Here's my 2 cents...

Being a DIY system, you do need to know more than an average EFI system IMHO. You'll need to understand everything from fuel pressure, injector size to other details like ground loop & electrical noise, etc.

I have spent the last year rebuilding my engine & was brave enough to megasquirt the car with fuel & ignition at the same time. She seems to be running pretty good now & I sure learned a lot.

If you are not into tuning nor problem solving then I think going with another commercial system that someone can debug & design the system for you would be a better choice.

I am hoping the smaller injectors are the answer as I have gone over everything 10 times as I know how to check things. I replaced a new pressure regulator with another new pressure regulator. I am running two vacumn manifolds one just for the brake booster the other for distributor,ECU and fuel pressure regulator. I've double and triple checked VE tables,AFR tables,injector settings etc. etc. I am not a electrical engineer and had I known this was less of a plug and play as I thought I wouldn't have gone down this road but here I am. I've had people that claim they are experts in Megasquirt scratch their heads as to why it's not working. Every vacumn line is new,all fittings are new. Injectors,throttle bodies are new. The WB O2 says it's pig rich regardless of changes to VE tables what more is the average backyard mechanic to do???? Sorry for the rant but this is pissing me off!!! I've never had a problem I couldn't resolve but this one is bringing me to my knees. I'm thankful I'm only trying to get injection working as I have left ignition stock.

I really would look at your vacum source though I may be talking out my ass I know that if not correctly hooked up it defaults to pig rich

"People that say EFI is overrated usually don't quite understand how it works and are scared by presumed complexity."

Careful there fella....
I wonder how many folks ever gave consideration that EFI just might not be the best fueling system for their application.
If this guy's SC is stock with no plans for a cam or piston change then EFI is a huge waste of time and money.
Yes, properly tuned EFI is great stuff. But so is properly tuned PMOs or properly tuned CIS. Each has their application.
Which system is best for the SC in question? Probably a mute point sense all the money has been spent. The board is a wealth of info, you can coach him through it.

Can you post up what you engine MAP is? I'm with the poster above, it really looks like a vacuum source issue. When that's off nothing works correctly on MS. My SC with the Tbitz system was a champ, it's going back on once I finish my rebuild. No other modification that I had done in the past my SC come alive like my EFI kit.

Rarly and others: Can we define for others (and myself) what each application my be better for regarding different types of future motor work (or none, just plain re-build)? I was thinking EFI and low-boost turbo for my tight 3.0, but I love the idea of PMO's. After reading this thread, I realize that I (and maybe others) have no clue as to whether EFI is the way to go for turbo, or high-comp rebuild, or... Please clarify...

Sorry for the hijack, this is just so interesting.

Thanks much!

Eric

The throttle bodies each have one vacumn port on them and the passenger side manifold has two vacumn ports. I built a vacumn manifold for the ECU,distributor and fuel pressure regulator out of 2 inch PVC pipe 6 inches long. On each end I have 1 brass nipple screwed into the end cap ( with sealant on the threads ) and then 3 brass nipples on top. The 3 are for ECU,fuel regulator and distributor. Before I closed up both ends I took fiberglass and rolled it up and stuffed it inside I was told this is a good trick to straighten out the pulses of the engine. The two vacumn ports on the manifold I have running to a second vacumn cannister and all it drives is the brake booster. I can't recall what my MAP is but I wonder if it matters as I am running 100% TPS readings. I was told by someone that setting MS to 100% TPS we can rule out false vacumn spikes if there are any. I really think what was thought to be 30 lb. injectors may have been even larger but I can't verify that until I pull them. I do want you guys to know I really appreciate the feedback and suggestions it's just that I am very frustrated.

Hello!

I suggest starting by finding a reason why your VE changes doesn't affect idle AFR:s.

First of all: do you use closed-loop lambda? If yes, disconnect it.

Second: are your injectors too big, so that you run into pulse-width granularity issues?

Third: is there a possibility that one of injectors is bad, drizzling fuel into the engine?

Fourth: you are using ITB's. ITB's are a b*tch to get good vakuum signal from. First of all, you need to synchronize all butterflys so you get samae amount of vacuum in all of them. It's not a trivial issue even withouth EFI. If barrels aren't sucnhronized, you'll have one cylinder being too lean and another being too rich at the same time.

Fifth: when your barrels are synchronized, how do you obtain your vakuum signal? Just tapping one of them won't do it as it's in ITB's nature to fluctuate vacuum from cylinder to cylinder. You need to run a hose from EACH runner into small pressure vessel, then run a seventh hose from vessel into the MAP in order to get ironed-out and averaged vacuum signal.

Sixth: make sure you have clean 12V feed w/o spikes. Check it with oscilloscope.

Seventh: are your injectors peak-and-hold low-impedance injectors or high-impedance injectors? Low impedance injectors open lazily and that's the reason you won't find big low-Z injectors.

When all above is done, try to change VE:s once again and chech if it leans out. If not, you either have hardware issues or injectors are so big that MS resolution isn't enough. Granted, six 30lb injectors is quite a lot for a N/A engine. MSII has better resolution on PWD.

If it's still hard to tune idle on 20lb's I suggest going over to mixed Alpha-N + Speed-Density mode.

Just dig into it and be systematic.

It's not a trivial task at all. You are running a hobbyst EFI on a quite demanding motor (ITB's, unstable vacuum, big injectors). It would pose a problem with any kind of ECU.

