Hey Willie, I read a post last week:
Blower Woes
You said that a torque converter locking up in third could severely limit topend mph in the quarter. I've attached a run I made last night which I think pertains exactly to what you are talking about. The car ran great last night in first and second but felt like a dog in third. The car is a procharged 305 TPI with all the goodies, except the TCI breakaway TC. Currently I'm running stock TPI plenum, runners, with Accel base behind a 8:31 compression 305 with the LT4 hotcam. The SC is a P1SC with 12lb pulley and three core intercooler, the rest can be found in my signiture. Before the blower I was running 13.4@104 with a SuperRam intake. The attached time slip shows that I'm falling dead at the 1/8th after 80-85mph. Do you think I should go back to the SuperRam to get a higher topend mph? What can I do to assure my TC isn't locking up in third? You said you modified your PROM in the TCC Unlock Prevent to 255mph, did that help? I just want to find out why the car is dying when it should really being flying. Any help will be appreciated.

 

May be a little short on injectors... what are your PW numbers?

I'm running 30's in my 305 with 12 lb boost.

 

Pretty sure injector pulse width is fine--i.e.maxing at 73%. I'm sure the problem concerns my torque converter or intake considering the performance in first and second gear. The stock intake seems to be the most likely candidate because it maxes out at 4500-4800 rpm. I'm just trying to see if the TC could produce these results without having to change back to the SuperRam which is a PITA to put on. I'll scan it later tonight to get some good PW numbers, but I think the injectors are adequate. Any other suggestions?

 

Kendol,

Comparing your time slip to mine, I can see somewhat of the same pattern, although mine was more prominent. Have you recorded data during your passes? This would confirm whether the ECM is locking your converter. I was seeing 102 - 106 mph with a locked converter and 112 - 117 unlocked with almost identical 1/8-mile speeds.

Although I set my TC Unlock Prevent to 255mph, I have not had a chance to verify its functionality. To be perfectly honest, when I discovered that my TC was locking at WOT over one year ago, I spliced a relay in-line on the TCC lock circuit. This relay is controlled by a WOT switch, thereby disabling this circuit. So it doesn't matter that my ECM is locking the converter, it is physically impossible for this to occur because of the relay.

I was planning on checking the TC Unlock Prevent by recording data the next time at the track. Unfortunately, I had a "small" problem which has set me back somewhat. Currently, my engine is completely disassembled.

Willie

 

Using my AutoX-Ray and WinALDL I don't see TCC stuff. Am I missing something? By the way I did do what you suggested in your previous post, made a TCC switch and checked for lockup in third by cruising above 90 mph and trying to lock the converter. The rpms didn't drop, but I also couldn't get it to lock at lower speeds or loads. The transmission was built by DANA at Probuilt and is one of his H/D units. Does he disable the computer TCC controls in favor of manual lockup? I'm only asking this because the switch didn't work at low speeds either. I did however notice a difference in lockup points with the ARAP bin, so I'm assuming the computer is still controlling lockup. What do you think about going back to the SuperRam? By the way I just received my 15# pulley (3.40 in.) from ATI and tried to put it on. The 12# belt, which ATI assured me would fit, didn't. It was too long, I ran out of adjustment with my tensioner. The next smaller belt was too short. Got any suggestions? I considered changing idler pulley diameters but have yet to find anything that will work. I'm actually considering spraying the motor in third to make up for the lack of power--DANGER WILL ROBINSON, DANGER--IM GIVING YOU ALL SHES GOT CAPTAIN, BUT DON'T KNOW IF SHE'LL HOLD TOGETHER. LOL!!!!!!!!!

 

You said:

" I spliced a relay in-line on the TCC lock circuit. This relay is controlled by a WOT switch, thereby disabling this circuit. So it doesn't matter that my ECM is locking the converter, it is physically impossible for this to occur because of the relay."

Could you give me some more info on how you did this or a link to a site that will provide me with the necessary info? By the way, hope you get things up and running soon!

 

Using my AutoX-Ray and WinALDL I don't see TCC stuff. Am I missing something?

Interesting... See pic below. This is what mine displays.


