Unraveling the 961

I have a 2018 Mustang Shelby GT350R. As you know new vehicles are also throttle by wire, you can tune out the throttle response lag or you can install a piggy back throttle controller called a “Pedal Commander” it doesn’t add hp, but it does eliminate the hesitation when the throttle is pressed. Easy plug n play, no wires to cut.
https://www.pedalcommander.com/

In the case of my car, I tuned it, eliminated the throttle hesitation, and also gained 88 rear wheel hp. Most importantly when you slam the gas pedal it’s responce is like a cable actuated throttle.

Interesting, I presume it remembers your settings when you switch off?

Back on topic - fuel injectors back. As suspected no problems, but he asked where the filters were, I didn't know what he was talking about. Turns out the injectors should have a fuel filter inserted into the top of the injector.



He's fitted them now. The black insert is the filter, you can just see the little mesh basket that forms part of it inside the injector. I don't know why it's not fitted, I haven't refitted the injectors yet, but will be checking clearances carefully when I do as the filter sits slightly proud. But could be something worth checking on your bikes.

Secondly, with regard to the idle problem, I asked SCS-Delta if there was a software strategy I could employ to mitigate the cylinder stealing issue.

Got this back...

You can’t fix a mechanical problem with software unfortunately. It is charge robbing because of the way the cam timing works and the uneven firing angles.

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I'll have more to say after this weekends testing is complete.

Maybe Rob Jameson could tell us why Norton doesn't use the filter . Is it possible the fuel rail won't seal or fit it its used ? I like the idea of having them and a final defense against clogging .

As a car mechanic I’ve never seen a injector without a screen filter installed in both oem or performance injectors. Odd.

If you look at richard-7’s fuel injection manual you can see the filter is not fitted either.

ntst8 said:

Petrol VW's are similar, and the auto engine cut off often decides to do its thing just as you are about to floor it, which adds another 1/2 second or so to the get go timing.

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That's why I'm still buzzing around in a 200HP 02 Jetta Gli. I used to have a diesel Golf. 0 to 60 in about a week. Luckily, and currently, gas is cheap in the US. 2.40 US

More testing today. I wanted to see what effect blocking the IAC valve had on the each cylinder's AFR. Disconnected it and stuck my thumb over it and maintained as close to idle RPM as I could get with the throttle instead. Practically no change.

I continued to play around with the individual cylinder fuel trims and although I can't improve cylinder 1's lean condition I could smooth out the idle and have the engine sounding a little happier. Quick vid of playing around with cylinder 1's fuel trim, you can also see just how lean cylinder 1 runs.



So far my conclusions are:

• Due to the throttle bodies being linked by the IAC pipe cylinder 1 runs very lean at idle,
• Cylinder 1's o2 sensor is practically worthless as there is little the ECU can do with its information. However retaining cylinder 2's o2 sensor may be useful for achieving lambda 1 (14.7:1 AFR) at idle and cruise conditions.
• Blocking the IAC valve does not help balance the cylinders.

The solution to all this is to remove the IAC valve and block the pipe joining both throttle bodies. This would prevent cylinder 2 robbing from cylinder 1. If you did this then the o2 sensors would aid in helping the engine to idle by ensuring both cylinders were at lambda 1 (and avoid the problems those with euro 4 bikes have encountered when attempting to remove them). Although I would pull the plug to the IAC valve first to see if it causes any faults/problems. Then set the idle using the throttle position screw. All depends on how well your own bike runs as to whether you bother.

Tomorrow I'll put everything back together, connect cylinder 2's o2 sensor to see if it can contribute to achieving a stable idle. Might even manage to get a few miles in!

Why not just remove the O2 completely?
When using the megaphones, you don’t have o2 sensors.

Absolutely, but most don't have megaphones. Secondly people can get confused as to their role. Sometimes they're there to ensure the catalytic converter is working - this is when you need to fit an eliminator if you remove the cat. But the o2 sensors in front of the cat give the ECU really useful information to correct errors in the fuel map - no map is perfect esp. a factory map that has to work in all engines. In addition they're only used in a relatively small number of situations.

The image below is copied directly from the Norton factory map.



