arghx

iTrader: (3)

Hey guys,

I've got an s4 n/a with the ZEMS Plug & Play Megasquirt that I'm tuning in conjunction with a shop, but they aren't that knowledgeable about rotaries specifically. The car takes forever to start... a good 6-8 seconds when cold. It turns over and sputters for a while, kinda like the sound you get when your car is flooded, but sometimes it helps a bit to lightly tap the throttle. But it still takes forever. I've got the VE table dialed in decently and now I'm trying to get my cold starts right and my accel enrichment.

I've still got the basemap cranking pulsewidths on there, but the thing is, I've got 550 secondaries. Do the secondaries squirt during cranking? They do kick in around 3800 on the ZEMS right? Maybe I should lean it out a bit?

Yet I'm thinking this is more spark related. I read the "cranking pulsewidth questions " thread but that had to do mostly with a 12A and lots of stuff like trigger angles and junk that I never set up and don't exactly understand. I know that a friend put a timing light on the CAS before I installed the megasquirt and just lined it up on the marks, so I think all that stuff is completely stock. Is there anything you guys can recommend me mess with to help this out? I just don't know where to start. I have no intention of pulling my CAS out or changing a constant that would make my spark map useless. We had to advance the timing in the cruising range to keep the car from sputtering viciously.

Are cold start problems usually more of a spark issue or a fuel issue?

EDIT:

Oh and one other question: does this ZEMS thing control the BAC valve? I jumpered the two blue wires on the harness so my A/C would work with the megasquirt, but I'm having trouble getting it idling. Reading all these threads is frustrating b/c I don't completely understand how the ZEMS is set up compared to all the bazillion other ways to set up a megasquirt on a rotary. My idle is just hard to get smooth... it will be smooth and then randomly drop rapidly and then go back and be smooth for a second or two. Is this a spark thing too? I need to get this stuff figured out before Tuesday evening when I got back to the shop for another tuning session. We went into the spark map and changed the values in the idling area to 9 or so from 5 and ran a little better, but it still randomly drops sometimes. I mean the car is ported but it idled way better on the stock ECU.

arghx

iTrader: (3)

s4 n/a running ZEMS PnP megasquirt with a somewhat tuned VE and spark table.

Ok I just made a second thread in order not to clutter up my other one about cold starts. Tuesday I'm going back to the shop for a followup tuning session. I'd like to run MAPdot accel if possible, but one of the big things I've noticed is that if I tap the throttle lightly the wideband goes full lean and the car stumbles. How can I set my accel enrichments in order to prevent that? With AE off (TPSdot threshold at 40) it stumbles if I lay into the throttle. With AE on, TPSdot or MAPdot, the car will run lean and stumble for a sec, then usually run rich (so jump from 18:1 to like 10.2:1) and then seems to smooth out to the 13ish range.

Another thing with enrichments: when I have accel enrichments on, it makes the whole care run richer at WOT, with my pedal held steady to the floor. When I was on the dyno I turned off AE (TPSdot threshold at 40) and got it dialed in pretty good, with AFR's in the low 13's and steady. But the second I turn AE on it just runs richer all over the place. Shouldn't it just be adding a bit more fuel as I tap the accelerator pedal? Should it be in accel mode under WOT? One of the reasons I turned off accel enrich was because I was having this problem on dyno pulls where, according to datalogs, it would steadily be in accel mode, then randomly jump out of it, then jump back into it, causing valleys in dyno sheets.

Could somebody please explain further: when do I need accel enrichments, what is a solid procedure to determine all the values (Kpa/sec or TPS v/sec & pulsewidth) needed for precise AE?

Thanks for all the help.

muythaibxr

None of these problems are ZEMS specific problems. They're tuning problems caused by the fact that you're starting with our NA settings.

IT seems you've gotten most of your problems taken care of though.

The cranking problem is likely because you need to mess with the PWM idle and the cranking pulse-width settings.

As far as the idle oscillation, that can be fixed by messing with the VE table in the idle area. You generally want it to idle around 12:1... T2's seem to like running richer. You want the idle advance to be around -5 to 3 degrees... and I'd set this using the idle-advance settings in the Spark menu.

