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Practical Diesel Tuning: 5. Confirming The Tune On The Road

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5. Confirming The Tune On The Road

23.36

00:00 - We're back in the truck today and we are on the road.
00:02 So we've taken the truck off the dyno, we've verified on the dyno that we make 480 horsepower to the tyre, 20% increase from our factory file and now we're going to take that horsepower, we're going to take this truck out on the street and see how it behaves.
00:16 It's important to street drive the truck after you do the tune on the dyno for a few reasons.
00:19 Most importantly, the customer's going to drive the truck, we want to make sure that the truck drives and has good throttle control, good drivability.
00:28 What is good drivability? It's easily controlled by the throttle, so does it back up nicely, does it go forward nicely, can a customer hook it up to a trailer easily? Does the throttle do as predicted? Does the truck shift well? So we want to make sure that with the added power and torque that we added that the truck is going to go through the gears, it's going to shift firmly but not too abruptly and it's going to put the power down to the tyre.
00:53 There's really no sense in having that extra power if the truck doesn't put it to the tyre appropriately and that shift quality, allowing the truck to learn the shift and potentially modifying the TCM, that could go a long way to improving that shift quality.
01:05 Also the way that you bring the power in on the throttle, can have a large impact on shift quality.
01:13 So let's talk about low speed maneuverability, The first thing I want to draw your attention to is this driver demand engine torque table.
01:19 Now this table commands how much torque the engine gets at a given throttle positon and RPM.
01:24 Across the top here is RPM, on the side rows is accelerator pedal position.
01:29 If the truck is not responsive enough at say 10 to 33%, we can highlight those cells and we can add 10% by typing 1.1 in and multiplying.
01:46 Now that's going to give 10% more torque in those throttle ranges between 10.4 and 33%.
01:51 Similarly if the truck is too touchy in that throttle range, we can subtract 5 or 10%.
01:56 I always recommend operating in those 5 or 10% increments, just makes things not too abrupt but enough so you can tell the difference as you're driving the truck.
02:09 OK so let's set the computer over here.
02:14 Let's turn our datalogger on.
02:16 Always important to datalog the truck while you're driving it.
02:18 If anything weird pops up that you don't like, it's nice to be able to see it in the data log otherwise you really have no record of it unless you know exactly from experience where to go back and look.
02:29 And if you're new to this, you're not going to have that.
02:30 So I've got our log recording, I've got the truck in the parking lot here and we're just going to take a slow cruise around the parking lot.
02:39 And I'm just moving the throttle between 0 and 15%, feeling how the truck responds.
02:44 Now in our tune file we did not mess with that driver demand table.
02:48 So I wouldn't expect the truck to have any aggressive lurch or any strange response in that throttle area.
02:56 But I also want to feel, does the truck feel excessively lazy in that area? Is this an area for opportunity? The truck feels smooth, I like the stock feel of the truck.
03:08 Some of your guys tuning may want the truck to feel more responsive in that area.
03:11 That's fine, go ahead and turn the pedal, driver demand to torque up just like I showed you in the tune file.
03:22 As you recall from our power addition, the majority of our adjustments to the tune were made in that 585 foot pounds on up.
03:31 So remember those rows, there was 585 up to 1033 foot pounds and we added 20% of fuel and we added another 5% of fuel? So really any difference from stock, any oddities compared to a stock driving truck are going to occur in that range.
03:50 So really you're not going to feel that until you're on the throttle 50 or 60%.
03:55 So what we're going to do is we're going to look for how that throttle transition feels as we go into those, the higher load section we'll call it.
04:03 That higher load section would be where I would anticipate maybe a sloppy shift or something not quite feeling smooth like it should.
04:11 I have some cars in front of me here which makes testing higher load a little bit more difficult.
04:17 I would recommend to you if you're regularly tuning trucks, find a loop out on the back roads where you can go and do a similar run without the inconvenience of traffic.
04:31 I have a nice mile by mile square that I go out and I can slow down and speed up and kind of test multiple run ups through the gears without feeling the pressure of someone driving behind me.
04:43 It's important to run the truck for a few days if you can, especially if it's a tune that you're working on that's new.
04:50 Certainly if you've tuned 100 of these trucks and you're giving it to the customer, you don't need to test it, every one for 2 days but if you're working on a new file, you want to drive the truck regularly.
04:59 The refinement process is iterative.
05:02 It's something you want to put time in, make adjustments, put time in, make adjustments.
05:06 A lot of the time you're not going to find those little hiccups unless you're driving the truck under multiple different load scenarios.
05:13 OK so interestingly one of the first things I've run into is as I go to creep into the throttle, I feel the truck cutting me back and it's flashing reduced engine power, it's really unhappy with me.
