I have an ATS five star, and an ATS valve body in my otherwise stock tranny. When it was installed a few weeks ago, everything looked beautiful. Bright colored ATF, no material in the pan. Filter wasn't new, so I assume it hadn't been serviced recently. (Just bought the truck a few months ago, so have no idea of service records.) The trans has been great since it got put back in, and I'm getting used to the firmer shifts, and the very firm lockup.

After I did a fuel plate and GSK last night, the thing is acting different.

Wierd thing now, is when gently cruising in 3rd gear with OD shut off, the TC will periodically unlock. It will lock up again in a few seconds, and after a bit, do it again. Also will do it sometimes in OD.

Also, is it normal for the trans to shift at a pretty low RPM after a GSK? If I give it lots of throttle, the 1-2 and 2-3 shifts come at a pretty low speed. Just curious.

I wouldn't think I could have messed up my new ATS parts that easily. I wonder if it has something to do with throttle position.

Hopefully someone has some pointers or advice! Any and all is greatly apprreciated.

Thanks,
Chad

 

mine would do the same thing if i was really into the throttle in drive the converter would unlock because of the tps. it makes sense for a gasser but not these engines. what i did is install a tc lockup switch to keep it locked when im mashin it in drive. i have stock shafts and leave it locked for the shift from drive to overdrive but i always let off the throttle for the shift then get back into it. its alot quicker and feels really cool. the 1-2 and 2-3 shifts are usually really early on these trucks, thats normal. youre usually in 4th gear by 40mph but it feels like a 5 speed when the converter locks and puts you in the seat. it just feels different when the shift pressure is increased you actually feel the shifts. youre in good shape.

 

Yeah, I know it's all good as far as the shifting goes, and I'm used to the firm lockup. I plan to install a lockup switch so it will remain locked in 4th when I floor it.

My problem is that it now unlocks when I'm cruising at an even speed. If I accelerate again, it will lock back up. It's like the trans thinks I'm letting all of the way off of the throttle, whih would normally make the converter unlock.

I adjusted my idle speed after I did the GSK and fuel plate. During the test drive after that is when I noticed that the converter was acting differently.

Could the idle speed adjustment have screwed up the TPS or somethng else that would cause this?

I called ATS today, and they reccomended checking the lockup solenoid in the trans to make sure it's nott sticking. While I'm sure that a sticky one could cause an issue, it just seems too coincidental that it would start sticking right after tuning mods.

Whatcha think?

 

There are some voltage values that need to be addressed for your T.P.S.
As I remember, you should adjust your T.P.S. to show about 1.0 volts at idle setting to get normal trans operation. You can make adjustments by loosening the two mounting screws and twisting the housing around. When you adjusted idle RPM, you probably changed the T.P.S. adjustment also.

You really need to confirm the voltage settings I gave, since I have not looked those up in a long time. That voltage helps the ECM to engage OD and lock the convertor at certain points. When you adjust the idle, you will also adjust the T.P.S. setting inadvertantly.

If your T.P.S. is "dirty" on the inside, it will send an erratic signal and the ECM will lock and unlock the convertor. Also, check the brake switch adjustment. Too tight, and the brake switch will engage on bumps and unlock the convertor and you will have never even touched the brake pedal.

Good luck and let us know if we can help any more.

Ronnie

 

Thanks! I think we adjusted the idle speed incorrectly. I was in the truck watching the tach while another guy adjusted it. I think he may have been adjusting the turnbuckle type thingy. I'll double check with him on it though.

Next question is where is the TPS located, and how do I check or adjust it?

 

Sounds like he knew what he was doing with the idle speed adjustment, although it is set a little high.
Stock TPS should read 1.2 volts. Mine was at .7, so I adjusted it to 1.37 volts. Converter is still acting up. I'll call ATS again tomorrow, unless one of you gentlemen has the answer for me!

 

Go to TECH Facts in the header bar, at top of this page, then to 12valve section then to the TPS section. It gives you what you need. Just now saw that you found the voltage levels. Any help from ATS? I cleaned my TPS and it worked for quit a while but some times it just has to be replaced. It has a wiper inside on a wire linear coil and the wiper wears out or gets dead spots in it.

 

ATS suggested looking at the lockup solenoid in the trnny. I guess they can get sticky. I kind of figured it miht have had something to do with the work I did on the fueling end, since that's when it started acting up!

 

Not hard to check TPS on your own. A bad wiper will show up on a meter across the wiper to coil pins. Should be a smooth movement across the whole coil with no dead spots. Can do that right at home. Just a thought.

 

Not sure about the terminology, but I think that's what I already did.
I metered between the black and orange wires, and it looked like a nice linear voltage increase as I turned the throttle linkage.
I'm going to drop the pan in the next few days and check the lockup solenoid.

(Not a daily driven truck, so it's not needing to go anywhere.)

 

The brake sw can be at just a point that hitting a bump in the road can get the peddle to hit the sw just enough to kick out the LO , OD & cruse , adjusting the sw is done by one hand pressing brake peddle , the other pulling sw foot out [ towards peddle , it can get out of adjustment too easy by just a little lift on peddle .
An other issue can be interference from alternator , rapping small wires from back of alt to computer has helped many .
For checking shifting in trans , it is easiest to put jumper wires to connector at trans to a low impedance meter [ these go back to computer so low impedance is important ] to see if the signals are what they should be .
Once all out side the trans is known to be good , the best way to check trans is with gauges under running conditions .

 

The brake switch could be the gremlin. Only cost 10-20 dollars and easy to install.
The speed sensor on tailhousing could also be a gremlin. Mine had a wiring issue at the connector.

 

I had trouable with my brk. sw. [96 4x4 2500 ] when i hit a bump it would kick out but also if you have cruise on it would shut it off also. just my 2 cents
scarry

 

just hit me that you mentioned the idle adjustment after the gsk install. im guessing you had to lower the idle. if you did then your govenor springs might be too tight and you have to loosen them and of course raise youre idle. what i think is happening is you are almost all the way off the throttle at this point your lockup disengages but your rpm's are still hanging up. if you are cruzing at say 65 70 mph give it some throttle and let off. if they dont drop as fast as they did before the gsk your springs are too tight. the spring on the outside is your idle spring and it wont defuel as much when you let off the gas at mid- high rpm, all springs are compressed by the locknut on the end of the shaft. hope this helps.

 

This makes some sense. Not sure where the springs are set. The guy that helped out said he has always put the new ones in as far as the old ones.

How far should I back them off?

BTW, the truck will rev to at least 3300 RPM. Maybe a little closer to 3400. Is that higher than normal for a 3K GSK?


Thanks!