I've labelled the settings, as you can see anytime the throttle is more than 25% open no o2 sensor, whenever RPM exceeds 4,000 no o2 sensor. That's it.

I've keep them in my megaphones for the above reasons, although as I've discovered the cylinder 1 sensor will be going!

Air / fuel ratio of over 30:1 is crazy ‘hole a piston’ lean!

Is this fuel ‘stealing’ phenomenon only at idle?

What about wider throttle openings, including WOT?

Fast Eddie said:

Air / fuel ratio of over 30:1 is crazy ‘hole a piston’ lean!

Is this fuel ‘stealing’ phenomenon only at idle?

What about wider throttle openings, including WOT?

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Predominaly at idle, haven’t seen what’s going on under load. Starts to even out as you open the throttle plates (no load through). But given the engine has at least 40 full throttle dyno runs and a track day under its belt I don’t think there’s a big problem above idle. But will be taking a close look when it goes back on the dyno.

Well, you've convinced me about the port robbing. So I've blocked the passage between the two sides to see what happens. I'll post the details in a separate thread to avoid hijacking this one too much.

Ken

Which side is the idle motor feeding then ? If I understand this correctly the IAC tee's to both ports . I will wait for your post .

Good on you Ken, feel free to pollute away! I know you have a wide band o2 sensor so please let us know what you observe. I have the bike back together and was correct in thinking leaving cylinder 2’s o2 sensor connected would help the the ECU maintain a stable AFR in cylinder 2.

Just about to connect cylinder 1’s o2 sensor to record the result and confirm my observations to date.

TonyA said:

Which side is the idle motor feeding then ? If I understand this correctly the IAC tee's to both ports . I will wait for your post .

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It feeds both, there’s a single pipe that goes from the IAC valve to a tee-junction in the tube that joins both throttle bodies.

Looks like the Shelby’s are running cold air intakes with K&N type air filter from the factory. May want to try the BMC air filter in the Norton Factory air box if you stay with the air box that is.

iwilson said:

Good on you Ken, feel free to pollute away! I know you have a wide band o2 sensor so please let us know what you observe. I have the bike back together and was correct in thinking leaving cylinder 2’s o2 sensor connected would help the the ECU maintain a stable AFR in cylinder 2.

Just about to connect cylinder 1’s o2 sensor to record the result and confirm my observations to date.

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At the moment I only have a single channel O2 sensor controller (WEGO III), and it's tied up on another project bike, so nothing to report yet. I will be buying a twin channel controller and sensors asap to use on the 961.

Ken

Here’s the crazy vid. In this one I switch both o2 sensors on and watch the ensuing chaos. Cylinder 1 screams for more fuel and you can see the fuel trim number rapidly increasing as the ECU adds fuel. This fuel of course is ending up in cylinder 2 which the ECU attempts to trim (negative number).

The REALLY interesting thing that you see happening is that the AFR display starts to show both cylinders getting closer to equal readings, although both are lean. I’m wondering if this is because cylinder 1’s injector is staying open much longer (as it adds loads more fuel) and as a result cylinder 2’s piston/valves have moved sufficiently to reduce the charge robbing effect on 1 - or more likely pooling a lot more fuel on the throttle body (which takes more time to vaporise). Conversely cylinder 1 is getting very little fuel from its own injector and maybe if I had let it run a little longer it may have settled down - but it was sounding like it might stall. But I’m just guessing and hopefully someone who knows a bit more will correct or confirm my thinking.

In the second part of the vid I only turn on cylinder 1’s o2 sensor which adds lots of fuel which as can be seen on the AFR display which just leads to cylinder 2 getting much richer as the ECU is blind without the information provided by cylinder 2’s o2 sensor. I can see it on the AFR display but the ECU has no knowledge.

Perhaps I’ve missed the introductory lesson gents, but, can someone please explain how the fuel robbing works?

The injectors inject fuel (atomised?) into each port. So each port has a charge of a given air fuel ratio.

I can understand a cylinder robbing charge, but this charge would contain air and fuel in the above given ratio... so such robbing would not dramatically effect air fuel ratio.

How does one cylinder rob only the fuel from the other?

I wouid like to know as well


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