, and so is marginal in some places on the 914 that get pretty hot. The rear trunk, for example, appears to get too hot on a hot day. The front of the engine bay, from previous measurements, doesn't seem to get much more than 10dC above ambient, so unless you're driving across Death Valley in mid-summer at high noon, you're OK. The MSII processor (HC12) is a 125dC part, so it's plenty safe even sitting on the engine itself.

L-Jet injector connectors work with D-Jet injectors. The D-Jet injector connector is pretty bad, just slotting into the outer plastic bit fairly loosely and depending on a rubber shroud to hold it in place. The L-Jet connector has a plastic surround that covers the electrical connection, and has a wire clip to hold it in place. You may have to do a bit of cutting on the L-Jet connector surround to get it to fit perfectly, but it will fit.

L-Jet was used on a zillion cars, so find a car with an approximately similar cylinder size that was made in the early to mid 80s, which increases the chance of it using a hose-barb fuel connection, instead of a fuel rail. I know some Italian cars (V6 Alfas) used the hose-barb L-Jet injectors throughout the 1980s, and the 2.5 V6s have roughly the same cylinder size as a 1.7 four. The SDS site also has a handy chart showing flow rates v. max horsepower to give you a rough idea of sizing. The 914 1.8 used L-Jet with what's otherwise a 1.7 plenum and runners, so "L-Jet" injectors, at least some of them, are identical to D-Jet injectors.

I wouldn't be TOO hung up on the large size of the 2.0 injectors. If Dave has gotten in running with the fixed pressure FPR (and I have no doubt that he has), then it will work. You may find it advantageous to use the hi-res code, or MSII, so you get better than 0.1ms injector timing resolution. 0.01ms should be good enough, and I think the hi-res code did 0.001ms or better. MSII does even better still, as I recall. I'm using 1.7 injectors because I have them, and they'll work.

There's more than one kind of Subaru injector. Searching for posts by airsix will get you more detail. He's using injectors off a 1.8 Subaru on his turbo 1.7, and I'm pretty sure he's using a stock 1.7 intake setup. He'll be able to confirm this.

[Jeff Nelson]

James, thanks for your reply. As I've already got a bunch of green injectors I'll start with those. The L-jet connector seems the hot tip however. I know that Ray Greenwood (ShopTalk forums) has mentioned the superior connector.

The existance of the high-res code went right over my head. I do see that you sacrifice PWM drive of the injectors using it. I plan to eventually do spark control with MSnS-E and I assume that high-res doesn't exist in that code version.

I plan on using a manifold pressure referenced FPR and the one by MSD or a DIY equivalent looks attractive. The Summit page states that the pressure range is 36-45 psi. That would seem incompatable with D-jet injectors (29 psi).

As manifold pressure is already an input, the installation of a fuel pressure sensor tied into MS and some code to support it would seem to accomplish the same thing as a manifold pressure referenced FPR. Perhaps the processor overhead is too much or it's considered overkill when the appropriate FPRs exist. Then again there are some things that are just better done in a continuous (non-digital) fashion.

[fiid]

Regarding thermal stuff - I was reading yesterday that the MS version 3 board is setup to handle the full automotive thermal range - which goes up to around 125oC. I would imagine the MS-II processor board is also specced in this way - so if you're running the newer stuff you should be in happy land.

[bd1308]

what solder do you all use?

i have like ten kinds and each time I find something else......

b

[gklinger]

QUOTE

I plan on using a manifold pressure referenced FPR and the one by MSD or a DIY equivalent looks attractive. The Summit page states that the pressure range is 36-45 psi. That would seem incompatable with D-jet injectors (29 psi).

I'm using the MSD FPR and can verify that it is definitely adjustable to 29-30 psi.

[yarin]

QUOTE (bd1308 @ Feb 2 2006, 08:12 AM)

what solder do you all use? i have like ten kinds and each time I find something else...... b

I used 60/40, i looked into silver solder 63/37 but that actualyl has a slightly lower flow point.

Check temp ratings here: http://www.alchemycastings.com/lead-produc...ucts/solder.htm

Sn 60 (60/40) melts at 362F and flows at 375F.

The higher the Pb content the more difficult it is to solder and the hotter the gun you need. I used oversee technicians soldering with SN 10, SN 5... much more difficult to work with than good old radio shack 60/40.

