Ggbluesman

I can't disengage the OD with the button on the shifter. But, this may sound crazy , it seems the OD is active every other time I start the car. One time I have no OD, the next start I do. The shifter switch makes no difference. What up wit dat.

tequilaboy

Sorry, I didn't see which year car.

Is your car chipped to disable od by default?

If so this can lead to the on again off again ign cycle routine. I have my 88 4+3 od off by default via the tunercat method, which prevents a few bits from being set at start-up to activate od. This is not a perfect solution.

Here is the behavior that I see:

On the first start-up, od is off like it should be. If I happen to stall and restart without keying off for some time first, the od will be active for the 2nd ignition cycle.

This has been happening alot lately as I am still sorting out my idle due to a recent superram installation. Somehow the bit setting/clearing is not happening on the 2nd start. Does this fit with what you are seeing?

Also, If I hit a big bump and my eprom rattles around in the ZIF-socket I have installed on my memcal, od will reactivate, when previously off. It Can be annoying. The ZIF socket will be removed once I get a more stable tune worked out. This shouldn't happen with a stock memcal, but you never know. One more thing to consider.

It should still respond to switch input, otherwise you may have a problem with your switch/wiring etc.

redrose

psychotic activity of the ecm gives the 4+3 its bad rep... i swore at mine hundreds of times..did a lobotomy on mine and now its a great piece...slight variations year to ear on how to go to full manual control...say your year if you want to try it

tequilaboy

Redrose,

for full manual control, I assume you are tricking the ecm to believe the car is still in first gear, other than ecm programming.

Does 86 have a first gear switch, or did you add one, or have you come up with another hardware/wiring method? Interested in your approach.

GRX

redrose

mines an 86, cant remember if it has 1st switch or not , been a while since i've been under mine, but i did everything topside anyway...
first time i cut the ecm feed (actually its a ground) to the od relay and used an 84 m/t console to add a switch to prevent the ecm from prematurely (in my opinion) engaging the od ...that sorta works but full throttle kickdown, no od response for weird (but programmed) reasons,etc still was not satisfactory ...so...
second try- pulled the ecm ground feed wire(same wire as first try) and the wire that feeds to the pushbutton on the shifter(both) from the ecm connector, hooked em together (solder would be better but is permanent) and taped em....shifter pushbutton on 86 (not all years are same) pushes rod to momentary switch for ecm signal only, bypass needs full time on/off, i found just the right little pushbutton switch in my electrical junk box, i think its from the overhead courtesy lites on early 90's grand-am...tiny bit of fabrication to replace the momentary oem switch at the base of the shift lever with the on/off....second try cuts ecm out entirely, now have eight forward gears, no jump/kickdown in/out when passing (that kickdown in/out is murder on the od friction plates--always use the clutch)...you'll forget once to switch the od off at a standing start

c4cruiser

One of the things that controls OD operation is coolant temp. The OD is normally "off" until the coolant temp reaches a certain level. When the ignition switch is cycled after the temp reaches a point where the OD will work, the OD should default to "on"

Check out this link for how the different years of the 4+3 OD operates:
http://www.5speeds.com/43table.htm

Ggbluesman

Thanks for the replies. I've an '88 and I need to get up to speed on this condition and the suggested solutions. I'm going to read all the replies a few more times....maybe it will sink in.
But until then, bottom line, what should I do. I would like to be able to engage the OD when I want it.

GRX

First, check to see if previous owners have modded the circuit design. Check the circuit against a factory manual. Check if the OD filter is clean. Check that the OD relay is performing ok. Check if the OD switch is ok. Check to see if any previous owner has modified the ECM programming. Check to see that the kickdown cable is adjusted correctly and not binding. Lastly, and I've never fiddled with it; check to see that the OD solenoid is working correctly.