legacycentral bbs

I built the FCD that you posted on your site. Tested it on the lab bench at University where I attend and it works great, just like it is supposed to. However it doesn't work in the car?? I attached all wires to the device by splicing into the wires under the hood near the sensor. Ground is spliced into the red wire on the MAP (presure) sensor, 5v+ is spliced into the white wire of MAP sensor and then the black wire was cut running the sensor output into the boards input and the boards output back to the black wire making it's way to the ECU. The 12v+ is hooked up to the green (and yellow?) wire that goes to the Pressure exchange solenoid or whatever the solenoid is that feeds the MAP sensor. So as soon as I hook it up and start the car the white 5v+ feed to the sensor goes into a 2.?V limp mode it seems and then my black wire output from the sensor goes to zero which pulls my output on the circuit to 0. Get any boast and the car shuts down. So if I connect the sensor output wires and bypass my circuit when I reset the computer all is well again and I have 5V+ at my input and a varied output? Just not sure why the computer instantly goes into a limp mode when the output is run through my chip as it works fine on a test bench at school? Not sure if you have any ideas? I checked all connections from the wires I spliced into to the chip and they are good, just don't get any voltage into my input when it's hooked up? Right now I have it hooked up but don't have the input plugged in, this just gives me the output which the 5V source is at – which like I said is 2V right now cause of limp mode or something. Any ideas would be helpful?

-Thanks
-Mark

Woah, dude, use paragraph breaks! It'll make it a lot easier to follow what you're saying. :D

The green/yellow wire at the pressure exchange solenoid isn't the one you want. That's the switched ground side. Tap the yellow-with-red-stripe wire at the pressure exchange solenoid for +12v.

The other connections seem fine, and since you confirmed the circuit's functionality on the bench, fixing that one thing ought to do it. Good luck!

Well it's looks like I did tap into the yellow with red strip after all. I thought I had checked and made sure I had 12V+ on the board.

So now I am confused, perhaps I'll just try another reset and see what happens? Anyways thanks or your reply and if you happen to think of anything else I am all ears. I'll let you know if I get it working.

-Thanks again
-Mark

Hmm, okay...

Well, as far as I know the ECU never intentionally lowers its 5-volt rail's voltage to around 2 or 3 volts, so I'd worry that you're somehow loading the rail too much.

Can you verify that the 47K and 10K resistors you used are actually 47K and 10K?

I used 10 and 47 ohm resistors. Guess that explains it. Thought it was just the ratio didn't think about load.

-I'll swap them out and let you know what happens
-Thanks
-Mark

Woah! Yeah, that's definitely your problem.

You're right that the ratio is more important than the actual values, but you do need to make sure they're high enough. You could probably get away with 1K and 4.7K, for example... But I'd recommend at least 10K and 47K if not higher.

Well tried the 47k and 10k, seems like I get a bit to much voltage out of that though. Get fuel cut of still but not the same as I did before.

Anyways, now going to swap out the 10k for a 12k, and that should bring me down enough to work I do believe.

-Thanks again, I was starting to go crazy...
-Mark

What do you run for timing? I have a resitor that is grounded now - (may be one more wire used aswell can't remember it's been in there so long) that is hooked up to the knock sensor input on the ecu.

Pretty good advance I think and never retards. (Had real good success with it last year on another 91T I set up for a little track use) I was wondering if we could have a similar circuit for timing though... Knock sensor varies resistance so it's different but could there be something similar.

Perhaps I am way off and the knock sensor doesn't effect it but it seems to make a difference. I bought a Gtech Pro Competion last year and did about a million 0-60 and 1/4 miles with different settings. Anyways, just wondering if there was a way to control timing too.

Ok, all is well now little circuit works like a charm, but car didn't feel to quick.

But now it's all starting to make a bit more sense to me... about the timing and what I thought I was doing with the resistor on the knock sensor. Ya was looking at your timing vs load and rpm map.

I see why it felt like I had so much more power before I put the FCD in.
I use to have a one way valve in line with the map sensor to get rid of fuel cutout. Well at first I just bled the pressure for a while then I just blocked it with a valve. Looking at the maps I was getting a very high advance

I was under the impression this little mod controlled fuel maps not timing and I thought I could use some more fuel over my old set up. Ooops.

