84 T-Type surge at cruise below 45 mph

[MoeJr]

I just wanted to get some fresh ideas. I am still trying to figure out this car's surging at cruising under 45 mph. I have gone thru all the setting and everything is reading as it should. IAC is 26 at hot idle and tps is .42. TPS is brand new and IAC is functioning as it should according to my scan tool(snap on modis).

I just went out and tried to eliminate the coil pack. I ohmed all the towers and they all read 11.1k. I warmed the car up and put it in drive and held the brake tight. I ran it up against the brake to see if the coil pack would start breaking down but it was totally smooth no hiccups. I put my hand at the tailpipe and the air coming out was smooth as could be.

This all makes me lean towards the TC lock up solenoid. Is it possible that it could get stuck half way? Once over 45 and the TC locks completely it runs nice and smooth. From a stop, give it a bit of pedal it runs fine. It is when I try to take off normally or I am cruising under 45 that you can feel it. It really baffles me. I have tried even dropping the tranny into 1 and shifting it myself and it still shows the same symptoms.

Any ideas are greatly appreciated.

Moe

 

[84GNGary]

When the TCC solenoid acts up it keeps the torque converter locked up when it should be released. The problem I experienced was after driving at
45+ mph for a while then stop when you start out again it feels like you are in 4th gear and it stalled out sometimes too. Usually the TCC dosen't act up until everything is hot and been driving over 45 for a while. So if the surge you feel does it when the car is cold most likely its not the TCC solenoid. You could also try unplugging it, it's the round 4 wire plug on the drivers side of the tranny then see if it stops.
TH200-4R TCC Solenoid Transmission Problem

 

[MoeJr]

Gary you make excellent points. That's what has me baffled. I know what the cars do when the TC is stuck locked as I had to repair a few when My Dad and I had our shop. This one seems like it is stuck where it doesn't fully unlock yet it locks up just after 45. This car doesn't not try and stall nor does it act like it is in 4th gear when I stop and take off. I am gonna have to think it is in the Trans somewhere. It is raining/snowing here and I warmed the car up and like I said held the brake and rolled the throttle on and that engine didn't miss a beat. That's why I have kinda ruled out it being engine related. I do have a request in for a used ecm. Hopefully the guy contacts me and still has it. This really has me baffled. All my sensor reading are where they are supposed to be.

This thread here has the info from when i did a road test with the scan tool hooked up.

http://www.turbobuick.com/forums/transmission-talk/213149-transmission-tc-lock-up-sequence.html

Moe

 

[forcefed3.8's]

Unplug the TCC and see if it goes away. If not the TCC, a bad EGR valve or EGR solenoid will make a car feel sluggish at slow speeds.

 

[MoeJr]

Can you unplug the egr or egr solenoid to see if one of them is bad? I'll disconnect the TCC switch as soon as I can get under the car.

 

[MoeJr]

I disconnected the TCC plug on the side of the Trans. I disconnected it before I even started the car. I let the car run a couple minutes and took off. It seemed to be running great. Once it got fully warm it started the surging feeling again. I then stopped and put my foot on the brake and gave it gas to see if it was the coil breaking down when warm. It was smooth as silk so it only does it when driving. I checked EGR. The diaphragm move up and down easily and is not too easy it is firm like it should be. I did however pull the hose off the egr and tried it but still the same. Not sure where to go next.

 

[MoeJr]

Another quick update. I went thru my Motor Manual and attached a vacuum pump to the egr. Got it idling and then pumped 10" vacuum to it and car stumbled which according to the book means the egr is working. Keep the ideas coming. Even though I am selling it as it sits if I can figure this out it would help to be able to tell the buyer what they have to do to fix it.

 

[grnadnasty84]

I don't mean to steal your thread but i believe my tcc solenoid is burnt up and this seemed like the best place to ask if i'm about to spend too much money. I went out a bought a tcc solenoid today and drove around trying to find a shop to put it since I don't have any tools down here at school. I finally found one that was willing to put it in for a $100. Does that sound reasonable?

 

[MoeJr]

100.00 isn't bad. Takes about an hour to do according to my labor guides.

 

[grnadnasty84]

thanks for the feedback.