Jump to content
slowlearner

L18, ITBs, Megasquirt and other questions

Recommended Posts

Hi guys,

 

In the throws of getting a hot L18 ready for a 510 I've just bought. The plan has always been to convert the car to EFI using a megasquirt 2 (Microsquirt) ECU. Then yesterday, my neighbor, an old ski boat racer and machinist suggested we try something different than building a plenum for my weber manifolds and welding injector bungs on them. In a moment of brilliance I pulled out these old ITBs I had for a VW motor and the spacing of the ports is very similar. So we're hoping to make some alloy adaptors and use them with more modern injectors.

 

 

I personally think they'll suit the era and look of the Datsun, but I've never used ITBs before. I had a single TB on my last car with turbo/Microsquirt EFI and loved it. So I have some questions...

1. I'm not going to use a plenum, because I have foam sock filters. I'm wondering about using the intake air temp and where to put it. Would it be ok to put it in the open air right next to the sock filters?

2. Are there any things I need to know about L series 4s and ITBs? Do they have some weird flow dynamics I should know about?

3. I assume my brake booster and MAP sensor will need a vacuum block to work correctly with the ITBs?

 

Any other insights on EFI on L series 4s is highly appreciated. I'm a Datto newby atm having moved across from aircooled VWs.

 

 

Share this post


Link to post

I'm curious about the ECM/ECU technology these days. With the rising popularity of systems like FiTech and Holley Sniper, is there a simpler system for the non-4 barrel crowd. What I mean is, could one simply purchase an FiTech system (because they're cheap) and scrap the throttle body, but use everything else. If so, would the computing be up to par for a custom application? They are "self learning", which can be good and bad.

 

It's on my list of things to try.

 

 

Share this post


Link to post

Consider picking up an AUDI vacuum pump for the brakes.

They are cheap, and have a built in switch, so they only come on when the vacuum drops below about 25 inches of vacuum.

 

Then do as you mentioned, and run a line from each bore to a small plenum chamber for the MAP signal.

You get the benefit of those lines acting as a balance chamber, equalizing all bores during idle, making balancing the ITBs easier, and getting a much better idle.

Those old style twin bore ITBs sometimes would even be off on flow from one barrel, to the other on the same body, making for poor idle, and especially when just cracking the throttle off idle.

 

And sock filters never flow as much as a single large filter, so if you are going for performance, they are not the way to go.

On my bike carb set up, I used an old Z-car oval filter assembly by cutting the 2-carb backing plate, and making a new one with 4 holes.

 

DSC08126.jpg

  • Like 1

Share this post


Link to post

What I like about more main stream stand alone ECUs, is that the people making them have base programs for just about every engine application.

So you wire it up, load the base map, and fire it up to do final tuning. Not spending a day trying just to get it to idle, and hope you don't blow it up just trying to tune it.

To me, the mega-dribble ECUs are archaic at best, and lack the sophistication of something like the new AEM Infinity.

 

It would be easier to just use a stock ECU, with all the stock sensors, injectors, and TPS from something like a NA CA18, and a simple Apex-I Super AFC to fine tune it.

Cost less than a mega-dribble, and more reliable.

  • Like 1

Share this post


Link to post
4 hours ago, G-Duax said:

What I like about more main stream stand alone ECUs, is that the people making them have base programs for just about every engine application.

So you wire it up, load the base map, and fire it up to do final tuning. Not spending a day trying just to get it to idle, and hope you don't blow it up just trying to tune it.

To me, the mega-dribble ECUs are archaic at best, and lack the sophistication of something like the new AEM Infinity.

 

It would be easier to just use a stock ECU, with all the stock sensors, injectors, and TPS from something like a NA CA18, and a simple Apex-I Super AFC to fine tune it.

Cost less than a mega-dribble, and more reliable.

 

Don't knock it til you try it. 😉

 

As mentioned in the original post, my previous ACVW with the simple Megasquirt (Microsquirt) ran great. The only things that let me down were factory parts off other cars, idle motor and injectors. It is the cheapest ECU money can buy here too. Our current exchange rate is US0.67c, paypal then lowered that to 64c. For that reason alone, I avoid any of the big brands like Holley etc. The features of MS2 are about level with Mid-late 1990s factory ECUs. If I wanted to go crazy, I could add sequential spark and fuel, but for a street motor it's hardly warranted.

 

As for tuning, with the autotune function, I just got the car running with conservative ignition figures and took it for a drive. The software would adjust the fuel table and give me a good running tune. Then I just needed fine tune cold start and accel enrichment. 

 

With regard to sensors, GM parts are pretty cheap here so I'll be using them as on the last motor. 

 

BTW, Thanks for the tips on socks. Maybe I'll rethink that, but I'm trying to keep costs down as you can imagine. 

  • Like 2

Share this post


Link to post

The backing plate with velocity stacks doesn't really cost anything if you build it yourself. All you need is a donor air filter housing.

 

The look cool too. Vintage vibe.

  • Like 1

Share this post


Link to post

I use a microsquirt on our Bonneville motor.  I'd share my program file when you're ready for it.  

Add a cam sensor to the valve cover, reading off the front fuel pump eccentric, cut back to a single 2mm wide tooth.  

The IAT can be mounted anywhere fresh air is entering the engine bay, near the ITBs.  