Try to use the smallest diameter you can find, it makes things easier. Always clean the tip and make sure to scrub all the flux off the board with 99% isopropynol, i used a firm toothbrush.

I couldn't imagine buildnig a MS system without a relay board. Unless you fab your own interconnect box connecting and troubleshooting your inputs/outputs becomes much more difficult. The relay box lays everything out for you and includes... well duh.. relays and fuses (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

I bought my single ended relay cable from DIYautotune, however I going to crimp my DB-37 connector instead of using their solder cup type. I already have the female connector and plugs. The other end was already crimped to 12 feet of wire with a nice hefty amp connector.

Where did you guys put your fuel pressure gauge? I've seen an inline adapter, but i'm not crazy about adding two more fuel line clamps.

[Mueller]

(IMG:http://www.914world.com/bbs2/html/emoticons/hijacked.gif)

Dave H and Ben M, if you guys want a few COP's (coil on plugs), let me know and I'll send you each 2 of them, I have a bad one on my truck and I bit the bullet and bought 8 replacement units...

Britt,

the MS manual (which you should be read) recommends .030 solder, but does not mention which kind except for rosin core.

At work I use a "No Clean" solder which does not leave traces of the flux which can lead to trouble down the road if not cleaned off properly

[lapuwali]

QUOTE (Jeff Nelson @ Feb 2 2006, 07:56 AM)

James, thanks for your reply. As I've already got a bunch of green injectors I'll start with those. The L-jet connector seems the hot tip however. I know that Ray Greenwood (ShopTalk forums) has mentioned the superior connector. The existance of the high-res code went right over my head. I do see that you sacrifice PWM drive of the injectors using it. I plan to eventually do spark control with MSnS-E and I assume that high-res doesn't exist in that code version. I plan on using a manifold pressure referenced FPR and the one by MSD or a DIY equivalent looks attractive. The Summit page states that the pressure range is 36-45 psi. That would seem incompatable with D-jet injectors (29 psi). As manifold pressure is already an input, the installation of a fuel pressure sensor tied into MS and some code to support it would seem to accomplish the same thing as a manifold pressure referenced FPR. Perhaps the processor overhead is too much or it's considered overkill when the appropriate FPRs exist. Then again there are some things that are just better done in a continuous (non-digital) fashion.

On the manifold pressure...

It's not that MS can't compensate for manifold pressure differences, it can. The difficulty lies in physical limitations of the injectors themselves. Injectors, being mechanical devices, aren't all that fast. They take approximately 1.7ms to fully open and fully close, minimum. During that time, some amount of fuel flows as the injector is opening, and as it's closing, but the amount varies somewhat from cycle to cycle, so running the injector right down to its minimum time results in fairly inconsistent fueling. Worse, with the default MS code, the minimum step you can use to adjust injector pulsewidth is 0.1ms. So, you can set it to 1.7 or 1.8, but not 1.75. Ben (airsix) is running his smaller-than-1.7-injectors at 1.85ms at idle on his 1.7 (he's not running MS, so he has better resolution), so roughly 1.8-1.9ms is the rough idle range for a Type IV with stock fuel pressure, and the difference between 1.9 and 1.8ms is 5.5%, so that's the minimum step size you can use to tune idle with with a 0.1ms resolution. If you're running, say, 3% lean, you have to bump it up nearly 6%, and run 3% rich. No option.

A manifold referenced FPR raises the pulsewidths you can use with a given injector, by lowering the pressure across the injector at idle, so the resolution becomes less of an issue. If the idle pulsewidth goes from 1.8 to 3.0ms, then a 0.1ms step size drops from 5.5% to 3.3% per step (I'm just making these numbers up, btw). You're also less subject to the inconsistent fuelling caused by running the injector so close to it's lower limit.

With the 2.0 injectors, you at least don't have any problems at the top end, as you're generally not going to run them anywhere near the 80% duty cycle limit, even without a manifold referenced FPR. Dave Hunt's experience with using the 2.0 injectors shows that you can get a good running car w/o the FPR, but he also says he's gotten smoother running at idle with the HiRes code, showing that you'd see SOME gains with using one.

