rebuilt 4l60e shift problem

[Chris Schofield]

Don't need 2 experts arguing, just want some new ideas to try. Rebuilt 4l60e will not shift at WOT. Shifts under normal load at about 2800 rpm. TC rebuilt also. Tried new TPS. No change. Looking at testing VSS. Guy that rebilt it moved a good distance away. Trans shop wanted to rebuild it again, even though it only has 5 miles on it. Cost me $500 for him to change out the TC (2800 stall) and tell me absoulutly nothing. Got opinions from some of yoy guys before. Reminder, it is not a street car.

[Mystery Bird]

It shifted fine before the rebuild? and tuned for the converter and gears I assume?

[Chris Schofield]

Actually no. Old trans would not shift in any forward gear. Rearend tore up and apparently hurt the trans also. Picked this one up with a bigger stall. Not shifting into 2nd under the gun was the reason for rebuild. PCM for less was stumped also and tuned my 2nd computer for the new gear change. Went with a 12 bolt strange with 4:30 gears and moved from a 2400 to vigilante 2800 that came with the new trans.

[Xzauhst]

I'm no trans expert at all, probably the exact opposite, but I had this problem before I got mine built. I thought it was a tune, pressure, I tried anything but I never thought it was the actual transmission. I had just bought the car a few months before so I really didn't know where to start.

It was my transmission that was bad. The bands had just enough to shift under normal conditions but WOT was just neutral for every gear.

Since your transmission was just built, I'd thought it would be a tune. The best thing tbh is to buy your own tuning software like I did so you can actually see where your shift points are. Then you can lower them to see if it makes any difference. Even if that's not the problem, you can always use the software later down the road for when you do other mods.

Wait for a transmission expert to give their advice. Maybe they know exactly what the problem may be. Best of luck.

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[Chris Schofield]

Not a bad idea. I read your thread prior to posting mne. Trans guy that built it wanted to check the 1-2 solinoid. the actuator rod for freeness. I think your trans was a 4l60? Regardless, what did you buy? and pay? I still have my old trans and was thinking of pulling out the valve body and separator and installing it to see if it made a difference. Changing out a solenoid I guess is not too difficult, so I hear. Lack of trust in trans shops has forced me to take matters into my own hands and do it myself.

[Xzauhst]

Mine is a 4L60E. I paid $1,900 for a built 4L60E for 600+ hp, new stock torque converter, and they also replaced my rear seal because I had an oil leak. I went to starias transmissions on long island. They knew a lot about what they were doing. They basically took everything out of the tranny, fixed what GM did wrong, and gave me the nice firm shifts I wanted. I'd go there again with any camaro if I had to. They even have a camaro with over 700hp on my same transmission there.

If you're in the area I'd give them a call and see what's up. They charged me nothing to find out what was wrong. If it didn't shift before and still doesn't now, and you got it rebuilt, and its only WOT, maybe the tune is wrong. Just maybe. Who knows. Tuner cats program and cord for tuning is only $100 I believe. Couldn't hurt to have it later down the road anyway. Especially since here in NY nobody even has the software to tune my car. I can always just give them mine when I go. Hopefully you get this straightened out.

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[Mystery Bird]

Tuning would be my first guess if you know the trans is good. If your shift points or RPM tables don't match the stall and gears you will have all sorts of shifting issues especially at WOT.

[Dynamic396]

You don't say which shifts are affected, but you need to find out if the PCM is commanding the shifts. If it is commanding the shifts, and the transmission is not executing the shifts, that will lead you in one direction (transmission). If the PCM is never commanding the shifts at WOT, and it just bounces off the rev limiter, that will lead you in another direction (tuning).

One thing that can happen when installing a looser converter (higher stall speed) is that the engine rpm will hit the rev limiter before your road speed reaches the shift point because of the greater speed differential between impeller (engine) rpm and turbine (input shaft) rpm. PCMforless should have accounted for this in their tuning, but I've seen it quite a few times. You have to either raise the rev limiter (risky, depending upon engine setup), or lower the shift speeds at WOT.

If you had a bad shift solenoid, you would not get any shifting at normal throttle settings. Besides, they should both be brand new. Same thing with the VSS - it either works or it doesn't...

[Chris Schofield]

Good point. The current shift point is 6000 rpm. It will shift if I take my foot off the gas. Maybe I can swing a deal with PCM for less and have them lower my shift point to say, 5500? Or will that just end up the same thing being that my foot is still buried in the throttle?

[Dynamic396]

That's just it... Shift points are calibrated in MPH (road speed), not RPM. And your rev limiter is calibrated in engine RPM, not MPH. That's where a loose converter can really screw with you. What you typically have to do is tweak your shift maps to where at high TPS readings, your shifts are initiated at a slightly lower road speed (MPH) than they were with the stock converter because your differential between engine RPM and road speed is going to be greater with the looser converter. This is why when you're at WOT, road speed will never quite reach the WOT shift point and it will just bounce off the rev limiter. But as soon as you back out a little, the TPS voltage comes down and the PCM "reads" a different portion of your shift calibration maps where a lower shift speed is specified, and it commands the shift.

A stock LT1 converter, behind a stock engine will stall at around 1800-1900 rpm, give or take... You've added approximately 1000 RPM to your stall speed, plus you have a few engine mods, which will add some torque, further exaggerating the effect. I'd definitely have PCMforless take a look at it.

[Xzauhst]

I agree, that's what I was trying to say I just didn't know exactly how to say it. I didn't know you added a bigger stall than before, I guess I wasn't reading lol. But I do recommend buying your own tuning software. I changed my shift points in less than a half an hour. You can always adjust it to how you like also without having to wait for a mail order. That way you can always back it down if you don't want to risk that extra 100-200 rpm any time you want. And the software does everything too. Not just a simple shift tuning.

[Chris Schofield]

OK, thats the best explaination of something that has been very confusing, atleast to my dumb ass. I fully agree and will call Keith or Brian tomarrow and run it by them. One thing I do need to bring up is that when the B&M 2400 and 4:10 gears were in the car it worked great. Rearend, gear change and torque converter all happened at the same time. Car has not made a sucessful pass down the 1/8th since April. Thought on several occations and all the extra money I threw into this that we were ready to go. Still would like some info on what tuner I need to adjust all this stuff myself. Have to get a lap top also. No problem there. JEGS and Summit have a few to choose from but not sure if other manufacturers might be better.

[Xzauhst]

Look up tuner cats. They send you everything you need. The cables and software. You can also tune for gear changes, I believe stall, and stuff like tire size and engine stuff too. Do some research into it. I've only used the program twice for my shift points. Haven't had the car because of a transmission and now possibly the engine. I have to stop my racing habits lol. Wish I could help more.

[Chris Schofield]

Thanks for the info. I"ll check it out right now. Also, for Dynamic 396, thanks also, and the rev limiter right now is set at 6300

[cocobolo95]

Unfortunately, tunercat doesn't work with 96 and up obd2 cars. You'll have to go to a more expensive obd2 tuner, unless you want to convert your car to a 94 or 95 obd1 pcm. It is not a hard project. Then you can use tunercat as your tuner.