Advice needed on tuning a 2.8 IP - Defender Source
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Old May 7th, 2013, 08:54 PM
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mark kellgren
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Question Advice needed on tuning a 2.8 IP

So I understand well the functions of the fuel screw, the preload wheel and the smoke screw on the Bosch IP, and have been tinkering with them all on my 2.8 (and keeping a log of what I'm doing). I have read the 300 TDI tuning threads and tuning document that is out there. However, I'm still struggling to dial in that perfect nervana setting striking the balance between economy and power. While all the online advice has been helpful, it's all written for the 300 TDI and not the 2.8. since the entire boost diaphragm is driven off boost pressure, there is clearly a tuning difference between a 300 that has to build boost over an rpm range and a 2.8 that get's max boost right off the bat (1/2 throttle and I'm at 16 psi).

So does anyone have recommendations on tuning with the assumption that you get max boost very quickly?

When first installed, the factory setting delivered about 17-18 mpg and clearly wasn't rich enough on the highway at cruise. Now I'm at 3/4 turn + on the fuel screw and getting about 15 in the city and 15-17 on the highway, but I have plenty of oomph going up low grade hills, EGT's are happy, and it's happy cruising at 75 on flats.

My goal is to improve the economy of city driving-I have more than enough power for traffic; I could give some up. I don't want to lose my highway WOT performance, but want to gain some economy on cruise when I'm under 1/2 throttle.

my dream/goal is to hit 20 mpg, my realistic goal is to get back to 18 but put some boot in the ass on the highway.

thoughts?
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  #2  
Old May 8th, 2013, 09:17 PM
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Do you try to keep you RPM's under a certain point ? We have a 300Tdi with a ZF 4HP22 auto and we get around 22mpg but we keep the rpm's at or below 2200.

We also have an '06 Liberty with a 2.8 CRD. This diesel, with the variable turbo, will jump off the line like a gas car if we're not careful to keep our foot out of it and ignore the pressure of other vehicle to "go faster". With it, we try to keep it under 2000 rpm's and in town it'll get 22 mpg and highway 29 holding it with cruise control at 2K rpm which translates to 67mph.

With the mileage you're reporting, my 1st suspect would be lead in your right foot.
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Old May 8th, 2013, 09:44 PM
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or that I have a 1.4 ratio t-case. Doing 70 mph puts me at 2900 rpm. seriously considering getting a 1.2 t-case and giving it a try. I think the 2.8 has the power to push it.
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Old May 8th, 2013, 09:54 PM
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In our D90 @ 2200 rpm's we're going about 63.5 mph. There's a lot of traffic pressure out there to go faster. We do have the 1.2 Tcase (LT230Q)

On another note what kind of IR temps are you seeing on T-stat housing when you're up to full operating temp's ?
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Old May 9th, 2013, 07:16 AM
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Don't forget boost, the more time you spend on it, the more fuel is going to be dumped into your engine regardless. When I stay off boost on the 200tdi, it returned some pretty amazing MPG numbers 25-28. Of course, power was weak. On boost, it burns fuel pretty quickly.
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Old May 9th, 2013, 07:25 AM
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Quote:
Originally Posted by sonoronos View Post
Don't forget boost, the more time you spend on it, the more fuel is going to be dumped into your engine regardless. When I stay off boost on the 200tdi, it returned some pretty amazing MPG numbers 25-28. Of course, power was weak. On boost, it burns fuel pretty quickly.
staying off boost is not easy with a VNT.
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Old May 9th, 2013, 07:57 AM
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I wonder if there is a simple way to cut boost on the vnt
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Old May 9th, 2013, 09:32 AM
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2.8 tuning

Mark,

You have a 1.4 case, but What size tires? Looks like 255's or something, also what trans, gears. I would suspect if you switched to a 1.2 and ran 235 85 tires you would see a significant increase, use a hard compound tire like the xzl and more MPG, take off the jungle gym LR saw fit add (for the obvious safety reasons) and you would see another huge increase. unscrew the offroad gear etc etc

I nearly bought an overdrive, I suspect I will eventually. I figured that would be a decent MPG increase, the Canadian Co. roamer/rover drive had a nas110 with a 2.8, he might be good to chat with, I thought he was, kinda doubted his mpg claims, be didn't doubt he got a bit more. I wonder if there is a difference in the two turbo versions of the 2.8.

I have the same NAS110 2.8 1.4 255 setup. So this will be interesting to see what you come up with.

Cheers, -Gustaf
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Old May 9th, 2013, 10:23 AM
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yes, 255 tires. the gear I have is not negotiable. no intent on removing mods for mpg. 1.2 Im opento pursuing at some point. I may buy a good spare and swap as an experiment at some point. what I do want to do is make sure my IP is tuned to an optimal setting uses the different adjustments I have to make. thats the low hanging fruit. Since nobody has done a 2.8 tuning specific writeup in English anywhere on the web, why not start here.

Eric at NLX North America has 2x 110's now with 2.8's, so we may trade lessons learned.
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Old May 9th, 2013, 11:28 AM
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Mark:
I know you're trying for the optimal settings, without "outside performance help".
Since you are experimenting with tuning adjustments, have read several threads/articles where by a propane boost was added for the lower RPM driving that can be manually switched off for highway driving (or at any time for that matter).

When installed the fuel was trimmed back to give economy (say in your case the 20 MPG) you seek for highway driving. So the propane was set to inject into the air induction when the petal was more than half way down, so off the line it had the fueling to complement boost. Then on the highway while maintaining cruising speed, the propane can be switched off.

Also consider a slight timing advance.

Your probably thinking I'll keep playing with the adjustments that I am comfortable with, but here are some points you may not have considered...

Hope this helps.
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Old May 9th, 2013, 09:55 PM
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ok, here some of mine experiences.

I own two 110's with a 2.8 TGV. Both station wagon, both with 285 tires, BF Goodrich Mud terrain.

The first has a tuned engine, more fuel, bigger intercooler, timing, 150 HP on a rolling road. Gearcase 1,2. Top speed 158 km/h (=99 mph), fuel economy appr. 15 mpg.

The second is not tuned, 1,4 gearcase, topspeed never tested, fuel appr 21 mpg.

Personally I would never go for the 1,2 gearcase anymore . Highway is nice but in town you can hardly use fourth gear without exceding the max speed. You have to shift between 2 and 3 much more then with a 1.4. THe 1.4 gives much better driving in corners and at low speed even in combination with a tuned engine.
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