Whats up guys I've got an issue with my wife 88 305 700R4 Iroc. So heres the story. Got the car for her in august 15'. Did a tuneup, new IAC, plug wires, fuel filter, air filter, new ignition coil. Recently I did wheel bearings in the front, new brake calipers and lines and put a rebuilt 700R4 & Converter from Fred Brown Transmissions in Bay Shore Long island. Everything was good until i did the brakes...on the way home I got a weird stumble. Car has good power, but if you drive it and get it too about 25mph then lets say slow down to brake and get back on it, it hesitates and stumbles and chugs till you step down on the throttle and then the rpms spikes and takes off. If you drive the car normal and accelerate its fine. I plugged in my snap on modis, I work as a marine technician i work on mercruisers and outboards and rebuild engines so I do this for a living, anyway I got a TPS code and a MAF code Low voltage, so I replaced the TPS and its in range and replaced the MAF, MAF burn off and a new MAF sensor. clear codes road tested and same crap. I now have no codes. I checked fuel psi and got 35-36PSI idle and goes up to around 43-44 driving even with the stumble too. Im kind of stumped and she needs it to get to work. Car also has new heated 3 wire ac delco o2 sensor, installed when i did the headers. Im hoping this isn't a trans problem. Weird thing is after disconnecting the battery, and reconnecting the trans wouldnt shift out of 1st. Shut it down and restarted and it was fine..idk what that was about. I feel a slight slight miss at idle but this problem is only at low rpm letting off the gas and trying to get back on it lightly. Im going to clean the throttle plates tommorow and see if it helps. Timing is at 6* at idle, car idles smooth, i just feel a slight miss but thats me so **** about things. What do you guys think? Thanks ---Mike

 

Hi Mike ,

I'm 101 % certain that there is no electrical/electronic involvement whatsoever with the shifting of a 700R4 from 1st to 4th gears that could be "reset" or otherwise affected by disconnecting the battery . The ONLY electrical devices in our transmission are the solenoid that locks up the torque converter clutch and a pressure switch that tells the ECM that the transmission is in 4th gear (so that the ECM can know when to apply the lockup) . Those two items , and an electric VSS to tell the ECM (and the speedometer) the car's road speed (won't engage lockup under 45 MPH) are all that are in there . If your car would not come out of 1st I would STRONGLY recommend that you search out the procedure for properly setting the "TVC" (Throttle Valve Cable) tension . You will find in your reading that this is MUCH more than just a "kickdown" cable as lots of folks think , it actually does things like varies transmission fluid "line pressure" and shift points and if it's not working properly transmission damage is certain if it's driven too long .

If your curious about what each and every part of our 700R4 looks like inside , go the the sticky threads at the top of the transmission subforum here and look at my "pictures of every part of a 700R4" thread . There you will see the lockup solenoid and the 4th gear switch as well as all the rest of it .

 

I adjusted the TV cable, its tight an is in full range with the accelerator @ WOT. The cable is in good shape. Im assuming maybe the lockup solenoid possibly stayed engaged in first and it wouldnt come out? Trans shifts great if you drive the car and get on it. The injectors are the original injectors as well. The Front driver side caliper was sticking and after i replaced that this problem arose. I'm thinking maybe along the lines of a sticking or low flowing fuel injector. Like I said I feel a very slight miss, maybe the injectors are not flowing enough @ idle per say and when i jump on it i get enough fuel to drive the car? I don't wanna pull the transmission again its a PITA.


When it was in first it would stay in first gear and felt like the convertor was locked up, so maybe it was an electrical issue for that split second idk.

 

Oh btw before i forget, the old transmission had a pressure switch on the side of it and under the steering wheel there was a toggle switch. the trans shop said to not hook this up so i just tie wraped the wire and put some heat shrink around the connectors.... I dont know if this has any thing to do with it...??? but i did that 3 weeks ago and the car was driving fine so idk kinda wierd


I want to say the feeling is a lugging of the engine, Either A Low Power/Fuel Injection Issue or B Torque Convertor is locking up in 2nd, feels like when u get on the Go pedal it unlocks....

 

UPDATE, figured it out was the damn switch the previous owner installed and it was flipped to lock the converter. All is good now thanks. Still going to do those injectors anyway bc there 28 yrs old! lol