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View Full Version : Anyone with a 7.3 could I get some insight?


Deeds
06-23-2019, 01:57 PM
Hey I'm trying to get a bit of insight here, I know it's bad to lug a diesel and that 7.3s like rpm, but I'm not sure if it's normal to struggle on acceleration like I am...
My TTs 6k lbs and my truck does fine accelerating in 1st and 2nd and I can keep my rpms up but when it shift 3rd with the torque converter being locked my rpms dump to around 1300 to 1400 rpm and being out of my powerband it kinda has to lug back up to the sweet spot but once I'm there its gotta shift to 4th/od and I gotta work on getting my rpms up again... I am constantly getting told to chip it and I really don't want to do that, I just dont know is this normal for these trucks to hate their own gear ratios like mine does or do I gotta look for other issues? Thanks anyone in advance that provides input!

Ken / Claudia
06-23-2019, 03:00 PM
All I can say is with my two 7.3s I never had a lugging problems going through the mountain passes in this state with a truck camper and boat or the current TT, it is around 7400 lbs as I recall. I normally would tow only in O/D when on flats, up or down hills it was not in O/D. Normally left it in 4th uphill, on real long grades go into 3rd. Downhill normally 3rd.
You might want to have it checked sounds like your not getting boost. Turbo? issue?
East stuff to check, air and fuel filters. I recall the fuel is to be changed around 15,000. I would change out or clean the air every year which was 5,000 to 8,000 miles. I have a friend who refuses to be proactive and his 7.3 runs like crap. He thinks it's OK since it runs.

chuckster57
06-23-2019, 03:35 PM
What year truck? What trans? What rear end?

Deeds
06-23-2019, 03:35 PM
Maybe lugging isn't the right word, I will say that I've done a ton of work to this truck over the last two years...new turbo, sensors and just a ton of maintenance catch ups... fuel filters are new and no noticeable boost leaks normally 7 to 9 lbs while towing at a steady 55, it pulls good I just find once it shifts with the tc locked up my rpms dive to the 1300 to 1400 rpm range and i find it odd that it would bring itself out of its ideal rpm range. Did you ever notice your truck doing anything like this when accelerating from a dead stop? I can definetly power through I just find it to be a short shift

Deeds
06-23-2019, 03:37 PM
It's a 2000 cclb auto, I believe it was 3.73s but not 100 percent sure has 190k on the clock

IMASAP
06-23-2019, 04:42 PM
I've got two 7.3s ….. one in an F350, and one in an Excursion. I find the sweet spot is about 1800 RPMs. I like to tow our TT at around 63 MPH... I'm pretty conservative. That has me turning less than 1800. Hitting a decent hill @ 63 will make the truck downshift out of OD if I'm below 1800. Speed up a little to 67 or higher and I'm above 1800 @ the bottom of a hill, and there is no hill (or mountain) I can't accelerate up. My tires are a little taller than stock, so that amplifies things. My TT is 6500 lbs. If we ever get a larger trailer, I would probably re-gear to 4.30 gears. That all being said, the truck has plenty of power for me.

IMASAP
06-23-2019, 04:45 PM
It's a 2000 cclb auto, I believe it was 3.73s but not 100 percent sure has 190k on the clock


If your truck is SRW, it has 3.73s

Deeds
06-23-2019, 05:01 PM
Yes mine is srw I thought I was right with the 3.73s. I'm in mn so no huge hills and at cruising speeds I rarely ever downshift it pulls very good at hwy speeds, I guess my question was more about accelerating up to hwy speeds. I may be used to my old 6 liter gasser, but that thing would always keep high rpms through every shift until I let off, this 7.3 only will keep 2k to 2500 rpm through first and second than 3rd gear once shifted dumps the rpm to 1300 or so rpm even if I'm deep into the pedal

Customer1
06-23-2019, 06:14 PM
Sounds like bad gear ratio choice in the transmission. I had a 1979 Ford gasser with what they called a four speed overdrive. In between second and third it fell on its face because of the huge gap in ratios.

Ken / Claudia
06-23-2019, 06:41 PM
I can't say I manually shifted from dead stops while pulling. D was the gear. I never had problems you list. What is you boost while in higher rpms or whats the highest numbers you see.

Badbart56
06-23-2019, 07:58 PM
I put an Edge programmer in my 97 . Even though it was a dually with the 4:11 gears, the four speed automatic seemed to reach a dead spot in third and fourth gears with moderate to heavy loads. The Edge changed the shift points as well as provided more fuel so that was a big help. Something to consider.

Stircrazy
06-24-2019, 04:34 AM
If your truck is SRW, it has 3.73s


my old 99 was a SRW and it had 3.55's.

Steve

IMASAP
06-24-2019, 05:25 AM
Interesting. I know on the 97 & earlier, the 3.55 was an option. This is the first I've heard of a Superduty srw with a 7.3 or 6.0 that didn't come with the 3.73s.

