Hello all, I have had my edge for quite some time, but haven't pulled a trailer.

I have the following set up
Edge Lvl 2
WOT Shift points: 5250 for 1-2 and 2-3 4800 for 3-4
Max rpms: 5400
WOT Fuel: +1.6
Max Speed: 110
Shift pressure: +8
Adjusted for 295/70R17

It seems that on a normal take off when it shifts into overdrive the RPM goes from ~1700 to ~1200, and the engine almost becomes silent. Driving down the road without anything behind me is fine, I have had no issues.

Just recently I hooked up a trailer of about 6 four wheelers and pulled down some fairly hilly highways. I instantly noticed that as it shifted into overdrive the engine almost acted like it had a huge load on it, and I'm assuming because of the really low rpm. I don't think using over drive is my problem, i know there are mixed feelings there sometimes but with the other tires and no edge I never had any problems. I guess I'm just wondering if its only me that has this problem and is this normal for these settings on lvl2? And if not what I need to fix in my settings to change this around a little.

I have the starter off my truck being rebuilt right now because of some issues with it, but when I get it back on I will try to take a camera video of the edge read out and you can hear whats happening also.

 

Did you mess with the regular driving shift points or torque converter lock/unlock points?

You might want to go back to the canned shifting characteristics whenever you tow. As in, reprogram back to level 2 but only change the tire size and gear ratio.

I'd say your WOT shift points are good, the WOT fuel could be cut down some. I've found 1.3-1.4s works pretty well.

Also what tire size are you using? Does the truck's speed match up to a gps?

 

You need 400 between the WOT shift point and max RPMS. Raise the max to 5650.

 

I can't remember off hand what the tire size number is, but it's calculated from what the manual shows. At around 70ish the spedo is a little ahead of my edge read out. Also when we tow the jeep I will probably put the stock tires back on since it's a long trip, but i wouldn't think tire size should effect it when you recalculate that in the programmer.

Okay, I will raise that up and fix it. I don't think this will effect the shift patterns will it?

 

no, won't affect the patterns but it can cause some crazy stuff to happen when you get on it. The engine has to have some rev room during that split second between shifts or it will bog. Whatever your shift point is, the max rpms should be 400 more, always.

 

Watson, you are running 33" tires (I'd try 2562mm for the Tire Size), and you did not say what your Gear Ratio is. You MAY be "under geared". Your RPM figures tend to confirm that in my mind.

A trailer with 6 quads is going to have a bit of weight, and I think you are feeling the effects of "under gearing". You can raise the part throttle upshift/downshift and torque converter lock/unlock points to compensate for that. This would put you into a higher rpm band at each shift and reduce the feeling you have of the engine being "lugged".

- Jack

 

I have the factory 3.73 gearing. I wouldn't think that with the 3.73's and 33's I would have any feeling of being under geared.

I know here its like comparing apples to oranges but this is why it seems strange to me. Last year I had 265/70R17's which are not to much bigger than the stock tires. They where General Grabber AT2's. I pulled the jeep with no edge, about 768 miles round trip. Yes there were times we would be rolling down the interstate and come to a large uphill section and I would have to kick into over drive and you could tell it was struggling. But for the most part it pulled pretty good for being a gas truck.

Now I have 295/70R17's, and pulled 6 quads which I can imagine would way more than that jeep if any at all. Now I have an edge on lvl2 and it seems to be really bogging down just on straight highway.

I know there are way more factors that effect it, but to me it just seems like I should have gained some performance with the edge even with the bigger tires. Maybe like you said I have went past that gearing stage where I'm slightly under geared. Just doesn't quite make since.

You state that I could change the "part throttle upshift/downshift and torque converter lock/unlock points." What settings would you suggest to do there, or something I just need to play around with? Maybe a close ballpark figure I could start with.

 

Because of the larger tires, you would have to change to 4.10 gears to have the same final drive ratio as the stock setup. I would assume that you are slightly undergeared compared to what most people think the truck should be like.

You can raise the 3rd and 4th gear shift points. You can also raise the 4th gear torque converter lock/unlock point to, like Jack said, bring the rpms up higher into the power band.

Here is an example I often use on the PHP forum:

Notice at how the rpms significantly drop when the torque converter locks (green dot). This drop will also make the truck "lug" and have a large loss in power because of the lack of engine speed. Many people hit the O/D off button when towing if the torque converter keeps locking and unlocking. The dotted line I drew is a forcast of where the rpms will be after the lock by adding 5 and 10 mph to the lock/unlock points.

When you are making changes like these, do them gradually (as in +/- 2 mph) at a time.

