Post your ITB Setup

[rwest]

Do you think the MFI filter unit is sealed well enough that you could take an accurate summed MAP signal off of it?

[montauk]

Originally Posted by rwest

Do you think the MFI filter unit is sealed well enough that you could take an accurate summed MAP signal off of it?

Did you mean MAF? That’s a great question—there are quite a few potential leak points to consider. I made gaskets to seal the connection between the filter bases and the ITB tops using plain gasket paper, but ideally, they should be rubber or silicone for a better seal. The rubber gaskets between the filter bases and the top seem snug, so those shouldn’t be an issue.
There’s also a large rubber seal behind the circular air intake piece, which helps maintain a tight seal. I’ve ensured the drain pipe on mine is completely sealed, but I’m not sure how to handle the hose from the oil tank. It would likely need to be routed to a catch can, with the opening at the filter sealed.
Do you think our cars would benefit from a MAF

[rwest]

I was thinking MAP, as you could get an average of the system rather than taking it off of each throttle body therefore leaving the individual vacuum ports available for idle air for those of us not having drive by wire benefits.

[montauk]

Originally Posted by rwest

I was thinking MAP, as you could get an average of the system rather than taking it off of each throttle body therefore leaving the individual vacuum ports available for idle air for those of us not having drive by wire benefits.

Oh, I didn't realize that was an option. You're way ahead of me with all this. Frankly, I'm surprised my car runs as good as it does. Beginner's luck I suppose.

[rwest]

Originally Posted by montauk

Oh, I didn't realize that was an option. You're way ahead of me with all this. Frankly, I'm surprised my car runs as good as it does. Beginner's luck I suppose.

I have nothing on you! Your methodical approach has almost guaranteed a good running system.

I’m running on MAP and factory pedal linkage, so not able to use the vacuum ports to introduce idle air to raise my cold idle and keep the car running without me holding the gas down slightly until warmer. I think I’m going to try to set up a TPS based VE table and see how that works. My car does run pretty well with MAP as my compression ratio is low and my cams are mild.

[SiracHaile]

MAP should be read after the throttle blades before the intake valves.

[rwest]

Originally Posted by SiracHaile

MAP should be read after the throttle blades before the intake valves.

Thanks! I was thinking that might have been the case, appreciate you chiming in before I might have spent a bunch of money for naught.

[mikesarge]

… however… a MAF signal would really be the trick. Fewer folks tune that way around here, but it is an extremely accurate way to gauge how much air is entering your engine.

I ended up bailing on MAP (and megasquirt actually) in favor of a TPS based system and so far the car is running much better, and I have a functioning IAC. Haven’t done any track work yet but so far around town it’s much smoother and faster than the MAP or even the “ITB mode” based systems I was working with before. I still think a MAF would be the ideal air metering solution

[SiracHaile]

Yes for ITB TPS base tuning is better due to the lack of stable vacuum for ITBs. The plenum is too small to provide a smooth signal. Some have made it work but speed density(MAP) based tuning is better if you have a single throttle valve and a plenum. A very good tuner can blend the two and utilize both TPS and MAP. My tuner recommended using the MAP sensor on my ITBs and he has been able to successfully tune ITBs on GTRs and other ITB engines. Hoping to finish mine by the end of the year so I’ll update on my setup. Haltech R3, Clewett ITBs, full built 2.7 with forged internals. Hopefully it does well.

[Showdown]

If you intend on using MAP to tune (speed density) then you must do a few things:

1.) make sure that the vacuum readings come from after the butterflies. This is absolute and not negotiable.

2.) collect all 6 hoses from each ITB and gather them into a common manifold, even better is to group 123 into a manifold and 456 into another one and then group those into a third. Wanna be even better; fill each manifold with open cell foam to further limit pulsing.

With that (after you balance your ITBs) you'll have a really stable and even MAP signal that will allow you to tune with Speed Density.

If you're on software that allows it, you can scale your VE table, or use dual tables like I did: one table for 30-80kpa, and the second for 80-100kpa. this gives you really tight and precise control over the active range of the MAP signal (80-100 in my case) so you can pinpoint what AFR you want where...

Totally possible to get a really great tune with speed density.

