Engine and Transmission Tech

Well, it started right up. Sounds really fierce.

Doesn't miss a beat either, but it's idling at ~2070 rpm and way too lean (~18:1).

Guess that's a start anyhow. What do I do now?

Settings: Bonnie1_2013-05-31_20.35.14.msq
Datalog: 2013-05-31_20.23.02.msl

Good news Curtis!

Are you saying you can't get the idle down?

18:1 is a bit lean so you'll want to fatten that up some before you do anything else, just go to the VE map. move the red X to the green dot and raise that area.

Then if the idle speed won't come down start concentrating on air control. Close the throttle all the way, block off the IAC and if that doesn't do it start looking for air leaks.

Jim

Curtis,

Heres how I like to block off the IAC as Jim mentioned.
With the GM IAC motor, what I do is remove it and extend the plunger out with your fingers (be careful not to pull it out all the way). Then bolt it back into your throttlebody. When you tighten it down the throttlebody seat will push the pintle back inwards to the fully closed position.
Then leaving the IAC motor connector disconnected so MS3 can't retract it. Start the engine and let it warm up. Once warmed up go ahead and set your minimum idle speed using the throttle stop screw (IAC still disconnected).

I like to start adjusting the VE bins after I have the idle settings close and it is normal to have to go back and readjust the idle speed as you get your A/F ratio dailed in.

Once you have the A/F close and minimum idle speed set, then go ahead and reconnect your IAC motor.

Bill



Edited 1 time(s). Last edit at 06/01/2013 02:09AM by MG four six eight.

What Bill said.
You can fatten it up initially with the warmup wizard. IIRC, 100% is zero enrichment and the current temp of the engine will be highlighted. You should try bumping that up to maybe 150% and see if it likes it, then scale the other bins back to 100% at operating temp. Go for the settings that make the engine sound happiest.

Jim

Awesome! You guys are the best.

I found one error in my initial programming. My fuel injector flow volume was too low by a factor of four. I had grabbed a 15 second measured volume off the flow bench report (i.e. 58cc instead of 232cc per minute.)

Bill's stepper motor blocking trick worked easy. Adjusting my idle speed screw... not so easy. With the IAC blocked, idle speed was too low. My fuel rail is in the way of the screw, so I slid a 0.012" feeler gauge into place instead and that gave me a stable idle of ~700rpm. I went ahead and reconnected the stepper motor, and didn't notice any immediate problems like before. I'll remove the throttle body now to adjust the screw properly. AFR was steady at ~13.7:1 when the engine was cool but it crept upward with coolant temperature. By the time I shut down at ~165F it was ~16.9:1. (Idle speed also crept up: 880rpm.)

VE and warmup adjustments coming soon.

You're on your way Curtis!

On the VE table and the timing table you can set the red X to follow the green dot to the nearest grid intersection. This is useful for identifying areas that need raised or lowered since by just using the Q and W keys, (I think) you can lower or raise the map intersects, without even looking at the screen. Very helpful for tuning while driving. You don't necessarily want to hit the sweet spot, just identify a trend. Then when you pull over you can smooth out the map in between those points. Do that a few times and you'll be very close.

But initially you can turn follow on and then off to take the cursor to the closest intersect, then while holding steady on the throttle, work the intersects around the green dot for smoothest running, adjust engine speed up a bit and repeat. For the higher rpm's just follow the curve to redline and a bit beyond unless you want fuel cut, in which case you can drop it off sharply. (I haven't tried that personally) This will get the base line of your map established at low load. For fuel simply raise the map for higher loads initially by sloping it up. Once you drive it you will establish some trends that will help you set the slope.

Same basic process with the ignition advance. Your coolant temp, a knock sensor, and egt will help greatly here.

Also you may want to fatten up the mixture and play with the advance below your normal idle speed to help the engine recover if the engine speed drops. Like if you let out the clutch without giving it any gas. About this time you'll want to begin experimenting with the accelerator pump functions.

Jim

I'M SO FRUSTRATED! I thought I'd be driving this car by mid-afternoon. Here it is - midnight - and I still haven't got the Idle Air Control valve working right.

With the IAC valve blocked off, the engine idles really really nice.

No matter what I do, the IAC jacks up the idle to over 2500rpm whenever it's connected up. I've tried two different valves. I checked the wiring, found out the connector was wired backwards, and corrected it... and that did change how the valve moves in test mode, but it didn't bring the idle down. (Now at least I can get the valve to close... with the throttle body off for valve inspection.) I've tried every combination of start values and step values imaginable. I don't know what to try next.

But extending the pintle and leaving the connector off always provides the expected reality check: purrs like a lion.

Curtis, on start-up I believe the MS has a homing cycle it runs on the IAC (are you using the GM type 4 wire stepper, or something else?) where it cycles the IAC and closes it all the way then brings it back out to the start-up position. Have you observed its motion on power-on? Could be that something is interfering with this initialization cycle. I believe that this is how the MS creates its zero reference so if for any reason the cycle is not completed correctly the calibration will not be right. Of course you will probably want to have some kind of a stop set up so the IAC does not over extend, and this is mostly speculation since I haven't tried this myself, but I think that's the approach I would try.

Jim

That's the tip I needed. Thanks Jim! I took the throttle body back off, yet again, and watched the valve's behavior on ECM power-up. Yesterday I had tried swapping leads, but evidently I swapped the wrong pairs. Once I could really see the valve's behavior on power-up, I re-wired the valve correctly and got it stepping the right direction.

(MS3-Pro's blue/white "1A" lead needed to end up in the "B" cavity of the IAC's connector, not the "D" cavity where GM put their blue/white lead. MS3-Pro's green/white "2A" lead needed to end up in the "D" cavity of the IAC's connector, not the "B" cavity where GM puts their green/white lead. Etc.)

