4+3 issues, what a suprise this is

[Oldskool153]

Last month I posted a thread on here about my 4+3 the wouldnt come out of OD, i took it to my local corvette shop (Corvette Paramedics, very reputable shop been there over 25 years, all the chevy dealers in the area go to these guys with their questions) anyway, they changed my tps and my OD worked as it should (my switch on the shiftknob hasnt worked from day one, but atleast now the computer was wokring correctly) that lasted about 2 weeks than i started getting erratic shifting engaged in 2cd but not in 3rd, engaged in 3rd but not in 2cd, sometimes engaged in 4th, sometimes not engaged in 4th, ect... anyway I took it there today and they iinformed me that alot of people just disconnect the OD unit but unplugging the groundwire and that i can simply use it as a 4spd...I had them do that and so far I love the way it shifts and I enjoy the car much better with out worrying about the OD working properly or not.. my question is, is driving it as a 4spd bad for the transmission? one person told me it was but everyone including the owner at Corvette Paramedics told me they have been doing it for years with no complaints and the tech told me that it isnt bad for the trans at all.. so i was just simply wondering if i can drive it as a 4spd with now with worries?

 

[vetteoz]

"my OD worked as it should "
Your other post stated that it would not disengage O/d ; are you saying it was now dropping out of O/d on accel / decel ?
That would suggest the O/d itself is fine and you have a control problem

Did they check / replace the O/d relay ,the connector at relay; know problem areas?

I don't see why you can't drive without the O/d but if it is a ECM control problem you can't overcome then you can just wire a manual switch and operate it when you want without any input from the ECM.
As a note if you had TPS problems, the O/d would be the least of your problems; car would be running like *&^%@ in limp home mode.
TPS is one of the essential sensors for engine operation.

 

[Oldskool153]

well at 1st it wouldnt disengage from OD at all, they did a check and it came back as my TPS (car was running ok but idleing alil too fast) they changed my tps and the trans OD was engaging and disengaging as it should have been (again by itself because my switch doesnt work) I drove it that way for 2 weeks (maybe 350 miles if that) and i started getting irratic shifts in and out of OD at the obvious wrong times...for example I would be at a stop light and shift from 1st to 2cd at maybe 15mph the ODlight would come on in 2cd, than at 30mph when I would shift into 3rd the light would go out..and not come on again until I recycled it by comming to another light.. sometimes when slowing down in 3rd it would just pop out of OD.. so i took it back and he said its now giving an 02sensor code and an MAF code (no check engine lights tho)..he said those could cause the trans to act irraticly due to breaking the closed cirrcut..anyway rather than spending $ to fix it and even if i did have it fixed who knows when something else would go wrong with it? (i have lost enough sleep worrying about the OD) I simply had them dissconect it and now im using it as a four speed..they all say its not bad for it and i trust there reputable opnion, i just wanted to double check with all of you guys on here

 

[DPC Racing]

Driving without the od really won't hurt anything but you will miss it on the hwy.I would hook up a manual switch like vetteoz said and just use it on the hwy.The TPS out of adj on the 86 will make the trans act funny[4+3] good luck with it I hope I helped.

 

[Oldskool153]

thanks btw mines an 88, lol but anyway luckly I dont drive the car much so fuel economy isnt a huge issue for me, i have a company car so i use the vett on weekends when its nice out..thanks for the advice I may check out that relay or relay connector, but at the same time if i get it working properly again, im gonna be paranoid as to what will go wrong next..as for right now it feels nice to have a 4sp and not worry about it lol

 

[tequilaboy]

I responded to your earlier posts on one of the other forums. Since you car's behavior doesn't fit into the normal patterns. I'm really curious as to what could be wrong.

What we know:
Erratic behavior
No response from shifter switch

Both conditions cannot be explained by a single failure, unless the shifter switch wiring is damaged and the switch is randomly shorting, causing the O/D to be turned on and off in a random fashion.

So you have a faulty shifter switch or related wiring and another failure to the tps, rpm or vehicle speed signal, relay, solenoid or pressure switch or related wiring.

The other possibility is that you have the wrong chip or a modifed chip in the ecm resulting in the strange control.

An 86 4+3 chip would result in strange 4+3 behavior and would not respond to the shifter switch, since the shifter switch and 87-88 first gear switch wiring is reversed.

An 89 6 speed chip would also result in strange behavior due to the CAGS control logic instead of the 4+3 control logic. It wouldn't respond to the shifter switch or downshift as expected, but could upshift once on the 1-2 shift. The cags signal is output on the same ecm pin as the 4+3 clutch or tcc.

One of these days I'll try an 89 six speed chip in my 88 4+3 just to see what happens.

I still think that this is a possibility that you have the wrong chip.

Check the shifter switch and wiring to the ecm first.

If that checks out, try and verify that you indeed have an 88 4+3 memcal in the ecm.

Good luck.

 

[Oldskool153]

lol im curious as to why its acting the way it is too...but if one of those things was a factor (i.e the wrong chip) then why would the tps solve the problem for two weeks? when they changed the tps the trans was working as it should (again except for the shifter switch) for about two weeks. I think that im done worrying about this problem and gonna call it a day and stick with using it as a 4spd, although its a shame because its gotta be somthing stupid if its working sometimes that means the OD itself is working, just some type of glitch somewhere, but not worth pulling my hair out over lol.. thanks again