Stircrazy
06-25-2019, 04:27 AM
Interesting. I know on the 97 & earlier, the 3.55 was an option. This is the first I've heard of a Superduty srw with a 7.3 or 6.0 that didn't come with the 3.73s.

ya it was a 2wd so that might have been the difference.

Steve

Badbart56
06-25-2019, 05:02 AM
Interesting. I know on the 97 & earlier, the 3.55 was an option. This is the first I've heard of a Superduty srw with a 7.3 or 6.0 that didn't come with the 3.73s.

The OP didn't identify his year or model, but prior to the 99 model the only Superduty that existed was the F-450. And it has never been offered in a SRW platform. Yes, 3:55 was offered as well as the 4:11 which I had on my 97. At times I wished it had the 3:55's for better mileage but after going up Monteagle Pass a few times towing fifth wheels that weighed between 9K and 12K pounds I was happy to have the lower gears. I could hold 55 mph as long as I didn't have to slow down for any semi's that were in the passing lane. Even so I maintained a 10 mpg average while towing and 17-18 empty. I set the cruise at 55 mph once on the interstate just to see how much mileage I could get and was surprised to see 20.7 mpg! But obviously 55 mph is not a practical interstate speed. My newer truck (6.7) with all the hp/torque and six speed automatic, well, not really any comparison.

Fishsizzle
06-26-2019, 04:41 AM
What size are your tires?

jsb5717
06-30-2019, 07:42 AM
I drove a 2000 7.3 for 13 years towing about 8k lbs. I know what you mean. Perhaps some maintenance is needed but I always felt that it wanted to upshift too soon. That would drop the RPM's and lose momentum in the hills. Then it would downshift, rev up to speed, then upshift too soon again.

I solved it with one of these. Setting it to Heavy Tow changes the shift patterns and made a world of difference.

sonofcy
06-30-2019, 07:43 AM
Hmm, my 6.7 runs with tow/haul, cruise, auto exhaust brake. It flies up hill and maintains almost perfect speed downhill. It's 14,000 lbs of F450 towing a 16,700 lb fifth wheel. Occasionally if I need to position myself around trucks I will take my foot off the floor to operate the throttle and can easily accelerate going up hill. Maybe my 4.30 rear end has something to do with it? Also I don't try to 'outsmart' the truck, I let the engine computer and tranny computer do the gear selection. Works fine for my truck. I do hear from a lot of guys who do have problems but one thing they all do is try to 'outsmart' the computers. Might be a clue there.

jsb5717
06-30-2019, 07:45 AM
Part of the issue is the 4 speed tranny vs the 6 speed in my RAM. The other issue is apparently how it's programmed to shift in the upper gears when in stock mode.

RickReichert
06-30-2019, 08:24 AM
Tire size can have an effect on this. Are the tires standard or larger in diameter?

sonofcy
06-30-2019, 08:28 AM
BTW, the 450 tires are 19.5"

Matt1959
06-30-2019, 11:00 AM
Mine started doing that right before the transmission blew up. New trans fixed it.

RVFD20
06-30-2019, 11:33 AM
From my experience the 7.3 was a beast out of the gate but quickly lost momentum in the mid range. About ten years ago my brother had a 2002 250 with the 7.3, my dad had a 2005 250 with the 6.0, and I had a 2001 6.6 duramax. We all pulled the same loads frequently doing construction work and here was my experience from those trucks. Off the line the 7.3 would out pull all of them but once you hit the mid range you are referring to it would lose steam and the duramax would pass it by. The 6.0 was the fastest of them all empty but it struggled to find a happy place at cruising speed and constantly downshifted, especially loaded. Those 7.3’s are practically bulletproof other than high pressure oil pumps and seals, and a downright mule off the line, but they definitely saw improvements with programmers that would also time transmission shifts. They weren’t known for speed either but you could rest assured they would get you and your load wherever you were going.

rburckhart
06-30-2019, 11:33 AM
I had a Banks 6 fun tuner put on my 01 7.3 and was very pleased with how much better it performed. I never went past the #3 level and it worked great!

moodman
06-30-2019, 02:51 PM
So I'm wondering if anyone has ever changed out their differential for a different ratio, like a 4:10? If so, how much difference did it make? I am considering this instead of building up the engine and want to know how much more pulling power I could expect and what other issues it might cause.
Thanks.

mwemaxxowner
06-30-2019, 02:56 PM
Mine was a 6 speed manual, but she never struggled with my 8,000ish lb camper anywhere in any gear. It had a 3.73 rear end.

