How firm are your shifts?

4PASNU · March 06, 2003, 08:58:28 PM

I just bought my TGP and was out taking it for a drive today. I noticed that at WOT the tranny shift very firm. It's too firm! The car feels like it's going to break in two with the 1-2 shift. Under normal driving everything feels good. Do I have a problem or is everyones like this?

eclipse5302 · March 06, 2003, 09:22:14 PM

After I fully rebuilt my TSTE trans it shifts like that. At part throttle, it shifts nice (sort of firm, but not too much). But, under full throttle it chrips into second--I built it to do that. But the car has been fully repaired/updated (almost all problems fixed, LOTS of new parts), running a TG160 chip, and I just rebuilt the engine as well.

You should be OK. But, You should replace the trans modulator. It determines the shift firmness. In fact, if you pull the vac line off of it and there's any trans fluid in the line, it's bad. It can cause drivability problems too if it's bad, because the engien sucks trans fluid through the line and bruns it. They cost about $20, and the replacements are usually adjustable. Check out my site for info on replacement.

http://www.turboste.com/modulator.html

Jason

Jeff M · March 08, 2003, 12:31:18 AM

Hey, can I add something? Owners of TGPs with hard/harsh shifts at light/part-throttle positions (and at times harsh engagement shifting from P or N into R or D) need to test the Check Valve/Turbo Boost Pressure Relief Valve there at the Modulator! These can fail creating a vacuum leak that causes the Modulator to make the part-throttle shifts too firm. To test, first understand the check valve is also a bleed off valve, in one direction it will hold against a vacuum from the engine vacuum line, in the other direction it will bleed pressure/boost from that same engine vacuum line. So, the port that is open is the Bleed Port/Pressure Exhaust Fitting, the other goes into the tranny Modulator and the other is the signal/source of either vacuum or boost from the upper intake manifold. You want to yank the plastic Check Valve off and check these functions, blocking the port that went to the tranny and blowing through the hole that was feed from the upper intake manifold vacuum line, it should pass air and this is proper. Next suck on that same port, it should hold a vacuum (the ?Check Valve? action of this device), if it leaks, then replace it!!! GM discontinued these years ago (must of sold out of these, not surprised :x ) but Shawn Lin was kind enough to do some research and found another that would work :D , GM part number 14056648 and is only a few bucks, get it!! For those that can?t see this in their mind or on their car then here!:

http://www.turbograndprix.com/VacModChk1.jpg

And YES I very much vote as well to check for tranny fluid at the vacuum line there at the modulator, I just had an owner call me 2 weeks ago with a dead tranny as his modulator was leaking bad enough to suck the tranny dry before he knew what hit him!!

Jeff M

eclipse5302 · March 08, 2003, 12:47:50 AM

Good point Jeff, I forgot about that!

Seems like you're gathering some nice info on your site, when are you going to get her done? Can't wait!

Jason

Jeff M · March 08, 2003, 01:14:38 AM

Getting close to having some time to devote, I got hordes of stuff I can't wait to do, but am (trying) to hold those over my head till I get more of the meat typed up. The years of Fix-It and such info that owners, pre-owners are looking for/need most of all. Next week I should be hooking up with the printer on those TGP posters, last 2 weeks been sicker than sh-t so doing some catch up right now, been bombed with pipe and chip orders for the last month, seems my statements on the other board must of convinced a lot of people about a reputable background :lol:

Jeff M

4PASNU · March 08, 2003, 02:06:27 AM

Do all TGP have this valve? Unless I'm looking at the wrong thing I don't think my car has one. There is just a straight vacuum line from the modulator to the engine.

Jeff M · March 08, 2003, 02:16:14 AM

Uhhh, then that explains the problem!!! Do this.......tell the dealer who is selling the TGP that your tranny guy told you that the harsh shift is because the the tranny is going out/needs rebuilt, then offer the dealer guy less money for the car!!!

Then when you buy it, get that dang check valve installed like it is supposed to be on all TGPs and TSTEs!!!

Good luck

Jeff M

4PASNU · March 08, 2003, 11:06:21 AM

Well that idea won't really work as I already own the car and I bought it from a private seller. The thing that gets me about this is that the car seems to drive/shift just fine under normal conditions, it's just at WOT that it shifts really hard. Does anyone have an actual picture they can post or e-mail me (4pasnu@seacgp.org) of this check valve so I can verify that I do/do not have it installed. I'm going to take a picture of mine and see if I can post it so you all can comment.