Anyways, may have to go back to the old set up as the advance is great and doesn't seem to wreck anything, have driven like that for over a year. Just have to put 93 in it... and make sure boost is 15 psi or slightly under (Have a wrx turbo on it now). Well it's ok like that for winter, last summer in the other 91T with same set up I also had the wrx intercooler in. Haven't taken the time to put in this car yet - requires a liitle use of a hammer

Thanks again
-Mark

The FCD doesn't directly control maps or anything like that. All it does is clamp the measured manifold pressure reading.

I don't think the ECU uses manifold pressure in the load computation; it just tacks on some boost-based timing retard and dumps in some extra fuel after the rest of the computations are done.

If I were you I would hook my knock sensor back up. I've heard from several tuners that EJ engines can lightly detonate without it being audible, especially to untrained ears.

Other than the TD04 turbo, what mods do you have to justify increasing boost?

To justify increased boost?? Do I need to...

Umm not much at all, have a 3" turbo back exhaust (well start about 8 in back from the turbo), put a 3"high flow catco cat in a few months ago (starting to clamp down on exhausts around here) and run just a straight through muffler - it's rather loud, think I will put a chambered one on. Other than deadning the knock sensor and increasing the boost the car is stock. Well I guess I have a tranny out of a newer legacy with 4.11 gearing but that obviously doesn't help the engine in any way.

I just have had good success with the set up, it's quick and hasn't given me any problems. Does go through a ton of fuel though??? Not sure why such bad millage - like 15 or 16 around town??

On the highway its not bad though.

Anyways always looking for some cheap mods to help out...

-Mark

Well, if you assume that the car was designed by engineers who knew what they were doing, then you shouldn't increase boost unless you've done other modifications to reduce underhood temperatures, improve flow, and improve knock resistance (intercooling, freer-flowing exhaust, etc).

15 psi with a TD04 with just an exhaust seems a bit high in my opinion, especially when you've reduced the ECU's ability to detect detonation.

I agree with vrg3.

Personally, I wouldn't run much over 10 psi without an intercooler.

Put an intercooler on quick. If nothing else you'll be amazed at how much harder your car will pull. Trust me, it's well worth it.

I hear what you are saying, just been doing it for a year without any problems so far - who knows though - figuring on a high factor of safety:) If I had some extra money I would certainly do a few things but as a poor student in mechanical engineering thats the way it goes for now.

On the other car when I parked it for the winter I had a 255l/h pump (which seemed to make no difference) a hood scope off a Mustang with air ducting through the intercooler and a water nozzle spraying on the intercooler (came on with boost switch) What else, had a tranny cooler and smaller tires (205/50) with the the 4.11's and the TD04. Also lightened it to 2500 pounds with me it. Wasn't much left inside but it was pretty fun to drive.

The car only cost $500 bucks too so was just trying to see how fast I could make it spending as little as possible. - Hence stripping it down - which I wish I hadn't have done now, then I wouldn't have had to park it for the winter)

Anyways, thanks again for your help and I'm sure I'll be asking you some questions again at some point.

Oh, I was looking on your web page and saw the AUV project. That's cool, our university has entered the ROV competition which looks the same to me (just bigger I guess). They did real well last year with it, in fact I think it won first place at a competition this summer too. Anyways, neat stuff. Were you heavily involved in the AUV?

-Mark

mreese wrote:On the other car when I parked it for the winter I had a 255l/h pump (which seemed to make no difference)

Unless you have fuel problems to begin with a high-flow pump won't help anything. It's usually necessary when you start doing upgrades that require a lot more fuel and so bigger injectors.

a hood scope off a Mustang

Oh, neat. What generation Mustang? How hard was it to fit?

Did you have trouble fitting the TD04 turbos? From the looks of it, the hardest part is apparently just getting a 90-degree bend for the compressor inlet -- is that right? I've heard that the TD04 isn't really much better than the stock Legacy turbo, but I've also heard that it is noticeably better... what's your take on it?

Oh, I was looking on your web page and saw the AUV project. That's cool, our university has entered the ROV competition which looks the same to me (just bigger I guess).

Well, the difference between an ROV and an AUV is the difference between remote operation and autonomy... It's a different kind of application, since the AUV can't have any communication with other computers or with people.

They did real well last year with it, in fact I think it won first place at a competition this summer too.

Pretty cool! Which competition? What school do you go to?

