3000 Stall was put on the car about 2 1/2 months ago but this has just started happening the last couple weeks. Car has tranny cooler and larger fluid pan so it's not overheating.

It basically feels like it is locking and unlocking around 45-60 mph making the car shudder. It only happens when I have my foot lightly on the gas and then when I give it a little more gas it stops. If I put it in 3rd it also doesn't do it and that's why I just think it is something with the lockup.

Someone told me about an electical component (PWM or something) in the tranny that may not be allowing the stall to lock.

Can anyone help me diagnose???

Thanks!

 

Please send me and email at performabuilt@yahoo.com and ill send you some info to diagnois

 

Interesting, I had a Vigilante 3200 installed in the middle of June and have a similar problem. I notice when the car shifts between 3rd and 4th gear (under normal driving) there is a little bit of shack or a shudder. It almost seems like it is taking a little longer to shift into 4th or struggling to shift for a moment. The car is stock for the most part other then a Prostock lowering kit, lid and the converter.

Any insight would be great.

 

email sent

 

Mine just started doing the exact same thing. Please send me the same info.

 

I believe you need to change your lock up to a higher mph

 

Are you there? Can you help?

 

THATS WHAT WORKED FOR ME

 

is that just in a tune?

 

Yep "tcc Lock Up Vs Mph" Table.. Mabye Performa Built Can Chime In Here As To Weather This Is Just A Workarround Or Really The Fix But I Know It Works

As Of Now My Car Dosent Lock Up Until About 70mph And Only Locks Up In 4th Gear At A Low Tps... From What I Read Most Any Lockup Clutch Is **** And Will Now Hold Up To Hi Hp Beating So U Wanna Use It Sparingly... My Midwest 4000 Seems To Have An Extra Shitty Clutch And Accordingly It Has A Slight Shutter When Locking Between The Speeds Of 45-60 So I Figure Just Not To Use It Until Im Above Those Speeds

My Old Tci Ssf 3500 Never Gave Me Any Problems During Lockup But I Dont Think The Midwest Problem Is Gonna Be A Big Reliablity Concern

 

Performabuilt - want to chime in???

 

Did you find anything else out?

 

Proformabuilt? Anyone?

 

mine does that too, with a built trans and Art Carr 3600... right around 2000 rpmish

 

yep... 2000 to 2500 rpms... anyone have any other ideas for a cure yet? I will be having someone look at tuning the problem this weekend probably. I'll let you guys know if that works.

 

Well first sorry I didnt come back to this post it slipped under the radar. The likly cause is converter clutch slip and its likley not because theres and issue with the converter but rather PWM the problem is PWM varies the lockup clutch presure in the stock unit to allow a certain amount of slip , This happens for two reasons 1 by allowing the converter to slip it can lock earlier and stay locked partially anyway to improve efficency, However the percentage of lockup is based on a 12 inch converter, And I see many are running small diameter converters 9.5 inch to 10 inch converter which have aprox 30 percent less area than the full size converter. So for instance if you have PWM comand of 60 percent lockup you have a real percentage of 40 percent, This will wear on the converter clutch after a while and slip will increase as it becomes glazed causing the shudder. There are two solutions 1- which is the one we do to all our units is to elimnate PWM completely lockup becomes a simple off and on function. (This one I prefer) 2- In tuning max out the lockup percentage and raise the lockup mph , I am not a tuner so dont ask me how its done but it does seem to solve the issue, Now if you have had this problem for a while you may have already damaged the lockup clutch in which case improvment will be minor an temporary.
Im sure other builders will have other ideas on ways to deal with this , The No 1 way listed above is the one we have had the best luck with.

 

Many countless times we have been faced with similar questions ourselves.

The scenario goes like this.... Customer calls a few weeks after installing his new high stall converter... high stall is defined as anything that stalls above the stock stall speed... and now he has a condition that makes the car shudder and vibrate. It is very depndant on vehicle speed and throttle pressure in each and every case, and each and every case is different in that it may exhibit the symptom right out of the box or it may exhibit the symptom weeks or months later. It may do it in 3rd or 4th or both 3rd and 4th. Usually if it is in 4th the deal is it will engage at a light throttle and the MPH increases so the driver releases the throttle and the TCC disengages and so on. Basically the TCC is hunting the TPS.

The reason no two are the same is because of the different mods, the different tunes, the different power levels of the engine vs. the gears out back and so on........

The one underlying constant with all of them is that the throttle pressure required to engage TCC is now the throttle pressure that is required to maintain a given speed, and that can be a conflict if the tables are not set properly. TCC is very dependant upon TPS vs. MPH. It's that simple.

We too eliminate PWM as it has no place in a performance application whatsoever.Yes, PWM can have an effect, but ordinarilly the condition is related to the fact that the PCM needs to be "taught" that it now has a higher or lower threshold for TCC now that the converter has been changed. It is 9 times out of 10 related to a software issue.

It is very very similar to changing gear ratio's and then seeing your speedometer reading innacurately. If you change the gear ratio then the PCM needs to be tuned for it if it is an A4. Same thing with a converter. It can be considered a fix or a workaround... you decide! If the converter was not changed the PCM would not need to be modified.... it's the same theory as tuning for a cam swap!

It is interesting to say the least! And because no two are ever the same we assume a baseline for tuning transmissions. Bascially we want a higher TPS input vs MPS so we make a coarse adjustment and then drive the car all the while we are dialing in the TCC and other necessary tuning tables.

g

 

Ok Answer This,

Im Using A Flt Lev 4 Tranny With No Pwm And Its Vacc Modulated .. So Basically Both Of Those Thigs Were Set By Flt.. Mine Barely Does It (more Like A Slight Roughness To The Lockup)

Its Only In 4th B\c The Car Is Set Only To Lock In 4th And By Moving The Lockup Mph Up From 30 To 70 It No Longer Has The Issue But The Lower I Try And Lock The Converter The More It Happens.. At 70 There Is No Noticable Shutter And At 50 Its Barely Noticeable..


Btw Thanks Guys For The Reply This Seems To Be A Ongoing Issue For Many Folks

 

Could This Be A Bad Lockup Clutch? And Not A Issue With The Tranny?

 

Alright, so the tuning helped a little bit but it still does it around 40-45 mph. Does this mean I have to do elimnate PWM completely as you mentioned? How would I do this?