Tooky · March 08, 2003, 12:40:40 PM

I can confirm what has been posted. My 1990 TGP would SOMETIMES have a very hard part throttle shifts (enough to make the dash plastic creak) and coming to a stop at 8 MPH it would downshift into 1st so hard that it would startle passengers. Unfortunately I could not solve this and it probably damaged my tranny as I drove about 5000-7000 miles with this problem!!

It turned out I needed to use the new plastic check valve just as Jeff M has posted and it solved all my problems. The funny part is I already had bought the new check valve a long time ago and I had it sitting on my shelf thinking I didn't need it (I bought it to fix another problem with my tranny but it didnt solve that so I hadn't ended up using it.)

Finally I will say my original check valve did not seem to test out any different than the new one when I blew with my mouth! So if your car is having the clunking just go ahead and try replacing the check valve anyway , its like a 3 dollar part and easily worth a try since it takes 30 seconds to swap.

Jeff M · March 08, 2003, 01:05:04 PM

Quote from: 4PASNUWell that idea won't really work as I already own the car and I bought it from a private seller. The thing that gets me about this is that the car seems to drive/shift just fine under normal conditions, it's just at WOT that it shifts really hard. Does anyone have an actual picture they can post or e-mail me (4pasnu@seacgp.org) of this check valve so I can verify that I do/do not have it installed. I'm going to take a picture of mine and see if I can post it so you all can comment.

DUDE, pay attention!!! In my post above there is a link to the pic you want/THE CHECK VALVE!! :silly: Click on the link, see the pic, be the pic, do the pic!! :headbang:

Jeff M

turby · March 08, 2003, 01:13:29 PM

Quote from: TookyCatand coming to a stop at 8 MPH it would downshift into 1st so hard that it would startle passengers.

Mine used to do the same thing. After I replaced the dogbones it quit doing it. When I took the old ones off the rubber bushings fell out on the ground. :drinking:

4PASNU · March 08, 2003, 01:13:49 PM

No need to be rude now. I did see the link and I did look at the picture but if you were paying attention and read my post I would like to see an ACTUAL picture, not just a drawing! Please remember that I'm new to the whole TGP scene and I'm just looking for a little friendly help. Thanks.

Tooky · March 08, 2003, 02:13:22 PM

Here is a link to a picture of what the new ACDelco check valve will look like. Your old one should be similar but beige in color (at least mine was).

http://www.rockauto.com/ref/ACDelco/Detail.html?14056648.jpg

Chris A · March 08, 2003, 02:25:42 PM

I don't think Jeff was being rude. Its soooo hard to get tone in a post. Notice the funky smilies? If not for them I guess it would have seemed rude, but I know Jeff and he was just trying to be light about it.

However, he did say an ACTUAL picture....

And here is where it goes....

Chris

Jeff M · March 08, 2003, 02:39:30 PM

4pasnu, no one (me) is picking on you, that is why I used a few cool funny face emocons :D :D :D when I was getting after you/funning with you! Though its not easy to "hear" the tone of my voice to know if I am yelling or razzing you, those emocons work great at helping in that sence, and my "see the pic, be the pic do the pic" and headbanger guy was funny/funnin with you!!

As for the pic or drawing, it sounds as if you don't have the item on your car and since you need it, when you buy it you will see what it looks like :P And the drawing is the way in must be installed, harder to tell in a photo with the lighting and such. You can still ask for a pic, someone might have a good pic, I don't but I am not the only guy on here 8)

So, welcome aboard, we have fun here while we work/help each other so know now that we will give you some harrassing from time to time, not disrepect, and you can do the same right back, we like it long as its in good taste :drinking:

And, we like helping and even though its not nessisary, give those who help you a nod (like tookycat and Chris A, they got your pic!!) once in a while, little recognition for our efforts is nice, we get too many that dine-and-dash, suck our brains then never return with how our help worked out, or help someone else who comes with a problem, you will get the hang of things here, just give people the benifit of the doubt, most all here will go to great lengths to help, and slap you around in a good sort of way :) !

Jeff M