Anyways, neat stuff. Were you heavily involved in the AUV?

For the first few years I was. I was on Cornell's team the very first year and it was really cool to progress as far as we have. This year I'm not doing anything on the team and last year I did very little. They seem to be doing really well without me though. The most fun part for me was establishing the foundations anyway.

The hood scope was off an old 5.0L. It happened to be black and so was my car. Actually I just drilled four little holes in my hood and on it went. It seemed to fit the profile of the hood well. If you really wanted it perfect I am sure just a little filler would make a nice contour from the hood to the scoop but it didn't stand out. It actually worked real well, that and the spay on the intercooler where good for 2/10 on the car in the 1/4. Kept it from getting heat soaked when you were boasting for long periods. Well maybe only 1/10 on the first run but if you did another run within a few minutes 2/10 on that one

The TD04... ya hard to say, not way way better but for the price was a great upgrade - the stock one is just so tiny. If I didn't have one on the car I would deffinately grab one off ebay for the $150 or less they go for sometimes. Just that much cooler temps at the same boost and with the same exhaust housing spool up doesn't seem that much slower. I have an auto anyways so with break launches you make full boost before you ever start moving so no lag when doing that... Sheared an axle once though... ooops. Sheared off inside the cv boot right where the outer cv attaches. It was at night and the shaft didn't come out of the boot so it looked fine - I thought I had killed the tranny for sure - I can't believe how tuff the 4EATs are. Anyways you can't hold it for too long when spooling - lesson learned.

The exhaust side of the turbo appears to be identical but it's a good bit bigger on the intake side. Had a friend weld up a little aluminum elbow to feed it and then had to cut the hard plastic piece that feeds the intake on an angle to line up with the outlet. When the intercooler went on that required a bit more work but certainly worth it. Was doing a little homemade water injection before I put the intercooler on but for 60 some bucks off ebay it was a good addition too.

Hmm... so the AUV totaly controls itself? Wow that's cool, must be some pretty sophisticated programming involved. What did it have to do?

I can't remember the compitition actually, I'll have to look at the poster at school. Think it was somewhere in California this summer, not sure where else they went. The school is Lake Superior State University. Just a real small school in the Northern tip of Michigan, right on the border of Canada. I actually live in Ontario but attend school in Michigan since it's only 6 miles from my house accross the border to the school.

sorry to be the spelling nazi. but it's spelled boost

Is that the only spelling mistake I made? That would be amazing! I bet all my posts are filled with spelling mistakse if you look a little closer so you may have a lot of work on your hands...

Oh, so you didn't do any cutting on your hood (other than drilling mounting holes)? It kind of fit over the stock scoop's hole?

I didn't know the TD04 was really any larger than the stock turbo. That's interesting... I wonder if it would be possible to weld on the stock turbo's elbow.

Yup, the AUV is completely autonomous. The mission changed every year, and most of the time nobody really had any hope of accomplishing the entire mission. You can read a little about the missions at the competition web page:

http://www.auvsi.org/competitions/water.cfm

Each year's press release is probably the easiest place to get a blurb on the mission.

Ah, I think you're talking about MATE's ROV competition then. Lake Superior took first place last year:

http://www.marinetech.org/rov_competition/2003/

Pretty cool.

there have been other mistakes, but you made the "boost" one repeatedly

Well I am going to pull of the TDO4 tommorow, seems as if my oil return line is leaking. If I can find the origional turbo I'll put them side by side and see if my bro will lend me his digital camera. Then you can see the difference.

Ya, it was the MATE contest your right.

-Mark

mreese wrote:Well I am going to pull of the TDO4 tommorow, seems as if my oil return line is leaking. If I can find the origional turbo I'll put them side by side and see if my bro will lend me his digital camera. Then you can see the difference.

Sorry you've got a leak, but I'd really appreciate some side-by-side pictures. Silver lining... :)

I'm also interested in seeing how you made the 90-degree elbow.

We'll see what happens, I have to walk through a few feet of snow to a little shed in the back and see if I can find the stock turbo. Hopefully it's on the top of the pile of old parts

Should have it posted tommorow evening though.

-Mark

Well not sure how to post picks, do I need to upload them to a site first??
-Mark

Yes, you need to post them up somewhere on the web first.

If you don't have any web space, I'll PM you my email address; you can email the pictures to me as attachments and I'll post them up on my web space.