Megasquirt Help

[JH282]

Hi guys, I recently installed a Bitz Racing CIS to EFI kit into my 3.0 911, the car starts every time, and runs. The issue is the car will not run under 1500 RPM. I've fiddled with both, the idle screw and the throttle stop. Anytime you get it below 1500 RPM the car stalls.

I've looked for vacuum leaks using propane, and we did a smoke test this morning, no leaks found.

I don't know much about the history of the car, but I suspect it may have a cam. At 1500 RPM it sounds more "lumpy" than a buddies SC, not 100% sure though. Vacuum seems a little weak.

I ran the Tuner Studio auto tune, and it didn't help. Added a little fuel, RPM lowered to 1300 RPM but it eventually stalls just the same. Pulled a little fuel, idle surges and it stalls. AFRs look Ok.

I've got a Microsquirt hooked up to my LS powered Cayman, and that thing was a breeze to get dialed in with Tuner Studio. Am I getting my ass kicked by this Megasquirt 1 or does this seem like a mechanical issue with the car?

[flat6pilot]

Can you post print screens of the fuel setup from megasquirt?

What all did you change/add/remove from the CIS?
i.e. WUR still in place... etc...

Are you using a wideband AFR sensor/gauge to tune?

Did it ever idle when you first started tuning?

Are you sure the fuel pump is running (wired correctly through MS)?

[JH282]

CIS is bare bones, trimmed air box or "clean look", new couplers for each runner, one of those cobra head 90s on the throttle body and a cone filter. No WUR, it's a '74 so I use the hand throttle to get the car to operating temp.

I'm using the O2 sensor that came with the kit. No wideband installed yet.

It never ran below 1500 RPMs at any point. When I set the hand throttle to 1500 RPMs, or when I set the throttle stop (I know I'm not supposed to do that) to 1500 RPMs, it idles fine, revs and sounds great, it just won't run unless RPMs are up there.

Fuel pump is audible, fuel pressure is constant according to the gauge, and I ran through the system into a catch can before hooking the return line up to make sure it was working.

This thing is beating me up

[trond]

in the normal tbitz setup the fuel pressure is NOT constant but regulated by the manifold pressure. You might want to check what type of fuel pressure regulator you have and if it is the correct type that regulates pressure by a vaccum hose to below the butterfly; is it hooked up correct ? To the correct port in the throttle body (not the timed vacuum port for instance)....

[Marwil]

I had success by running stable VE values in what would be the bottom left portion of thie VE table - consider going to around 46 in the 3 x 3 block of cells in the bottom left. I would also consider going to an AFR of 13.8 in the same region of the AFR table.

[targa44]

...My 3.0 ltr is happiest in the idle area at 12.5 - 13.0 afr. I'm trying to give it what it wants, not what I think it needs. So, a bit more fuel than you've targeted. Marwil's suggestion of blocking out that lower left of the VE with the same numbers should help any wandering/surging when you get your idle down - a good initial approach... then, experiment with that small cluster of idle area and see what happens adjusting that group up or down. I believe this should be done after you're fully warmed up.

[trond]

my engine likes even richer than 13.8 at idle too. More like 12-8-13 for stable idle. The OP would need wideband for that

[jpnovak]

Do you have a datalog of what is happening as you try to reduce idle? You should be able to see if your are going lean (limit fuel cutoff) or rich (misfire) leading to engine shut-off. This will bring you closer to the actual reason.

I assume you are controlling fuel only. Tony does not include ignition in his kit.

Have you watched the timing with a light as you back down the idle speed? Does ignition cut out or get funky before it shuts off? Is the timing correct? Do you have vacuum advance pots connected? What is your MAP value at idle?

Does the engine slowly and smoothly die as you back down idle or start to get very unhappy (misfire) before it dies? Does the engine try to catch and can't?

Does the tach signal match on the dash and the PC?

[JH282]

Trond, what I meant was, when the fuel pump is on, the fuel system is constantly pressurized, it never loses pressure. It's an Aeromotive FPR set to 2.5 bar, vac nipple on the FPR is connected to the small nipple below the butterfly on the TB. Despite the fact that it's weak vacuum, it's getting vacuum.