05:25 Now one of the things that I forgot to do while I was building this tune was to go into the torque control table and allow it to produce more torque than it was expecting.
05:37 We'll pull off and I'll show you what this table is.
05:43 OK so when we build the tune, we had a situation where we were testing the truck on the dyno, we had a base cal, we're going from our test from 1800 RPM, full tilt on the dyno up to 3300 RPM.
05:54 Now we're here on the street and I'm leaning into the throttle at lower RPMs and I'm having the truck flash at me, reduced power and it's really upset with me.
06:03 And this is just a situation I didn't come across on the dyno.
06:07 So it's really important to road test the truck obviously.
06:10 So what did we run into? OK if you'll remember back to the Toyota Camry, we had some issues with runaway cars or allegedly runaways, inability to control throttle.
06:20 So what the manufacturers ended up doing was putting a control into the ECU that's called torque monitoring.
06:27 What that monitoring does is it has an expected torque value and it has an allowance above or below that expected torque value, above is what we're concerned about so if you're running at an expected torque of 400 foot pounds and you're above let's say by a certain threshold, in this case we'll look at this level 2 offset table and you can see based on the percentage of inner torque, and the RPM if you're above by 12%, you're going to be flagged.
07:00 So that's what's happening to us here is we're above by more than 12%, especially at low RPM, remember the lower the RPM, the more aggressive the torque curve raise is.
07:11 So 'cause I did not massage this table, I'm being flagged pretty aggressively by the ECU.
07:20 OK so what I'm going to do is highlight this table.
07:24 We'll set it to 99 which means that the torque value has to be 99% higher than expected in order to flag a monitoring fault.
07:38 I'll go ahead and save that.
07:42 That's version 1.2.
07:47 And then we can flash that and be on our way with the data log.
07:50 OK so I have our tune revision in, we now have, should have the ability to use all the torque that we're commanding and we're going to take the truck out and go do some higher power runs.
08:00 Unfortunately, I had to bring the truck back to the shop to reflash it because I didn't have internet on the street so I'm going to drive it back out there and get on a back road and give it a little more power.
08:10 I will tell you on these Fords, the traction control is really aggressive so if you're going from a stock tuned truck to something that's modified and it starts to spin the tyres, the traction control's going to jump in really aggressively and cut that fuel rate back, it's going to feel like an issue with the tune at first and it's going to unlock the torque converter as well which takes a lot of power out of the truck so creature of habit, as I tune these trucks I always reach over and turn off the stabilitrack just so that I know that I'm not being interrupted by the traction control as I'm using the power.
08:46 OK so as we head over to our test spot here, what are the things that I'm looking for as I'm going to run the truck at high horsepower? On the dyno, remember we had the fuel rate at that 120 stock and then we went up to about 148 in a 480 horsepower tune.
09:03 So of course we've made that fuel rate on the dyno in 5th gear.
09:07 On the street I have my log file as well so I'm going to look at I go through my run, I'm going to start at a roll on, maybe 1st or 2nd gear and let the truck go through the gears and I want to make sure that the truck can achieve that same fuel rate and that it does so with some consistency because we want that power that we made on the dyno to transfer onto the street.
09:27 So if the truck was making 140 on the dyno and then all of a sudden it makes 120 or 125 on the street, well we know we have something holding us back there.
09:34 Similarly I want to look at those shift defuels so I want to look at the trace of the fuel rate.
09:41 Is the truck shifting cleanly, is it defueling appropriately on every shift or is the shift defuel really aggressive? In our previous module on the Alison we saw what the shift learning strategy looks like.
09:55 The 6R140 is a nicer trans in my opinion.
09:58 It seems to learn quicker, it holds better, the shifts are less pronounced as far as defuel goes.
10:05 So it should do pretty well to this power level but I like to just pay attention to that as well.
10:11 And then we're also going to be concerned about exhaust gas temperatures.
10:15 So on my data log I have 4 exhaust gas temperatures pulled up.
10:19 I have the EGT directly post turbo and then I have downstream exhaust gas temperatures as well which are not really useful as far as performance but the exhaust gas temperature directly after the turbocharger which is called number 1 in this log is useful and at most it'll be about 350° off of manifold temp so we want to see just how high that gets so that we can make sure that we're not out of the realm of what we would call safe.
10:54 One of the really important things with tuning emissions equipped trucks is regen frequency.
10:58 Customers are going to ask about it, it's something you should be concerned about as you tune.
11:02 It's a big reason why we control lambda and try and make sure that the truck understands the amount of fuel it's injecting.
11:08 Also the airflow.
11:10 As you're test driving the truck and doing your development on the truck, I'd recommend resetting the trip odometer on a reflash, especially one that changes any stoichiometric values, so any time you're changing lambda or potentially using more fuel or less fuel, It's important to know your mileage so on this truck for instance, 400 to 450 miles between regens is pretty normal.