On thermal stuff, the BOARD and all of the non-processor parts can do 125dC. The HC08 processor, however, is still a 70dC part (maybe an 85dC part). This is a big difference with MSII, which is using a 125dC version of the HC12. Put the MSII daughterboard on the v3 main board and you have a 125dC ECU. Myself, I'd rather use the Microsquirt board than the v3/MSII combo, simply because it's then all surface mount with a vastly lower parts count, so vibration resistance and general mechanical reliabilty should be much improved.

[fiid]

I think it's only the MegasquirtII daughtercard that's surface mount.....

[lapuwali]

QUOTE (fiid @ Feb 2 2006, 02:14 PM)

I think it's only the MegasquirtII daughtercard that's surface mount.....

The brand new, not-yet-released Microsquirt board is all surface mount except for the connector (which is a waterproof AMPSEAL). Tiny board, roughly businesscard sized. No on-board MAP sensor. Currently, there's only one ignition driver, but it appears Bruce may bend to pressure to fit a second, since the target is things like bikes that MUST do DIS, and most are fours. In about a year, it should be a pretty hot item.

[fiid]

QUOTE (lapuwali @ Feb 2 2006, 02:24 PM)

QUOTE (fiid @ Feb 2 2006, 02:14 PM) I think it's only the MegasquirtII daughtercard that's surface mount..... The brand new, not-yet-released Microsquirt board is all surface mount except for the connector (which is a waterproof AMPSEAL). Tiny board, roughly businesscard sized. No on-board MAP sensor. Currently, there's only one ignition driver, but it appears Bruce may bend to pressure to fit a second, since the target is things like bikes that MUST do DIS, and most are fours. In about a year, it should be a pretty hot item.

Oh - that's the MicroSquirt or something isn't it?

[lapuwali]

Even has its own page, now

[gklinger]

QUOTE

Where did you guys put your fuel pressure gauge? I've seen an inline adapter, but i'm not crazy about adding two more fuel line clamps.

Mine is mounted in the stock location. What's a couple more clamps? I think I used 16 in the engine bay...

[yarin]

QUOTE (gklinger @ Feb 2 2006, 03:41 PM)

QUOTE Where did you guys put your fuel pressure gauge? I've seen an inline adapter, but i'm not crazy about adding two more fuel line clamps. Mine is mounted in the stock location. What's a couple more clamps? I think I used 16 in the engine bay...

Just more opportunity for leaks. I just drained the tank and removed the carbs tonight. The SS lines were fused to the cheap crappy plastic T that splits between both carbs. While trying to pull it off it split in 1/2. All that stuff is going straight in the garbage. No engine fires for me.

I had some time to plan placement of the MS and relay board. I've decided to add a little shelf in the corner next to the stock relay board mounted to the back side of the firewall. I already have 6 bolts I can play off that are being used for a race seat and harnesses.

Right now I don't have a rear window, eventually I'll cut one out of plexi because my roll cage ties to the rear shock towers. Here are pics of my car the day i bought it: BTW i'm looking to sell that Kirkey seat, it's a great race seat abut i need to drive this to and from events. Presently the car is registered and insured, just never really got a change to drive it because of never ending carb problems. http://coewww.rutgers.edu/~yarin/my914/

So I was poking around came up with an interesting idea. Since I don't have heat in the car why don't I run the relay board cable through the drivers side heating duct? I can mount the MS box in the drivers side foot well. There are two issues I see with this:

1) The cable must be heavily padded or wrapped to prevent it from banging around the empty tube.

2) The entrance for the heating duct is below the engine tin, possibly exposing the cable to some heat. Perhaps I can thermal wrap it as a safety and shield it from noise.

What do you guys think? My old plan was to run secure the cable to the roll cage, through the rear window and down across the floor. hopefully entering the tunnel at some point. Then mounting the MS in the dash somewhere. However this greatly increases my wiring lengths from about 6' to 10' or so. Comments?

[lapuwali]

If you're mounting the ECU in the cabin (esp up front), and the relay board in the engine bay, then also add the common hack to move the MAP sensor to the relay board. You don't want a 10-12' long hose there, messes up the MAP response times.

Were I to mount the ECU in the cabin, I'd probably instead mount it to the firewall behind the passenger seat, and just run the wires down through the access panel and through the stock firewall hole. That hole is HUGE, way bigger than the stock harness really needs. You'd have to work up some way to seal it around the two harnesses, of course.