Marwil, I tried your setting, no change. My MAP kPa is at 80 when the car is idling at 1500 RPM, so I don't think I'm even touching that portion of the table. That's also why I'm thinking there might be a cam?

Targa44, I've got at least 16 hours on trouble shooting this thing, and it seems to like the opposite. As I pull fuel, I can get it to idle at lower RPM. I pulled A TON of fuel this morning, blocked the entire MAP range between 700-1500 RPM and got it to idle at 900 RPM, but then I hit the gas, and it won't rev.

Jpnovak, I honestly can't make heads or tails of the data logs. I've posted them on the Bitz Yahoo group and got nothing. If I post a screen shot you mind taking a look?

With the Bitz kit I can only control fuel, timing looks to be at 5 or 6 degrees BTDC when it's at 1500 RPM, when I got it to idle at 900 RPM like I mentioned above, it was at 5 BTDC. No vac connected anywhere on the distributor. MAP is around 80 kPa at 1500 RPM

When the car stalls it's very smooth, no misfires, doesn't surge, RPMs drop and if I give it a little gas it comes back to life. The car has no issues starting up as long as the idle is a little high.

The tach in the car reads 1200 RPM while the gauge on Tuner Studio reads 1500 RPM. Don't know how accurate the tach in the car is, so I'm going off the Tuner Studio gauge.

[jpnovak]

If your car idles at 80kPa then you have a serious air leak or giant cams. What is the build configuration?

Normally an SC will idle about 45kPa. Find out where that air is coming from.

[Tippy]

You'd have to have some huge cams to lope at 1500.

I suspect you are running very lean (causing lopey, big cam sound) but your WBO2 is not reading correctly. Have you free air calibrated it? Sorry if you have mentioned.

[JH282]

The original owner passed away, I purchased the car from a family friend of his. No clue how the original owner built the engine, but he definitely threw money at the car. I wouldn't be surprised if it had a crazy cam.

All I can come up with is air leak. I've used carb cleaner, propane, and smoke tested looking for air leaks. Found nothing. I don't like the idea of pressurizing the system, but I'm going to try it right now. It can't be anything else right?

[jpnovak]

Pressurizing is easy. And won't damage anything unless you use too much pressure.

Pull the filter elbow. tape the intake closed. Duct tape works fine. Put 5 psi on an air hose and inject into the vacuum port. Listen for air leaks. They are usually easy to find.

Also, Even a Mod_S cam with 102 lobe center will idle at 70kPa and 800 rpm with EFI.

[JH282]

No leaks. Pressurized the intake, heard nothing, sprayed a ton of soapy water, no bubbles, wiggled and poked at everything I could. Even did a poor mans version of a smoke test blowing cigar smoke into the intake and all it did was make me dizzy.

Going to pick up a vacuum gauge and see what it says.

I've hit a wall.

[timmy2]

Have you adjusted the AFR and VE tables as was suggested earlier? My ‘78 won’t run at anything above (leaner than) 13.5 AFR at idle. (700-900) columns in the 50-70 kpa areas.
I’ll post up a copy of my screen shots for both in a bit.

[timmy2]

Just saw your latest Bitztacing email.
Responding here is easier....
Here are my screenshots of my ‘78 settings. Haven’t been touched since April 2014.

Lots of tunerstudio time spent on these. A little rich for later year engines, but the ‘78 big port loves it and really performs well set up like this.

AFR


VE table

[JH282]

Hey Timmy, I've messed with the VE table all day and still can't seem to find a sweet spot, and it seems the Bitz MS1 won't allow you to play with AFR tables. The only place I see where I can mess with the AFR is under the advance setting under the auto tune. Basically if I didn't pay for the Tuner Studio upgrade, I don't see where or how I could change the preloaded AFR table that came from Bitz. Am I right? How are changing yours?

The Microsquirt in my Cayman, allows me to tune VE, AFR, control timing, control cooling fans and other accessories, and does a **** ton more at the price tag of $350. I paid $1600 for the Bitz kit, and I feel like I got taken for a ride.