11:35 Of course if I'm driving the truck really aggressively, that regen frequency's going to go up but if I'm driving the truck like I would expect one of my customers to drive it, I like to track the regen frequency, keep a notepad in the centre console.
11:47 That way I can jot down every time I see the truck go into regen, OK that was 400 miles, that was 500 miles, that was 270 miles but it was used aggressively.
11:56 Make notes like that, it's going to really help you understand what the regen frequency is on the truck, it'll help you troubleshoot any future customers who might be running this tune and may have excessive regen frequency, at least you'll know you did the testing on it, you'll know what to be able to tell them as far as what the regen frequency is.
12:17 OK so as we're getting to the quiet road as we'll call it, just kind of rolling the throttle again in 5th and 6th gear.
12:25 Just to feel that torque and where the truck went into derate before and was flashing reduced power at me, it's not longer doing that so that's a good sign.
12:35 That table that we adjusted definitely did the trick.
12:40 OK so I'm on a roll.
12:43 My log file's going and I'll flat foot the throttle.
12:52 Torque inverter clutch lock up.
12:59 That felt good.
13:03 The trans felt smooth, I say we could maybe use a little bit firmer shift but that might learn its way in, I might give that a few more goes just to see how well it comes around.
13:15 If you listen closely in the audio, I don't know if you can hear it or not but there's a little bit of a chirp on one of the shifts there and these 6R140s are kind of notorious for that.
13:22 At first I thought it was the tyres spinning but it's not, it's the transmission that chirps just a little bit..
13:45 Truck feels really nice, I like that.
13:48 Just going to pull over here on the side of the road.
13:53 We'll pull our computer out and have a look at our log file real quick just to see what we got.
13:58 So I'm going to stop it, log file save.
14:05 Remember we saved our dyno log file under the horsepower number that it was making so really important that we save our street test V 1.2.
14:23 I just save that so that I know OK which version of the tune does that go with? And then I can go back and I can look through my log file here on the street.
14:33 OK so what are we seeing? Right at around 19 miles an hour I go and flat foot the truck, RPM jumps up, let's see we've got a shift point of about 3100 RPM.
14:49 You can see we have the fuel rate falling off a little bit after 2950 so in my torque curve, I don't have the truck running all the way out to 3200 RPM, it starts to pull fuel after 3000 RPM or right around 3000 RPM.
15:02 So now that I'm seeing a shift point or I'm seeing the truck kind of run in that 3100, 3200 range, I know I might want to change that a little bit.
15:11 If you look at the downslope here, on the fuel rate, that's not a performance thing so we want the fuel rate to be up here in the 140 plus but we're seeing it fall down a little bit.
15:24 It's normal for it to fall down a little bit on the shifts but that dip, we'll keep an eye on that.
15:31 Got our next shift here, we're at 127, 129 so the truck is really hanging out at 3000 RPM for quite a while, so it's not locking up the torque inverter.
15:40 That's kind of interesting so on the dyno we had the truck locking up the torque converter, we started our run at 2200 RPM and then we ran out to 3000 RPM.
15:49 On the street what we're seeing is the truck is hanging out over 3000 RPM, kind of pushing through the hydraulic coupling of the converter and not locking up, not putting the power down, that we would expect on the dyno.
16:01 Until we get into the higher gears.
16:03 OK so once we get up to 65 mph, we can see the truck, right here you can see where that RPM shows a really stiff linear line.
16:15 That's my signal for lockup.
16:17 I could log the TCC PID and see that as well which I haven't done but if you want to, you can do that.
16:24 I can tell just by looking at the shape of that RPM growing that that's where the torque converter clutch has locked up.
16:32 We can see a pretty high fuel rate there as well, 143.
16:36 Then we come down to the shift here at 3100 RPM, you can see the fuel rate dropped to 94 and then as we get into the higher gears here at 76 mph, we're in 5th gear and that's where the truck really pulls down. 2500 RPM and that's where we see the fuel rate come up to the same fuel rate that we saw on the dyno.
16:54 So we're seeing that same 147, 148 that we saw on the dyno and it's pulling really hard in 5th gear I'll tell you that.
17:03 44 pounds of boost ambient so 29, 30 pounds of boost so the fuel rate's up, boost is up, the truck's clearly making the power in 5th gear but it's not quite putting the power down in the earlier gears.
17:17 That's kind of an interesting thing.
17:20 We'll get back to that in a second.
17:22 The next thing I want to look at is exhaust temps so down here I have all 4 of my exhaust temps.
17:28 The EGT B1S1 is the direct post turbo so add 300° to that and that's about what our exhaust temps are.
17:36 Fahrenheit, so call it 1165 would be the peak exhaust temp.