For refrence, I live in a hilly area where my truck will bog down on a climb so (through much testing) I have adjusted my 4th gear torque converter points at 0 but my 3rd torque converter gear raised up. This will keep the rpms nice and low on regular cruising but when in 3rd gear locks the torque converter close to the same rpm as the 4th gear unlocked at the touch of a button (O/D off button). I'm not saying what I did will solve your problem but I'm illustrating how testing different settings gradually and independently will usually result in more suitable operation for your needs.

 

Okay I will play around with it. I guess really I don't understand much on torque converters to understand truly how the lock/unlock works in them, but I will read up on that to get a better idea. Also your image isn't showing up that you posted, even when direct linked.

I guess my next question is, if I tune my edge to fix these settings will this be an "okay" way to fix it so to speak or should I just try to avoid trailers with my tires. I wouldn't mind to get new gears eventually, but what I am afraid of is to get new gears, then take trips pulling and decide to put the stock tires back on to do that. Then my gearing will be off for no reason.

 

Your image is fine for me Longshot. I suspect the problem is in Watson's web browser.

Watson, your new tires are over 1.5" wider than your old ones (1.65" actually). I know that doesn't seem like much, but by putting those big feet on, it's the same as if you had regeared with 3.54 gears, which are not the greatest for towing.

I'd actually raise the part throttle up/downshift and torque converter lock/unlock points by the max for ALL shifts and gears. The changes aren't really that much: (+2, +3, +5mph for shifts) and (+2, +3, +5, +10mph for TC).

The torque converter is a fluid clutch that allows your engine to spin when you are stopped and in gear. As the engine speed increases, the viscosity of the fluid transmits the torque back to the transmission itself, and then on to the driveshaft. As long as the TC is unlocked, the engine operates at a higher rpm, generating more torque, that is ultimately carried back to the wheels. But, at a certain speed and loading, the TC locks up, which slows the engine, but saves on gas.

With your big feet and low effective gearing, you need the added torque.

Yes, a programmer will help some, but you lost about 5.2% of your available towing force when you mounted the new rubber. That's what you're feeling.

- Jack

 

Okay, so let me ask this. Can i change a few settings to help out just a little during normal driving but be able to keep the mileage i get? (Right now I get about 16-20 on highway according to edge)

Then from what I understand once I put the stock tires back on to tow and arrange my settings I will be fine because I will be back to the original gearing ratio.

 

Jack, I think there is something funky going on. This isn't the first time I have found pictures not working on the forum recently. On another thread one of my pictures did not show up at all, not even a link. When I went to edit I could easily see the link was there but otherwise it was like I never even included it. Might be me because I'm also having trouble with pictures at PHP as well.

Here is the post that has the image as an attatchment. It's an old thread so I know it works.
http://forum.gopowerhungry.com/close...html#post32702

Do as Jack says and raise the settings to the max. At 70 mph(or whenever you feel the TC lock) everything is going to be running as if you hadn't made those changes.

 

Thanks everyone, I appreciate everyones help.

 

And Watson, when I said your new tires were "wider", I meant they had a larger diameter (what I said sounds "stupid" to me now). :o I think I SHOULD have said "taller", which is what they are. The taller tire puts less "pushing" force on the road (a loss of about 6.7% for each 2 inches in tire diameter increase in the 30" range). I personally think you can feel a 6% loss in "push" (acceleration).

You're probably not going to get all of that back with any programmer or tune, so the next best thing would be to shift up at a higher gear setting. That's what raising the part throttle shift points does. Keeping the TC unlocked longer does much the same thing too, it keeps you in the higher rpm range for higher torque longer.

But, as Longshot says, this is all happening during an acceleration phase or when you are climbing hills. During cruise, you are operating your engine at a higher load, due to the taller tires, but your rpms will be a bit lower, so it's probably a "wash". If you're not towing, the upshifts and TC locks will happen sooner (due to the lower load) so you should be fine.

There's actually a "sweet spot" for mileage that is dependent on speed and load, which is probably closely optimized by the factory gearing and tire setup. I'm not saying you can't do better than the factory setup, but larger tires almost always give you a hit both in performance and in mileage.

Longshot - I don't know what to say about the image. It's fine for me and I haven't seen anything you've posted acting funky. Watson, were you able to click on the image link in Longshot's last post to see the image? (It's a thumbnail there, so you have to click on the thumbnail).

- Jack

 

I can now see the problem with his image. He has linked off the attachment at power hungry. They require you to be registered and logged in to view the attachment. I wasn't registered, so that's why I couldn't view it. Now that I'm logged in I can. If a user is registered yet not logged in they also wont be able to view it.

I guess to me its hard to make heads or tails of what I'm seeing there on that chart. I do understand about the larger tires, I guess at first just hard to believe a small change would throw me completely out like that. I think most of my towing will be done with my stock 255 tires, so regearing will not be something I will do. Because I will tow with the stock tires I shouldn't have any issues there. I may try to tweek it a little for every day driving but for the most part its fine.