If you buy a set of Weber manifolds and Weber DCOE style throttle bodies, you'll get cleaner pulses into each individual cylinder instead of sharing runners, which will never be ok due to the firing order.  With your VW manifolds you'd be just as well off installing a FiTech on a DGV manifold.  It'll have all the same problems, as I've installed 3 FiTech systems and they're pretty good compared to say an Edelbrock carb or a base model Holley.  

With the VW manifolds you don't have ITBs, you have shared throttle bodies.  Your airflow velocity will be terrible, pulling from 2 TBs at a time.  It'll be super difficult to stabilize the MAP signal and even harder to get the injector pulsewidth to handle low and high rpm.  

 

Stoff - I've thought about the same thing with FiTech, and the short answer is that their self-learning parameters are based on the airflow through their throttle body so everything would change when you ditched it.    At least with MS you can alter the parameters (such as the required fuel and injector size) until the self-tune works without a skew.  

  • Like 1

Share this post


Link to post
On 9/7/2019 at 1:32 AM, distributorguy said:

I use a microsquirt on our Bonneville motor.  I'd share my program file when you're ready for it.  

Add a cam sensor to the valve cover, reading off the front fuel pump eccentric, cut back to a single 2mm wide tooth.  

The IAT can be mounted anywhere fresh air is entering the engine bay, near the ITBs.  

If you buy a set of Weber manifolds and Weber DCOE style throttle bodies, you'll get cleaner pulses into each individual cylinder instead of sharing runners, which will never be ok due to the firing order.  With your VW manifolds you'd be just as well off installing a FiTech on a DGV manifold.  It'll have all the same problems, as I've installed 3 FiTech systems and they're pretty good compared to say an Edelbrock carb or a base model Holley.  

With the VW manifolds you don't have ITBs, you have shared throttle bodies.  Your airflow velocity will be terrible, pulling from 2 TBs at a time.  It'll be super difficult to stabilize the MAP signal and even harder to get the injector pulsewidth to handle low and high rpm.  

 

Stoff - I've thought about the same thing with FiTech, and the short answer is that their self-learning parameters are based on the airflow through their throttle body so everything would change when you ditched it.    At least with MS you can alter the parameters (such as the required fuel and injector size) until the self-tune works without a skew.  

 

Thanks. A base tune would be awesome.

 

The VW manifolds are ITBs. The TBs are not shared. I'll post a better pic and you'll see what I mean. There's a wall between each runner.

 

 

In other news, my Microsquirt turned up the other day. So I guess I'll be working on that at some stage. Also got my Spartan Wideband.

 

The spartan manual says I need the sensor 2' from the port. Here's my issue. My headers are 4-2-1. 2' from the port is part of the 2 section, not the big 1 section past the last merge. Is this going to be ok for WB figures?

 

 

 

Share this post


Link to post

You need to install  the O2 in the collector, or in the pipe after the collector if you can guarantee  no leaks.  If you don't read all cylinders, you'll have a harder time tuning.  I suggest the band-clamp turbo-flange style weld-on collector attachment like you can buy on Amazon for attaching your header to the exhaust  pipe.  

Share this post


Link to post

Re-reading your post, you need the sensor "at least" 2' from the port.  Any closer and you shock the O2 and damage it.  

 

Your best bet for an O2 controller is the gauge that can both display and acts as its own controller.  Wiring is far less cluttered.  One less thing to mount under the dash.  

https://www.amazon.com/Innovate-Motorsports-MTX-L-Wideband-Ratio/dp/B004MDT8MW

This way you can skip the LC-2 which becomes a pain in the ass and needs to be recalibrated frequently.  Sensors are less expensive than the early kind, but can fail more often if out of spec too frequently.  Don't forget to order a mount for the gauge - either a plate or cup style.  

 

If you plan to use the distributor, it'll be simpler but you'll need to get it recurved to suit.  I can do that very effectively.  I suggest using single points not electronics to make the signal clean.  

Then you can skip the cam sensor.  If you chose to use a cam sensor, then you need a crank trigger installed (you really need it anyway) and you could add coil packs and go distributorless.  That's a major plus.  I used the expensive Innnovate coil packs and don't regret it.  

 

If i send you a tune file, you'll need to make a LOT of changes unless you go to distributorless with the same cam sensor and  coil packs.  Its anything but easy.  

  • Like 1

Share this post


Link to post

Right, that makes sense. I bought a Spartan II, so I'll be using that. I agree the LC2 is a pain. It forever ate sensors. I also don't really see the point in a gauge once the motor is set up and tuned as the ECU looks after mixtures. During the tuning, the software tells me my mixtures anyway from the Spartan's input. 

 

I'm not using a distributor. On the last motor I used just a crank angle sensor and a 36-1 wheel. Like last time, I'm also using the VW golf coilpack MS recommends for wasted spark. I never had a drama. I guess I could use the dizzy as a cam signal.

 

BTW, here's a pic of the ITB flange. As you can see it's heavily ported for a VW motor. I'll need to make sure I can get the gasket right for the datto.

 

fim8LaD.jpg


 

 

Share this post


Link to post
3 hours ago, slowlearner said:

Right, that makes sense. I bought a Spartan II, so I'll be using that. I agree the LC2 is a pain. It forever ate sensors. I also don't really see the point in a gauge once the motor is set up and tuned as the ECU looks after mixtures. During the tuning, the software tells me my mixtures anyway from the Spartan's input. 

 

 

It's still a good monitoring tool in real time when driving. Like a tach or oil pressure gauge.

Share this post


Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.