By the way I did do what you suggested in your previous post, made a TCC switch and checked for lockup in third by cruising above 90 mph and trying to lock the converter.

By 90 mph, the converter would have already been locked up, so throwing the switch won't do anything.


The rpms didn't drop, but I also couldn't get it to lock at lower speeds or loads.

Then it seems something is amiss. Try connecting a test light (or dash LED as I've done) to the TCC lockup wire. This is confirmation that the ECM is grounding the lockup circuit. To do this, connect a test light to a 12-volt source and ALDL Terminal F. It will light when the ECM commands lockup. If the light turns on but you don't feel a reduction in rpm, then the problem must exist in the wire to the transmission or within the transmission itself. Or you can test your manual lockup switch while in Park and the test light hooked up. Obviously, lockup will not occur because the transmission cannot lock up the converter in Park (or even first gear), the circuit can be tested this way.


The transmission was built by DANA at Probuilt and is one of his H/D units. Does he disable the computer TCC controls in favor of manual lockup?

I cannot directly answer your question. Mine was built by Dana too, but the odd thing is my "Dana" unit did not come with a high gear switch. Instead of three wires (internally) to the transmission connector, it only had two. Although this has nothing to do with TCC lockup, I find it curious.


I'm only asking this because the switch didn't work at low speeds either. I did however notice a difference in lockup points with the ARAP bin, so I'm assuming the computer is still controlling lockup.

The EPROM does not control lockup. It only controls at what vehicle speed lockup is allowed to occur. At least that's how I understand it, but I'm pretty "transmission illiterate".


What do you think about going back to the SuperRam?

As any good engineer would do, change only one thing at a time. If you suspect a problem, don't mask it by changing something else.


By the way I just received my 15# pulley (3.40 in.) from ATI and tried to put it on. The 12# belt, which ATI assured me would fit, didn't. It was too long, I ran out of adjustment with my tensioner.

Who the heck at ATI told you this? Were you using the 3.70" pulley prior? There's a 1/2-inch difference in belt length between the two pullies!! From memory, I was using the following length belts:

4.00" -- 65.0 inches
3.70" -- 64.5 inches
3.40" -- 64.0 inches

The next smaller belt was too short. Got any suggestions? I considered changing idler pulley diameters but have yet to find anything that will work.

Contact ATI and get the right belt!! Ask for Dorian and tell him I sent you his way.


I'm actually considering spraying the motor in third to make up for the lack of power

Same philosophy as above. I wouldn't do it until you've solved the problem. Then.........

Willie

 

My AutoX-Ray is the 1995 XP240, maybe it lacked the programming the new model like yours has. As for the test light idea, you said:

"Or you can test your manual lockup switch while in Park and the test light hooked up. Obviously, lockup will not occur because the transmission cannot lock up the converter in Park (or even first gear), the circuit can be tested this way."

What would this prove? My switch grounds the F terminal by way of the A terminal. Putting a test light in the circuit would only show that my switch is working (i.e. the switch would allow the 12V source for the test light to ground to the A terminal thereby lighting the test light). I'm kinda lost here, it seems as though I'm missing something. Wouldn't it be easier to drive up to 75 mph with the test light in place and see if the F terminal grounds out above 76 mph? Or have you tried this without any results. I noticed you have an LED showing you TCC lock. Does it illuminate when your at WOT and the TCC locks?

I noticed the PROM has the TCC Unlock Prevent threshold set to 76 mph, I'm not entirely sure what its function is, but it is a constant and therefore my interpretation is that the converter cannot unlock above 76 mph. Is this correct? How about messing with the Minimum Coolant Temp for TCC Lockup? Say raise it from the stock setting of 122* to 330*. Obviously this wouldn't be for daily driving, but how about for racing?

As far as belts are concerned, are you saying that you always bought your belts through ATI? Cause they're super expensive compared to the $28 I pay at NAPA. The 3.70 pulley uses the 080645 Gates belt (I'm assuming this is where you got 64.5 in belt) which actually measures 65 1/4 in (per back of packaging box). The next belt size down by Gates is the 080644 which measures 65 in. this is still too long. After that the next size available is 080640 which measures 64 1/2 in. but this belt is 1/4 in. too short (can't bolt up the blower with the belt on the pulley). What's up with this?

