JoeTR6 Reader
Aug. 11, 2013 8:44 p.m.

After about a year of ordering parts and reading lots of documentation, I finally got the TR6 running with Megasquirt and fully sequential injection. Now the fun really begins. I'm amazed at how good the idle was once it warmed up. No hunting, settled into a smooth 1100 RPM. For the initial start up, I'm using the ITB setting for fuel which is a mix of MAP sensor based engine load and throttle position sensor. I'll play around with getting a better vacuum signal from the ITB manifold, but so far it's only working so good. There's a single port at the end of the balance tube, but I also have ports on the individual runners and can try different sampling settings. There seems to be a dead spot right after cracking the throttle (AFR going lean). Once above 2500, it revs nicely with the AFR staying in a reasonable range.

The next step is to fix the slightly sticking throttle and take it for a short drive to see what the engine does under small loads. Overall, I'm pretty excited that the damn thing didn't simply blow up or refuse to start.

Feedyurhed Dork
Aug. 11, 2013 9:05 p.m.

Let us know how it goes.....

Jaxmadine Reader
Aug. 12, 2013 6:14 a.m.

Did u bump the compression as well?

Dashpot Reader
Aug. 12, 2013 6:40 a.m.

Bump up your "acceleration enrichment" offset. It's been a while, but that and the warmup enrichment offset can take a bit of fiddling if I recall.

Paul_VR6 HalfDork
Aug. 12, 2013 11:39 a.m.

On decently sized ITB's the accel trigger should be pretty low, but with a cell tuned at that lower level.

Nice to see another one running MS.

GameboyRMH UltimaDork
Aug. 12, 2013 12:48 p.m.

I've heard that using the ITB/blended setting at first is for masochists and you should start with Alpha-N mode with barometric correction (atmospheric MAP sensor).

I've also heard that putting a fuel filter between the MAP sensor and vacuum manifold is a good way to smooth out vacuum pulses to the sensor.

turboswede PowerDork
Aug. 12, 2013 12:51 p.m.
GameboyRMH wrote: I've heard that using the ITB/blended setting at first is for masochists and you should start with Alpha-N mode with barometric correction (atmospheric MAP sensor). I've also heard that putting a fuel filter between the MAP sensor and vacuum manifold is a good way to smooth out vacuum pulses to the sensor.

Or a simple restrictor (think welding tip) after plumbing all of the individual cylinder vacuum signals together.

jpnovak
jpnovak New Reader
Aug. 12, 2013 1:55 p.m.

I have been through this a few times with ITBs.

  1. disable all accel enrichment until your table is well tuned. Once tuned you should require very little AE.

  2. The transition likely occurs at your MAP/TPS changeover point (are you still using the defualt 90kPa?). It may take some datalogs to figure out what changeover curve you should use. Megalogviewer will allow you to plot the data and find the optimal changeover points.

  3. for vacuum lines: run a single line from each throat with a restrictor into a common vacuum plenum. I used an aluminum manifold port. Then run a single line to the ECU. You may also need a restrictor to this.

Are you running MS3?

JoeTR6 Reader
Aug. 12, 2013 8:51 p.m.
Jaxmadine wrote: Did u bump the compression as well?

Compression is 10.5:1. The head has been worked, and it's running a tubular 6-to-1 header. The cam is a Richard Good GP2 cam with extra lift from the roller rockers (yes, the block was line-bored to accept cam bearings).

I decided to use a MS3 to run fully sequential injection (and eventually ignition, maybe). Plus, I like the SD card logging for autocross.

Thanks for the tips on improving the vacuum signal. I suspected the single port is simply too unrestricted. The plan was just to get it idling before doing to much experimentation. The individual vacuum ports are 10-32 thread, so about the size of a welding tip. I'm going to make a vacuum manifold with a restrictor on the output side. Worst case, I'll switch to alpha-N until I've got the vacuum signal where I want it.

Paul_VR6 HalfDork
Aug. 12, 2013 9:18 p.m.

Having done a stupid amount of itb tuning, I wouldnt recommend turning ae off, ever. That will make you want to throw the car in the trash quickly! Leave it on, make sure it isnt absurd and use ve analyze for the rest. It filters out accel anyway so there is no reason to take it off.

Disregard the above if your itbs are rediculously small for your displacement. ;)

mthomson22 SuperDork
Aug. 13, 2013 8:06 a.m.

I would second the notion of running vac lines from each intake runner to a vac block, then adding a welding tip in your MAP feed line to the MS. This is my IRTB Miata, and that setup has worked well for me.

You'll need to log in to post.

Also on Grassroots Motorsports

Modern Day Track Junkie

4 hours ago in Articles

Christina Lam went from the sidelines to full-on track enthusiast in 8 simple steps.

2017 Audi A8 L

5 hours ago in New Car Reviews

When it comes to luxury sedans, Audis are usually front-runners. The A8 L is the biggest and maybe most comfortable ...

Slight Project Pause for Our BMW M3

7 hours ago in Project Cars

Few things slow down our project car progress more effectively than a broken arm.

Grassroots Motorsports Experience Ticket Renewals Have Been Sent

1 day ago in News

Check your inbox for our Grassroots Motorsports Experience renewals.

First Drive: Turbo ND MX-5

1 day ago in News

We hit the track with Flyin' Miata's latest power adder.

Project Turbo Miata: Fire Fighting

1 day ago in Project Cars

We transfer the fire system to our new Miata.

Vintage Views: GMC Syclone and Typhoon

2 days ago in Articles

All-wheel drive, turbo power and a Q-ship’s stealth.

Classic Motorsports Mitty Presented by Hagerty Celebrates Porsche

3 days ago in News

Gearhead heaven? We think it looks something like this.

Meet the Rebels Who Started the Cannonball Run

3 days ago in News

Relive those desperado days through movie excerpts, and hear the real facts and wild stories from the legends themselves.

This Weekend at the Mitty: The Ultimate Auto Festival

6 days ago in News

Gates open this Friday for the Classic Motorsports Mitty at Road Atlanta.

ND Miata Turbo Kits Now Available!

6 days ago in News

Add 70 horsepower and 70 ft.-lbs!

What's the Plan, Man?

1 week ago in Articles

Thoughts on our racing plan for the year.

OUR SPONSORS

Grassroots Motorsports Magazine

Subscribe Today

Also get your instant access to the digital edition of Grassroots Motorsports Magazine!

Learn More
h6B4kMn4FLWaS1zfJ1HiHDXjsxefK9Wu