My guesstimate is that problem is some of or a mix of:

1. Too big injectors
2. Unstable vacuum / butterfly synchronisation
3. Granularity of MS at small injector PWD times.

Post the part number off an injector. I have a database that should tell what size it is.

I am about to install my system. I am using 21# injectors to start. I also think 30# are too big. If you know you have the right fuel_req file loaded and you can not tune below 10:1 then there is a problem with either the injectors or what signal the computer is sending to the injectors.

What is the pulsewidth listed in Megatune2.25 that the injectors are running at idle? What about 2K, 3K, etc? Assume car in neutral and no load.

At what rpm can you tune the AFR to 13.5:1 or greater? Is the pulsewidth increasing as you rev the motor to this rpm?

Is the warmup signal (icon) lit at the bottom of the Megatune screen when the car is this rich? Does it ever go out? At What temperature does the idle enrichment cut-out? Have you tried setting the temp enrichment to 0 at all temps to rule out idle enrichment?

Its true that if you are running alpha-n (no MAP) the vacuum signal is irrellevant. But... Do you read a MAP signal on the realtime displays? Does it look stable or erratic? Why not run with speed density(MAP) enabled? FYI for those reading the TWM ITBs have a single port that connects all three throats through a milled hole in the casting. The single vacuum signal is therefore a measure of all three.

Don't give up. I know it can be frustrating as can any problem without an easily presentable solution.

I am running in speed density mode but with injector control 100% TPS. I have adjusted the throttle bodies with a unisyn sync gauge. Pulse width at idle is about 1.7 to 1.8. I have a hard time getting her to rev higher as she is pig rich. I have not been able to get any RPM to be 13.5-1 per my O2 reading in megatune. I have the required fuel calculated on 3000 cc engine with 6 cylinder and 30 lb. per hour injectors. I don't have a osciloscope nor am I going to buy one. I'd rather throw this in the ocean than buy more tooling to support it. The 12v source is the 3 fuse setup in the engine bay. Warm up light does light when engine is cold but does go out at 160 degrees. I have not tried turning off cold enrichment. The MAP signal appears to be jumpy per the megatune gauge how much flutuation is considered normal? Keep the suggestions coming guys!!

Hi,
A few observations...
a) If you MAP signal is fluctuating non-stop, then it will be very hard to get the car to idle properly, EFI or not.
b) Like all electronics, and I found out myself, that MS NEEDS a steady +12V. A fluctuating +12V (if you are running low impedance injectors, then the flyback circuit will/can cause MAJOR +12V changes - BTW, what version board are you running?) will cause MAP signal to fluctuate, as discussed on the MS forum.
c) 1.6/1.7ms idle PWM does sound a bit low... assuming you are running MS-1, the resolution is 0.1ms. Assuming the "standard" injector opening time or around 1.0ms, you are talking about 16% changes in fuel everytime your idle pulsewidth alters by 0.1ms.
d) Just for information - what is your idle MAP?
e) As Goran said, if you made a big change to the VE entry around the idle bins, you should see your AFR change. If not, something is not quite right.

Make sure you are doing your tuning with O2 correction turned off. If it's turned on the ECU is correcting out the changes you are making.

How are your plugs? Since you have been running rich for so long, it is probably time to replace them.

Mike I replaced the plugs today in anticipation of the new smaller injectors. Where/how do I turn off O2 correction? hobieboy I'm running MSII version 3.0 with megatune version 2.25.

With MS-II, idle PW shouldn't be a concern. Other than turning off closed-loop as others suggested, you should alp take a look at your battV log - if your battery voltage is having big swing (7V-17V) then that might explain some of your MAP fluctutation.

See this MS forum thread - http://www.msefi.com/viewtopic.php?t=19871&postdays=0&postorder=asc&sta rt=80&sid=ce2789ecb4913689a004695476214bc2

You really need good star-wired ground & I'd put a power filter before the +12V for MS.

I'm not sure if I understand how you setup MS - if you are using speed density, then your "normal" PW (except accel, etc) woukd strictly be a function of rpm & map; not tps. But you reference "injector control 100% tps"?

To turn off The O2 sensor control go to settings>EGO Control> choose disable, burn to ECU and close.

My Stim gives a PW of almost 3ms with 21# injectors. I think that 1.6 is quite low but I don't have mine installed on a car so that may be fine.

I have "acceleration wizard" set to 100% TPS, sorry I confused this with fuel injection control. I will disable EGO control once I get the smaller injectors.Battery voltage indicated by megatune gauges says consistant 13.9 to about 14.1.

If your car is drivable, why not just disable EGO, set your accel threshold very high (to prevent it from kicking in) and go for a drive now, rather than wait for the injectors?

This way, it will give you another sense about tuning vs hardware issue.

I think you should make restrictors (~1mm)for the vac lines instead of the stuffing, this is not a very predictable method.

Can you run on 'tps only' mode with MS like you can with SDS? This allows you to set fuel values with only RPM and TP, it will remove the unstable vacuum from the equation. I don't like the driveability of this setup for the street, but it might allow you to at least run the engine and do some other debugging. Once again, not sure if MS will do this.

Just out of curiosity, how much is a Mega Squirt system?

And i mean everything that went into the conversion to EFI, ITB's, wiring, ECU, injectors etc.

I went from Crankfire/MFI to a dealer installed Motec system last year and love it.

Paul

MS-II can run in 100% Alpha-N mode (TPS v. RPM) which takes the MAP signal out of the equation.