As far as timing goes... You can check the timing once you get the engine running fairly easily... just get it idling (possibly change the PWM idle settings to get the idle higher, it's hard for us to set this for every car, because people often change their own idle speeds), then open your spark menu, And edit the spark settings. Change Fixed angle to -5, and then make sure the timing lines up with the timing light. If it doesn't, then adjust the CAS until it does. This could at least partially fix your cranking settings.... and might fix the cruising settings that were causing you a problem.

muythaibxr

with the MAPdot threshold at 40, MAPdot is not turned off, it's actually pretty sensitive.

The settings that the unit came with should've been decent to get you started... we've been driving on those settings with no stumbling problems.

If you're running richer at WOT with accel enrichments you have the threshold too sensitive. You're triggering accel enrichments with no throttle movement.

Next time you drive, (every time really) and next time at the dyno, please datalog your problems, and send an msq, it'll be a lot easier to help you that way.

Also, for generic tuning questions, using this forum is fine, but please don't bring up ZEMS specific issues here without first contacting tofuball and asking him.

I'll leave this thread open because your questions are valid tuning questions, but we had no idea you were having these problems because you never contacted us first.

Also, we will have a base-map in the next week or so which should fix most of your problems. The map you started with was our NA map because our TII was broken until recently, so we're still generating our TII base map..

Tofuball

I belive Ken has gotten everything answered allright, if you're still having issues, and you think it is a ZEMS specific issue, don't hesitate to send me a PM and I'll do my best to help you out.

arghx

iTrader: (3)

Alright I just went out and did some datalogs. In this log, I am cranking the car warm and letting it idle for a little while. Then I try to A/C and it idles really low and practically cuts off, so I turn it off for the rest of the log. Then I'm driving to the highway onramp, doing a couple WOT pulls on the highway, going up and down a few hills, setting cruise, getting off the highway and turning around, setting cruise again, then getting off the highway and going home. I'm also attacing my .msq file . Note that TPSdot threshold is
40 intentionally to turn accel off... I just haven't been able get the thing not to dump fuel all the time.

In a different session that is not logged (and not in the MSQ file) I went into the idle control menu to set the PWM idle and was daunted by all the million options I had. I wasn't sure where to start. The problem isn't the idle when it's cold, it's the idle when the car is warmed up and especially when the A/C is on. I tried closed loop idle and that seemed to help a little bit, but I wasn't sure what numbers to put in. I tried setting the warm idle to like 900 but it didn't do much. It was still loping between 700 and 800, just not as bad as when I had closed loop idle off.

EDIT:

It won't let me attach the datalog... says a 300kb zipfile is too big. How can I get it to either of you? I'm going back to the shop in Tuesday evening so I'd like to get your input before then if it's possible.


I guess part of the problem is that despite reading the megamanual and other stuff, I still don't understand completely how all these million settings work together to control idle and AFR's around town. I've spent a long time messing with the VE table but that's only part of the puzzle. Also, do you have any idea what TPS threshold I should try for accel? When I had it at like 5 it was causing that problem of randomly turning accel on and off during dyno runs. Oh and should I calibrate my TPS when the car is cold or warm? I just adjusted it yesterday and I'd like to get it set right in the Megasquirt.

Thanks again for all your help with my admittedly large number of questions.

muythaibxr

calibrate the tps when it's warm.

I can't see your msq or your datalog... did you attach them?

I admit that the options for closed loop idle are a bit daunting. I will mess with these when I'm back from my vacation, and give you the settings that work for us.

I've used 1-2v for rx7's for TPS accel enrichments, but I've found that mapdot works better... I usually use a threshold of 40-60 kPa/sec, and settings of 40-60 (for the bottom bin, it should be wherever you set the threshold), 80-100, 200, and 300. You can mess around with these until you get it right, but you have to do what the manual says and get freerevving to work with light throttle movement, then a little faster, and then faster still, etc... I've recently gotten my accel enrichments pretty good on our corolla (20v silver top with ITB's... a devil to tune) using this method.

