35" tires, 42R, towing issues now

After all the trans and converter replacement, the 35s are putting a hurt on towing. Even with an 8-9K car trailer.

Now that the trans or converter wont slip, this thing wont get out of its own way now in top gear. It used to be that you could grab throttle and the rpms would come up 3-400, then the vehicle speed would catch up. Obviously not right, but for the turbo it was perfect. Now at 60-65, the rpm sits at 1700 in top gear and climbs only with road speed, so any throttle drives EGTs skyward. I cannot get on top of the turbo in top gear unless Im driving 70+. Towing in 3rd gear is about I can do, even then EGTs are at 1000-1100 all the time.

Pulling back fuel, also pulls back power and makes the turbo less responsive.

For the first time of owning this truck and the trans has never worked better, but its really making me unhappy at the moment. Big tires may not be for me. Ugh..

Wow interesting....

What stall converter?

4294 or 4202?

I think I remember it being the 4294, right?

Marty said:

What stall converter?

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Nothing special was spec'd-- 3 disk, billet 6.0. With the towing that it sees I really didn't want a looser converter. Should it have a looser one? I don't know what was in the last one except it was supposed to have been a BTS (PI) converter that had a Dodge stator and guts in it. Was said that it looked just like ATS inside.

4294 or 4202?

I think I remember it being the 4294, right?

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Derek, the 4294


Last night was the first time I towed with everything redone. Ive only briefly towed with the 35s when everything was slipping.

Read this thread. http://powerstrokearmy.com/forums/showthread.php?t=3459

I see your problems. Too much tire, not enough gear, tuning not optimized.

Converter stall has nothing to do with a locked converter in OD towing a trailer.

Change your driving habits.

Gordon said it towed great and kept pushing me on my 4202 but I am hesitant...LOL

uncool said:

Read this thread. http://powerstrokearmy.com/forums/showthread.php?t=3459

I see your problems. Too much tire, not enough gear, tuning not optimized.

Converter stall has nothing to do with a locked converter in OD towing a trailer.

Change your driving habits.

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Agreed-- that's what Ive discovered. The issue was the slipping transmission/converter that hid other issues. For now, Im going back to the smaller tire and we'll start to look more at tuning. The turbo always took some different driving, but its really noticeable now that everything works right. The worms got out of the can..

Derek,
When is the next live tuning session? LOL

Gordon said it towed great and kept pushing me on my 4202 but I am hesitant...

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No to the 4202... haha

Gears is a good question... what gears do you have?? What are the RPMs at when your talking about not being able to bring them up? How easily does it down shift during this acceleration? Some larger single trucks just require a more aggressive downshifting schedule.

That turbo you have has always been a GREAT option for 7.3 owners. Now days there are options on the market for much less money that are every bit as capable though. Never should towing be an issue on a 475-500hp truck, it should be instant power.

Gotta be 3:73 at least.

3.73s-- the combination of the tires and the lack of slippage has created a big change. The tow tuning for fuel and trans strategy definitely needs to be looked at.

The 42 has always been a blast when empty and took some different driving when loaded, but I never thought it was 'ideal'. You were always under it unless the speed was fairly high and the air was moving. It takes pretty aggressive throttle to backshift it to 3rd today.

We'll get through it...its just a new truck now. I appreciate the thoughts and ideas.

Thinking about how this thread started, I do understand the things going on here. My point was the surprise of how much the truck has changed over time and how much it changed with the refresh.

Going from a 285/75/16s to the 295/60/20s, is not a huge diameter change, but it has made the 42 that much tougher to light with the trailer back there. I also need to get back on the AE to reset for the tire diameter since it has changed the trans calibration relative to throttle input.

Ive got no doubt it would improve with the smaller tire, but I don't want to put them back on. I love them 20s

Who else has a similar setup that struggled with this? What did you do?

i have the same struggle with my wimpy 238/80s and a 38r

lariat 7.3 said:

i have the same struggle with my wimpy 238/80s and a 38r

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You have a problem if you have this issue with a 38r

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It's your gears
Your rpm has to be min 2000 rpm cruise or you'll be under the charger.
And if you don't like or want to change gears then get a smaller turbo. It's that simple .

Wayyyyyy off track. Happy to see this tech talk going on, and spent some time reading that 7.3 turbo thread. Nice to see actual discussions going on, than 10 new build threads a week of a new platinum with forces, and rigid lighting all over. Need a "too much flatbill" emoticon.

Swaan said:

It's your gears
Your rpm has to be min 2000 rpm cruise or you'll be under the charger.
And if you don't like or want to change gears then get a smaller turbo. It's that simple .

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What he said. I've towed my GN with 8000 lb pick up on with 2000 with s475, stock injectors,3:73 gears,33" tires, tow tune and under 2000 rpm it's a little smoky and won't pick the rpms up until it downshifts and gets things turning. Need a smaller turbo or different gears.

Wayyyyyy off track. Happy to see this tech talk going on, and spent some time reading that 7.3 turbo thread. Nice to see actual discussions going on, than 10 new build threads a week of a new platinum with forces, and rigid lighting all over. Need a "too much flatbill" emoticon.

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^^ Jason lol -- but you speak the truth... too much conversation is spent on trucks not doing truck work.

It's your gears
Your rpm has to be min 2000 rpm cruise or you'll be under the charger.
And if you don't like or want to change gears then get a smaller turbo. It's that simple .

Click to expand...

Yup, get it--Ive said the same thing. I doubt the gear will be changed, but may need to go back to a 32-33" tire. The charger is another possibility, but gonna tune on this one first. Im fine with backshifting to 3rd and running some grades at higher rpm, but was surprised at how the EGTs jumped after the trans efficiency improved. The tow file may need some fuel taken out and shifting strategy adjusted.

We talk about it, but anyone wanting a bigger single that tows decent loads needs to think about this stuff. 42 works good on the street EMPTY--in fact, its way fun. We have elevation changes and traffic around here that catch you off boost all the time. The 96 2wd stocker with 4.10s would tow circles around this truck with ease.

No whining about it (I understood and made the decisions), but to help inform and gather other thoughts/ideas.

What to do to fix it... For now, the trip to Boise in two weeks will be done with the shorter tires. Then need to look at the long term plan.

I guess I never felt it with 35s and 3.73s. I had 250/100s with the E99 turbo lol. Did amazingly well.... towing egts were a bit high, but I had a leaking manifold, and up pipes lol. Still ran amazing.

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You are on the right track. Getting the speedometer reading correctly will help with the extra throttle needed to get that downshift a little sooner.

I converted mine over to a 4R, so I have a PCS for trans control. When towing with the 76S400, I cancel O/D and let the 76 come up to about 45 psi and we are off. Not too much more than a little puff of smoke. This is with 3.73's and 285/75/16's.