Help with EFI ITB Tuning

[KMoore68]

Hi,

I have installed the EFI ITB kit that is the Triumph ITB kit that Clay pioneered a few years ago on my 1977 911 S Targa. I am running a Megasquirt ECU and I have downloaded TunerStudio to tune the car.

I can start the car, and it idles a bit rough but I'm having some difficulty with the tuning.

I've been reading the ECU Tuning thread and find it quite informative but I was hoping for some other assistance.

On startup, the AFR is indicating a lot of fuel and I can smell it but I'm not sure what adjustment I need to make. Here are my settings.

You can see that the AFR is quite low but after running for a few minutes, it does jump up to between 12 - 13.

My thoughts are to take the car to a local dyno and get it professionally tuned but I wanted to make sure it was ok to drive to the dyno.

Any thoughts?

[kclem19]

I think it’ll be hard to hurt the engine part throttle to drive it to a tuner. But if you haven’t driven it yet, it is probably not drivable and will need some tuning to get it down the road.

More info-
1) is this a fresh engine build or not? If you have to break in the engine, make sure you run in cams first..
2) have you verified static timing adjustment? If static timing is confirmed and you have a conservative timing table, 10-25 to maybe 30 degrees across the map
3) what fueling straeggy is being used? Speed density? ITB mode? Alpha N?


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[Showdown]

Balance your ITBs. It looks like you aren’t balanced.

It also looks like you need to check and confirm timing.


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[KMoore68]

Originally Posted by kclem19

I think it’ll be hard to hurt the engine part throttle to drive it to a tuner. But if you haven’t driven it yet, it is probably not drivable and will need some tuning to get it down the road.

More info-
1) is this a fresh engine build or not? If you have to break in the engine, make sure you run in cams first..
2) have you verified static timing adjustment? If static timing is confirmed and you have a conservative timing table, 10-25 to maybe 30 degrees across the map
3) what fueling straeggy is being used? Speed density? ITB mode? Alpha N?


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This is not a fresh engine build, I removed the CIS from the engine and installed the EFI and ITBs.

I am using the stock distributor, so no ECU control with the timing.

I am using Speed Density.

[KMoore68]

Originally Posted by Showdown

Balance your ITBs. It looks like you aren’t balanced.

It also looks like you need to check and confirm timing.


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I'll double check the balancing but I thought they were pretty close to the 5-6 kh/hr that Al recommended.

I am using the stock distributor. I haven't altered the timing at all.

Should I look into getting a timing light and confirm the timing is still ok?

[Showdown]

I presume you’re control fuel only and not ignition.

Even if that’s the case, check timing and confirm it’s correct.

Next is to make sure that each throttle body is getting the same airflow and that all 6 are in sync. The exact number is irrelevant so long as they’re the same and it gets you a stable idle at 900-1000 or whatever you’re shooting for.

Then you need to check that at 2000, 3000, 4000, 5000 rpm’s to make sure that it’s close if not perfect. Steady at idle is great but you don’t drive at idle.

Then you can start with tuning and for that, check the thread that Jamie Novak posted with step by step directions.

Don’t bother with a dyno until timing is confirmed and iTBs balanced.


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[KMoore68]

Originally Posted by Showdown

I presume you’re control fuel only and not ignition.

Even if that’s the case, check timing and confirm it’s correct.

Next is to make sure that each throttle body is getting the same airflow and that all 6 are in sync. The exact number is irrelevant so long as they’re the same and it gets you a stable idle at 900-1000 or whatever you’re shooting for.

Then you need to check that at 2000, 3000, 4000, 5000 rpm’s to make sure that it’s close if not perfect. Steady at idle is great but you don’t drive at idle.

Then you can start with tuning and for that, check the thread that Jamie Novak posted with step by step directions.

Don’t bother with a dyno until timing is confirmed and iTBs balanced.


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Thanks, i'll work on confirming the timing and then confirm balancing of the ITBs.

I'm a bit stumped why the AFR is so off, when I start the car it sits around 7-8 for a few minutes and I definately get a smell of fuel in the garage.

[rwest]

On my car, I just kept taking out fuel on the warm up settings until it stopped being pig rich.

Ideally you would want a way to add additional air during warmup to increase the idle speed slightly. Many ways to do this, IAC valve, drive by wire throttle programing, holding the pedal down with your foot slightly or having a manual throttle lever like the older cars.

As others have mentioned, balancing the throttle bodies individually and side to side is very important and you’ll want to make very sure that you do that or you’ll be paying the dyno shop to do it or they will send you away to get it done.

Last note is to make sure everything on the engine and ignition is good otherwise the dyno tuning won’t be as useful and you may need to repeat it.

[kclem19]

Originally Posted by KMoore68

This is not a fresh engine build, I removed the CIS from the engine and installed the EFI and ITBs.

I am using the stock distributor, so no ECU control with the timing.

I am using Speed Density.

Ok as showdown said probably good to verify timing but likely not a problem. Definitely critical to verify your ITBs are synchronized..

How is your vacuum reference plumbed? I notice your Map is scaled down to 30kpa. My experience tells me you only get to that amount of vacuum under decel. You could probably rescale the table to get more resolution in idle area (maybe the Lowest row closer to 45 kPa??)

You also want a “shelf” at the idle area so fuel is constant (four cells with basically same VE - but also need to be aware of axis scaling as to not make this a huge area. Maybe +\- 100 RPM from idle target and +\- 5kpa from idle vacuum). However, this is more critical in an ignition table (which you don’t have) and likely less of a problem with fuel (but could be if your PW output is oscillating more than 5% at idle)

I bet Jamie’s thread is good to reference from that point on.. but I’ll say it’s critical to understand which tables are multipliers in the fueling equation and which aren’t. Most are multipliers of the VE table. Is “multiply AFR” selected in your tune? Can’t remember where that is in the software, but I’m Pretty sure I have it off in mine.. if it’s off, you can forget about AFR and AFR correction for now. Make sure you log all your runs. Get it up to temp and start dialing in the VE table.. later, will focus on warm up corrections

Another thing, look for wild changes in injector PW (output of fuel calc) I had cases where noise in my MAP signal was triggering map based acceleration enrichment dumping fuel!




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[Joesmallwood]

Originally Posted by kclem19

Another thing, look for wild changes in injector PW (output of fuel calc) I had cases where noise in my MAP signal was triggering map based acceleration enrichment dumping fuel!




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The graph above looks like this might be happening. The spikes in PW would lead me to believe the Acceleration Enrichment is triggering. For this initial tuning, I would recommend turning all of the AE off until these other items are confirmed.

Lastly, Tunerstudio has a separate VE table and timing table that can be used for idle. I found this incredibly useful for tuning that eliminated a lot of issues using an IAC valve, warmup transient VE issues, etc. Isolating idle parameters from active parameters was key. This also eliminates the need for scaling around the idle area.

Speaking of scaling, the load scale should be scaled to add resolution where the MAP changes are the highest - typically around 90 kpa for ITBs. Having as many rows in this area is key to smooth transient fuel/load. If you plot MAP vs TPS you can see what this means - the MAP signal changes dramatically when the butterfly cross-sectional area starts to open up.