As far as changing one variable at a time, I was just wondering if the stock plenum and runners were strangling the motor in third, because the SuperRam should cure this. Might be intersesting to see if just that change alone picks up the mph in the 1/4. By the way you said when you compared my slips to yours that they showed "somewhat the same pattern," is this because my mph was over 105? Do you think there might be something else I'm overlooking? By the way when at the strip I disconnect my knock sensor to eliminate false knock.

 

It was under the Flag Data tab not Operational Data. What else could cause 3rd to be a dog compared to 1st and 2nd. The car should be a low 12 to high 11 second car. Its race wieght is 3430 with driver and half a tank of gas. Last weeks dyno session showed 419hp/486 lb*ft and good AFR across the board. By the way the car gained 2 mph by raising the base timing 4*, but excessive tire spin became appearent in 1st and 2nd. This is because I'm still using the stock PROM advance table, I'm trying to be cautious to avoid over advancing the timing and causing detonation. I'd also like to add the 1.776 60 ft was accomplished with stock suspension/BW-rearend minus subframes on drag radials for those of you who think aftermarket control arms, torque arms, and traction bars are mandatory for decent 60 ft. times.

 

Hey Willie, you go to sleep? If so no problem, but please get back to me when you can. Hope your "small problem" can be fixed without you pulling your hair out later!

 

Could you give me some more info on how you did this or a link to a site that will provide me with the necessary info?

The TC is locked when the ECM grounds the appropriate circuit. All I did was interrupt this circuit (#422) from grounding with a relay: Cut this wire (tan/black in my case) and connect each loose end to #30 & #87A on the relay. You will need to fab some sort of WOT switch to energize the relay. When NOT in WOT, the relay's #30 & 87A contact, thereby allowing lockup to occur. When at WOT, the relay energizes, disconnecting #30 & 87A and opening the circuit. Now, if the ECM grounds the circuit, it has no effect -- no lockup!


By the way, hope you get things up and running soon!

Thanks. I'm taking advantage of this situation to replace internals with 4340 forged pieces and converting the 2-bolt into a 4-bolt.

Willie

 

My AutoX-Ray is the 1995 XP240, maybe it lacked the programming the new model like yours has.

I just so happens that I have two scanners, one is an XP240. It also displays Lock/Unlock status, so I'm not sure what's going on with yours.


".... the circuit can be tested this way." What would this prove?

It proves that the circuit, including ECM is functioning correctly. In diagnosing a problem, we need to eliminate one variable at a time. Since this is the simplest "variable", its functionality should be tested to verify. Then we move on.


My switch grounds the F terminal by way of the A terminal.

Understood. The A terminal is ground.


Putting a test light in the circuit would only show that my switch is working (i.e. the switch would allow the 12V source for the test light to ground to the A terminal thereby lighting the test light).

Exactly. It's confirmation that the switch works.


[b]I'm kinda lost here, it seems as though I'm missing something. Wouldn't it be easier to drive up to 75 mph with the test light in place and see if the F terminal grounds out above 76 mph?

Easier? That depends. Two points:

1) Is it easier to hook up a test light and do as you suggest, or would it be easier to hook up the test light and with your car idling, throw the manual lockup switch? The result is the same -- the light should light.

2) I think you're confusing this "lockup @ 76 mph". This parameter is valid only in fuel enrichment mode. If you decide to hook up a test light, you don't need to hit 76 mph for lockup to engage. In closed loop, there is another ECM constant that determines minimum vehicle speed for lockup to engage. This is the speed you'll need to attain for the test light to light.


I noticed you have an LED showing you TCC lock. Does it illuminate when your at WOT and the TCC locks?

Yes. Regardless of condition (cruise or WOT), when my TC locks, the LED lights. I can also light it at any time by flipping my manual lockup switch. Note: The TC will lock when I flip the switch, except in first gear (Park and Neutral too).


I noticed the PROM has the TCC Unlock Prevent threshold set to 76 mph, I'm not entirely sure what its function is, but it is a constant and therefore my interpretation is that the converter cannot unlock above 76 mph. Is this correct?