I've got it idling at ~800rpm with the stepper motor connected now. I've got the step values set much lower than I think other people use though: 25 steps from closed at 120F, down to 0 steps from closed at 180F. I may need to raise those step numbers a bit (and simultaneously back-off the idle speed screw setting).

Gawd, I luv carbs! ;)



Edited 1 time(s). Last edit at 06/02/2013 11:58AM by MGBV8.

E.F.I. ROCKS!

I've just returned from my very first test drive with EFI, and I guess I got carried away.

It was an hour and twenty minutes long.

Even after all the pain and suffering of getting my idle valve set-up right, I still needed to bleed my brakes, replace a damaged oil pressure gauge fitting, re-assemble my rear suspension, and get my floor jack back from the neighbor who borrowed it. (My car was stranded on jackstands all afternoon, waiting for a jack.)

But the test drive! Without adjusting a thing, my car was running as well as it ever did on a carb. Better in some respects. For example, my Edelbrock carb always misbehaved on high-G turns (e.g. when autocrossing) due to fuel sloshing around in the float bowls. That's gone, obviously.

The MS3-Pro system includes a tuning tool called TunerStudio, and within TunerStudio there's a self tuning function called "VE Analyze"... ten minutes into the test drive I turned that feature "on" and started seeing how it recommended adjusting the tuning tables. That's fun! A really great graphic interface makes it easy to see what combinations of engine speed and engine load the program needs to complete its tune-up, so you can adjust your driving accordingly. After awhile my confidence in VE Analyze ("veal") had grown, so I just let it adjust my tuning tables automatically in real time... my car drove better and better as the drive grew longer!

Obviously there's no such thing as a self-tuning carburetor, is there Carl?

My first impression is that the new EFI installation has improved my engine's overall smoothness remarkably. The engine is running much better at engine speeds over 3000rpm, and especially over 4500rpm. (It really feels great up there!) I'm not sure that it's got the same grunt at 2000rpm that I my old system had. (Keep in mind that I haven't driven my car since last August... so my perception may be way, way off. Maybe the grunt in improved, but it's overshadowed by high end performance.) I'm told that MS3 has a nifty new accelerator pump emulation feature, and I hope playing with that feature might give me the some of the low-end grunt I'm looking for. And... I've only taken one test drive.

.....and no more changing jets and rods when you come down out of the mountains and head East.

That is good news Curtis! The newer tuner studio with MS3 works SO much faster and is way easier to use now!

As you start getting the VE table dialed in closer and closer, you find that your requirements for accel enrichment should drop as well. Also you can adjust your MAP and RPM bins to the most comon engine load/RPM where your engine spends the most time during normal driving.

Also you'll get to a point where Tuner Studio will want to add fuel in a specific bin and maybe on the next test drive will want to take away fuel. At this point your tune is pretty much dailed in for that bin and I usually with will go with the value at which the engine runs the best!!

I think that you'll find that the data logger feature is very handy. What I'll do is save serveral data logs in my computer then minimize them on my computer so that I can pull them up to review them back to back quickly and easily.

Come'on Carl, step over to the dark side! We have cookies!!;-)

Bill

I'll probably be right there with y'all when I get an LS under the hood.

Quote: I'll probably be right there with y'all when I get an LS under the hood.

Vision without execution is hallucination ;).

Nice work Curtis!!!!

Once you get it dialed in you can help me tune mine this winter. I have beer..... ;)

Did someone say beer? I'm in!

Curtis, congrats on the tuning success. I gotta add, however, that you now have one of the coolest looking engine bays I've ever seen. I'm not into the glossy chrome hot rod look. I can't really put into words a description of the look that I like (industrial? simple? clean?) but whatever it is you nailed it. Maybe you weren't going for looks, but that is one cool looking engine.

Congratulations Curtis, I really envy you. Nice clean project and A1 technical execution.

Just a little bit of a follow-up here.

Before my BritishV8-2013 roadtrip, I turned off my idle air valve because it wasn't operating properly. I finally traced that to a poor connection between one of the female terminals (in one of the two Amp connectors) with one of the male terminals on the MS3-Pro computer. (Those female terminals are a progressive die stamping. They have three fingers ~120 degrees apart that are supposed to contact the circumference of the male terminal. I'm not sure that the terminal was actually defective... I may have damaged it or knocked it off-center when removing extra leads, to get the bundle size down, and/or when reinstalling the secondary lock. At any rate... I used a tiny pick to bend the three tabs inward so they make firmer contact.)

The IAC feature is now turned-on and it's working! The engine is still idling a little too fast for my taste, but the idle speed is pretty stable regardless of temperature (between 890 and 950rpm today.) To get there, I've fiddled with the programming a bit. I adjusted the "IAC steps" and also the "ASE taper" (after start enrichment) curves to be steeper. (The X-axis of both of those functions is coolant temperature.)

Incidentally, I've also rotated my distributor to reduce ignition advance by about five degrees. I was running more than I realized and probably more than I needed. I didn't really notice until reviewing the MS3's datalogs, but I confirmed with my reliable old dial-back timing light. 15 degrees at idle with vacuum disconnected should be enough, eh? That's ignition stuff... not my main focus at the moment.

---

Philosophical question:

Should the throttle butterfly set-screw be adjusted to allow a tiny bit of air to pass the butterfly when nominally "closed", or should the throttle butterfly fully close? If the butterfly fully closes, I expect the IAC valve needs to be left open at least a few steps. Because the valve's pintle is rubber tipped, I expect it may last longer if it's left open slightly. Your thoughts?