capri debris

Can someone with cruise control and a vehicle speed sensor (mounted on the side of the tranny at the end of the speedo cable) check something for me?

There are two wires that are coming out of the VSS... one (+) and the other (-)

Can someone pull that plug and tell me if the (+)wire has 12 volts with the ignition key in the RUN position.

On my car, the wires from the VSS run up to a clip behind the gauges, then from that clip to a control module for the cruise.(mounted on the driver side kick panel area) My mass air conversion kit told me to run two wires from the computor to the two wires from the VSS. I have no power at either of the VSSwires and I think the control module they go to is junk. That would mean my computor isn't getting a signal from the inoperative VSS.

The white car I'm restoring is what I'm having this problem with. I fired the engine up this weekend and everything is OK except it has an irratic idle and I think the problem has to do with this dead VSS.

So, if someone can verify that one of the wires to the VSS is supposed to have 12 volts, then I can run a jumper wire to it and by-pass the bad control module and see if my idle smooths out. I just don't want to put 12 volts to the wire that goes to the computor and "fry" it if it'sNOT supposed to get 12 volts.

I hope someone will take the time to check this for me. Thanks in advance!!!

5.0stanger

I'll go look...hold on

5.0stanger

I got 3.8 volts on both wires. It make sense, the VSS is basically a generator, faster you go the more power it makes to let the ECM know how fast you are going. VSS wont cause a bad idle, I ran mine without one a little after my MAF conversion and the only problem I had was stalling when I was coming to a stop.

5.0stanger

I was just thinking...if this is the first time you started it, the ECM han't adapted tot he new parts yet. I would go out, un hook the battery for about 30 minutes, hook it back up, start you car with all accessories off, don't hit the gas and just let it sit there and Idle for 15 20 minutes and give it time to learn. Then after that you will have to drive it for about and hour total so it can learn it all. I would bet that is your only problem.

capri debris

Well, the 3.8 volts is actually coming from the wire that comes from the ECU. I tested them before I connected them to the VSS. The VSS had no power at either wire before I attached the wires coming from the ECU. The problem I have with my car is whenI fire it up, it will idle OK for about 10 seconds, then it will start surging up and down... like it almost stalls, then revs up... then almost stalls, then revs up...ect. It will do this for about a minuteuntil itfinally stalls. I can't check the timing because I can't get it to idle long enough to pull the spout. I have turned the dizzy back and forth while it's trying to idle to see if it smooths out... but nothing changes. I've checked and rechecked everything and the VSS is the only thing that I could find that may be a problem. No codes are showing up doing a key on engine off test. This is bugging the hell out of me. Anyone have any suggestions? I'm all ears. LOL.

Texas5.0

I went through a similar situation. it ended up being a leak in the lower intake. Idle was all over the place, died a lot. when I first started it it would idle fine... after a little bit the idle would start to surge up and down progressively getting worse until the car would finally crap out. I chased stuff for a long time. VSS AC wide open throttle relay... mass air, throttle body, TPS, fuel pressure, 02 senors, and on and on and on.... took the intake off and cleaned everything and put it back on and got it sealed.... no more idle issues at all.

capri debris

I thought about a vacuum leak, but everything on this engine is new. New upper and lower intake, TB, hoses, etc. All new gaskets were used too. Everything is tight and I can't see where anything would be leaking. I'm baffled.

ZachW04Stang

The vehicle speed sensor shouldn't be an issue at idle.

5.0stanger

Just try and give it some run time, it might smooth out on it's own.