I'm not exactly sure either as I discovered this constant with the most recent TunerCat EPROM definition. Your interpretation might be correct, although I read it a different way. I know for a fact that if I nail the throttle at from a constant speed, say 85 mph, the transmission will downshift and the converter will unlock. So I can't say with any degree of certainty.


How about messing with the Minimum Coolant Temp for TCC Lockup? Say raise it from the stock setting of 122* to 330*. Obviously this wouldn't be for daily driving, but how about for racing?

I've never thought of doing this. It might be worth a try.


As far as belts are concerned, are you saying that you always bought your belts through ATI?

I did purchase all three from ATI, but I did get awesome prices because of my involvement with the third gen twin intercooler setup.


The 3.70 pulley uses the 080645 Gates belt (I'm assuming this is where you got 64.5 in belt) which actually measures 65 1/4 in (per back of packaging box).

The ATI belts (I don't know who manufactures them) have the same belt length discrepancy. All I can tell you is that the 64-inch belt from ATI works with the 3.40-inch blower pulley.... wait a minute!! I just realized something.. I do not use the 12-rib 7.65" crank pulley. I used a marine application 8.5" 12-rib... my memory fades... now, to only recall exactly when I changed crank pullies....hmmmm.....


As far as changing one variable at a time, I was just wondering if the stock plenum and runners were strangling the motor in third, because the SuperRam should cure this.

Well, it certainly could. But wouldn't it be nice to know that the TC lock/unlock is or isn't causing your perceived low mph? I know I would need to know before making any other changes. Also, I like to think I cured the problem by not locking the converter. My mph is as high as its ever been. Maybe now, I should install the SuperRam??? After all, my engine is completely apart... now's the time???


By the way you said when you compared my slips to yours that they showed "somewhat the same pattern," is this because my mph was over 105?

1/8-mile speed (plus or minus 1 mph):
Yours: 88 mph
Mine: 88 mph

1/4-mile speed:
Yours: 105 mph (locked?)
Mine: 105 mph (locked), 117 mph (unlocked)

I am real curious to see what your mph would be knowing your converter is unlocked, don't you? I would definitely like to know if you can reproduce my results.


Do you think there might be something else I'm overlooking?

I was pulling my hair out when I was trying to figure this out. My clue were my timeslips. That's when I realized something was happening from the 1/8-mile marker to the finish. I don't know about you, but my acceleration felt good in first and second gear, so I don't think you're overlooking anything.


By the way when at the strip I disconnect my knock sensor to eliminate false knock.

I to do the same thing too. Tell me, what is your total advance and your IAT readings?

Willie

 

Hey Willie, you go to sleep?

Some say this is a constant state with me!! Typically up at 5am, down around 10:30pm....

 

How well do you know your model of valvebody? Some years have a TV lock-up valve which is the last failsafe to force lockup, if all else fails. Also there is a .380" checkball that comes in some of the shift kits for placement between the lockup selenoid and the valve, or those shift kits that recommend relocating the .380 inch "TV safety ball" to the location between the lockup selonoid and the lockup valve, those are both done to force lockup in case of electrical failure. Just something to think about for some of you that think a switch that shuts off the lockup selenoid can stop lockup in every tranny. Also putting a "inhibit" switch in your ride must be done like willie, if you just toss the job onto a regular toggle and forget to put it into the regular position while cruising and your tranny has no other TV lockup safetys then you can fry the converter as well as a few other parts in short order. This is not meant to scare you from doing it. Its just some food for thought. So before you all get confused over what I said, I will set it straight:

• some valve bodys have valves to force the lockup valve to sweep even if the selenoid isnt telling it to.
• Some peoples shift kits where a .380" ball has been dropped into the lockup selenoid orafice 'can' get a forced lockup if the selenoid isn't telling it to
• If you decide to electronically inhibit the selenoid do it like willie said, don't just use a toggle because if you forget it when cruising,you might not like the possibilities

 

AS far as your XP240 AutoX-Ray showing TCC lockup, I find this curious! The only other thing I can think of is that maybe its programming is different for a 350 vs a 305. I swapped my 350 for a 305 yet still use the same vin parameters as with the 350 to configure the scanner. Please tell me if it appears when you configure it for 89 GM, 8th vin 8, 4th vin F. Not sure if I should scan with different parameters considering all I changed was the overall displacement (old 305 was all I had while building 383).

