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Practical Standalone Tuning: Cruise Tuning

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Cruise Tuning

02.33

00:00 - With the engine correctly tuned on the dyno, we should find that the engine runs at our aim AFR on the road.
00:07 Occasionally though we may find there is a small variation in the air fuel ratio, compared to what we saw on the dyno.
00:14 By driving the car on the road, we can check the AFR, and make changes to the fuel map as required.
00:20 Since road cars spend most of their time cruising, spending time getting the AFR correct here can show a good improvement in fuel economy.
00:29 To check the cruise mixtures you need to have an accurate wideband meter that can easily be viewed without taking your eyes off the road.
00:37 It's great if the wideband reading can also be connected to your ECU for datalogging.
00:44 Drive the car normally as you would on the road and watch what the air fuel ration is doing.
00:49 If there are any areas where you're seeing a discrepency between that and your target, you can stop and adjust the relevant areas of the fuel map.
00:58 A tip when tuning your car on the road is to drive the car for a few minutes before you make any adjustments.
01:04 This will minimise the effect of heat soak and ensure the engine is operating at a normal temperature.
01:10 You also want to be very smooth with your throttle inputs to avoid acceleration enrichment affecting the displayed AFR.
01:19 Just like when you're tuning on the dyno, you want to make sure that the engine is operating in the middle of a cell before making any change to the fuel map.
01:27 If the ECU is interpolating between cells, it will affect the accuracy of any change you make.
01:34 The next job is to check and optimise the light throttle cruise areas of the fuel map.
01:40 Since most steady state dynos have very little inertia, it can make it hard to access the very light throttle areas of the fuel map and ignition map that we might expect to use when we're just cruising along at a constant speed or slowing down just barely touching the throttle.
01:56 The dyno needs a certain amount of torque to keep rotating and if we take our foot off the throttle the car will just slow down.
02:03 The process is very similar to what we've just done, but we'll be focusing on using lighter throttle openings to drop further into vacuum.
02:13 When tuning on the dyno, it's worth taking a note of which cells you've been able to access and tune.
02:19 The ones below this are where we want to now look.