TIE1-ON Posted November 25, 2008 Report Share Posted November 25, 2008 So, the GP has the fluid bleed off issue (that's what we think) with the TCC apply valve causing the tach to "bounce" in OD under mild load (not enough acceleration to unlock the TC). Not throwing any codes either. The Sonnax TCC regulated apply valve and kit is going in and while it's down going to replace the PCS and TCC PWM solenoid. For those like me thinking the valve body is located inside the trans. pan underneath think again. They put it on the side! So, anyone wanting to pull the valve body themselves and do these mods in the garage plan on a whole day getting to the valve body. So, I'm taking mine to a shop since it's my DD and I can't afford to have it down longer than a day or two. I'll update once it's done to verify that was the problem. Quote Link to comment Share on other sites More sharing options...
Brian P Posted November 25, 2008 Report Share Posted November 25, 2008 How much would the tach bounce? GM did design it to slip a little under acceleration starting around 1998. My sister's '02 Grand Prix has this "feature". If you're in lockup, and push the pedal about 10-20% further, the tach will jump and hold +200 RPM higher. I hate it, but that's considered normal operation. I had to access the valve body/channel plate once after I installed a reman tranny. I would never do it again (next time I'll pull it back out). Quote Link to comment Share on other sites More sharing options...
IRONDOG442 Posted November 25, 2008 Report Share Posted November 25, 2008 The trans case could be porous too ! Quote Link to comment Share on other sites More sharing options...
TIE1-ON Posted November 26, 2008 Author Report Share Posted November 26, 2008 How much would the tach bounce? GM did design it to slip a little under acceleration starting around 1998. My sister's '02 Grand Prix has this "feature". If you're in lockup, and push the pedal about 10-20% further, the tach will jump and hold +200 RPM higher. I hate it, but that's considered normal operation. I had to access the valve body/channel plate once after I installed a reman tranny. I would never do it again (next time I'll pull it back out). It's not that. The tach is bouncing up and down in OD on slight inclines while trying to maintain speed. This is due to the TCC apply valve allowing fluid to bleed past it thus causing the TC to lock and unlock in succession until either throttle pressure is increased to cause the TC to fully unlock or the throttle pressure is decreased causing it to lock. Known weakness in the 4T65E trans as over time as the TCC apply valve wears away the valve body causing the seal to fail. And it's not the pulsating TC lock feature on this trans. You can't even feel that pulse anyway unless you really focus on trying to feel it. My issue is the tach bouncing up AND down due to the TC locking and unlocking rapidly in OD while trying to maintain speed on slight inclines which normally would not be enough pressure on the accelerator to cause the TC to unlock. Again, I'd do the valve body rebuild myself if it were in the pan but since it's not and it's my DD I don't have the time for it to be down. Quote Link to comment Share on other sites More sharing options...
Brian P Posted November 26, 2008 Report Share Posted November 26, 2008 How much would the tach bounce? GM did design it to slip a little under acceleration starting around 1998. My sister's '02 Grand Prix has this "feature". If you're in lockup, and push the pedal about 10-20% further, the tach will jump and hold +200 RPM higher. I hate it, but that's considered normal operation. I had to access the valve body/channel plate once after I installed a reman tranny. I would never do it again (next time I'll pull it back out). It's not that. The tach is bouncing up and down in OD on slight inclines while trying to maintain speed. This is due to the TCC apply valve allowing fluid to bleed past it thus causing the TC to lock and unlock in succession until either throttle pressure is increased to cause the TC to fully unlock or the throttle pressure is decreased causing it to lock. Known weakness in the 4T65E trans as over time as the TCC apply valve wears away the valve body causing the seal to fail. And it's not the pulsating TC lock feature on this trans. You can't even feel that pulse anyway unless you really focus on trying to feel it. My issue is the tach bouncing up AND down due to the TC locking and unlocking rapidly in OD while trying to maintain speed on slight inclines which normally would not be enough pressure on the accelerator to cause the TC to unlock. Again, I'd do the valve body rebuild myself if it were in the pan but since it's not and it's my DD I don't have the time for it to be down. Oh I see, that's definitely not what I thought it was. I wasn't sure what you meant by "bouncing" earlier. Quote Link to comment Share on other sites More sharing options...
TIE1-ON Posted January 19, 2009 Author Report Share Posted January 19, 2009 Ok I promised I'd follow up and here's why it has been so long. After the Sonnax kit was installed the condition I referred to was helped a little bit. I mean very slightly. So, I was frustrated to say the least. I went back to square one and got second opinion after second opinion. I heard it could be everything from a bad torque converter to whole transmission rebuild necessary. None of that seemed to make sense though. So, fast forward to last week. The intake gaskets blow out and I have Dex-Cool leaking from the intake. I rip into the engine this weekend and replace both upper and lower intake gaskets, water pump, and radiator cap. I get the system flushed and while I'm in there I replace valve cover gaskets, AND spark plugs and wires. Now get this. I put it all back together and take it for a test drive to check leaks. No leaks AND no more transmission issue. I pull the same hills I pull everyday going to work and the RPMs stay steady. In fact my GP pulls the hills like it has a few extra ponies under the hood. So, the tach bouncing up and down under mild load (not enough to unlock the TC) was actually caused by bad plugs and wires and had NOTHING to do with the transmission. With that said before anyone decides to lay down some serious cash to have your transmission valve body rebuilt I suggest trying plugs and wires first. Quote Link to comment Share on other sites More sharing options...
Euro Posted January 19, 2009 Report Share Posted January 19, 2009 Mines done that for probably the past year. I put new plugs in the SII motor recently after I bought it, and they were transferred over when the new SIII motor was put in at the dealer.(cheap asses) Maybe I'll look into the plugs/wires. Quote Link to comment Share on other sites More sharing options...
TIE1-ON Posted January 30, 2009 Author Report Share Posted January 30, 2009 Here's a few pics inside the ol' engine in case anyone goes through similar: Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.