One problem with the accel enrichments is that when you get them right for freerevving from idle, it can go too rich on shifts, and it's a bit hard to tune to get a balance between good freerevving performance, and good shift performance... this is supposed to be where rpm-based tuning comes into play. I've done a bit of preliminary work with rpm-based on the rx7's and on our corolla, and for both, if you get it to freerev responsively, the shift performance is still pretty good.

One thing to check that you might not have thought about as far as the dyno and constant conditions is that you need a restrictor in your MAP line, otherwise it'll be hard to get a good tune. What I normally do is take the map line (like the one we sent you) and use a connector to connect that line to the stock line. The stock line has a restrictor built-in.

Try to get me those datalogs and the msq though so I can try to suggest some changes for you.

arghx

iTrader: (3)

file was too big to attach

click here

http://fileshare.variousstuff.net/0000004460/


i'll give that MAPdot method a shot. My motor has been rebuilt and I doubt that my pressure sensor was using the original pressure sensor hose. I currently have the hose you sent me connected to some fuel line type of stuff b/c it wasn't long enough to run through the driver side firewall (just ran the MAP line through a pre-existing hole I had on the driver's side. Could explain again what the advantages are of a restrictor in the MAP line?

I appeciate your input.

muythaibxr

OK, your harness has electrical problems... not the one we gave you, but the stock one... You'll need to check your harness grounds and make sure they're clean and bolted down well... You can tell that there's noise by looking at the CLT and MAT sensor signals, and later in the logs the throttle position, and MAP signal. all the signals should be very smooth, and it's likely that the noise is causing accel enrichments to trigger when you don't want them to... I've never actually seen a log with this much noise.... especially one where there isn't any noticable noise from the CAS.

Some of what I'm seeing on the MAP line is probably due to the fact that you have no restrictor... the restrictor basically takes the "jitter" out of the MAP signal. The jitter is due to the fact that the rotary has such strong intake pulses, and a lot of back pulsing up into the intake.

This is weird though, your rpm signal looks great, and the rest of the signals look very noisy. Generally any noise can be tracked to bad grounds, or in some cases things like running low impedance injectors directly without a resistor... things like that.

You're also running closed loop, and it's leaning out the values in your VE table in some places... have you looked at the AFR table?

Also, I misread your previous posts, I thought you had a T2, so ignore any previous comments about that...

I have to say that your VE table doesn't look anything like ours though, and you're running much richer in most spots than we are.

I'm willing to bet that most of your problems are due to that noise problem though... get rid of that and your car will likely run a LOT better.

muythaibxr

I've just thought about it, you might want to check your alternator and its wiring as well... those could be causing noise.

arghx

iTrader: (3)

hmm i had my stock 70amp alternator rebuilt to 100amp spec at a local shop (it is not an FD alternator). Would that somehow cause electrical noise?

I couldn't even get the car to start when I first put the ZEMS in b/c of bad CAS noise. I cleaned the CAS connector, the ground on the starter, and ground on the passenger side strut tower and then the car got a tach signal just fine. I didn't pull off the manifold and clean that ground though.


The VE table I sent you runs somewhat leaner on my car than the one that came with the ZEMS. I have 550cc secondaries, which I had installed a year ago b/c the car was running lean due to an unrelated (or so I realize now) problem. I think all the electrical noise is contributing to this. My ports are wired open right now b/c for some reason my electroninc 6PI doesn't work without the stock ECU, plus the motor is heavily modified and made 172rwhp on stock ECU.

I dunno, I'll figure it out.

muythaibxr

alright, the alternator being rebuilt could cause this noise if the rebuilder didn't do a good job. Some AC noise could be leaking into the car's DC circuits if some of the electronics in the alternator aren't working.

So it sounds like your car had some interesting problems before putting the MS on.

arghx

iTrader: (3)

I don't have any more time or money to mess with it now that school is starting again. I'm going to sell it to someone whose wiring harness is in better shape (I will plug in a spare stock ECU and my old MAF and it should be good to go). Thanks for taking all this time to help me out. This N/A unit will work on the T2 right?

muythaibxr

It'll work anywhere with the right settings.

I'm sorry to hear that you're selling it, as you're probably very close to having the problem fixed... Chances are that if the alternator is causing you problems, it's probably affecting the stock ECU too.