One of the benefits is that it's based on what the engine actually needs, not an assumption (TPS) and it's much faster to change than TPS so when dialed in, the engine genarelly feels super snappy.

[KMoore68]

Julian,

Do you have any more information on creating dual tables? I'm running Alpha-N and I'd like to investigate how I can get tighter control over my low TPS % numbers

[montauk]

I finally had the chance to put some local miles on the car while recording data. This was also my first drive with an air filter—until now, I've been running solely with the velocity tubes for about 50 miles. Honestly, I can't say I notice any difference with the filter installed.
For the MAP signal, I routed all six tubes into a single manifold before connecting them to the ECU’s built-in sensor. I ensured all six tubes were the same length, though I have no idea if that actually makes a difference. I might experiment with running on MAP, but so far, TPS has been performing excellently.
Here’s the long-term trim data. I'll incorporate these values into the base VE map before my next drive. I haven’t populated many cells yet, but I’m hoping to get the car on the highway soon.

[rwest]

Have you seen this thread? EFI Tuning - How to Process Description

Jamie put down a lot of info from his years of experience.

He also has a great method to cover most of the cells. He calls it left foot dyno. You use the throttle to hold a steady rpm of the cells you want and then by applying the brake and giving more throttle to keep it at the proper rpm, you can cover the whole scale. He discusses this starting at post #6

[Showdown]

I only know how to setup dual tables on TunerStudio and Megasquirt. I’m. It sure if other ECUs have that capability.


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[shamrok]

I've run TPS-only, MAP-only, blended ITB mode (Megasquirt's iteration) for years each and...I can't really tell the difference when they're all tuned. I've settled on TPS-only simply to clean up the engine bay and eliminate most vacuum lines. Don't overthink it, tune whatever you can best wrap your head around IMO.

[KMoore68]

Originally Posted by Showdown

I only know how to setup dual tables on TunerStudio and Megasquirt. I’m. It sure if other ECUs have that capability.


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That's what I'm running

[winders]

I worked with Oscar Zelaya to tune my race engine. He used to work at MoTec USA and now has his own company and works for the Cadillac GTP team. Oscar has tuned a zillion ITB-based engines and unequivocally said to use Alpha-N (TPS) to tune the ITBs…even for part-throttle areas of the tune. Setting up an air plumbing system to accurately read the MAP is problematic at best and likely inaccurate. You are better off using Alpha-N and a closed loop lambda setup with a lambda sensor for each bank. Of course you would have air pressure sensor to read barometric pressure as well so adjustments would be made based on that. It would also be good to have an ECU that could be given the injector flow profile based on fuel pressure.

With this setup and drive by wire, you don’t need an idle air control setup and you get rid of the vacuum hose mess…much cleaner and super reliable.

[montauk]

Originally Posted by rwest

Have you seen this thread? EFI Tuning - How to Process Description

Jamie put down a lot of info from his years of experience.

He also has a great method to cover most of the cells. He calls it left foot dyno. You use the throttle to hold a steady rpm of the cells you want and then by applying the brake and giving more throttle to keep it at the proper rpm, you can cover the whole scale. He discusses this starting at post #6

Yes but thanks just the same for the reminder. I'll go through it again. He's the Yoda of all things ITB.

[jac1976]

Originally Posted by montauk

Yes but thanks just the same for the reminder. I'll go through it again. He's the Yoda of all things ITB.

I’m calling him Yoda from now on

[montauk]

I recently posted on Showdown's thread about using the Haltech ECU to drive the stock oil pressure and temperature gauges, and I thought I’d share my settings here.

In addition to controlling the gauges, I’m using the ECU to trigger the low oil pressure warning light through a conditional statement. This was something I had considered during the build, but I wasn’t entirely sure it would work. Not long after I got the car running, my ten-year-old oil pressure sensor failed. Rather than spending money on a new one, I decided to let the ECU handle the job.

To make this work, I had to purchase a combination pressure/temperature sensor, which conveniently uses the same threads as the oil warning light sensor, making the swap straightforward. The trickiest part was configuring the DPO (digital pulsed output) signals. Since there’s no predefined setup, I had to rely on trial and error. While I’m still fine-tuning the settings, the gauges appear to be accurate

Here's a few photos of my settings.