I hooked up a cheap vacuum gauge, I'm getting 8-10 HG at 1500 RPM while the engine was cold. Seems low so I decided to see if my rings where blown. I went back to the default tune before pulling plugs and every plug was extremely sooty. I'll get new ones tomorrow.

Compression test: Cyl1=115 Cyl2=110 Cyl3=115 Cyl4=115 Cyl5=115 Cyl6=118 Engine was at about 120 degrees when tested.

I'm guessing I need to address the low vacuum issue before I keep messing with the Megasquirt? Leak down test? I don't have a leak down tester. Should I go ahead and buy one and test? Any recommendations on a tester I can buy at a store or am I stuck ordering one?

Should I pull my valve covers and double check the valve adjustment?

This thing's got me going a little nuts. If my car had a face I would have punched it repeatedly today.

[timmy2]

Well, if you change the values on your VE table to the ones on my VE table and load it as a new tune your car should be at close to the same AFR values as mine are.
I don’t know what the AFR tables will do for you without a wideband O2 for measuring accurately.

Yes, I bought Tunerstudio for $60 years ago, have a wideband O2 sensor installed as well.
(Innovate LC-1, cheap on eBay)

$1600 is a relative bargain for EFI nowadays, ITB’s with MS will run you $4k before you can blink an eye! (I know as I have PMO ITB’s and a new MS system in a box in my garage waiting for me to install it)

Are you doing all adjusting with engine at full operating temperature?

Before you start tearing things apart....
Where are you located for a time zone? I’m in Oregon so pacific time.
Send me a PM with a phone number if you want to and we can talk on the phone and go over all of your settings as compared to mine.

[JH282]

I've ordered an Innovate wideband, it's on the way. I'll try the AFR table once I get everything hooked up, Thank you.

This is my first 911, so I guess I'm still getting used to the whole P tax thing. I've built a bunch of 2JZ and LS powered cars. An AEM stand alone for a 2JZ will cost you $600-$100 depending on what you want, and theres a ton of support for it. The LS is ridiculously easy and cheap, great support as well. I don't think you can purchase an MS1 anymore, but the MS2 is $450 built. I guess for the money I expected the wiring to be a little better quality, (you cant tell me that trailer light plug connector made you smile) I hate those tap connectors, maybe braided loom instead of the cheesy plastic stuff, but of course I'm mostly *****ing because I haven't had a whole lot more success with the kit.

Anyway, yes, I'm using the handle throttle and I let the car idle for 15-20 mins before I start messing with the tune.

I'm in Asheville, NC. I'll send my number here in a sec.

Thanks again for the help.

[Nux]

Originally Posted by JH282

Hey Timmy, I've messed with the VE table all day and still can't seem to find a sweet spot, and it seems the Bitz MS1 won't allow you to play with AFR tables. The only place I see where I can mess with the AFR is under the advance setting under the auto tune. Basically if I didn't pay for the Tuner Studio upgrade, I don't see where or how I could change the preloaded AFR table that came from Bitz. Am I right? How are changing yours?

The Microsquirt in my Cayman, allows me to tune VE, AFR, control timing, control cooling fans and other accessories, and does a **** ton more at the price tag of $350. I paid $1600 for the Bitz kit, and I feel like I got taken for a ride.

I hooked up a cheap vacuum gauge, I'm getting 8-10 HG at 1500 RPM while the engine was cold. Seems low so I decided to see if my rings where blown. I went back to the default tune before pulling plugs and every plug was extremely sooty. I'll get new ones tomorrow.

Compression test: Cyl1=115 Cyl2=110 Cyl3=115 Cyl4=115 Cyl5=115 Cyl6=118 Engine was at about 120 degrees when tested.

I'm guessing I need to address the low vacuum issue before I keep messing with the Megasquirt? Leak down test? I don't have a leak down tester. Should I go ahead and buy one and test? Any recommendations on a tester I can buy at a store or am I stuck ordering one?

Should I pull my valve covers and double check the valve adjustment?

This thing's got me going a little nuts. If my car had a face I would have punched it repeatedly today.

The Bitz MS1 will let you tune with ease - but it is essential to have a wideband. Tony's standard tune works with standard engines, so if your car is modified, you'll need to correct it, which is impossible without a wideband. Ask me how I know......