Loved that truck.2253422535

Deeds
06-30-2019, 04:08 PM
Hey everyone I want to apologize, I didn't think this thread had any interest until Al (aka alleycat) private messaged me and realized the thread was going strong and my notifications were in spam... Al and I came to the conclusion that my truck might be slightly confused on shifts just due it being a lighter trailer, everyone has always said put the pedal down and that's all well and good but I fly when doing so and I refuse to tow that way, when I'm lighter on the throttle i get the early shifts and I agree with Al's take on it that it does seem like my truck is confused if it's supposed to pull like its empty or pull like it's full! It's the last thing that I feel it could be this truck has been looked over front and back and my parts list is to the max! I make 7 to 9 lbs boost at about 55 to 60 while towing and I do have 285/75/16s I think that answers 2 questions that were asked earlier... I might now be investigating a chip/Tuner with a tow haul mode. Thank you guys for your help and input I wasnt getting this from a different forum everyone just wanted to say put the pedal down or I need up pipes yadayada so thanks a ton!

mwemaxxowner
06-30-2019, 04:30 PM
I think tuning could help you with that a lot. I don't know what sort of magic they could work on those transmissions, but the shifting of my 6r80 is cleaned up very much with a tow tune. Tuning turned my '99 7.3 into a whole different truck, but there was no tranny tuning involved, so no experience there.

Ken / Claudia
06-30-2019, 07:49 PM
FYI, I owned the 02 until this year. Put the super chip tuner in at 40,000 miles blew up the tranny at 42,000 or so. Due to over torquing the factory tranny. When it blew up I was left with 1st gear. I went with a aftermarket tranny, gauges, 2x lager tranny cooler with electric fan to use if it got hot again. That tranny was around 5400 including the other items it was around 6,000 bucks back in 08. It was wonderful and worked much better than OEM tranny. I had that so long I forgot about the old days and old shifting patterns. It was costly, but it worked and likely will as long or longer than the engine. Most I knew back then blew their trannies up if towing heavy RVs and many were buying upgraded ones from a shop in CA. I sold mine in March with 183,000 miles on it. The dealer placed it for sale at 21,775. Partly due to overall condition ,but also due to the tranny. I had the paperwork to show what it was.
Back in 1996, I test drove a 7.3 with 4:10 or 4:11 rear end and my opinion was if it was a ranch truck or always a heavy loaded work truck it would be ok but the 3:73 is better. When at freeway speeds the RPMs were higher, truck louder, taking your foot off the throttle at 65 mph was like putting the brakes on. Unknown by me what the fuel mileage was. After test driving a truck with each the answer was easy for me. I got the 1996 7.3 super cab 4x4 off road and maybe would still have it but wanted, not needed a crew cab.

mwemaxxowner
07-01-2019, 02:18 AM
I wouldn't do anything like superchips. I'd go with a custom tuner who will review data logs and edit the tuning to your liking. Gearhead is known for great trans tuning, but I don't know what he does with the 7.3. I would think the goal here is little to no increase in power output, and better shift/TC strategies.

slman
07-02-2019, 06:51 AM
Mine is the same. I live with it. When towing, lock out OD, but when flat, or downhill, i hit the release button, and it pulls fine. ( Pretty much means freeway time only)


Hey I'm trying to get a bit of insight here, I know it's bad to lug a diesel and that 7.3s like rpm, but I'm not sure if it's normal to struggle on acceleration like I am...
My TTs 6k lbs and my truck does fine accelerating in 1st and 2nd and I can keep my rpms up but when it shift 3rd with the torque converter being locked my rpms dump to around 1300 to 1400 rpm and being out of my powerband it kinda has to lug back up to the sweet spot but once I'm there its gotta shift to 4th/od and I gotta work on getting my rpms up again... I am constantly getting told to chip it and I really don't want to do that, I just dont know is this normal for these trucks to hate their own gear ratios like mine does or do I gotta look for other issues? Thanks anyone in advance that provides input!

Stircrazy
07-03-2019, 04:37 AM
if your looking at tuning, check out DP tuners, he was the best 7.3 tuner around for many years. I had a couple of his towing tunes with some custom lock ups on the torque converter and it towed a 9000lb trailer like a dream.

Steve

mwemaxxowner
07-03-2019, 04:39 AM
DP is who I used to tune mine. They treated me well and the tunes were great. Strong but apparently plenty safe. I drove the bajeezus out of that truck from 200,000 miles to 340,000, and the new owner is still without issues.

Thomasbeau
07-03-2019, 06:43 AM
I have a 2002 F250 with the 7.3. I added the TS Performance 6-position tuner to my truck a couple years ago. I also upgraded the exhaust to a 4" system and added a gauge for EGT. When I tow my 33" Hideout 299RLDS I usually set it to the 75hp setting. This is a noticeable difference in power and helps to keep my EGT down. I do knock off the overdrive at times when I notice the EGT moving up on long hills. The rpm's increase but the EGT drops substantially.