Hello everyone,

I own a early 99 F250 super duty with a 7.3. I have a mildly beefed suncoast transmission. The tranny is a 4R100 with transgo tuger accumulator valve body, .500 lines, transgo valve body kit, upgraded intermediate shaft, all built by suncoast with a triple disc billet converter. Also installed is a TC performance 6 position chip. I am running Power Hungry tunes on the chip. The chip has been installed since the trans was put in. There are now about 8k miles on the trans. There was never an issue with chip and trans.

That should cover all the background info i think.

About 2.5-3 weeks ago I was driving my kids to school and everything seemed fine. I came to a red light and accelerated a little quick because the lane merged... then the transmission shifted really hard into 2nd. It felt like I was rear ended. I then noticed that it did this a few times... really anytime I was over 2000 RPM. Under 2k and it shifted like silk.

Removal of the chip and everything seemed to be normal (I have no honest base of normal because I have never driven without the chip until now), but I had no issues. I then performed a manual flush and filter change. The shifting problem was still there but did not seem as harsh. drove it for about 2 weeks until taking it to a trans shop.

Took it to a local trans shop yesterday and the tech performed diagnostics and found nothing. I asked if he gave it some get up to see if it shifted bad and he said he drove it normal. He also said that the diag didn't show anything unusual. I picked up the truck and it was still doing it. Now completely frustrated I told the wife I was gonna "test" something. I picked a empty back road and put it in position 5 (100 hp) and stood on it. shifting to second was at about 2900 rpm, perfect shift, into third was at 2500, hit hard during that shift, into OD was normal. So I called trans shop and he said bring it back and i can take him for a drive so he understands whats going on.

When I left the driveway this morning it was driving perfectly like nothing was wrong. After about 30 minutes the shifting started getting harder during that RPM range (about 2100-2600 based on my visual of the tach). Tech felt hard shift this morning and decided to check wiring and to diag trans without the chip, still found nothing. He called me and said he did not want to open it up because he feels its with the chip and not internal. I talked to my cousin who I bought the truck from, he is a well versed individual with 7.3's, and he is stumped and advised posting on forums.

I do apologize that this post is so long, but i wanted to make sure I provided all the info and background I could. I hope you guys have some ideas for me.

No I have not erased and re-burned the tunes on the chip yet, will be doing that soon. I'm also gonna be cleaning contacts on PCM and chip tonight when I pick it up from shop as well as do a test drive in the tow modes which have lower line pressure than daily driver mode and performance modes. I will update with results.

Update after picking it up. Cleaned the contacts, which were spotless but figured it couldn't hurt. Drove the truck lightly to get it warmed up, which is when the issues seem to arise. Tow modes are 25hp extreme tow, 45 heavy/med tow and 65 med/light tow. all of these modes still had the same shifting issues. although I did notice that the kick/slam shift was lighter in the lower modes. As i increased the chip position, increase to hp and line pressure, I noticed it shifted a little harder than the previous tune.

I know it's late and im sure most people are as stumped as I am. But any assistance is greatly appreciated.

Again, thank you all for the assistance that you guys provide to these forums.

 

Welcome to FTE.

Even though your issue seems to be strictly related to the transmission, I moved your thread to the 1999 - 2003 7.3L Powerstroke Diesel forum since it hasn't gotten any response in the Super Duty forum. These folks are great and should be able to help you out.

 

Choose a tow program from the PHP server that doesn't have additional line pressures added. Load one of the tunes with Trans tuning in, say, Postion 1, and the tunes without Trans tuning in Position 2 and see if there is a difference.

 

If it drives normal with the chip removed then the problem is the chip. The first step I recommend is to completely remove the chip and see what happens.

 

Hey mark, this is the same post from PSN. Didn't know how many would be on both. I have removed the chip for now but I'm not noticing any issues without chip. But I never drove it without the chip before the problem so I can't accurately say if it has a problem right now.

I thought at first it might be the chip, but either a chip works or it doesn't. It wouldn't foul up one segment of code across all 6 tunes. If the tunes went bad then the truck should run like crap. But that's just an amateurs best guess.

I will be heading to my cousins soon and will try the tow tune without increased line pressure to see if that helps.

Also the weirdest thing about this issue is that after the truck has sat for an hour or more, it will drive and shift fine for 10-15 minutes. Is it possible the solenoid pack is going out? And that it can't keep up with the boosted line pressure, but operate properly at normal tuning?

