MAP sensor?

[HotRodPC]

I'll wait till I get confirmation from CK on his make and model for sure, but I am beggining to think his TCC solonoid could be stuck in the on position. So if as soon as he hits 4th gear the TCC is locked, then I'd say that's it. The only reason why he is unlocking with throttle pressure and hitting the brake is because those override the TCC solenoid. Also just a guess and wonder if the governor may not be sticking, as when he slows down it should be downshifting. If it downshifts to 3rd on a slowdown, that should unlock the TCC also. Doesn't sound like its downshifting as needed either unless he floors it at which time the TV cable will take over and bypass the governor and cause a downshift.

 

[89Suburban]

If he shifts it into 3rd/drive and trys to drive like that and see if it does the same thing that could tell ya sumtin, right?

 

[HotRodPC]

I don't believe his model will lock up in 3rd anyway. Some do and some don't but I am fairly certain it was the early 700r4's that did.

 

[CknightK10]

OK!!! Thanks HRPC, and I apologize for my absence. I have been computer-less for a bit there!! So here is some updates. Since the day my truck stalled I drive without OD on while im in town and only allow it to go into OD when I am on the highway. However my truck has been down for a few weeks because my intake manifold gasket started leaking so I just replaced it and just finished installing a new water pump (was seeping from the weep hole) tonight.. I installed a TB spacer and i do have a few questions about adjusting the TV cable that maybe you can help me with as well. Also if anybody knows If and how to do a idle learn procedure I could use some advise!!! Im not sure if or what I have to do for that.

Anyway, The truck is a 1985, but I have a 1992 TBI 5.7 swapped in. The engine itself is bone stock and it will shift down on its own without touching the gas or brake, but it will wait until I hit about 20mph.... It only stalled once. Shifts into OD at about 35mph which is normal, but lets say I am doing 35mph and I coast down to about 25mph then give it a little bit of gas to maintain 25mph. It stays in OD and lugs the engine very bad and will not downshift unless I give it about half throttle, but the second I let back off the gas it will somtimes shift back up into OD.

 

[89Suburban]

I can;t believe it shifts into OD at 35 mph. You sure your speedo is right?

 

[HotRodPC]

So another question, if its been converted to 92, is the speedo using a VSS or still a manual speedo cable? So its the ECM controlling lock up, not the older vac type lock up switch on the firewall.

Where is Pops, lets get his input on this too. I am more old school, he is more new school, so between the 2 of us, him and I usually do pretty well. POPS !!! Getcha Ass in here dude !!!

 

[CknightK10]

Well I always thought that the 700r was used up until the vortec in 95?? So i think it is the manual cable. No my speedo has not been re calibrated.... But I only have 33s so it is fairly accurate, about 5mph off at the most at lower speeds

 

[HotRodPC]

Ok, so you are probably still a manual speedo cable then. 700r4/4L60 is thru 92. 93 up is 4L60-E. So yes you still have the manual cable, and your speedo off a bit might be why you do get into OD a little early. I think 40 mph is about where OD will take over in right conditions. That is going to be decided by the governor rather than a VSS. If I understand right, you are throttle body, no carb. So is your throttle body the right geometry for the 700r4 TV cable? Should be if its 92. Then you want to make sure at full thottle, you are getting full pull on the TV cable. Look over this info, see if it makes any sense to you and can help you out. Good info here, but its a bit tough for everyone to follow. Some grasp it easily, so do not.
http://www.tciauto.com/Products/Instructions/instructions/gm_tv_cable_adjust.htm

 

[CknightK10]

I printed it out. haha Its coming out to the shop with me right now... Yes I had all the right geometry, I just had installed a throttle body spacer so It threw it off i think. i am gonna go adjust it now.

 

[oneluckypops]

Well well well!!!!
Sounds like you have alittle bit of a "custom" set up. That can be good and BAD especially when it comes to diagnostics.

The TV cable (throttle Valve) will cause a lot of shifting issues with a 700R4.
The TCC solenoid (Torque converter clutch) should NOT be applied in any gear other then 4th, even then it should NOT apply untill around 40-45 MPH.

You can easilly check the TCC solenoid but kind of need to know for sure what transmission you have. either way the ohms resistance should be 20-40 ohms@68 degrees. If we knew for sure what trans you have then I could tell you which wires and pin locations to check.

If you do have a VSS (vehichle speed sensor) they can cause shifting issues. But I doubt that is your problem.

I am almost leaning to you having an acutaul 4L60E, does your trans have a funny shaped black switch where the linkage comes out of the DS of the Trans?
If it is a 4L60E you could have a software problem,
the 60E is essentially the same as the 60 except it is controlled by the computer you should have a grey connecter with 13 wires on the PS of the case. If its a 60E
The switch on the DS that is Black that has 2 plug ins to it is NOT a shift solenoid it is the TR switch (Range selector) aka neutral safety switch. Been along time since I have had to mess with a trans. that is not electronic.

If your sure you have a TR Cable then it is NOT a 60E. when you swapped to TBI what did you do for electronics? as far as the Brake switch?

 

[HotRodPC]

Well well well, look who decided to pop in !!!

I already ruled out its an -E cuz he says he has TV cable. Here is the part I don't understand cuz of the conversion, is his lock-up controlled by ECM or the old style vac switch? Cuz even TBI ECM will control lock up on a 700r4.
That we need to know, but I have a feeling CK may not even know that since he didn't do the conversion.

 

[bucket]

My '88 700R4 will lock up in 3rd and 4th, as far as I know, that's how it's supposed to be.

 

[oneluckypops]

OK!!! Thanks HRPC, and I apologize for my absence. I have been computer-less for a bit there!! So here is some updates. Since the day my truck stalled I drive without OD on while im in town and only allow it to go into OD when I am on the highway. However my truck has been down for a few weeks because my intake manifold gasket started leaking so I just replaced it and just finished installing a new water pump (was seeping from the weep hole) tonight.. I installed a TB spacer and i do have a few questions about adjusting the TV cable that maybe you can help me with as well. Also if anybody knows If and how to do a idle learn procedure I could use some advise!!! Im not sure if or what I have to do for that.

Anyway, The truck is a 1985, but I have a 1992 TBI 5.7 swapped in. The engine itself is bone stock and it will shift down on its own without touching the gas or brake, but it will wait until I hit about 20mph.... It only stalled once. Shifts into OD at about 35mph which is normal, but lets say I am doing 35mph should be 40-45mph and I coast down to about 25mph then give it a little bit of gas to maintain 25mph. It stays in OD and lugs the engine very bad and will not downshift unless I give it about half throttle, but the second I let back off the gas it will somtimes shift back up into OD.

I re read this again. I suspect your cable is Mis adjusted reason in red But I would still check your TCC ohms you could have a few issues still guess well wait to see what you find

 

[HotRodPC]

OH, and I add, but from his discription, he has a speedo cable, if not mistaken, doesn't TBI need VSS to be able to contol TC LU??? Or No? That I am unsure of.

 

[HotRodPC]

I re read this again. I suspect your cable is Mis adjusted reason in red But I would still check your TCC ohms you could have a few issues still guess well wait to see what you find

And his may be delayed even longer since his speedo is lying and not accurate.