I have 3.1 V6 from a 91 auto car swapped into a car with a manual trans, and for the time being I need to trick the car into thinking it's in drive so it doesn't forget how to idle after driving in "park". I'm using the full automatic harness and ECU from the donor car and I can't find the wire that goes from the ECM to the gear select switch. My Haynes manual says it's an orange and black wire but the only orange and black wire coming off the ECU goes straight to the ALDL connector. Could anyone point me to the right place?

 

Iirc ground pin d16 of the ecm

 

Just curious did you change the calibration chip in the ecm ?

 

The PROM? Unfortunately no. Can't source seem to find one online for a manual and by the time I've bought all the stuff to burn one myself I could afford a microsquirt, so I'm just tryna to do what I can yo keep it idling somewhat stable until then.

 

I think I have a memcal or can program over your uv prom. Just a thought.

 

Or

https://ebay.us/m/Q4VQMS

 

Dude you're awesome! I must've spent an hour looking on ebay and couldn't find it lmao. Ordered it. Out of curiosity how does the ECU know if the manual trans is in neutral or not? My understanding is that these cars don't have a neutral safety switch, only a clutch switch that doesn't even communicate with the ECM?

 

On a manual with the proper calibration I don’t think you need to ground the p/n switch. The ecm knowns your moving because of Vss input. No p/n rpm adder.

 

I love this website. My car runs better today because of tips like this. Don't forget to give us an update after the new PROM.

 

Good to know but that does throw another wrench into the mix. The car used a speedo cable, which I didn't think would be an issue because I was just gonna mount a hall effect sensor behind the U-Joint on the rear axle so each of the 4 bolts would send a pulse each, but the hall sensors I have are 3 wire (Power, Signal, Ground) and from what I can find the ECU has 2 wires going to the VSS for "signal high" and "signal low". I'm far from being a sparky so I have no clue what that means or how I'd go about making a hall effect sensor communicate with the ECU properly...

 

The t5vss is hard to find and often expensive. The ecm is expecting a 4k ppm magnet pulse. You might see if jags that run have anything they can provide to help. Signals can be converted with Dakota digital sgi-100bt might read about what it’s capable of converting.

 

With the Vss loss you can get stalling on deceleration since the iac doesn’t know your moving .

 

Well the PROM arrived and she drives like a dream now. I still haven't figured out a VSS solution but the engine seems fine enough without it. The worst that happens if I press the clutch in while engine braking the revs will drop to a lil below idle and then go right back up, but that's really it. Starts smooth, drives smooth, shifts smooth, stops smooth. It does idle a little high but that's probably because I have the idle stop screw set in a little too far to compensate for the issues I had before, but I'm also afraid to touch it because I worry that setting the idle screw to spec will make the lack of VSS cause stalling. In any case, thanks for the help!

 

I would probably leave the stop screw alone until you get a Vss signal to the ecm. Glad to hear you got the right tune memcal.