 

I have the same thing in my truck I have a sun coast shift kit and it shifts just like you are saying yours does word for word. I have been talking with a friend of mine that does a ton of truck pulling and he says it is completely normal to shift like that when you have pressures cranked up. I can tell you when I put a load on my truck it shift like a dream but empty it shifts hard cause there is not load on the truck to make up the difference in the tranny. Have you called sun coast? Please keep me in the loop I would like to know what you do to fix this problem. If it really is a problem or if it is something that is just annoying.

 

I suppose that's possible, but it sure doesn't make sense to me.

Let's review. It runs fine without the chip. You install the chip and it has problems. That says to me there is something in the chip causing the problem.

I don't know that anything is corrupted in the chip, it just may be bad programming. I don't know what they programmed into it, but it sure seems clear to me that the chip is the issue.

 

Jake- my truck has always shifted so seamlessly you almost didn't know it shifted, and my passengers usually never could tell, so no this is not normal. This is not just firm shifting, it shifts so hard it feels like I'm being rear ended while driving. Maybe not quite so harsh as an actual rear end but that's the base of it.

Not bad programing if this was never an issue for the last 18 months. The truck has had the chip long before trans installed, installed trans, updated the tunes and everything has been fine for 18 months.

Mark I understand what you are saying, but it has driven fine for almost 18 months with chip and then out of nowhere this happens. And it's all tunes. No other issues detectable with chip, so it just doesn't seem logical that the chip is the issue. Yes chips do go bad or files get corrupted, but then the truck runs like such garbage it's usually undrivable. It's not possible to only have the trans pressure portion of 6 tunes to go bad over night and nothing else in the programming. So I just can't grasp the chip as the issue, the issue is there and the chip just makes it noticeable. And that's what I'm trying to figure out, I think it may be shifting hard without chip but....until this issue I have always had chip so I'm not sure. If problem is there without chip what you think it was mark?

 

I'm not the DJ (a tuner), but I've danced this dance with my HD4R100. The tunes are not "One throttle fits all" with shifting. There is a "ramp" of sorts. With a deeper throttle, the shifts are modified to take the added torque. If you have a modified transmission with a tune set for a stock transmission, you'll feel like kids are in the back seat - kicking the back of your chair.

Dan V saw "PHP" and "Hydra" popped into his head, but you have a TS... so you can't do as he suggests.

If you have modified tunes, they may need some adjustment. You can send the TS chip in to be dialed, and run stock while you wait - or just stay out of the throttle. Both of my chips have been the type to receive tunes over the internet and update with a laptop connection - to prevent what you are experiencing now.

In order to help the tuner sort it out, you need to document where in the throttle things go wrong... and how bad the shifts are (like slight, moderate, and severe).

 

I've already sent an email to bill from power hungry. He says it's not tuning. He also said if I wanted lower pressure he would code it for me, for a price.

I am already running enhanced tuning from power hungry, I beleive that was in the OP. I have 25hp extreme tow, 45hp heavy tow, 65 light, 80 daily driver, 100 performance and 140 extreme. They have all been tuned for my tranny. So unless a 1 in 10 billion chance occurred and the only segment of code that got messed was pressure, it's not chip or programming. The chip and tranny have both been installed for 18 months with 0 issues.

I did say in the previous posts the severity, it's not just a firm shift, I know what that is. This is a slam like being rear ended and it only happens between 2100ish RPM and 2600ish.

First I'm just gonna have chip erased and reburned at my cousins since he has a burner and can change tunes whenever needed. I'll go from there I suppose. Even bill is confused on the issue.

 

You could drop the pan and remove the accumulator body. Check the 1-2 accumulator valve for damage or sticking in the bore. If I had a diagram to show you which valve that is I would post it here, but I don't have one.

 

Ok I'll look, I've already looked at the diagram, I'll download it to be sure though. I should be looking for sticking issues, marring and other markings correct?

 

Not sure if this helps or not, Mark?



Or possibly this thread? https://www.ford-trucks.com/forums/7...ml#post6111578

Stewart

 

Ah... I re-read the OP. Sorry for the wild path there.

Here's another one, if the other ideas don't pan out: My rear-end clunked pretty bad after a lot of tire shredding with bigger sticks. The tune no longer mattered, even stock power clunked. I had to install ladder bars on my stock-height truck because of axle wrap, and the unintended byproduct was much smoother shifts. Maybe something worked loose back there... I dunno.

No suggestions here, just sharing my experience.

 

That's right.

That's the diagram. Check the valve labeled for the 1-2 shift. While it's out you really should check all of them.