17:42 We're not really in the danger zone on this truck, there's still room left as far as the tune goes.
17:48 Remember we built this tune for a truck that has a trailer behind it.
17:51 So we're in a good position here as far as exhaust temps go.
17:54 I'm not really concerned about anything.
17:57 So what can we do about the torque converter clutch lockup? That's the question.
18:03 If we go to the engine tune, the trans tune is built in, there are torque converter clutch tables that are apply and release and these TCC maps, if you go to base, they show when the torque converter clutch locks up.
18:24 So the columns you're looking for are called slip, so first slip, never locks up in first, second slip, never locks up in second, third slip locks up over 1460 OSS, so output shaft speed and then fourth slip, looks like we lock up pretty good in fourth.
18:43 Well why can't we lock up sooner? If we flat foot the truck in second gear, and we want the torque converter clutch to lock up in second gear and give us that bite that we're looking for, that's what I would advocate to you, that's a really nice thing to do.
18:57 You can do that by lowering these values here.
19:05 So we can look at when the truck shifts into second and then we can drop these second gear slip tables and if we drop these second gear slip tables into a more reasonable RPM say shortly after the truck shifts into second at that high load, then we can really get the truck to bite down and put the fuel to the ground.
19:24 If we can pull the truck down below 3000 RPM, that's where it's going to really make power and torque, so that's what we'd look to do.
19:31 I'll show you that shift schedule, so if you want to see that.
19:35 On 1 to 2 so at let's say 665 output shaft speed we'd be into second gear over, 65% throttle or so.
19:51 So if I take that 680 back into my torque converter, I could do something like this.
20:06 And what that would do would force the torque converter clutch to lock up under heavy throttle input any time the output shaft speed is over 680.
20:13 Now similarly, you want to do the third gear slip kind of raise that up so that as it goes from 2nd to 3rd it stays locked up and there's a few other tricks of the trade that you can do in the TCM as well.
20:27 Not going to get too far into that but really in as much as the TCM keeps the engine in its powerband, it's important to be able to handle the shift schedule and the torque converter clutch lockup.
20:37 OK so we talked about low speed handling and we talked about that high throttle, we did a few of those wide open throttle runs and looked at the fuel rates.
20:45 Now if you remember, we talked earlier about how the fuel rate was ramped in right around that 50-60% throttle range.
20:50 So it's important not to neglect the medium throttle inputs.
20:54 So you just creep on the throttle to 50 or 60% and see how that feels.
20:59 The truck feels really meaty right there, I like that torque curve a lot, this thing is going to be really fun for the driver.
21:06 But I want to make sure, I'm trying to feel for abruptness, does the truck feel abrupt as I increment the throttle up 'cause if it does, we'll need to blend those rows in a little bit more.
21:18 As the truck increases throttle position we want the fuelling rate to increase at a linear rate, we don't want it to have an exponential feel or have any hiccups or any really abrupt feeling in the fuel delivery.
21:31 So once you're happy with the low speed response, you're happy with the wide open throttle response, the truck's making the fuel rate you want and it's putting the power down like you want, you're happy with the mid speed throttle transitions and you've put the truck through its paces in development, that means putting those 1000s of miles on it and recording your regen frequency, then the tune is ready to go onto your customer's truck.
21:57 I would not recommend tuning emissions equipped trucks on one day and then sending them off out to your customers.
22:03 It's really important to keep track of lambda, one of the nice things to add onto a truck like this would be the wideband O2 sensor just to make sure that the lambda that you're tracking in the tune, remember in this tune we're calling for between 1.15 and 1.25 lambda, that that lambda is tracking with what you're seeing on your wideband gauge.
22:22 If it's not tracking then your pulse width table might be off or you may have to use a fudge factor as you work between those two.
22:29 What I like to do is run the truck in a stock tune first, check my lambda there at wide open throttle and during throttle transitions and see what's the worst that I can do in the stock tune? Can I get it down to 16.5, can I get it down to 16.0 AFR? Down to 1.15 lambda, what's my lowest lambda that I can get to, what's my rich lower limit.
22:50 And then I try in my performance tunes not to go below that.
22:54 So that'll keep the regen frequency in line with what the customer was seeing in the stock file, keep everybody happy and you won't have near as much troubleshooting to do.
23:05 I hope you enjoyed the tips and tricks in this practical example.
23:08 There's more than one way to skin the cat, there's a lot of things you can experiment with on these trucks.
23:13 Certainly if you see a way to do it differently, I would encourage you to try it.
23:15 Use those 5 or 10% increments.
23:18 Don't get crazy with it, test each iteration, don't get ahead of yourself but have fun with it and if you have any questions, I'm on the forum, I'm happy to help.
23:26 I'm under the practical diesel tuning and diesel fundamentals, just ask for Nick and we'll see you on the next one.