AS for IAT readings: At the track, coolant temps were ranging from 170*-200* and intake air temps were 104*-108*.

My timing table is as GM left it for the original GTA L98 350 and it has been attached. As I said before it did pick up 2 mph by advancing the base 4*. I intend on playing with my advance tables as soon as I find out whats up with 3rd. I'll likely add 4* to the attached table above 3000 rpm to limit tire spin down low.

I hope poeple don't start shouting "ITS YOUR TIMING DUDE!" Put simply 1st and 2nd are just scary for a full weight street car, and my latest runs at the Motorplex are showing that something is wrong specifically in 3rd, not 1st and 2nd. From this and my 8th trap speeds I'm thinking its not the timing, though obviously it still needs work--I don't think it would cause a 8-10 mph discrepency.

By the way Willie, what rearend gears do you have? I'm still using 3.27 and use a 27.75 in. tire to reduce the overall gear ratio in 1st and 2nd to help reduce tire spin. With this combo tire spin is minimal (given a good burn out), but maybe its too much for the 1.00 trans gear in 3rd. What are your thoughts?

As for changing the intake, are you still using the stock plenum and runnuers for your 115-116 mph 1/4. If so, I'll relax on changing it since its not hurting you. By the way, the plenum was port matched to the Accel 1000 cfm TB, other than that the plenum and runners are stock.

For those who doubt the problem solely being appearent in 3rd, my cricked neck and sore neck muscles are proof of the power in 1st and 2nd. Tilting my head makes me feel like a NASCAR driver, LOL!!!

 

Assuming WinALDL's TCC L/UL flag works properly, it should give me what I need even though the XP240 doesn't. However, I still find the XP240's lack of TCC parameters CURIOUS!!!!!!!!

If I can just get 3rd to pull like 1st and 2nd, I'll be happy--for NOW. The 3.40 pulley looks more and more appealing every day--LOL!!

 

Your right using a switch to manually cause lockup can be dagerous. If you forget to switch it back tranny woes are in your future. As for me, I use a momentary contact switch instead of a throw switch. So as long as I don't hold the button down while normally driving I'll be just fine. Thanks for the info though!

 

I didn't read the whole post but...


I usually set my car up to lock up the torque convertor in third at 5200rpm (spins up to 6400). I do it via TCC unlock prevention speed.

Its usually worth almost a MPH but no gain or loss in ET. You can disable it by just setting it up to like 120

 

Willie.....

Switch works like it was designed, not to poke fun but I have a BS and MS in electrical engineering. Just hooked up the light in series with the switch and it lights the bulb when ever the button is depressed (car running). Therefore, I'll make the assumption that the TCC is working properly and I can control it.

My wife is driving the car right now and my laptop is logging WINALDL flag data, so when she gets back I'll take a look at it to see if its locking at all speeds above 76mph (she has a lead foot so it should be easy to see).

By the way if you have the SuperRam why weren't you running it before? It extends the available rpm range by 1500 rpm--I'm running the stock box because I couldn't find an annoying air leak when I had the SR on. I really need to remedy that!

 

I didn't read through this entire post so I apologize if this has already been said ...

The Torque Converter has a mandatory lockup in third gear around 72-78 mph (depending on the BCC of the PROM). Changing the 'Mandatory Torque Converter Lockup' speed will change this. I tested and verified this over 2 years ago. It works.

Tim

 

Thanks TRAX!!! Please provide more info though on what constant you changed and what bin and ecu file you were using. I read some ecus didn't support the TCC Unlock Prevent Threshold!

 

dude i said the exact same thing 2 messages ago

 

My bad Your right. I'm assuming you changed the TCC Unlock Prevent Threshold from 76 mph to 120 mph, right? Are you sure that its not locked? What bin-ecu are you using? Just want to eliminate this problem before I move on. Thanks again and I'm sorry I over looked your post.